XI. LITERATURE AND HISTORY (part 2 of 5)

XI. LITERATURE AND HISTORY (part 2 of 5)

Cortical shell spherical, covered with short conical by-spines, twice as broad as the medullary shell; both with regular circular pores three to four times as broad as the bars. Two major spines cylindrical, with conical apex, three times as long as the four others, which are conical and about as long as the shell radius; basal breadth of all six the same (equal to one pore). Similar to Hexalonche anaximenis (Pl. 25, fig. 5), but distinct in the enormous prolongation of two opposite spines.

Dimensions.--Diameter of the outer shell 0.12, inner 0.06; length of the two major spines 0.2, of the four minor 0.06, basal breadth 0.02.

Habitat.--Central Pacific, Station 267, depth 2700 fathoms.

{191}3. Hexaloncharium hystricinum, n. sp.

Cortical shell spherical, three times as broad as the medullary shell, and densely covered with oblique bristle-shaped by-spines. Pores irregular roundish. Two opposite major spines three-sided prismatic, longer than the shell diameter; four minor spines pyramidal, scarcely half as long as the shell radius. (Somewhat similar to Hexalonche hystricina, but distinct in the prolongation of two major spines.)

Dimensions.--Diameter of the outer shell 0.15, inner 0.05; length of the two major spines 0.2, four minor 0.03, basal breadth 0.02.

Habitat.--South Pacific, Station 288, surface.

Genus 78. Hexalonchidium,[108] Haeckel, 1881, Prodromus, p. 451.

Definition.--#Cubosphærida# with two concentric lattice-spheres and six simple spines of different sizes in pairs; the two opposite spines of each pair equal, the three pairs unequal.

The genus Hexalonchidium exhibits the same relation to Hexalonche that Hexastylidium bears to Hexastylus; the growth of the three spine-pairs is different, whilst both spines of each pair are equal; they correspond therefore to the three axes of a rhombic crystal.

1. Hexalonchidium axonometrum, n. sp.

Cortical shell thin walled, covered with short bristle-shaped by-spines, twice as broad as the medullary shell; both with regular hexagonal meshes, twice to three times as broad as the bars (inner meshes half as broad as the outer). All three spine-pairs three-sided prismatic, of very different length but of equal breadth (equal to three pores). Major spine-pair twice as long as the shell diameter; middle pair about equal to the latter, minor scarcely half as long. (Similar to Hexalonche anaximandri, Pl. 22, fig. 5, but distinct in the different length of the spines.)

Dimensions.--Diameter of the outer shell 0.12, inner 0.06; length of the major spines 0.25, middle 0.1, minor 0.04.

Habitat.--Indian Ocean, Madagascar, surface, Rabbe.

Subfamily HEXACONTIDA,[109] Haeckel, 1881, Prodromus, pp. 449, 452.

Definition.--#Cubosphærida# with three concentric, spherical, or octahedral lattice-shells.

{192}Genus 79. Hexacontium, Haeckel,[110] 1881, Prodromus, p. 452.

Definition.--Shell with three concentric lattice-spheres and six simple spines of equal size.

The genus Hexacontium, the ancestral form of the Hexacontida, is probably derived from Hexalonche by duplication of the medullary shell. As in the latter, all six spines are of equal size, opposite in pairs in the three dimensive axes, and correspond therefore to the three equal axes of a tesseral crystal.

Subgenus 1. Hexacontanna, Haeckel.

Definition.--Pores of the cortical shell regular or subregular, of nearly equal size and similar form; surface smooth, without radial spines or papillæ (other than the six main spines).

1. Hexacontium phænaxonium, n. sp.

Cortical shell thin walled, smooth; its pores regular hexagonal, six to nine times as broad as the bars; twelve to sixteen on the radius. Radial proportion of the three spheres = 1 : 2 : 4. Both medullary shells of the same structure as the cortical shell, only with smaller pores. The three spheres connected by six thin radial beams, which are prolonged on the outside into six strong triangular pyramidal spines, as long as the radius of the cortical shell, and, at the base, as broad as one of its pores. (Differs from Hexastylus phænaxonius and from Hexalonche phænaxonia, Pl. 21, fig. 3, in the larger size and the triple shell.)

Dimensions.--Diameter of the outer sphere 0.2, middle 0.1, inner 0.05; cortical pores 0.008, bars 0.0012; length of the spines 0.1.

Habitat.--Central Pacific, Station 270, surface.

2. Hexacontium axotrias, n. sp. (Pl. 24, fig. 3).

Cortical shell thin walled, smooth; its pores regular circular, five to six times as broad as the bars; eleven to thirteen on the radius. Radial proportion of the three spheres = 1 : 3 : 8. Outer medullary shell with hexagonal frames around the regular circular pores (five to six on the radius). Inner medullary shell with simple small circular pores (three on the radius). The two outer shells connected by six triangular prismatic beams, which are prolonged outside to the length of the cortical radius or more.

Dimensions.--Diameter of the outer sphere 0.2, middle 0.07, inner 0.025; cortical pores 0.016, bars 0.003; length of the spines 0.1 to 0.015, basal breadth 0.02.

Habitat.--North Pacific, Station 253, surface.

3. Hexacontium hexactis, Haeckel.

Actinomma hexactis, Stöhr, 1880, Palæontogr., vol. xxvi. p. 91, Taf. ii. fig. 7.

Cortical shell thick walled, smooth, or a little rough. Pores regular circular, of the same breadth as the bars; five to seven on the radius. Radial proportion of the three spheres {193}= 1 : 3 : 6. Both medullary shells of the same structure, but with smaller pores. Six spines triangular pyramidal, nearly as long as the diameter of the outer shell, three times as broad at the base as one pore.

Dimensions.--Diameter of the outer sphere 0.1, middle 0.05, inner 0.016; cortical pores and bars 0.008; length of the spines 0.08, basal breadth 0.025.

Habitat.--Fossil in Tertiary rocks of Sicily, Grotte, Stöhr.

4. Hexacontium lævigatum, n. sp. (Pl. 24, fig. 6).

Cortical shell thick walled, quite smooth. Pores regular circular, with double margins, eight to ten on the radius, of the same breadth as the smooth bars. Radial proportion of the three spheres = 1 : 2 : 6. All three spheres connected by six very thin radial beams, which are prolonged outside into six short, stout, triangular, pyramidal spines, half as long as the radius of the outer shell.

Dimensions.--Diameter of the outer shell 0.13, middle 0.04, inner 0.02; cortical pores and bars 0.008; length of the spines 0.04, basal breadth 0.02.

Habitat.--South Atlantic, Station 332, depth 2200 fathoms.

5. Hexacontium triplosphærium, n. sp.

Cortical shell thick walled, smooth. Pores regular circular, three times as broad as the bars; ten to twelve on the radius. Radial proportion of the three spheres = 1 : 3 : 10. Six spines conical, about as long as the radius of the cortical shell.

Dimensions.--Diameter of the outer shell 0.16, middle 0.05, inner 0.016; cortical pores 0.012, bars 0.004; length of the spines 0.07, basal breadth 0.02.

Habitat.--Central Pacific, Station 268, depth 2900 fathoms.

6. Hexacontium octahedrum, n. sp.

Cortical shell a regular octahedron, thin walled, with twelve more or less rounded edges (between the spine-bases) and with smooth surface; its pores regular circular, five to seven on the radius, four times as broad as the bars. Radial proportion of the three shells = 1 : 3 : 9. Both medullary shells spherical, with very small circular pores. Six inner bars very thin; six outer spines (their prolongations) triangular pyramidal, as long as the radius of the outer shell. (Differs from Hexalonche octahedra, Pl. 22, fig. 8, almost solely in the duplication of the medullary shell.)

Dimensions.--Diameter of the outer shell 0.12, middle 0.04, inner 0.013.

Habitat.--Central Pacific, Station 271, depth 2425 fathoms.

7. Hexacontium circumtextum, n. sp. (Pl. 25, figs. 7, 7_a_).

Cortical shell double, enclosing a simple medullary shell. Radial proportion of the three spheres = 3 : 10 : 12. Inner cortical shell very thick walled, with regular circular, double-edged pores, four times as broad as the bars; seven to nine on the radius. From each nodal-point between {194}every six pores arises a small, bristle-shaped, radial spine, as long as the diameter of one pore. The distal ends of all these spines are connected by very delicate tangential threads, and consequently form by their attachment an outer cortical shell, with regular hexagonal meshes and smooth surface. Six main spines short, three-sided prismatic, scarcely as long as half the radius of the outer shell.

Dimensions.--Diameter of the outer shell 0.12, middle 0.1, inner 0.03; pores of the middle shell 0.004, bars 0.001; length of the spines 0.025, basal breadth 0.01.

Habitat.--Central Pacific, Station 274, depth 2750 fathoms.

Subgenus 2. Hexacontella, Haeckel.

Definition.--Pores of the cortical shell regular or subregular, of nearly equal size and similar form; surface covered with numerous conical or bristle-shaped, radial spines (other than the six main spines).

8. Hexacontium hexagonale, n. sp.

Cortical shell thin walled, bristly, with very delicate network; its pores regular hexagonal, twelve to sixteen on the radius, ten to twelve times as broad as the thin thread-like bars. At each nodal-point of the network (between every three meshes) arises a bristle-shaped, radial spine, as long as the diameter of one mesh. Six main spines hexagonal, as long as the radius of the outer shell, as broad at its base as one mesh. Radial proportion of the three spheres = 1 : 2 : 4. Pores of both medullary shells also regular hexagonal, but much smaller, in the middle shell eleven to twelve, in the inner, six to seven on the half meridian.

Dimensions.--Diameter of the outer shell 0.12, of the middle 0.06, of the inner 0.03; meshes of the outer shell 0.008; length of the six spines 0.05, basal thickness 0.008.

Habitat.--Indian Ocean, Ceylon, surface, Haeckel.

9. Hexacontium favosum, n. sp. (Pl. 24, figs. 2, 2_a_).

Cortical shell very thick walled, spiny, with regular, honeycomb-like network; its meshes funnel-shaped, with circular inner, hexagonal outer aperture, twice as broad as the bars; five to seven on the radius. Between every three meshes (at each corner of the hexagon) arises a short radial thorn, not so long as the thickness of the shell-wall. Six radial spines very short and stout, three-sided pyramidal, scarcely half so long as the radius of the outer shell. Radial proportion of the three spheres = 1 : 2 : 5. Pores of both medullary shells regular, circular, about as broad as the bars, six to eight on the half meridian.

Dimensions.--Diameter of the outer shell 0.1 to 0.12, of the middle 0.04 to 0.05, of the inner 0.02; meshes of the outer shell 0.008; length of the six spines 0.2 to 0.3, basal breadth 0.015.

Habitat.--Central Pacific, Station 265, depth 2900 fathoms.

10. Hexacontium sceptrum, n. sp. (Pl. 24, figs. 1, 1_a_).

Cortical shell thick walled, spiny, with regular, honeycomb-like network; its meshes funnel-shaped, with circular inner, hexagonal outer aperture, three to four times as broad as the bars; {195}five to six on the radius. Between every three meshes arises a short radial thorn, as long as the thickness of the shell-wall. Six radial spines sceptre-shaped, six-sided, somewhat constricted towards their middle part, strong, as long as the radius of the outer shell, as broad as one of its meshes. Radial proportion of the three spheres = 1 : 2 : 6. Pores of the two inner shells regular hexagonal, with thin bars, six to eight on the half meridian (fig. 1_a_).

Dimensions.--Diameter of the outer shell 0.13, of the middle 0.04, of the inner 0.02; pores of the outer shell 0.01, of the middle 0.008, of the inner 0.004; length of the six spines 0.06, basal breadth 0.015.

Habitat.--Equatorial Atlantic, Station 347, surface.

11. Hexacontium prionacanthum, n. sp. (Pl. 24, figs. 7, 7_a_).

Cortical shell thick walled, thorny; its pores regular circular, with elevated hexagonal frames six to nine on the radius, twice as broad as the crest-shaped bars. At each nodal-point of the hexagon arises one short conical papilla or thorn. Radial proportion of the three spheres = 1 : 3 : 10. Pores of both medullary shells much smaller, regular circular. Six main spines three-sided prismatic, longer than the radius of the outer shell, as broad as one of its meshes; their three edges serrated, with ten to twelve teeth.

Dimensions.--Diameter of the outer shell 0.15, middle 0.045, inner 0.015; cortical pores 0.01, bars 0.005; length of the spines 0.1, breadth 0.012.

Habitat.--West Tropical Pacific, Station 225, depth 4475 fathoms.

12. Hexacontium clavigerum, n. sp. (Pl. 23, fig. 5).

Cortical shell very thick walled, thorny; its pores regular circular, hexagonally framed, three times as broad as the bars, nine to twelve on the radius; between them short conical papillæ or thorns arising at the nodal-points. Radial proportion of the three spheres = 1 : 2 : 5. Outer medullary shell with regular circular, much smaller pores; connected with the cortical shell by numerous (twenty to thirty) thin radial beams. Six main spines very stout, club-shaped, scarcely as long as the radius of the outer shell, three times as broad as one of its pores, three-sided, with three to four teeth on each edge.

Dimensions.--Diameter of the outer shell 0.2, of the middle 0.08, of the inner 0.04; cortical pores 0.012, bars 0.004; length of the six spines 0.08, breadth 0.03.

Habitat.--South Atlantic, Station 332, depth 2200 fathoms.

13. Hexacontium floridum, n. sp. (Pl. 24, fig. 4).

Cortical shell papillose, thick walled. Pores regular, six-lobed, four times as broad as the bars, five to seven on the radius; each pore with six (sometimes also five or seven) concave indentations or lobules; between the pores at the nodal-points arise short conical papillæ or thorns. Radial proportion of the three spheres = 1 : 2 : 3. Radial main spines pommel-shaped, three-sided prismatic, longer than the radius of the outer shell, two to three times as broad as one pore.

{196}Dimensions.--Diameter of the outer shell 0.12, middle 0.06, inner 0.03; cortical pores 0.012, bars 0.003; length of the six spines 0.08, breadth 0.03.

Habitat.--Central Pacific, Station 266, depth 2750 fathoms.

14. Hexacontium hexaconicum, n. sp.

Cortical shell spiny, thick walled. Pores regular circular, of the same breadth as the bars, ten to twelve on the radius; between them long bristle-shaped by-spines, half as long as the six main spines. Radial proportion of the three spheres = 1 : 3 : 9. Six main spines conical, as long as the radius of the outer shell, four times as broad at the base as one pore.

Dimensions.--Diameter of the outer shell 0.18, middle 0.06, inner 0.02; cortical pores and bars 0.005; length of the spines 0.1, basal breadth 0.02.

Habitat.--Antarctic Sea, Station 157, depth 1950 fathoms.

15. Hexacontium asteracanthion, Haeckel.

Haliomma asteracanthion, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 816.

Actinomma asteracanthion, Haeckel, 1862, Monogr. d. Radiol., p. 441, Taf. xxiii. figs. 5, 6.

Cortical shell thin walled, spiny; its pores circular, without hexagonal frame (as a rule very regular, but in other specimens more or less irregular), often very variable in size, three to six times as broad as the bars, commonly seven to eight on the radius. Radial proportion of the three spheres = 1 : 2 : 4, or sometimes 1 : 3 : 8. Pores of the two inner shells also circular, but much smaller; those of the middle shell about half as broad, those of the inner shell one-fourth to one-sixth as broad as the pores of the outer shell. Six radial spines strong, three-sided prismatic, about as long as (or somewhat longer than) the radius of the outer shell, as broad as one of its large meshes. Accessory spines very numerous and very thin, bristle-like, usually half as long as the six main spines. (For the variability of this common species compare my Monograph, p. 442.)

Dimensions.--Diameter of the outer shell 0.1 to 0.12, of the middle 0.04 to 0.06, of the inner 0.02 to 0.03; cortical pores 0.005 to 0.01; length of the six spines 0.06 to 0.08.

Habitat.--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.

Subgenus 3. Hexacontosa, Haeckel.

Definition.--Pores of the cortical shell irregular, of different size or form; surface smooth, without radial by-spines or papillæ (other than the six main spines).

16. Hexacontium axophænum, n. sp.

Cortical shell thin walled, smooth. Pores irregular polygonal, three to nine times as broad as the bars; seven to ten on the radius. Radial proportion of the three spheres = 1 : 3 : 8. Both {197}medullary shells with smaller, irregular roundish pores. Six spines three-sided pyramidal, longer than the radius of the outer shell, one to two times as broad as one larger pore.

Dimensions.--Diameter of the outer shell 0.12, middle 0.045, inner 0.015; cortical pores 0.006 to 0.018, bars 0.002; length of the spines 0.06 to 0.12, basal breadth 0.02 to 0.03.

Habitat.--Central Pacific, Stations 266 to 272, at various depths.

17. Hexacontium polygonale, n. sp.

Cortical shell thick walled, smooth. Pores irregular roundish, with polygonal frames, two to four times as broad as the bars; eight to twelve on the radius. Radial proportion of the three spheres = 1 : 3 : 10. Six spines pyramidal, nearly as long as the diameter of the outer shell, with six to nine prominent edges (along the corner number of the polygonal meshes).

Dimensions.--Diameter of the outer shell 0.2, middle 0.06, inner 0.02; cortical pores 0.008 to 0.016, bars 0.004; length of the spines 0.16 to 0.18, basal breadth 0.02.

Habitat.--South Pacific, Station 295, depth 1500 fathoms.

18. Hexacontium antarcticum, n. sp.

Cortical shell thin walled, smooth, with irregular roundish pores, eight to ten on the radius, two to four times as broad as the bars. Radial proportion of the three spheres = 1 : 3 : 9. Both medullary shells with smaller roundish irregular pores. Six spines conical, pyramidal at their origin, about as long as the radius, as broad as one larger mesh.

Dimensions.--Diameter of the outer shell 0.18, middle 0.06, inner 0.02; cortical pores 0.006 to 0.012, bars 0.003; length of the spines 0.1, basal breadth 0.12.

Habitat.--Antarctic Ocean, Station 157, depth 1950 fathoms.

Subgenus 4. Hexacontura, Haeckel.

Definition.--Pores of the cortical shell irregular, of different size or form; surface covered with numerous conical papillæ or bristle-shaped, radial by-spines (other than the six main spines).

19. Hexacontium papillosum, n. sp. (Pl. 24, fig. 5).

Cortical shell thick walled, papillose. Pores irregular roundish, often somewhat lobed, five to six on the radius, two to four times as broad as the bars. Radial proportion of the three spheres = 1 : 2.5 : 5. Both medullary shells with subregular circular pores (inner much smaller). Six radial spines short and stout, pommel or club shaped, with three prominent wings, about as long as the shell radius, and as broad as the medullary shell.

Dimensions.--Diameter of the outer shell 0.1, middle 0.05, inner 0.02, cortical pores 0.006 to 0.012, bars 0.003; length of the spines 0.05, bars 0.02.

Habitat.--Central Pacific, Stations 266 to 272, at various depths.

{198}20. Hexacontium gladiatum, n. sp. (Pl. 25, fig. 8).

Cortical shell very thick walled, spiny, with irregular network; its meshes roundish, two to five times as broad as the bars, of very different size, ten to fifteen on the half meridian. Bars between them very strong, three-sided prismatic, armed with a great number of small thorns, and with large spines at the nodal-points between every three meshes. Radial proportion of the three spheres = 1 : 3 : 12. Six strong radial main spines three-sided prismatic, with three prominent, somewhat contorted wings, acute, broader than the diameter of the inner shell and as long as the diameter of the outer shell. These six main spines are situated in the same three dimensive axes as the six thin radial beams connecting the two medullary shells. But the six radial beams which connect the middle with the outer shell alternate with the former and lie in three other dimensive axes,--a very rare and remarkable disposition.

Dimensions.--Diameter of the outer shell 0.2, middle 0.05, inner 0.016; cortical pores 0.01 to 0.03, bars 0.006; length of the six spines 0.2, breadth 0.02 to 0.03.

Habitat.--Tropical Atlantic, Station 342, depth 1445 fathoms.

21. Hexacontium setosum, n. sp.

Cortical shell thin walled, with numerous bristle-shaped, simple, radial by-spines of variable length. Pores irregular roundish, five to seven on the radius, two to eight times as broad as the bars. Radial proportion of the three spheres = 1 : 3 : 9. Main spines three-sided pyramidal, as long as the radius.

Dimensions.--Diameter of the outer shell 0.1 to 0.015, middle 0.035 to 0.05, inner 0.013 to 0.016; cortical pores 0.01 to 0.03, bars 0.003 to 0.004; length of the six spines 0.05 to 0.08, basal breadth 0.012 to 0.015.

Habitat.--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface; also fossil in Barbados.

22. Hexacontium furcatum, n. sp.

Cortical shell thin walled, covered with numerous thin, bristle-shaped by-spines, which are forked and nearly as long as the main spines. Pores irregular roundish, eight to ten on the radius, two to eight times as broad as the bars. Radial proportion of the three spheres = 1 : 2.5 : 10. Main spines triangular pyramidal, shorter then the radius.

Dimensions.--Diameter of the outer shell 0.18, middle 0.045, inner 0.018; cortical pores 0.005 to 0.015, bars 0.002; length of the six spines 0.07, basal breadth 0.015.

Habitat.--North Atlantic, Station 354, surface.

23. Hexacontium drymodes, Haeckel.

Actinomma drymodes, Haeckel, 1862, Monogr. d. Radiol., p. 442, Taf. xxiv. fig. 9.

Cortical shell thin walled, covered with numerous thin, bristle-shaped spines, which are double forked and half as long as the main spines. Pores irregular roundish, eight to ten on the radius, {199}two to eight times as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 4. Main spines three-sided prismatic, with prominent, often somewhat contorted edges, at the distal end cuspidated; longer than the radius of the outer shell.

Dimensions.--Diameter of the outer shell 0.15, middle 0.07, inner 0.035; cortical pores 0.01 to 0.03, bars 0.04; length of the six spines 0.11, basal breadth 0.03.

Habitat.--Mediterranean (Messina), surface; Canary Islands (Lanzerote); Haeckel.

24. Hexacontium periplectum, n. sp.

Cortical shell double, enclosing a simple medullary shell. Radial proportion of the three shells = 1 : 4 : 5. Inner cortical shell thick walled, with irregular roundish pores, two to eight times as broad as the bars; five to seven on the radius. Numerous radial spines, arising from it, are connected below their distal ends (at equal distances from the centre) by delicate branched threads, and so form an outer, irregular, thin, cortical shell, with spiny surface. Six main spines three-sided pyramidal, about as long as the radius.

Dimensions.--Diameter of the outer shell 0.22, middle 0.2, inner 0.045; cortical pores (of both outer shells) 0.01 to 0.03, bars 0.001 to 0.005; length of the spines 0.1, basal breadth 0.02.

Habitat.--North Pacific, Station 241, surface.

Genus 80. Hexadendron,[111] Haeckel, 1881, Prodromus, p. 452.

Definition.--#Cubosphærida# with three concentric lattice-spheres and six branched spines of equal size.

The genus Hexadendron differs from Hexacontium in the ramification of the six dimensive spines, and from the similar Hexancistra in the duplication of the medullary shell. As in the latter instance, each spine can bear either three simple lateral branches or three rows of pinnate lateral branches.

1. Hexadendron quadricuspis, n. sp.

All three shells spherical, with radial proportion = 1 : 2 : 6. Pores of both medullary shells regular circular, twice as broad as the bars. Pores of the cortical shell irregular roundish, four to six times as broad as the bars; surface a little thorny. Six radial spines prismatic, with three prominent wing-like edges, which are prolonged below the distal end in three curved lateral branches. (Differs from Hexalonche quadricuspis, Pl. 22, fig. 11, mainly in the double medullary shell.)

Dimensions.--Diameter of the outer shell 0.15, middle 0.05, inner 0.025; length of the spines 0.12, breadth 0.01.

Habitat.--Central Pacific, Station 272, depth 2600 fathoms.

{200}2. Hexadendron bipinnatum, n. sp. (Pl. 23, fig. 1).

All three shells regular octahedral, with very delicate network of irregular polygonal meshes, and very thin, thread-like bars between them; their radial proportion = 1 : 2.5 : 7.5. Surface of the cortical shell covered with numerous bristle-shaped by-spines, as long as the radius. Six main spines very large, three-sided prismatic, with three rows of pinnate, lateral branches, on the three wing-like, spirally twisted edges (similar to those of Hexancistra mirabilis, p. 189, Pl. 23, fig. 3).

Dimensions.--Diameter of the outer shell 0.12, middle 0.04, inner 0.016.

Habitat.--Central Pacific, Station 272, surface.

Genus 81. Hexacontarium,[112] n. gen.

Definition.--#Cubosphærida# with three concentric lattice-spheres and six simple spines of different size; one opposite pair larger than the two others.

The genus Hexacontarium exhibits to its ancestral form Hexacontium the same relation that Hexaloncharium bears to Hexalonche; the former is developed from the latter by duplication of the medullary shell. As two opposite spines of one pair are larger than the four others, they correspond to the three axes of a quadratic crystal.

1. Hexacontarium dentatum, n. sp.

Cortical shell with regular circular, hexagonally framed pores, twice as broad as the bars, with smooth surface. Radial proportion of the three spheres = 1 : 2 : 5. Six radial spines three-sided prismatic, half as broad as the inner medullary shell, with three dentated edges. Two opposite major spines longer than the shell diameter; four other minor spines only half as long as the radius. (Similar to Hexacontium clavigerum, Pl. 23, fig. 5, but distinct by the prolongation of the spines of one axis.)

Dimensions.--Diameter of the outer shell 0.15, middle 0.06, inner 0.03; length of the major spines 0.2, minor 0.04.

Habitat.--Central Pacific, Station 266, depth 2750 fathoms.

2. Hexacontarium clavatum, n. sp.

Cortical shell covered with short conical by-spines and irregular roundish pores, three to four times as broad as the bars. Radial proportion of the three spheres = 1 : 3 : 8. Six radial spines three-sided prismatic, at the distal end club-shaped; two major spines three times as long as the four others, which are equal to the shell radius.

Dimensions.--Diameter of the outer shell 0.16, middle 0.06, inner 0.02.

Habitat.--Central Pacific, Station 272, depth 2600 fathoms.

{201}Subfamily HEXACROMYIDA,[113] Haeckel, 1881, Prodromus, pp. 449, 453.

Definition.--#Cubosphærida# with four concentric spherical lattice-shells.

Genus 82. Hexacromyum,[114] Haeckel, 1881, Prodromus, p. 453.

Definition.--#Cubosphærida# with four concentric lattice-spheres and six simple spines of equal size.

The genus Hexacromyum possesses four concentric, spherical, or octahedral lattice-shells; two inner medullary shells within the central capsule, two outer cortical outside it. The four spheres are connected by six radial beams, which are prolonged outside into simple spines of equal size, opposite in pairs in the three dimensive axes. This genus can be derived from Hexacontium by duplication of the cortical shell.

1. Hexacromyum elegans, n. sp. (Pl. 24, fig. 9).

Shell composed of four concentric shells, with radial proportion = 1 : 2.5 : 7.5 : 10. First (innermost) shell with very small circular pores, second shell with larger circular pores. Third shell (inner cortical shell) with large, subregular, circular, hexagonally framed pores (eight to nine on the radius), twice as broad as the bars; from the elevated nodal-points of the hexagonal frames (between every three pores) arise thin bristle-shaped radial beams, which are united at the distal end by vaulted branches forming the delicate fourth shell. Surface smooth. Radial spines three-sided pyramidal, as long as the radius, as broad at the base as the innermost shell.

Dimensions.--Diameter of the four shells--(A) 0.02, (B) 0.05, (C) 0.15, (D) 0.2; length of the six radial spines 0.1, basal breadth 0.02.

Habitat.--Central Pacific, Station 271, surface.

2. Hexacromyum quadrigatum, n. sp.

Shell composed of four concentric shells, with radial proportion = 1 : 3 : 8 : 10. Structure of all four shells the same, with regular, circular pores, twice to three times as broad as the bars; size of the pores gradually increasing from the innermost to the outermost shell; surface smooth. Radial spines three-sided pyramidal, as long as the radius, half as broad at the base as the innermost shell.

Dimensions.--Diameter of the four shells--(A) 0.025, (B) 0.08, (C) 0.20, (D) 0.25; length of the spines 0.12, basal breadth 0.012.

Habitat.--North Pacific, Station 253, depth 3125 fathoms.

{202}3. Hexacromyum arachnoides, n. sp.

Hexacromidium arachnoides, Haeckel, 1881, Prodromus, p. 453.

Shell composed of four concentric shells, with radial proportion = 1 : 2 : 3 : 4. Innermost shell with regular, hexagonal meshes; the three other shells with irregular, polygonal meshes; bars between the large meshes in all four shells very thin, cobweb-like. Surface covered with thin bristle-shaped by-spines, as long as the radius. Six radial main spines three-sided prismatic, longer than the diameter of the whole shell.

Dimensions.--Diameter of the four shells--(A) 0.08, (B) 0.16, (C) 0.24, (D) 0.32; length of the spines 0.4, breadth 0.01.

Habitat.--South Pacific, Station 300, depth 1375 fathoms.

4. Hexacromyum octahedrum, n. sp. (Pl. 23, fig. 2).

Shell composed of four concentric shells which are not spherical (as in the three preceding species), but regular octahedral. Radial proportion = 1 : 2.5 : 6 : 9. Network in all four shells delicate, with irregular polygonal meshes and thin bars; the thickness of the bars and size of the meshes increasing from the innermost to the outermost shell. Six radial spines three-sided prismatic, increasing slowly in breadth towards the distal end, much longer than the shell diameter.

Dimensions.--Diameter of the four shells--(A) 0.02, (B) 0.05, (C) 0.12, (D) 0.18; length of the radial spines 0.2 to 0.3 and more, breadth 0.01.

Habitat.--Central Pacific, Station 263, depth 2650 fathoms.

Subfamily HEXACARYIDA,[115] Haeckel, 1881, Prodromus, p. 454.

Definition.--#Cubosphærida# with five or more concentric lattice-shells.

Genus 83. Cubosphæra,[116] n. gen.

Definition.--#Cubosphærida# with five to six or more concentric lattice-shells and six simple spines of equal size.

The genus Cubosphæra is developed from the preceding Hexacromyum by further addition of the concentric lattice-shells, their number amounting to five, six, or more. The innermost two of these are medullary shells, the others being cortical shells. All are connected by six radial beams, prolonged outside into six simple spines of equal size; these lie opposite in pairs in three dimensive axes, corresponding to the three axes of a cube.

{203}1. Cubosphæra cubaxonia, n. sp. (Pl. 24, fig. 8).

Hexacromyon cubaxonium, Haeckel, 1881, Prodrom. et Atlas.

Shell composed of five concentric spheres, with the radial proportion = 1 : 3 : 8 : 10 : 13. The two medullary shells with small regular, circular pores of the same breadth as the bars. Inner cortical shell (third shell) with large regular, circular pores, four times as broad as the bars, hexagonally framed. From each hexagon-corner arises a thin bristle-shaped radial by-spine, which at a fixed distance from the centre is united with the middle cortical shell (fourth shell), which has very small circular pores. The beginning of the fifth shell (outermost) is indicated by six small reticula, produced by the six main spines at equal distances from the centre. All five shells are united by six prismatic radial beams, ending outside in pyramidal furrowed spines.

Dimensions.--Diameter of the five shells--(A) 0.2, (B) 0.15, (C) 0.12, (D) 0.045, (E) 0.015.

Habitat.--Central Pacific, Station 272, depth 2600 fathoms.

2. Cubosphæra concentrica, n. sp.

Shell composed of six concentric spheres, with the radial proportion = 1 : 2 : 6 : 7.5 : 9 : 11. The two medullary shells with regular, circular pores, twice as broad as the bars. The four cortical shells of the same structure, with irregular, roundish pores, three to four times as broad as the bars. The size of these pores and the breadth of their bars gradually increase towards the smooth surface. All six shells are connected by six thin three-sided prismatic radial beams, which are prolonged outside in six stronger spines, angular pyramidal, with smooth edges, as long as the shell radius.

Dimensions.--Diameter of the six shells--(A) 0.02 (B) 0.04, (C) 0.12, (D) 0.15, (E) 0.18, (F) 0.22.

Habitat.--Central Pacific, Station 268, depth 2900 fathoms.

Genus 84. Hexacaryum,[117] Haeckel, 1881, Prodromus, p. 454.

Definition.--#Cubosphærida# with five to six or more concentric lattice-shells and six branched spines of equal size.

The genus Hexacaryum is distinguished from the foregoing Cubosphæra by ramification of the six radial spines, and therefore exhibits the same relation to it that Hexancistra bears to Hexastylus, &c.

1. Hexacaryum arborescens, n. sp. (Pl. 23, figs. 4, 4_a_).

Shell composed of five, six, or more concentric shells, which are united by six very large radial spines. The two medullary shells spherical, inner with regular, circular, outer with irregular polygonal pores. All cortical shells (third and following) not spherical, but regular octahedral, with irregular polygonal meshes and thin bars. Radial spines prismatic, with three wing-like, spirally twisted edges, which at equal distances send out thin forked lateral branches (six on each {204}verticil); by further ramification and communication of these branches the triangular net-plates arise, filling out the sides of the octahedral cortical shells. Diameter of all shells little different. The outer free parts of the six spines are arborescent, twice to three times as long as the enclosed inner parts, and bear six to eight verticils of free lateral branches, decreasing in size towards the distal end (similar to Arachnosphæra).

Dimensions.--Diameter of the six shells--(A) 0.015, (B) 0.04, (C) 0.1, (D) 0.16, (E) 0.22, (F) &c.; average distance of the concentric octahedra = 0.06; length of the radial spines 0.3 to 0.4 and more, breadth 0.02.

Habitat.--Central Pacific, Station 274, surface.

Subfamily HEXADORIDA,[118] Haeckel, 1881, Prodromus, pp. 449, 455.

Definition.--#Cubosphærida# with spongy spherical or octahedral shell (with or without enclosed concentrical lattice-shells).

Genus 85. Cubaxonium,[119] n. gen.

Definition.--#Cubosphærida# with solid spongy spherical or octahedral shell, without latticed medullary shell in the centre, and with six simple radial spines of equal size.

The genus Cubosphæra may be regarded as a form of Styptosphæra, which develops six radial spines, opposite in pairs in the three dimensive axes. The solid spongy framework of the shell assumes the outer form either of a sphere, or of a regular octahedron.

1. Cubaxonium spongiosum, n. sp.

Spongy shell spherical, composed of a very dense spongy framework of nearly uniform structure; the meshes three to four times as broad as the bars; surface almost smooth. Six spines cylindrical, twice to three times as long as the diameter of the spongy sphere, about as broad as one half mesh.

Dimensions.--Diameter of the sphere 0.2, meshes 0.006 to 0.008, bars 0.002; length of the spines 0.4 to 0.5, breadth 0.004.

Habitat.--South Pacific, Station 288, surface.

2. Cubaxonium octahedrum, n. sp.

Spongy shell octahedral, composed of a loose spongy framework of nearly uniform structure; the meshes ten to twelve times as broad as the bars; surface thorny. Six spines three-sided {205}pyramidal, longer than the diameter of the octahedron, arising from its six corners, as broad at the base as one mesh.

Dimensions.--Diameter of the shell 0.15, meshes 0.01 to 0.012, bars 0.001; length of the spines 0.2, basal breadth 0.01.

Habitat.--South Pacific, Station 300, surface.

Genus 86. Hexadoras,[120] Haeckel, 1881, Prodromus, p. 455.

Definition.--#Cubosphærida# with spongy spherical shell and one simple latticed medullary shell in its centre, having six simple spines of equal size.

The genus Hexadoras exhibits the same structure of the spongy shell as Spongoplegma, but differs from it in the production of six dimensive spines. In the centre lies one simple, latticed, medullary shell, which is either spherical or octahedral. In the latter case the six spines arise from the six corners of the octahedron.

1. Hexadoras axophæna, n. sp.

Medullary shell spherical, with regular hexagonal meshes, twice as broad as the bars. Cortical shell entirely enclosing it, with loose irregular framework and thorny surface. Diameter of the outer shell three times as large as that of the inner. Six radial spines arising from the medullary shell, four to five times as long as the radius of the cortical shell, three-sided prismatic, with straight dentated edges.

Dimensions.--Diameter of the outer shell 0.15, inner 0.05; length of the spines 0.3 to 0.4.

Habitat.--Central Pacific, Station 265, depth 2900 fathoms.

2. Hexadoras lychnosphæra, n. sp.

Medullary shell spherical, with regular, circular, hexagonally framed pores, three times as broad as the bars. Cortical shell enveloping it, with loose irregular framework and spiny surface. Diameter of the outer shell eight times as large as that of the inner. Six radial spines arising from the inner shell, three-sided prismatic, with dentated, spirally contorted edges, seven times as long as the diameter of the medullary shell, with three lateral branches at the distal end (similar to Lychnosphæra, Pl. 11, fig. 1).

Dimensions.--Diameter of the outer shell 0.5, inner 0.06; total length of the spines 0.4, breadth 0.01.

Habitat.--Central Pacific, Station 270, depth 2925 fathoms.

3. Hexadoras octahedrum, n. sp.

Medullary shell regular octahedral, with irregular polygonal meshes, five times as broad as the bars. Cortical shell enveloping it, with dense spongy framework, also octahedral with rough surface. {206}Diameter of the outer shell five times as large as that of the inner. Six radial spines very long, arising from the six corners of the inner and piercing the spongy mass of the outer shell, considerably exceeding it at the free distal end, three-sided prismatic, with elegantly denticulate edges.

Dimensions.--Diameter of the outer shell 0.2, inner 0.04; total length of the spines 0.3 or more, breadth 0.02.

Habitat.--Central Pacific, Station 266, depth 2750 fathoms.

Genus 87. Hexadoridium,[121] Haeckel, 1881, Prodromus, p. 455.

Definition.--#Cubosphærida# with spongy spherical shell and two concentric latticed medullary shells in its centre, having six simple spines of equal size.

The genus Hexadoridium differs from Hexadoras in the duplication of the medullary shell, and exhibits therefore the same relation to it that Spongodictyon bears to Spongoplegma. In the only known species the six spines are opposite, arranged quite regularly in pairs in the three dimensive axes, and consequently represent the three axes of a regular crystal or cube.

1. Hexadoridium streptacanthum, n. sp. (Pl. 25, figs. 1, 1_a_).

Both medullary shells spherical, with small regular, circular pores, twice as broad as the bars; outer twice as broad as the inner. Spongy cortical shell enclosing it with dense framework, five times as broad as the outer medullary shell, regular octahedral. Six radial spines, arising from the latter, are thinned at the inner end, three to five times as long as the diameter of the cortical shell, and nearly as broad as the inner medullary shell, with three dentated and spirally contorted edges. (Very similar to the common Spongosphæra streptacantha, with irregular and variable number and dispositions of spines; possibly its ancestral form?).

Dimensions.--Diameter of the cortical shell 0.2, of the outer medullary shell 0.04, inner 0.02; length of the spines 1 mm. and more, breadth 0.02.

Habitat.--Central Pacific, Station 271, depth 2425 fathoms.

Family X. #ASTROSPHÆRIDA# (Pls. 11, 18-20, 26-30).

Astrosphærida, Haeckel, 1881, Prodromus, p. 449.

Definition.--#Sphæroidea# with numerous (eight to twelve or more, commonly between twenty and sixty) radial spines on the surface of the spherical shell; living solitary (not associated in colonies).

The family #Astrosphærida#, the largest and most varied of all #Sphæroidea#, is distinguished from the other members of this group by the possession of numerous {207}radial spines, which are either regularly or irregularly disposed on the surface of the spherical shell. The extreme variability and richness of form in this family is mainly due to the different size, shape, and disposition of these radial spines.

The simplest Astrosphærida are the Coscinommida, with a single spherical or polyhedral lattice-shell. To this ancestral group all other subfamilies can be opposed as "Astrosphærida composita," since their skeleton is composed of two or more concentric lattice-shells: two in the Haliommida, three in the Actinommida, four in the Cromyommida, five or more in the Caryommida. In these four subfamilies the concentric shells are all simple (not spongy) fenestrated spheres or endospherical polyhedra. In the sixth subfamily, the Spongiommida, the shell is wholly or partially composed of spongy irregular wicker-work, with or without a medullary shell in the centre.

The Number of the Radial Spines in the Astrosphærida is extremely variable, and ranges from eight to forty or more; in many cases more than one hundred. Often each nodal-point of the network develops on the shell surface one spine. Still more frequently the number of the spines is less than that of the nodal-points. In all concentric Astrosphærida, having two or more concentrical shells, we can distinguish "primary spines," as outer prolongations of the inner radial beams connecting the shells, and "secondary spines," developed only on the outer surface of the shell. Naturally the former are of much greater importance than the latter. But we can also often distinguish among the latter larger "main spines" and smaller "by-spines," the latter commonly much more numerous than the former.

The Disposition of the Radial Spines, either regular or irregular, is a subject of great morphological interest, and remains to be exhausted by further observations. The following cases of regular disposition have been observed by me--(A) eight spines, opposite in pairs in four axes corresponding to the four diagonal axes of a cube; (B) nine spines, regularly disposed at equal distances (?) (not opposed in pairs); (C) ten spines, disposed at equal distances (?); (D) twelve spines, regularly disposed, corresponding to the twelve corners of the regular icosahedron; (E) fourteen spines, quite regularly disposed (six corresponding to the three axes of a regular octahedron, eight to the central points of its eight faces); (F) sixteen spines, regularly disposed (?); (G) twenty spines (very common!), either disposed in the same manner (after the law of Johannes Müller) as in the ACANTHARIA (?), or corresponding to the twenty corners of the regular or pentagonal dodecahedron, or disposed in the same manner as in many #Larcoidea# (Tholonida, &c., to be described afterwards); (H) twenty-four spines, regularly disposed (?); (I) thirty-two spines, quite regularly disposed (twenty corresponding to the twenty corners of the regular dodecahedron, twelve to the central points of its twelve faces); (K) forty spines, nearly regularly (or quite symmetrically?) disposed. If the number of the spines amounts to more than forty, it is as a rule impossible to determine their regular disposition in a satisfactory manner.

{208}Synopsis of the Genera of Astrosphærida.

------------------------------------------------------------------------- I. Subfamily Coscinommida. (One single latticed shell.) ------------------------------------------------------------------------- { All spines of the same Spines all simple, not { kind, 88. Acanthosphæra. branched and not { tubulous. { Larger main spines and { smaller by-spines, 89. Heliosphæra.

Spines hollow conical tubes with porous walls, 90. Conosphæra.

Between simple spines the pores prolonged in hollow tubes, 91. Coscinomma.

{ Spines with lateral { branches, 92. Cladococcus. Spines branched or forked.{ { Spines forked or { dichotomous, 93. Elaphococcus. ------------------------------------------------------------------------- II. Subfamily Haliommida. (Two concentric latticed shells.) ------------------------------------------------------------------------- { All spines equal, { simple, 94. Haliomma. { A. Elatommida, one { All spines simple, of medullary and one cortical{ two different kinds, 95. Heliosoma. shell. { { Spines branched, 96. Elatomma.

{ No by-spines, 97. Leptosphæra. { B. Diplosphærida, both { Inner by-spines, 98. Diplosphæra. shells cortical. { { Outer by-spines, 99. Drymosphæra. { { Outer and inner { by-spines, 100. Astrosphæra. ------------------------------------------------------------------------- III. Subfamily Actinommida. (Three concentric latticed shells.) ------------------------------------------------------------------------- { All spines equal, 101. Actinomma. Radial spines not { branched. { Larger main spines and { smaller by-spines, 102. Echinomma.

Radial spines branched or forked, 103. Pityomma. ------------------------------------------------------------------------- IV. Subfamily Cromyommida. (Three concentric latticed shells.) ------------------------------------------------------------------------- { All spines equal, 104. Cromyomma. Radial spines not { branched. { Larger main spines and { smaller by-spines, 105. Cromyechinus.

Radial spines branched or forked, 106. Cromyodrymus. ------------------------------------------------------------------------- V. Subfamily Caryommida. (Numerous, five to ten or more, concentric latticed shells.) ------------------------------------------------------------------------- Two medullary shells and three or more cortical shells (lattice work ordinary), 107. Caryomma.

{ Triangular meshes, No medullary shells { simple bars, without (lattice work { diagonal bars, 108. Arachnopila. arachnoidal); three-sided { prismatic spines, { Triangular meshes, with verticils of three { simple bars; diagonal forked branches. { bars between the 109. Arachnopegma. (Arachnosphærida.) { shells, { { Polygonal meshes, bars { branched, 110. Arachnosphæra.

------------------------------------------------------------------------- VI. Subfamily Spongiommida. (Spherical shell whole or partly spongy, with or without enclosed latticed medullary shells in the centre.) ------------------------------------------------------------------------- I. Tribe {Spongy {Spines simple, 111. Spongiomma. Spongodrymida, { sphere { without { solid. {Spines branched, 112. Spongodrymus. latticed { medullary {Spongy {Spines simple, 113. Spongechinus. shell. { sphere { { hollow. {Spines branched, 114. Spongothammus.

{Framework arising { from the medullary { shell, 115. Spongopila. { {Medullary {Framework {No medullary by-spines, II. Tribe { shell { separate { 116. Rhizoplegma. Rhizoplegmida, { spherical. { from the { with { { medullary {Medullary by-spines, one single { { shell. { 117. Lychnosphæra. latticed { medullary {Medullary {Framework arising shell. { shell a { immediately from { simple { the medullary { cube. { shell, 118. Centrocubus. { { { {Framework separate { { from the medullary { { shell, 119. Octodendron.

{Framework arising III. Tribe Rhizosphærida, { from the medullary with two concentric { shell, 120. Spongosphæra. latticed medullary shells. { {Framework separate { from the medullary { shell, 121. Rhizosphæra.

Subfamily COSCINOMMIDA, Haeckel.

Heliosphærida, Haeckel, 1881, Prodromus, pp. 449, 450.

Definition.--#Astrosphærida# with one single spherical lattice-shell.

Genus 88. Acanthosphæra,[122] Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 12.

Definition.--#Astrosphærida# with one simple lattice-sphere, covered with simple radial spines of the same kind.

The genus Acanthosphæra exhibits the most simple form of all Astrosphærida; a simple spherical lattice-shell, the surface of which is covered by radial spines of one and the same kind. The number of the latter is very variable, often twelve to twenty, regularly disposed; in other cases forty to sixty or more; and sometimes at each nodal-point of the network a spine is developed.

{210}Subgenus 1. Rhaphidococcus, Haeckel, 1862, Monogr. d. Radiol., p. 365 (sensu emendato).

Definition.--Pores of the spherical shell regular or subregular, all of nearly equal size and similar form. Radial spines arising from all the nodal-points of the network.

1. Acanthosphæra tenuissima, Haeckel.

Heliosphæra tenuissima, Haeckel, 1862, Monogr. d. Radiol., p. 351, Taf. ix. fig. 2.

Shell extremely thin walled, eight to ten times as broad as one pore. Meshes or pores regular, hexagonal, with thread-like bars; five to seven on the radius. At each nodal-point (between every three meshes) arises a bristle-shaped radial spine, as long as the diameter of one pore.

Dimensions.--Diameter of the shell 0.2 to 0.25, of the meshes or pores 0.025 to 0.03, bars below 0.0001; length of the spines 0.03.

Habitat.--Mediterranean (Messina), North Atlantic (Canary Islands).

2. Acanthosphæra tenuis, n. sp.

Shell very thin walled, about twenty times as broad as one pore. Meshes subregular, hexagonal, with thread-like bars; twelve to fourteen on the radius. At each nodal-point arises a bristle-shaped radial spine, about as long as the radius.

Dimensions.--Diameter of the shell 0.3 to 0.35, pores 0.015 to 0.018, bars below 0.001; length of the spines 0.12 to 0.16.

Habitat.--Central Pacific, Stations 266 to 274, depth 2350 to 2925 fathoms.

3. Acanthosphæra macropora, n. sp.

Shell thin walled, five to six times as broad as one mesh. Pores regular, circular, hexagonally framed, ten to twelve times as broad as the bars. Radial spines bristle-shaped, as long as the diameter of one pore, arising from all the nodal-points.

Dimensions.--Diameter of the shell 0.07 to 0.08, pores 0.012, bars 0.001; length of the spines 0.012.

Habitat.--Central Pacific, Station 271, surface.

4. Acanthosphæra micropora, n. sp.

Shell thick walled, forty to fifty times as broad as one pore. Pores regular, circular, hexagonally framed, half as broad as the bars. Radial spines bristle-shaped, as long as the radius of the shell, arising from all the nodal-points.

Dimensions.--Diameter of the shell 0.22, pores 0.003, bars 0.006; length of the spines 0.1.

Habitat.--South Pacific, Station 288, surface.

{211}5. Acanthosphæra dentata, Haeckel.

Cladococcus dentatus, Haeckel, 1862, Monogr. d. Radiol., p. 367, Taf. xiii. fig. 10.

Shell thin walled, eight to ten times as broad as one pore. Pores regular, circular, hexagonally framed, three times as broad as the bars. Radial spines arising from all the nodal-points of the network, three-sided prismatic, with dentated or serrated edges, longer than the shell diameter.

Dimensions.--Diameter of the shell 0.08, pores 0.01, bars 0.003; length of the spines 0.1, breadth 0.003.

Habitat.--Mediterranean (Messina), surface.

6. Acanthosphæra acufera, Haeckel.

Rhaphidococcus acufer, Haeckel, 1862, Monogr. d. Radiol., p. 366, Taf. xiv. fig. 1.

Cladococcus acufer, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 800.

Shell thin walled, eight to ten times as broad as one mesh. Pores regular, circular, three times as broad as the bars. Radial spines bristle-shaped, arising with thicker conical bases from all the nodal-points, about as long as the diameter of the shell.

Dimensions.--Diameter of the shell 0.08, pores 0.01, bars 0.003; length of the spines 0.08.

Habitat.--Mediterranean (Messina); North Atlantic, Station 354, surface.

7. Acanthosphæra castanea, n. sp. (Pl. 26, fig. 3).

Shell thick walled, thirty times as broad as one mesh. Pores regular, circular, nearly of the same breadth as the bars. Radial spines bristle-shaped, arising with thicker conical bases from all the nodal-points, scarcely half as long as the radius of the shell.

Dimensions.--Diameter of the shell 0.15, pores and bars 0.005; length of the spines 0.03.

Habitat.--North Pacific, Station 244, surface.

8. Acanthosphæra flosculenta, n. sp.

Shell thick walled, thirteen times as broad as one mesh. Pores regular, circular, three times as broad as the bars, with an elegant six-lobed frame (Pl. 28, fig. 1_b_). In the intervals between the six lobes of each mesh arise six conical radial spines (half as long as the radius), six around each pore. (Differs from the similar Haliomma flosculentum, Pl. 28, fig. 1, in the absence of an enclosed medullary shell and the stronger development of the spines.)

Dimensions.--Diameter of the shell 0.13, pores 0.01, bars 0.003; length of the spines 0.03.

Habitat.--Indian Ocean, Cocos Islands, surface, Rabbe.

Subgenus 2. Rhaphidocapsa, Haeckel.

Definition.--Pores of the spherical shell regular or subregular, all of nearly equal size and similar form. Radial spines scattered at some distance apart, not at all the nodal-points.

{212}9. Acanthosphæra insignis, Haeckel.

Heliosphæra insignis, R. Hertwig, 1879, Organismus der Radiol., p. 40, Taf. v. fig. 7.

Shell thin walled, about ten times as broad as one mesh. Pores regular, hexagonal, ten to twelve times as broad as the bars. Radial spines about one hundred and twenty, arising from certain nodal-points of the network, being as long as the diameter of the sphere, three-sided prismatic, with three thin denticulated edges.

Dimensions.--Diameter of the shell 0.2, pores 0.02, bars 0.002; length of the spines 0.18, breadth 0.003.

Habitat.--Cosmopolitan; Mediterranean (Messina), Atlantic (Stations 325, 347), Indian (Ceylon), Pacific (Stations 270 to 274), surface.

10. Acanthosphæra fortispina, n. sp.

Shell thin walled, about six times as broad as one mesh. Pores subregular, hexagonal, with thread-like bars; three to four on the radius. Radial spines about twenty, three-sided pyramidal, as long as the diameter, and one-third as broad at the base as one pore.

Dimensions.--Diameter of the shell 0.06 to 0.09, pores 0.01 to 0.014, bars below 0.001; length of the spines 0.07 to 0.08, basal breadth 0.03 to 0.04.

Habitat.--North Pacific, Station 244, depth 2900 fathoms.

11. Acanthosphæra mucronata, n. sp. (Pl. 26, fig. 7).

Shell thick walled, fifteen times as broad as one pore. Pores regular, circular, hexagonally framed, funnel-shaped, three times as broad as the bars. Radial spines twenty to thirty, dagger-shaped or spindle-shaped, angular, twice as broad in the middle as one pore, about as long as the radius.

Dimensions.--Diameter of the shell 0.11, pores 0.0075, bars 0.0025; length of the spines 0.06, breadth 0.015.

Habitat.--Central Pacific, Station 271, depth 2425 fathoms.

12. Acanthosphæra clavata, n. sp. (Pl. 26, fig. 8).

Shell thick walled, ten to twelve times as broad as one mesh. Pores subregular, circular, three times as broad as the bars. Radial spines twenty, club-shaped, angular, with prominent edges, twice as broad at the distal end as one pore, about as long as the radius.

Dimensions.--Diameter of the shell 0.11, pores 0.01, bars 0.003; length of the spines 0.06, breadth 0.02.

Habitat.--Western Tropical Pacific, Station 225, depth 4475 fathoms.

13. Acanthosphæra marginata, n. sp.

Shell thick walled, twelve times as broad as one mesh. Pores regular, circular double-edged, four times as broad as the bars. Radial spines conical, fourteen in number, about as long as the {213}radius, and as broad at the base as one mesh. Six spines correspond to the six corners of a regular octahedron, eight to the centre of the eight faces.

Dimensions.--Diameter of the shell 0.1, pores 0.008, bars 0.002; radial spines 0.06, basal breadth 0.01.

Habitat.--Central Pacific, Station 274, surface.

14. Acanthosphæra florida, n. sp.

Shell thick walled, fifteen times as broad as one mesh. Pores regular, circular, hexagonally lobed, separated by prominent funnel-shaped crests of half the breadth. Twenty conical radial spines, half as long as the radius, as broad at the base as one funnel.

Dimensions.--Diameter of the shell 0.15, pores 0.01, bars 0.005; length of the spines 0.04, basal breadth 0.02.

Habitat.--South Atlantic, Station 325, depth 2650 fathoms.

15. Acanthosphæra enneacantha, n. sp.

Shell thin walled, fourteen times as broad as one mesh. Pores regular, circular, twice as broad as the bars. Nine radial spines, regularly disposed, as long as the shell diameter, three-sided prismatic, with pyramidal apex, as broad as one mesh.

Dimensions.--Diameter of the shell 0.14, pores 0.01, bars 0.005; length of the spines 0.15, breadth 0.01.

Habitat.--Central Pacific, Station 265, depth 2900 fathoms.

16. Acanthosphæra octahedralis, n. sp.

Shell thick walled, octahedral, fourteen times as broad as one mesh. Pores regular, circular, three times as broad as the bars. Fourteen radial spines, regularly disposed, conical, as long as the radius of the shell, twice as broad at the base as one mesh. Six spines correspond to the six corners of a regular octahedron, eight to the central points of its eight faces.

Dimensions.--Diameter of the shell 0.14, pores 0.01, bars 0.003; length of the spines 0.08, basal breadth 0.02.

Habitat.--North Pacific, Station 253, depth 3125 fathoms.

17. Acanthosphæra compacta, n. sp.

Shell thick walled, about sixty times as broad as one mesh. Pores regular, circular, twice as broad as the bars. Thirty to forty radial spines, three-sided pyramidal, scarcely half as long as the radius, five to six times as broad at the base as one pore.

Dimensions.--Diameter of the shell 0.24, pores 0.004, bars 0.002; length of the radial spines 0.05, basal breadth 0.02.

Habitat.--Fossil in Barbados.

{214}Subgenus 3. Raphidodrymus, Haeckel.

Definition.--Pores of the spherical shell irregular, of different size or form. Radial spines arising from all the nodal-points of the network.

18. Acanthosphæra capillaris, n. sp.

Shell thin walled, with irregular polygonal meshes, twelve to twenty times as broad as the bars; eight to ten on the radius. Radial spines bristle-shaped, arising from all the nodal-points of the network, about as long as the diameter of the largest meshes.

Dimensions.--Diameter of the shell 0.15 to 0.2, pores 0.012 to 0.02, bars 0.001; length of the spines 0.02.

Habitat.--Central Pacific, Stations 260 to 274, surface.

19. Acanthosphæra arctica, n. sp.

Shell thin walled, with irregular roundish, polygonally framed meshes, three to four times as broad as the bars. Radial spines arising from all the nodal-points of the network, pyramidal at the base; in the distal half bristle-shaped, as long as the radius.

Dimensions.--Diameter of the shell 0.12, pores 0.006 to 0.008, bars 0.002; length of the spines 0.07.

Habitat.--Arctic Ocean, Greenland (in the stomach of Periphylla hyacinthina).

20. Acanthosphæra antarctica, n. sp.

Shell thick walled, with irregular, roundish pores, about as broad as the bars. Radial spines arising from all nodal-points of the network, conical at the base, half as long as the radius.

Dimensions.--Diameter of the shell 0.15, pores and bars 0.005 to 0.008; length of the spines 0.04.

Habitat.--Antarctic Ocean, Station 157, depth 1950 fathoms.

Subgenus 4. Rhaphidosphæra, Haeckel, 1881, Prodromus, p. 450.

Definition.--Pores of the spherical shell irregular, of different size or form. Radial spines scattered at intervals, not at all the nodal-points.

21. Acanthosphæra echinoides, Haeckel.

Cyrtidosphæra echinoides, Haeckel, 1865, Zeitschr. f. wiss. Zool., xv. p. 367, Taf. xxvi. fig. 5.

Shell thin walled, with irregular polygonal or more roundish pores of very different size. Forty to fifty very large meshes, separated by rows of much smaller meshes. Radial spines forty to sixty, half as long as the shell radius, bristle-shaped, with conical bases.

{215}Dimensions.--Diameter of the shell 0.13, larger pores 0.03, smaller 0.003; length of the spines 0.03.

Habitat.--Mediterranean (Nice), surface.

22. Acanthosphæra longispina, n. sp.

Shell thin walled, with irregular polygonal meshes, four to six times as broad as the bars; six to eight on the radius. Thirty to forty radial spines, three-sided prismatic, twice as broad as the bars, twice to three times as long as the diameter of the shell.

Dimensions.--Diameter of the shell 0.12 to 0.15, pores 0.012 to 0.02, bars 0.003; length of the radial spines 0.2 to 0.4, breadth 0.006.

Habitat.--North Pacific, Station 253, surface.

23. Acanthosphæra brevispina, n. sp.

Shell thick walled, with irregular polygonal meshes, twice to four times as broad as the bars; twelve to sixteen on the radius. Sixty to eighty radial spines, pyramidal, half as long as the radius of the shell, one-fourth as broad at the base.

Dimensions.--Diameter of the shell 0.2 to 0.22, pores 0.006 to 0.012, bars 0.003; length of the spines 0.05, basal breadth 0.02.

Habitat.--Central Pacific, Station 268, depth 2900 fathoms.

24. Acanthosphæra acanthica, Haeckel.

Cenosphæra acanthica, Stöhr, 1880, Palæontogr., vol. xxvi. p. 86, Taf. i. fig. 3.

Shell thick walled, with irregular, roundish pores, twice to three times as broad as the bars; seven to nine on the radius. Ten to twenty radial spines pyramidal, shorter than the radius, twice as broad at the base as one mesh.

Dimensions.--Diameter of the shell 0.12 to 0.16, pores 0.006 to 0.009, bars 0.003; length of the spines 0.04 to 0.06, basal breadth 0.01 to 0.015.

Habitat.--Fossil in Tertiary rocks of Sicily and Barbados.

25. Acanthosphæra haliphormis, Ehrenberg.

Acanthosphæra haliphormis, Ehrenberg, 1861, Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, Taf. ii. fig. 1.

Shell thick walled, with irregular, roundish pores, twice to four times as broad as the bars; four to five on the radius. Twelve to twenty radial spines pyramidal, longer than the radius, scarcely as broad as one mesh at the base.

Dimensions.--Diameter of the shell 0.11, pores 0.01 to 0.02, bars 0.005; length of the spines 0.06 to 0.08, basal breadth 0.01.

Habitat.--Arctic Ocean, near Greenland, depth 1000 fathoms.

{216}26. Acanthosphæra angulata, n. sp. (Pl. 26, fig. 4).

Shell thin walled; its pores irregular, roundish, with angular, double-edged margin, two to four times as broad as the bars; six to eight on the radius. Twenty to thirty radial spines pyramidal, angular, with prominent edges, shorter than the radius, as broad at the base as one small mesh.

Dimensions.--Diameter of the shell 0.2, pores 0.02 to 0.04, bars 0.01; length of the spines 0.06, basal breadth 0.02.

Habitat.--South Atlantic, Station 332, depth 2200 fathoms.

27. Acanthosphæra conifera, n. sp.

Shell thick walled, with irregular, roundish pores, twice to five times as broad as the bars; ten to twelve on the radius. Twenty radial spines conical, regularly disposed, half as long as the radius, as broad at the base as one of the largest meshes.

Dimensions.--Diameter of the shell 0.2, pores 0.008 to 0.02, bars 0.004; length of the spines 0.05, basal breadth 0.02.

Habitat.--Central Pacific, Station 268, depth 2900 fathoms.

28. Acanthosphæra maxima, n. sp.

Shell thick walled, with irregular, roundish pores, twice to eight times as broad as the bars; twelve to twenty on the radius. Radial spines very numerous (two to three hundred), short, conical, scarcely as long as the diameter of the largest meshes, and one-third as broad.

Dimensions.--Diameter of the shell 0.3 to 0.4, pores 0.008 to 0.03, bars 0.004; length of the radial spines 0.03, basal breadth 0.01.

Habitat.--Tropical Atlantic, Station 348, depth 2450 fathoms.

29. Acanthosphæra simplex, Haeckel.

Rhaphidococcus simplex, Haeckel, Monogr. d. Radiol., 1862, p. 366, figs. 5, 6.Taf. xiii.

Cladococcus simplex, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 800.

Shell thick walled, with irregular, roundish pores, three to six times as broad as the bars; eight to nine on the radius. Forty to sixty radial spines, about as long as the diameter of the shell, three-sided prismatic, not straight, but more or less bent.

Dimensions.--Diameter of the shell 0.12, pores 0.005 to 0.012, bars 0.0015 to 0.02; length of the spines 0.12, breadth 0.003.

Habitat.--Mediterranean (Messina), surface, Haeckel.

30. Acanthosphæra gibbosa, n. sp.

Shell thin walled, rugged or tuberculate, covered by about twenty hill-shaped tubercles or protuberances with flat valleys between them. Network very delicate, with thread-like bars and {217}irregular, polygonal pores; twenty to thirty on the radius. Radial spines very numerous, bristle-shaped, twice to three times as long as the diameter of the pores.

Dimensions.--Diameter of the shell 0.3, pores 0.01 to 0.02; length of the spines 0.02 to 0.05.

Habitat.--Central Pacific, Station 274, surface.

31. Acanthosphæra reticulata, n. sp. (Pl. 26, fig. 5).

Rhaphidosphæra reticulata, Haeckel, 1881, Prodromus.

Shell thick walled, with irregular, roundish pores, twice to four times as broad as the bars; six to eight on the radius. Surface of the bars covered with a peculiar delicate network of very fine crests. Twenty to forty radial spines, angular, pyramidal, scarcely one-third as long as the radius of the shell, as broad at the base as the bars.

Dimensions.--Diameter of the shell 0.22, pores 0.02 to 0.04, bars 0.01; length of the spines 0.04, basal breadth 0.01.

Habitat.--Central Pacific, Station 271, depth 2425 fathoms.

Genus 89. Heliosphæra,[123] Haeckel, 1862, Monogr. d. Radiol., p. 350 (sensu emendato).

Definition.--#Astrosphærida# with one simple lattice-sphere, covered with simple radial spines of two different kinds: larger main spines and smaller by-spines.

The genus Heliosphæra (in the mended definition here employed) differs from the foregoing Acanthosphæra in the possession of two different kinds of radial spines: larger main spines scattered on the surface or disposed regularly in limited numbers (twelve to twenty, sometimes forty to fifty or more), and smaller by-spines in much larger numbers, arising from all the nodal-points of the network (or sometimes also from its bars).

Subgenus 1. Heliosphærella, Haeckel.

Definition.--Pores of the shell regular or subregular, all of nearly equal size and similar form.

1. Heliosphæra hexagonaria, n. sp. (Pl. 26, fig. 2).

Shell very thin walled, about twenty times as broad as one pore. Meshes or pores subregular, hexagonal, with thread-like bars; fifteen to seventeen on the radius. Radial spines at the nodal-points of the network; about forty main spines three-sided pyramidal, half as broad at the base as one pore, and twice as long as the bristle-shaped by-spines, which are very numerous, and as long as the diameter of one pore.

{218}Dimensions.--Diameter of the shell 0.25 to 0.3, of the meshes or pores 0.012 to 0.015, bars below 0.001; length of the main spines 0.03, basal breadth 0.007.

Habitat.--Central Pacific, Stations 272 to 274, depth 2350 to 2750 fathoms.

2. Heliosphæra actinota, Haeckel.

Heliosphæra actinota, Haeckel, 1862, Monogr. d. Radiol., p. 352, Taf. ix. fig. 3.

Shell very thin walled, about ten times as broad as one mesh. Pores regular, hexagonal, with thread-like bars; six to eight on the radius. Radial spines at the nodal-points of the network, bristle-shaped, scarcely broader than the bars; about twenty main spines as long as the diameter of the shell, and numerous by-spines, only one-third to one-half as long as the former.

Dimensions.--Diameter of the shell 0.2 to 0.25, of the meshes 0.02 to 0.03, bars below 0.001; length of the main spines 0.2 to 0.3.

Habitat.--Mediterranean (Messina), Atlantic (Canaries, Azores), surface.

3. Heliosphæra echinoides, Haeckel.

Heliosphæra echinoides, Haeckel, 1862, Monogr. d. Radiol., p. 352, Taf. ix. fig. 4.

Shell thin walled, about six times as broad as one mesh. Pores regular, hexagonal, eight times as broad as the bars. Radial spines arising, not from the nodal-points of the network, but from the midst of the bars (very rare disposition!); twenty main spines regularly disposed, as long as the radius, four times as long as the numerous by-spines; all spines bristle-shaped, of the same breadth as the bars.

Dimensions.--Diameter of the shell 0.09, pores 0.015, bars 0.002; length of the main spines 0.04.

Habitat.--Mediterranean (Messina), surface, Haeckel.

4. Heliosphæra elegans, Haeckel.

Heliosphæra elegans, Haeckel, 1862, Monogr. d. Radiol., p. 353, Taf. ix. fig. 5.

Shell very thin walled, about ten times as broad as one mesh. Pores regular, hexagonal, with thread-like bars, which are crossed by tangential bars, so that each side of a hexagon exhibits a regular rectangular cross (exactly the same as in Pl. 19, fig. 5). All radial spines bristle-shaped, as thin as the bars, and arising from the nodal-points; twenty main spines as long as the radius, numerous by-spines scarcely one-sixth as long.

Dimensions.--Diameter of the shell 0.26, pores 0.026, bars below 0.001; length of the main spines 0.13.

Habitat.--Mediterranean (Messina), surface, Haeckel.

5. Heliosphæra pectinata, n. sp. (Pl. 26, fig. 9).

Acanthosphæra pectinata, Haeckel, 1881, Atlas.

Shell thick walled, combed, about fourteen times as broad as one mesh. Pores subregular, circular, with elevated hexagonal frames, three times as broad as the bars. Radial spines very {219}numerous and stout; thirty to forty main spines, three-sided pyramidal, nearly as long as the radius, as broad as one mesh; by-spines small, conical, everywhere scattered at the nodal-points of the network and on the high combs of the bars.

Dimensions.--Diameter of the shell 0.16, pores 0.012, bars 0.004; length of the main spines 0.07, basal breadth 0.016.

Habitat.--West Tropical Pacific, Station 225, depth 4475 fathoms.

6. Heliosphæra coronata, n. sp. (Pl. 26, figs. 6, 6_a_).

Acanthosphæra coronata, Haeckel, 1881, Atlas.

Shell thick walled, about ten times as broad as one mesh. Pores regular, circular, five times as broad as the bars; each pore surrounded by a regular coronal of six short, conical by-spines (fig. 6_a_); twenty to thirty main spines, also conical, half as long as the radius, as broad as one pore.

Dimensions.--Diameter of the shell 0.15, pores 0.015, bars 0.003; length of the main spines 0.04, basal breadth 0.015.

Habitat.--Central Pacific, Station 272, depth 2600 fathoms.

7. Heliosphæra floribunda, n. sp.

Shell thick walled about ten times as broad as one mesh. Pores regular, six-lobed, twice as broad as the bars; each pore surrounded by six small conical by-spines (as in Pl. 28, figs. 1, 1_b_); twenty main spines regularly disposed cylindro-conical, as long as the diameter of the shell or longer.

Dimensions.--Diameter of the shell 0.15, pores 0.015, bars 0.008; length of the main spines 0.16, breadth 0.008.

Habitat.--Central Pacific, Station 268, depth 2900 fathoms.

8. Heliosphæra cristata, n. sp.

Shell thick walled, about twelve times as broad as one mesh. Pores subregular, circular, twice as broad as the bars; each pore surrounded by an elegant coronal of ten to twenty small, conical by-spines; twenty main spines regularly disposed, conical, only one-third as long as the radius, as broad at the base as one mesh.

Dimensions.--Diameter of the shell 0.25, pores 0.02, bars 0.01; length of the main spines 0.04, basal breadth 0.02.

Habitat.--South Pacific, Station 285, depth 2375 fathoms.

9. Heliosphæra castanella, n. sp.

Shell thick walled, about twenty times as broad as one mesh. Pores regular, circular, of the same breadth as the bars. Whole surface densely covered with innumerable bristle-shaped by-spines, half as long as the radius; fifty to eighty main spines, conical, nearly as long as the diameter, {220}twice as broad at the base as one pore. (Very similar to some species of Castanella, Pl. 113, but without the osculum characteristic of this Phæodarian; may be easily confounded with it.)

Dimensions.--Diameter of the shell 0.3, pores 0.015, bars 0.015; length of the main spines 0.25, basal breadth 0.03.

Habitat.--North Pacific (Japan), Station 234, surface.

Subgenus 2. Heliosphæromma, Haeckel.

Definition.--Pores of the shell irregular, of different size or form.

10. Heliosphæra polygonaria, n. sp.

Shell very thin walled, with thread-like bars and irregular, polygonal pores (having four to eight angles, commonly five to seven); eight to ten on the radius. Radial spines at all the nodal-points of the network, bristle-shaped; forty to sixty main spines, as long as the radius, twice as thick as the numerous by-spines, which are not larger than one mesh.

Dimensions.--Diameter of the shell 0.15 to 0.2, pores 0.012 to 0.02, bars 0.001; length of the main spines 0.08 to 0.1.

Habitat.--Central Pacific, Stations 266 to 272, surface.

11. Heliosphæra heteracantha, n. sp.

Shell thin walled, with irregular, polygonal pores, twice to four times as broad as the bars; six to eight on the radius. Twenty radial main spines, three-sided pyramidal, nearly as long as the diameter of the shell, as broad as a larger mesh; innumerable bristle-shaped by-spines variously distributed on the bars and at the nodal-points of the net; half as long as the radius.

Dimensions.--Diameter of the shell 0.12, pores 0.006 to 0.012, bars 0.003; length of the main spines 0.1, basal breadth 0.012.

Habitat.--Equatorial Atlantic, Station 347, surface.

12. Heliosphæra hyperionis, n. sp.

Shell thick walled. Pores irregular, roundish, with polygonal frames, three to six times as broad as the bars; twelve to fourteen on the radius. Thirty to forty main spines, angular, pyramidal, scarcely as long as the radius and twice as long as the numerous bristle-shaped by-spines.

Dimensions.--Diameter of the shell 0.24, pores 0.006 to 0.012, bars 0.002; length of the main spines 0.1, basal breadth 0.012.

Habitat.--North Pacific, Station 256, surface.

13. Heliosphæra elector, n. sp.

Shell thick walled, with irregular, roundish pores, twice to three times as broad as the bars; eight to ten on the radius. Twenty main spines, three-sided pyramidal, somewhat longer than the radius and four times as long as the short bristle-shaped by-spines.

{221}Dimensions.--Diameter of the shell 0.12, pores 0.005 to 0.01, bars 0.003; length of the main spines 0.08, basal breadth 0.01.

Habitat.--South Atlantic, Station 325, surface.

14. Heliosphæra solaris, n. sp.

Shell thick walled, with irregular, roundish pores, about the same breadth as the bars; six to eight on the radius. Fifty to eighty main spines, conical, as long as the radius; by-spines very numerous, also conical, but only as large as one pore.

Dimensions.--Diameter of the shell 0.15, pores and bars 0.006 to 0.008; length of the main spines 0.08, basal breadth 0.012.

Habitat.--Central Pacific, Station 268, depth 2900 fathoms.

Genus 90. Conosphæra,[124] Haeckel, 1881, Prodromus, p. 451.

Definition.--#Astrosphærida# with one simple latticed sphere, covered with radial spines having the form of hollow cones with porous walls.

The genus Conosphæra differs from Acanthosphæra in the peculiar formation of the radial spines, which are not simple solid sticks, but hollow cones with porous walls, as immediate elevations of the hollow sphere.

1. Conosphæra platyconus, n. sp.

Pores of the shell regular, circular, twice as broad as the bars; ten to twelve on the radius. Conical spines about sixty, regular, broader than they are high, with six to nine pores in the wall.

Dimensions.--Diameter of the shell 0.16, pores 0.008, bars 0.004; length of the spines 0.012, basal breadth 0.024.

Habitat.--Central Pacific, Station 272, depth 2600 fathoms.

2. Conosphæra orthoconus, n. sp. (Pl. 12, fig. 2).

Pores of the shell irregular, roundish, twice to three times as broad as the bars; fourteen to sixteen on the radius. Conical spines about forty, regular, higher than they are broad, as long as the radius, with sixteen to twenty pores in the wall.

Dimensions.--Diameter of the shell 0.2, pores 0.008 to 0.012, bars 0.004; length of the spines 0.05, basal breadth 0.03.

Habitat.--Central Pacific, Station 271, depth 2425 fathoms.

{222}3. Conosphæra plagioconus, n. sp. (Pl. 12, fig. 4).

Pores of the shell irregular, polygonal, twice to five times as broad as the bars; twenty to twenty-four on the radius. Conical spines about eighty, irregularly formed and scattered, with oblique (not radial) axes; about as high as broad, with eight to twelve pores in the wall.

Dimensions.--Diameter of the shell 0.25, pores 0.005 to 0.015, bars 0.003; length of the spines 0.02, basal breadth 0.02.

Habitat.--Central Pacific, Station 265, depth 2900 fathoms.

Genus 91. Coscinomma,[125] n. gen.

Definition.--#Astrosphærida# with one simple lattice-sphere, covered with simple radial spines; the pores between them prolonged into hollow, conical, or cylindrical tubuli.

The genus Coscinomma exhibits among the Astrosphærida the same peculiar formation that distinguishes Ethmosphæra and Sethosphæra among the Liosphærida; each pore of the simple shell is prolonged into a short conical or cylindrical tubulus, as a rule either on the outside or on the inside of the shell, but sometimes on both sides.

Subgenus 1. Coscinommarium, Haeckel.

Definition.--Pores prolonged into short tubes both on the inside as well as the outside of the shell.

1. Coscinomma amphisiphon, Haeckel (Pl. 26, figs. 1, 1_a_, 1_b_).

Pores regular, circular, hexagonally framed, twice as broad as the bars, prolonged on the inside as well as on the outside of the shell into a short truncated conical tube; fifteen to eighteen pores on the radius. In each hexagon-corner arises a bristle-shaped radial spine, half as long as the radius.

Dimensions.--Diameter of the shell 0.22, pores 0.01, bars 0.005; length of the spines 0.1.

Habitat.--Central Pacific, Station 271, surface.

Subgenus 2. Coscinommidium, Haeckel.

Definition.--Pores prolonged into external tubes on the outside of the shell.

2. Coscinomma ectosiphon, n. sp.

Pores regular, circular, hexagonally framed, twice as broad as the bars, prolonged on the outside of the shell into a short truncated conical tube; ten to twelve pores on the radius. In each {223}hexagon-corner arises a short bristle-shaped spine, twice as long as the tube, one-third as long as the radius. (Very similar to Ethmosphæra conulosa, Pl. 12, fig. 5, but differs in the possession of radial spines.)

Dimensions.--Diameter of the shell 0.2, pores 0.012, bars 0.006; length of the spines 0.04, of the tubes 0.02.

Habitat.--North Pacific, Station 253, surface.

3. Coscinomma macrosiphon, n. sp.

Pores regular, circular, without hexagonal frames, of the same breadth as the bars, prolonged on the outside of the shell into a long cylindrical tube, half as long as the radius (eight to nine pores on the radius); between them bristle-shaped, at the base conical, radial spines of double length.

Dimensions.--Diameter of the shell 0.16, pores and bars 0.008; length of the spines 0.08, of the tubes 0.04.

Habitat.--Central Pacific, Station 274, surface.

Subgenus 3. Coscinommonium, Haeckel.

Definition.--Pores prolonged into internal tubes on the inside of the shell.

4. Coscinomma endosiphon, n. sp.

Pores regular, circular, hexagonally framed, twice as broad as the bars (fourteen to sixteen on the radius), prolonged on the inside of the shell into a short truncated cylindrical tube. In each hexagon-corner arises a thin, bristle-shaped, radial spine with pyramidal base, half as long as the radius, twice as long as the tube.

Dimensions.--Diameter of the shell 0.25, pores 0.012, bars 0.006; length of the spines 0.066, of the tubes 0.03.

Habitat.--South Pacific, Station 288, surface.

Genus 92. Cladococcus,[126] J. Müller, 1856, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 485.

Definition.--#Astrosphærida# with one simple lattice-sphere, covered with branched radial spines (the stem of the spine never forked).

The genus Cladococcus, together with the following Elaphococcus, is distinguished from the other Coscinommida by the ramification of the radial spines covering the surface of the simple hollow lattice-sphere. In Cladococcus each spine sends out three or more lateral branches, which are either simple or again ramified; but the stem of the spine itself is not forked, as in Elaphococcus.

{224}Subgenus 1. Cladococcalis, Haeckel.

Definition.--Branches of the spines simple, not ramified. Pores regular, all of nearly equal size and similar form.

1. Cladococcus arborescens, J. Müller.

Cladococcus arborescens, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 31, Taf. i. fig. 2.

Pores of the spherical shell regular, hexagonal, three times as broad as the bars; three to four on the radius. Ten to twenty spines, three-sided prismatic, two to three times as long as the shell diameter; towards the distal end each spine with three branches (one lateral simple straight branch on each edge of the spine).

Dimensions.--Diameter of the shell 0.1, pores 0.012, bars 0.004; length of the spines 0.2 to 0.3, breadth 0.02.

Habitat.--Mediterranean (Nice); North Atlantic, Canary Islands, surface.

2. Cladococcus spinifer, Haeckel.

Cladococcus spinifer, Haeckel, 1862, Monogr. d. Radiol., p. 368, Taf. xiii. fig. 9.

Pores regular, circular, hexagonally framed, three times as broad as the bars; five to six on the radius. Radial spines, arising from all the nodal-points of the network, three-sided, longer than the shell diameter, with six to twelve simple verticillate branches (two to four branches on each edge).

Dimensions.--Diameter of the shell 0.08, pores 0.01, bars 0.003; length of the spines 0.1, breadth 0.03.

Habitat.--Mediterranean (Messina), surface.

3. Cladococcus penicillus, n. sp.

Pores subregular, hexagonal, twice as broad as the bars; eight to ten on the radius. Sixty to eighty radial spines, three-sided prismatic, pencil-shaped, longer than the shell diameter; each at the distal end with a brush or pencil composed of nine to twenty-one short, simple, curved branches (three to seven on each edge).

Dimensions.--Diameter of the shell 0.1, pores 0.006, bars 0.003; length of the spines 0.12 to 0.16, breadth 0.006.

Habitat.--Central Pacific, Station 271, surface.

Subgenus 2. Cladococcinus, Haeckel.

Definition.--Branches of the spines simple, not ramified. Pores irregular, of different size or form.

{225}4. Cladococcus antarcticus, n. sp.

Pores irregular, polygonal, twice to four times as broad as the bars; five to six on the radius. Forty to fifty radial spines, angular, curved, of variable size and form, with three to nine irregular, simple, blunt curved branches.

Dimensions.--Diameter of the shell 0.14, pores 0.01 to 0.02, bars 0.05; length of the spines 0.1 to 0.18, breadth 0.007.

Habitat.--Antarctic Ocean, Station 157, depth 1950 fathoms.

5. Cladococcus japonicus, n. sp.

Pores irregular, roundish, of the same breadth as the bars; six to eight on the radius. Twenty to thirty radial spines, angular, longer than the shell diameter, with thirty to forty simple branches, decreasing in size from the middle part of the spine to the distal end (ten to thirteen branches on each edge).

Dimensions.--Diameter of the shell 0.12, pores and bars 0.007; length of the spines 0.15 to 0.2, breadth 0.004.

Habitat.--North Pacific (Japan), Station 240, surface.

6. Cladococcus quadricuspis, n. sp.

Pores irregular, roundish, twice to eight times as broad as the bars; eight to ten on the radius. About twenty radial spines, three-sided prismatic, as long as the shell diameter; in the proximal half simple, with smooth edges; in the distal half with three diverging simple branches, half the length of the spine, with dentated edges.

Dimensions.--Diameter of the shell 0.15, pores 0.004 to 0.016, bars 0.002; length of the spines 0.17, breadth 0.01.

Habitat.--Central Pacific, Station 265, depth 2900 fathoms.

Subgenus 3. Cladococcodes, Haeckel.

Definition.--Branches of the spines again ramified. Pores regular, of nearly equal size and similar form.

7. Cladococcus scoparius, n. sp. (Pl. 27, fig. 2).

Pores regular, circular, three times as broad as the bars; five to six on the radius. Twenty radial spines, broom-shaped, three times as long as the shell diameter; in the proximal half simple, in the distal half branched, with three to nine branches, which are again ramified; spines and their branches with three smooth edges, not dentated.

Dimensions.--Diameter of the shell 0.055, pores 0.0075, bars 0.0025; length of the spines 0.15, basal thickness 0.007.

Habitat.--Central Pacific, Station 271, surface.

{226}8. Cladococcus viminalis, Haeckel.

Cladococcus viminalis, Haeckel, 1862, Monogr. d. Radiol., p. 369, Taf. xiv. figs. 2, 3.

Pores regular, circular, hexagonally framed, four times as broad as the bars; five to six on the radius. Radial spines, arising from all the nodal-points of the network, twice as long as the shell diameter; in the basal half simple, in the distal half with three to six long, thin, curved branches, which are partly forked; three edges of the spines dentated.

Dimensions.--Diameter of the shell 0.08, pores 0.01, bars 0.003; length of the radial spines 0.16, basal breadth 0.003.

Habitat.--Mediterranean (Messina).

9. Cladococcus bifurcus, Haeckel.

Cladococcus bifurcus, Haeckel, 1862, Monogr. d. Radiol., p. 368, Taf. xiii. figs. 7, 8.

Pores regular, circular, hexagonally framed, four times as broad as the bars; five to seven on the radius. Radial spines arising from all the nodal-points, three-sided prismatic, with dentated edges, longer than the shell diameter. On each spine six to nine branches, which are for the most part forked, the distal branches only being simple. (May be regarded as a further developmental stage of Cladococcus spinifer and Cladococcus viminalis.)

Dimensions.--Diameter of the shell 0.08, pores 0.01, bars 0.0025; length of the spines 0.1, basal breadth 0.003.

Habitat.--Mediterranean (Messina), Canary Islands, Azores, surface.

10. Cladococcus pinetum, n. sp. (Pl. 27, fig. 1).

Pores regular, circular, polygonally framed, about the same breadth as the bars: two to three on the radius. About twenty radial spines, very large, three to four times as long as the shell diameter, branched like a pine tree, with straight, stout, three-sided prismatic stem; three prominent edges dentated. On each edge five to seven lateral branches, the distal ends of which are simple, the proximal again ramified, with numerous ramules. The figured specimen is a young one, with branches but little developed.

Dimensions.--Diameter of the shell 0.06, pores and bars 0.008; length of the spines 0.2 to 0.25 breadth 0.01.

Habitat.--Central Pacific, Station 266 to 274, surface.

Subgenus 4. Cladococcurus, Haeckel.

Definition.--Branches of the spines again ramified. Pores irregular, of different size and form.

11. Cladococcus abietinus, n. sp. (Pl. 27, fig. 3).

Pores irregular, roundish, twice to four times as broad as the bars; six to ten on the radius. About twenty radial spines, two to three times as long as the shell diameter, branched like a pine {227}tree, with straight, stout, three-sided pyramidal stem. From the dentated edges arise numerous verticillate branches, the proximal ends of which are thickly ramified. (Differs from the preceding and similar species mainly in the large size and irregular lattice-work of the shell.)

Dimensions.--Diameter of the shell 0.12 to 0.14, pores 0.006 to 0.012, bars 0.003; length of the spines 0.25 to 0.4, breadth 0.012.

Habitat.--North Pacific, Station 256, surface.

12. Cladococcus tricladus, n. sp.

Pores irregular, polygonal, twice to eight times as broad as the bars; eight to ten on the radius. About twenty radial spines, three-sided prismatic, twice as long as the shell diameter; in the proximal half simple, with smooth edges; in the distal half with three diverging curved branches, which bifurcate two to three times or ramify irregularly. (Closely related to the simpler Cladococcus quadricuspis.)

Dimensions.--Diameter of the shell 0.16, pores 0.04 to 0.016, bars 0.002; length of the spines 0.3, breadth 0.012.

Habitat.--Central Pacific, Station 268, depth 2900 fathoms.

13. Cladococcus stalactites, n. sp. (Pl. 27, fig. 4).

Pores irregular, roundish, once to five times as broad as the bars; eight to ten on the radius. About twenty radial spines, very stout, longer than the shell diameter, with three wing-like, prominent smooth edges. At the middle, or in the distal half, each spine bears a verticil of three strong, irregularly formed ramified branches.

Dimensions.--Diameter of the shell 0.14, pores 0.003 to 0.015, bars 0.003; length of the spines 0.16 to 0.2, breadth 0.02.

Habitat.--West Tropical Pacific, Station 220, depth 1100 fathoms.

14. Cladococcus dendrites, n. sp. (Pl. 27, fig. 5).

Pores irregular, roundish, with denticulate margin, twice to four times as broad as the bars; eight to twelve on the radius. Fifty to eighty radial spines, three-sided prismatic, with elegantly denticulated edges; in the proximal two-thirds simple, in the distal third with a bunch of ten to twenty short simple spines (three to seven on each edge).

Dimensions.--Diameter of the shell 0.16 to 0.2, pores 0.006 to 0.012, bars 0.003; length of the spines 0.2 to 0.3, breadth 0.01.

Habitat.--Antarctic Ocean, Station 157, depth 1950 fathoms.

Genus 93. Elaphococcus,[127] Haeckel, 1881, Prodromus, p. 450.

Definition.--#Astrosphærida# with one simple lattice-sphere, covered with forked or dichotomously branched radial spines (the stem of the spine always forked).

{228}The genus Elaphococcus differs from the preceding Cladococcus in the mode of ramification of the radial spines. These are forked; and the forked branches are either simple, again forked, or dichotomously ramified.

Subgenus 1. Elaphococcinus, Haeckel.

Definition.--Pores of the shell regular, of nearly equal size and similar form.

1. Elaphococcus furcatus, n. sp.

Pores of the spherical shell regular, hexagonal, four times as broad as the bars; four to five on the radius. Radial spines, arising from all the nodal-points of the network, cylindrical, as long as the radius, simply forked at the distal end; both branches half as long as the undivided part.

Dimensions.--Diameter of the shell 0.08, pores 0.01, bars 0.0025; length of the spines 0.04, breadth 0.004.

Habitat.--Tropical Atlantic, Station 348, surface.

2. Elaphococcus cervicornis, Haeckel.

Cladococcus cervicornis, Haeckel, 1862, Monogr. d. Radiol., p. 370, Taf. xiv. figs. 4-6.

Pores regular, hexagonal, ten to twenty times as broad as the bars; five to seven on the radius. Fifty to ninety radial spines (or more), arising not only from the nodal-points of the network but also from the bars between them. Each spine is cylindrical, longer than the shell diameter, and repeatedly forked (three to six times), having, therefore, numerous (thirty to sixty or more) curved branches. The distal ends of all branches fall in one spherical face.

Dimensions.--Diameter of the shell 0.07 to 0.09, pores 0.01 to 0.015, bars 0.001 to 0.015; length of the spines 0.1 to 0.15, breadth 0.005.

Habitat.--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface.

3. Elaphococcus elaphoceras, n. sp.

Pores regular, circular, hexagonally framed, three to four times as broad as the bars; six to eight on the radius. At each nodal-point of the hexagon arises a short bristle-shaped, simple by-spine. In addition, there arise from the bars thirty to sixty large main spines, longer than the shell diameter, repeatedly forked in the same way as in the preceding species.

Dimensions.--Diameter of the shell 0.1, pores 0.008, bars 0.002; length of the spines 0.12, breadth 0.002.

Habitat.--Central Pacific, Station 272. depth 2600 fathoms.

4. Elaphococcus umbellifer, n. sp.

Pores regular, circular, three times as broad as the bars; ten to twelve on the radius. Twenty to forty straight cylindrical spines, as long as the shell diameter, having at the distal end a regular {229}umbel composed of nine to twelve curved branches of equal length, which are again ramified and resemble the inflorescence of an umbelliferous plant, the distal ends of all ramules falling in a spherical face.

Dimensions.--Diameter of the shell 0.12, pores 0.006, bars 0.002; length of the spines 0.14, breadth 0.002.

Habitat.--South Atlantic, Station 325, surface.

Subgenus 2. Elaphococculus, Haeckel.

Definition.--Pores of the shell irregular, of different size or form.

5. Elaphococcus dichotomus, n. sp.

Pores irregular, polygonal, twice to four times as broad as the bars; six to eight on the radius. Thirty to sixty radial spines cylindrical, curved, as long as the shell diameter, simply forked at the distal end; both branches one-third as long as the undivided part.

Dimensions.--Diameter of the shell 0.15, pores 0.007 to 0.015, bars 0.004; length of the spines 0.2, breadth 0.004.

Habitat.--Arctic Ocean, Greenland, surface (Koch).

6. Elaphococcus umbellatus, n. sp.

Pores irregular, roundish, or polygonal, twice to five times as broad as the bars; six to eight on the radius. Forty to sixty radial spines cylindrical, curved, as long as the shell radius, having at the distal end an irregular umbel, composed of six to twelve short branches, which are irregularly ramified or forked. (Differs from the regular Elaphococcus umbellifer mainly in the irregularity.)

Dimensions.--Diameter of the shell 0.14, pores 0.007 to 0.015, bars 0.003; length of the spines 0.12, breadth 0.01.

Habitat.--South-east Pacific (Juan Fernandez), Station 299, surface.

7. Elaphococcus drymodes, n. sp.

Pores irregular, roundish, little broader than the bars; ten to twelve on the radius. Eighty to one hundred and twenty (or more) radial spines, cylindrical, three to four times as long as the shell diameter, irregularly forked or repeatedly dichotomous (each spine with forty to sixty forked branches); the distal ends of all branches fall in a spherical plane. (Differs from the regular Elaphococcus cervicornis mainly in the irregularity.)

Dimensions.--Diameter of the shell 0.1, pores and bars 0.003 to 0.008; length of the spines 0.3 to 0.4, breadth 0.01.

Habitat.--Arctic Ocean, Iceland (Steenstrup).

{230}Subfamily HALIOMMIDA,[128] Haeckel.

Diplosphærida, Haeckel, 1881, Prodromus, pp. 449, 451.

Definition.--#Astrosphærida# with two concentric spherical lattice-shells, united by radial beams.

Genus 94. Haliomma,[129] Ehrenberg, 1838, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 128.

Definition.--#Astrosphærida# with one medullary (intracapsular) and one cortical (extracapsular) shell, which are connected by radial beams, piercing the central capsule. Shell surface covered with simple radial spines of the same kind.

The genus Haliomma, one of the oldest known Radiolarian genera, contained in the catalogue of its discoverer, Ehrenberg, a large number of very different #Sphærellaria#, belonging to at least sixteen different genera. We limit here the conception of the genus to those Haliommida which bear simple radial spines of one kind on the surface of the cortical shell (the latter being separated from the medullary shell by the central capsule).

Subgenus 1. Haliommantha, Haeckel.

Definition.--Pores of the cortical shell regular, of nearly equal size and similar form; spines on the whole surface (commonly one spine at each nodal-point).

1. Haliomma hexagonium, n. sp.

Cortical shell four times as broad as the medullary shell, both having very thin thread-like bars, and regular, hexagonal pores (eighteen to twenty on the radius of the outer, five to six on the radius of the inner shell). The two shells connected by twenty thin thread-like radial beams. At each nodal-point of the outer shell arises a bristle-shaped radial spine, half as long as the radius. (Similar to Heliosoma radians, Pl. 28, fig. 3, but with all the spines equal.)

Dimensions.--Diameter of the outer shell 0.2, inner 0.05; pores of the outer 0.015, of the inner 0.01; length of the spines 0.05.

Habitat.--Equatorial Atlantic, Station 347, surface.

2. Haliomma arachnium, n. sp.

Cortical shell three times as broad as the medullary shell; pores of the former regular, hexagonal, with very thin thread-like bars (fourteen to sixteen on the radius); pores of the latter regular, {231}circular, three times as broad as the bars (four to five on the radius). The two shells connected by about forty radial beams. At each nodal-point of the outer shell arises one bristle-shaped radial spine, twice as long as the diameter of one hexagonal mesh.

Dimensions.--Diameter of the outer shell 0.15, inner 0.05; pores of the outer 0.012, of the inner 0.006; length of the spines 0.025.

Habitat.--Central Pacific, Station 266, surface.

3. Haliomma favosum, n. sp.

Cortical shell thick walled, three times as broad as the medullary shell, with regular, circular, hexagonally framed pores, twice as broad as the bars; eight to ten on the radius. Medullary shell with simple, circular pores, of the same breadth as the bars. At each nodal-point of the outer shell arises a short triangular spine three times as long as one pore.

Dimensions.--Diameter of the outer shell 0.12, inner 0.04; pores of the former 0.01, of the latter 0.005; bars 0.005; length of the spines 0.015.

Habitat.--Central Pacific, Station 271 to 274, surface.

4. Haliomma regulare, n. sp.

Cortical shell thin walled, nearly twice as broad as the medullary shell, and connected with it by forty to sixty thin radial beams. Both shells of the same perfectly regular structure, with an identical number of regular, circular pores, which are hexagonally framed, four times as broad as the bars, nine to eleven on the radius. The outer pores are twice as broad as the inner, exactly corresponding pores. Between every three pores of the outer surface (in each corner of the cortical hexagon) arises one short three-sided pyramidal spine, twice as long as the diameter of one pore.

Dimensions.--Diameter of the outer shell 0.2, of the inner 0.11; pores of the former 0.018, of the latter 0.009; length of the spines 0.04.

Habitat.--South Atlantic (Tristan da Cunha), Station 332, depth 2200 fathoms.

5. Haliomma melitomma, n. sp. (Pl. 20, fig. 4).

Melitomma formosum, Haeckel, 1879, Atlas, loc. cit.

Cortical shell thick walled, two and a half times as broad as the medullary shell, with regular pores of very elegant structure, twice as broad as the bars; eight to ten on the radius. The inner opening of each pore is simple, circular, the outer regular, six-lobed; corresponding to the six lobes are six short conical spines, which arise from the six corners of the regular hexagonal frames separating the pores. Pores of the medullary shell simple, circular, of the same breadth as the bars. The two shells connected only by six radial beams (in three dimensive axes).

Dimensions.--Diameter of the outer shell 0.17, of the inner 0.07; pores of the former 0.012, of the latter 0.004; length of the spines 0.005 to 0.01.

Habitat.--Indian Ocean, Zanzibar, Pullen, depth 2200 fathoms.

{232}6. Haliomma lirianthus, n. sp. (Pl. 28, figs. 1, 1_a_, 1_b_).

Cortical shell thick walled, three times as broad as the medullary shell, with regular, rosette-shaped pores, twice as broad as the bars; eight to ten on the radius. The regular structure of the elegant pores is the same as in the preceding species, but without prominent crested frames (fig. 1_b_). Also the medullary shell (fig. 1_a_) is different, much thinner and smaller, with simple, circular pores, which are three times as broad as the bars. The two shells are connected by numerous (twenty?) radial beams.

Dimensions.--Diameter of the outer shell 0.15, of the inner 0.05; pores of the former 0.01, of the latter 0.005; length of the spines 0.005 to 0.02.

Habitat.--Central Pacific, Station 271, depth 2425 fathoms.

7. Haliomma castanea, Haeckel.

Haliomma castanea, Haeckel, 1862, Monogr. d. Radiol., p. 428, Taf. xxiv. fig. 4.

Cortical shell thick walled, three times as broad as the medullary shell; pores of both regular, circular, twice as broad as the bars (seven to eight on the radius of the outer, four to five on the radius of the inner shell), the two connected by six to twelve (?) strong radial beams. Radial spines bristle-shaped, with conical bases, twice as long as the diameter of the cortical pores (one spine at the nodal-point between every three pores).

Dimensions.--Diameter of the outer shell 0.1 to 0.15, inner 0.03 to 0.05; pores of the former 0.005, of the latter 0.003; length of the spines 0.005 to 0.01.

Habitat.--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface.

8. Haliomma horridum, Stöhr.

Haliomma horridum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 87, Taf. i. fig. 10.

Cortical shell thick walled, two and a half times as broad as the medullary shell. Pores regular, circular, of the same breadth as the bars; eight to ten on the radius. Radial spines conical, stout, nearly half as long as the radius. (Differs from the closely allied Haliomma castanea in the smaller pores and larger spines.)

Dimensions.--Diameter of the outer shell 0.14, of the inner 0.06; pores of the former 0.004, of the latter 0.02.

Habitat.--Fossil in Tertiary rocks of Barbados and Sicily; living in the Atlantic, Station 9, depth 3150 fathoms, and Station 353, depth 2965 fathoms.

9. Haliomma datura, n. sp.

Cortical shell thin walled, only one and a half times as broad as the medullary shell, both having regular, circular pores, four to six times as broad as the bars (five to six on the radius of the outer, three to four on the radius of the inner shell), the two connected by numerous (forty to sixty?) thin, short, radial beams. Radial spines conical, twice as long as the diameter of one cortical pore, arising from all the nodal-points between them.

{233}Dimensions.--Diameter of the outer shell 0.08 to 0.12, inner 0.06 to 0.08; pores of the former 0.015 to 0.02, of the latter 0.007 to 0.012; length of the spines 0.02.

Habitat.--Central Pacific, Stations 268 to 274, surface.

Subgenus 2. Haliommetta, Haeckel.

Definition.--Pores of the cortical shell regular, of nearly equal size and similar form; the spines not covering the entire surface, but scattered at intervals (their number smaller than that of the nodal-points of the network).

10. Haliomma circumtextum, n. sp. (Pl. 28, figs. 7, 7_a_).

Cortical shell very delicate, with thin thread-like bars, and regular, hexagonal pores, little larger than the thick-walled medullary shell (= 7 : 6). Pores of the latter regular, circular, double-edged, with hexagonal frames, of the same breadth as the bars; from all the hexagon-corners arise thin bristle-shaped, radial spines, twice as long as the diameter of the pores, becoming connected at equal distances from the centre by tangential threads, regularly disposed, forming the cortical shell. Twelve strong, three-sided pyramidal, radial spines, as broad at the base as one mesh, and about half as long as the radius of the shell.

Dimensions.--Diameter of the outer shell 0.14, of the inner 0.12; pores of the former 0.012, of the latter 0.005; length of the radial spines 0.04, basal breadth 0.012.

Habitat.--Central Pacific, Station 271, depth 2425 fathoms.

11. Haliomma duodecinum, n. sp.

Cortical shell thick walled, three times as broad as the medullary shell. Both shells with regular, circular pores, twice as broad as the bars; eight to ten on the radius of the outer, five to six on the radius of the inner shell. Twelve conical, regularly disposed radial spines, as long as the radius, and as broad at the base as one mesh.

Dimensions.--Diameter of the outer shell 0.12, of the inner 0.04; pores of the former 0.005, of the latter 0.002; length of the spines 0.05, basal breadth 0.005.

Habitat.--Central Pacific, Station 265, depth 2900 fathoms.

12. Haliomma megaporum, Ehrenberg.

Haliomma megaporum, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 313.

Cortical shell thin walled, three times as broad as the medullary shell; the pores regular, circular, three to four on the radius, eight times as broad as the bars, quite as broad as the medullary shell, the pores of which are much smaller, twice as broad as the bars. Eight radial spines regularly disposed, conical, as long as the radius. (As the diagnosis of Ehrenberg is very {234}incomplete, and no figure is given with it, it remains doubtful whether his Mediterranean species be identical with my Atlantic variety.)

Dimensions.--Diameter of the outer shell 0.12, of the inner 0.04; pores of the former 0.04, of the latter 0.008; length of the spines 0.06.

Habitat.--Mediterranean (Grecian shore); North Atlantic, Station 354, surface.

13. Haliomma oculatum, Ehrenberg.

Haliomma oculatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, Taf. xxviii. figs. 2, 3.

Cortical shell thick walled, four times as broad as the medullary shell; its pores regular, circular, four times as broad as the bars, six to eight on the radius. Pores of the medullary shell regular, hexagonal, with very thin bars, three to four on the radius. Nine radial spines, regularly disposed, conical, as long as the radius, as broad at the base as one cortical pore. (In the specimen figured by Ehrenberg, only two spines were preserved, seven being accidentally broken off.)

Dimensions.--Diameter of the outer shell 0.16, of the inner 0.04; pores of the former 0.01, of the latter 0.005.

Habitat.--Fossil in Barbados.

14. Haliomma enneaxiphos, n. sp.

Cortical shell thick walled, four times as broad as the dark medullary shell, with regular, circular, hexagonally framed pores, twice as broad as the bars; eight to ten on the radius. Nine radial spines regularly disposed, three sided pyramidal, as long as the radius, as broad at the base as one mesh.

Dimensions.--Diameter of the outer shell 0.11, of the inner 0.03; cortical pores 0.008, bars 0.004; length of the radial spines 0.05, basal breadth 0.012.

Habitat.--Central Pacific, Station 272, surface.

15. Haliomma tenuispinum, J. Müller.

Haliomma tenuispinum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 39, Taf. iv. fig. 9.

Haliomma tenuispinum, Haeckel, 1862, Monogr. d. Radiol., p. 431.

Cortical shell thin walled, three times as broad as the medullary shell. Both shells with very fine, thread-like bars, and regular, hexagonal pores; five to seven on the radius. Twenty radial spines, very thin, bristle-shaped, as long as the radius.

Dimensions.--Diameter of the outer shell 0.12, of the inner 0.04; pores of the former 0.016, of the latter 0.006.

Habitat.--Mediterranean (Nice); North Atlantic, Station 353, surface.

{235}16. Haliomma longispinum, J. Müller.

Haliomma longispinum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 39, Taf iv. fig. 8.

Haliomma longispinum, Haeckel, 1862, Monogr. d. Radiol., p. 431.

Cortical shell thick walled, three times as broad as the dark medullary shell. Pores regular, circular, hexagonally framed, twice as broad as the bars; four to six on the radius. Twenty radial spines, very long, regularly disposed, four to five times as long as the diameter of the shell, three-sided prismatic, with elegantly dentated edges, as broad as one cortical mesh.

Dimensions.--Diameter of the outer shell 0.08, of the inner 0.03; pores of the former 0.01, bars 0.005; length of the spines 0.3 to 0.4.

Habitat.--Mediterranean (Nice); Central Pacific, Station 272, surface.

17. Haliomma capense, n. sp.

Cortical shell thick walled, twice as broad as the medullary shell, both with regular, circular pores, twice as broad as the bars; eight to ten on the radius of the outer, four to six on the radius of the inner shell. Forty to sixty radial spines, conical, as long as the radius, as broad as one cortical pore.

Dimensions.--Diameter of the outer shell 0.11, of the inner 0.05; pores of the former 0.01, bars 0.005; length of the spines 0.006, basal breadth 0.012.

Habitat.--Cape of Good Hope, Station 142, surface.

18. Haliomma denticulatum, n. sp.

Cortical shell thick walled, three times as broad as the dark medullary shell, with regular, circular, double-edged pores, of the same breadth as the bars; eight to ten on the radius. Thirty to fifty radial spines, three-sided pyramidal, half as long as the radius, with three denticulated edges. (Very similar to Actinomma denticulatum, Pl. 29, fig. 3, but with simple medullary shell.)

Dimensions.--Diameter of the outer shell 0.12, inner 0.04; pores and bars of the former 0.008; length of the spines 0.04, basal breadth 0.01.

Habitat.--North Pacific, Station 244, depth 2900 fathoms.

19. Haliomma grande, n. sp.

Cortical shell thick walled, five times as broad as the dark medullary shell, with small, regular, circular pores, half as broad as the bars; twenty to twenty-four on the radius. One hundred to one hundred and twenty conical radial spines, five times as long as broad, only half as long as the radius.

Dimensions.--Diameter of the outer shell 0.4, inner 0.08; pores of the outer 0.006, bars 0.012; length of the spines 0.1, basal breadth 0.02.

Habitat.--Equatorial Atlantic, Station 348, depth 2450 fathoms.

{236}Subgenus 3. Haliommilla, Haeckel.

Definition.--Pores of the cortical shell irregular, of different size and form; spines covering the entire surface (commonly one spine at each nodal-point).

20. Haliomma capillaceum, Haeckel.

Haliomma capillaceum, Haeckel, 1862, Monogr. d. Radiol., p. 426, Taf. xxiii. fig. 2.

Cortical shell very thin walled, seven to eight times as broad as the medullary shell, both with irregular, polygonal pores, and very thin thread-like bars; outer pores twice to three times as broad as the inner. Radial spines very numerous, straight, bristle-shaped, about as long as the diameter of the medullary shell.

Dimensions.--Diameter of the outer shell 0.2, inner 0.025 to 0.03; outer pores 0.02 to 0.04, inner 0.008 to 0.016, bars 0.001; length of the spines 0.02 to 0.03.

Habitat.--Mediterranean (Messina), Atlantic (Canary Islands), surface.

21. Haliomma erinaceum, Haeckel.

Haliomma erinaceum, Haeckel, 1862, Monogr. d. Radiol., p. 427, Taf. xxiii. figs. 3, 4.

Cortical shell thin walled, seven to eight times as broad as the medullary shell, both with irregular, polygonal pores, two to ten times as broad as the bars, outer pores much larger than the inner. Radial spines very numerous, bristle-shaped, as long as the diameter of the medullary shell, the majority or all being either curved or obliquely depressed, the greater part neither straight nor radial.

Dimensions.--Diameter of the outer shell 0.2, inner 0.025 to 0.03; outer pores 0.005 to 0.03, inner 0.008 to 0.016, bars 0.002 to 0.004; length of the spines 0.03.

Habitat.--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.

22. Haliomma tenellum, Haeckel.

Haliomma tenellum, Haeckel, 1862, Monogr. d. Radiol., p. 428.

Haliomma spinuloso affine, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 40, Taf. iv. fig. 7.

Cortical shell thin walled, three times as broad as the medullary shell, with irregular, roundish pores, and very thin bars. Pores of the inner shell regular, circular. Radial spines very numerous, bristle-shaped, straight, as long as the radius of the outer shell.

Dimensions.--Diameter of the outer shell 0.15, inner 0.05; outer pores 0.008 to 0.016, inner 0.005; length of the spines 0.07.

Habitat.--Mediterranean (Nice); Atlantic, Stations 349 to 354, surface.

{237}23. Haliomma spinulosum, J. Müller.

Haliomma spinulosum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 39, Taf. iv. fig. 6.

Cortical shell thin walled, twice as broad as the medullary shell, with irregular, polygonal pores, and very thin bars. Pores of the inner shell subregular, hexagonal, ten to twelve times as broad as the bars. Radial spines very numerous, bristle-shaped, one-sixth to one-fourth as long as the radius of the outer shell.

Dimensions.--Diameter of the outer shell 0.16, inner 0.08; outer pores 0.01 to 0.03, inner 0.02; length of the spines 0.02 to 0.03.

Habitat.--Mediterranean (Nice); Central Pacific, Station 266, surface.

24. Haliomma rhodococcus, n. sp. (Pl. 19, fig. 6).

Sethosphæra rhodococcus, Haeckel, 1879, Atlas, pl. xix. fig. 6.

Cortical shell very thin walled, little larger than the thick walled medullary shell (= 10 : 9). Pores of the outer shell very irregular, roundish, twice to six times as broad as the bars, about twenty on the radius. Pores of the inner shell twice as broad as the bars, six to eight on the radius, very regular, circular on the inner, six-lobed on the outer opening, separated by prominent hexagonal crests; in the hexagon-corners arise short conical radial spines, which at equal distances from the centre are united by the outer shell, but are prominent over its surface. (A very peculiar form; the two shells may better be regarded as inner and outer cortical shell.)

Dimensions.--Diameter of the outer shell 0.2, inner 0.18; outer pores 0.04 to 0.012, inner 0.01; length of the spines 0.01.

Habitat.--Tropical Atlantic, Station 338, depth 1990 fathoms; also fossil in Barbados.

25. Haliomma boreale, n. sp.

Cortical shell thick walled, four times as broad as the medullary shell, with irregular, roundish pores, twice to four times as broad as the bars; eight to ten on the radius. Pores of the inner shell regular, circular, twice as broad as the bars, four to six on the radius. Radial spines very numerous, conical, nearly as long as the diameter of the shell.

Dimensions.--Diameter of the outer shell 0.24, inner 0.06; outer pores 0.008 to 0.02, bars 0.005, inner pores 0.006, bars 0.003; length of the spines 0.2.

Habitat.--Arctic Ocean, Greenland ("Alert" Expedition).

Subgenus 4. Haliommura, Haeckel.

Definition.--Pores of the cortical shell irregular, of different size and form; spines not covering the entire surface, but scattered at intervals (their number smaller than that of the nodal-points in the network).

{238}26. Haliomma macrodoras, n. sp. (Pl. 28, figs. 6, 6_a_).

Cortical shell thin walled, twice as broad as the medullary shell, with irregular, polygonal meshes, three to six times as broad as the bars. Inner shell with regular, hexagonal meshes, ten times as broad as the bars. Twenty radial spines, very long, stout, three-sided prismatic, two to four times as long as the diameter of the shell, as broad as one medullary mesh, with three wing-like, denticulated edges. At the base of each spine three supporting curved beams.

Dimensions.--Diameter of the outer shell 0.14 to 0.16, of the inner 0.07 to 0.08; outer pores 0.01 to 0.02, bars 0.003; inner pores 0.01, bars 0.001; length of the spines 0.3 to 0.6, breadth 0.01.

Habitat.--Central Pacific, Station 271, surface.

27. Haliomma antarcticum, n. sp.

Cortical shell very thin walled, three times as broad as the medullary shell, with irregular, polygonal pores, and very thin thread-like bars. Inner shell with regular, hexagonal meshes, six times as broad as the bars. About forty radial spines, angular, pyramidal, half as long as the radius of the shell, as broad at the base as the largest mesh.

Dimensions.--Diameter of the outer shell 0.2, of the inner 0.07; outer pores 0.006 to 0.015, inner 0.008; length of the spines 0.05, basal breadth 0.012.

Habitat.--Antarctic Ocean, Station 154, surface.

28. Haliomma wyvillei, Haeckel.

Haliomma wyvillei, Haeckel, 1878, Protistenreich, p. 44, fig. 31.

Haliomma species, Wyville Thomson, 1877, Atlantic, vol. i. p. 236, fig. 54.

Cortical shell thin walled, three times as broad as the medullary shell. Both shells with irregular, large, polygonal pores, and very thin bars. From the inner shell arise very numerous (eighty to one hundred and twenty or more) radial spines, which pierce the outer shell, and are outside it, as long as the radius of the inner shell, straight, bristle-shaped, and as thick as the bars.

Dimensions.--Diameter of the outer shell 0.18, of the inner 0.06; pores 0.01 to 0.02, bars 0.001 to 0.002; length of the free spines 0.06.

Habitat.--Central Pacific, Stations 266 to 274, surface.

29. Haliomma beroes, Ehrenberg.

Haliomma beroes, Ehrenberg, 1854, Mikrogeol., Taf. xxxvB. B. iv. fig. 19.

Haliomma beroes, Haeckel, 1862, Monogr. d. Radiol., p. 434.

Cortical shell thin walled, three times as broad as the medullary shell, with irregular, roundish pores, twice to four times as broad as the bars. Inner shell with regular, circular pores, twice as broad as the bars. Both shells connected by four (or six ?) radial beams, perpendicularly crossed. Thirty to forty radial spines, conical, thin, shorter than the radius.

Dimensions.--Diameter of the outer shell 0.11, inner 0.04; outer pores 0.007 to 0.012, inner 0.005; length of the spines 0.03, basal breadth 0.005.

Habitat.--Atlantic, depth 2000 fathoms.

{239}30. Haliomma compactum, n. sp. (Pl. 28, figs. 5, 5_a_).

Cortical shell very thick walled, four times as broad as the thin walled medullary shell; pores of the former irregular, roundish, with high polygonal frames of very different size, twice to four times as broad as the bars. Inner shell with simple, small, polygonal pores, connected with the outer shell by eight (?) regularly disposed thin radial beams, opposite in pairs, prolonged outside into strong conical spines, longer than the radius.

Dimensions.--Diameter of the outer shell 0.08, inner 0.02; outer pores 0.005 to 0.01, inner 0.005; length of the spines 0.06, basal breadth 0.012.

Habitat.--Central Pacific, Stations 265 to 272, depth 2425 to 2925 fathoms.

31. Haliomma permagnum, n. sp.

Cortical shell thick walled, six times as broad as the medullary shell, with irregular, roundish, double-edged pores, three to six times as broad as the bars. Inner shell with regular, circular pores, twice as broad as the bars. One hundred and twenty to one hundred and fifty radial spines, conical, only one-fourth as long as the radius.

Dimensions.--Diameter of the outer shell 0.42, inner 0.07; outer pores 0.012 to 0.025, bars 0.004; inner pores 0.008, bars 0.004; length of the spines 0.05, basal breadth 0.03.

Habitat.--Central Pacific, Station 268, surface.

32. Haliomma patagonicum, n. sp.

Cortical shell thick walled, four times as broad as the medullary shell, with irregular, roundish pores, twice to three times as broad as the bars. Inner shell also with irregular, roundish pores, of half the size. Forty to fifty radial spines, cylindro-conical, about as long as the shell diameter.

Dimensions.--Diameter of the outer shell 0.24, inner 0.06; outer pores 0.012 to 0.02, bars 0.006; inner pores 0.005 to 0.01, bars 0.004; length of the spines 0.3, breadth 0.02.

Habitat.--South-east Pacific, west coast of Patagonia, Station 302, surface.

33. Haliomma clavatum, n. sp.

Cortical shell thick walled, three times as broad as the medullary shell, with irregular, roundish pores little larger than the bars; eight to twelve on the radius. Inner shell with similar but smaller pores. About twenty radial spines, club-shaped, as long as the radius, three-sided, with prominent edges, twice as broad at the distal end as at the base. (Similar to Acanthosphæra clavata, Pl. 26, fig. 8, but differs from it in the possession of a medullary shell.)

Dimensions.--Diameter of the outer shell 0.2, inner 0.06; outer pores and bars 0.008 to 0.02, inner 0.006 to 0.01; length of the spines 0.1, distal breadth 0.03.

Habitat.--Central Pacific, Station 265, depth 2900 fathoms.

{240}Genus 95. Heliosoma,[130] Haeckel, 1881, Prodromus, p. 452.

Definition.--#Astrosphærida# with one medullary (intracapsular) and one cortical (extracapsular) shell, the two being connected by radial beams piercing the central capsule. Shell surface covered with simple radial spines of two different kinds; larger main spines and smaller by-spines.

The genus Heliosoma differs from the preceding Haliomma in the possession of two different kinds of radial spines, and exhibits therefore the same relation to it that Heliosphæra bears to Acanthosphæra among the Coscinommida. The smaller by-spines are much more numerous than the larger main spines.

Subgenus 1. Heliosomantha, Haeckel.

Definition.--Pores of the cortical shell regular, of nearly equal size and similar form.

1. Heliosoma radians, n. sp. (Pl. 28, figs. 3, 3_a_).

Cortical shell very thin walled, with thread-like bars and regular, hexagonal meshes; twenty to twenty-two on the radius. Medullary shell only one-fifth as large, of the same structure. The two shells connected by twenty very thin radial beams, which are prolonged outside into twenty stout, three-sided pyramidal main spines, as long as the diameter of the inner shell. Between these, arising from the surface, numerous bristle-shaped by-spines.

Dimensions.--Diameter of the outer shell 0.25, inner 0.05, pores 0.012; length of the main spines 0.05, basal breadth 0.012.

Habitat.--Central Pacific, Stations 266 to 274, surface.

2. Heliosoma elegans, n. sp.

Cortical shell thick walled, with regular, circular, hexagonally framed pores, twice as broad as the bars; ten to twelve on the radius. Medullary shell half as large, with simple, regular, circular pores, twice as broad as the bars. The two shells connected by twenty very thin radial beams, which are prolonged outside into twenty slender, three-sided pyramidal main spines as long as the radius. In each corner of the surface hexagons a bristle-shaped by-spine one-fourth as long.

Dimensions.--Diameter of the outer shell 0.12, inner 0.06; outer pores 0.006, bars 0.003; length of the main spines 0.05, basal breadth 0.01.

Habitat.--Central Pacific, Station 271, surface.

3. Heliosoma echinaster, Haeckel.

Haliomma echinaster, Haeckel, 1862, Monogr. d. Radiol., p. 429, Taf. xxiv. figs. 1-3.

Cortical shell thin walled, with regular, circular, hexagonally framed pores, twice as broad as the bars; ten to twelve on the radius. Medullary shell one-fourth as large, with few irregular, large, {241}polygonal pores and very thin thread-like bars, connected with the former by nine similar thin radial beams, which are prolonged outside into nine pyramidal main spines, as long as the radius. From each corner of the surface hexagon arises a bristle-shaped by-spine, half as long as the main spine.

Dimensions.--Diameter of the outer shell 0.16, inner 0.04; outer pores 0.008, bars 0.004; length of the main spines 0.08, basal breadth 0.01.

Habitat.--Mediterranean (Messina), surface.

4. Heliosoma duodecilla, n. sp.

Cortical shell thick walled, with regular, circular pores, of the same breadth as the bars; sixteen to eighteen on the radius. Medullary shell one-third as large, of the same structure. Twelve radial main spines, regularly disposed, cylindro-conical, longer than the shell diameter, as broad as two pores. Whole surface covered with short conical by-spines.

Dimensions.--Diameter of the outer shell 0.15, inner 0.05; outer pores and bars 0.007; length of the main spines 0.2, breadth 0.02.

Habitat.--South Atlantic, Station 333, surface.

Subgenus 2. Heliosomura, Haeckel.

Definition.--Pores of the cortical shell irregular, of different size and form.

5. Heliosoma hastatum, n. sp. (Pl. 28, fig. 4).

Cortical shell very thin walled, with large, irregular, polygonal meshes, three to six times as broad as the bars; four to six on the radius. Medullary shell one-third as large, with small, regular, circular pores. The two shells connected by twelve regularly disposed radial beams, which are prolonged outside into twelve very stout three-sided pyramidal main spines, somewhat longer than the radius, spear-shaped; each of the three wings in the middle part with one tooth. Scattered on the surface numerous by-spines of the same form, half as long and only one-fourth as broad.

Dimensions.--Diameter of the outer shell 0.1, inner 0.033; outer pores 0.006 to 0.013, inner pores 0.002, bars 0.002; length of the main spines 0.06, breadth 0.015.

Habitat.--Central Pacific, Station 271, depth 2425 fathoms.

6. Heliosoma indicum, n. sp.

Cortical shell thick walled, with irregular, roundish pores, twice to five times as broad as the bars. Medullary shell of the same structure, only one-fourth as large. Thirty to forty conical main spines, as long as the radius; between them numerous bristle-shaped by-spines, only half as long.

Dimensions.--Diameter of the outer shell 0.2, inner 0.05; outer pores 0.004 to 0.01, bars 0.002; length of the main spines 0.1, breadth 0.01.

Habitat.--Indian Ocean, between Aden and Socotora, surface, Haeckel.

{242}Genus 96. Elatomma,[131] n. gen.

Definition.--#Astrosphærida# with one medullary (intracapsular) and one cortical (extracapsular) shell, the two being connected by radial beams piercing the central capsule. Shell surface covered with branched radial spines.

The genus Elatomma differs from Haliomma in the ramification of the radial spines, and exhibits therefore the same relation to it that Cladococcus, among the Coscinommida, bears to Acanthosphæra.

Subgenus 1. Elatommella, Haeckel.

Definition.--Pores of the cortical shell regular, of nearly equal size and similar form.

1. Elatomma pinetum, n. sp.

Cortical shell thick walled, with regular, circular, hexagonally framed pores, three times as broad as the bars. From its surface arise twenty to thirty large, three-sided prismatic, radial spines as long as the shell diameter, branched like a pine tree; on each edge of the spine five to six ramified branches, decreasing in size towards the distal end. Similar to Cladococcus pinetum (Pl. 27, figs. 1, 3), but differing in the possession of a medullary shell (one-third as large as the outer), with regular, circular pores, as broad as the bars.

Dimensions.--Diameter of the outer shell 0.2, inner 0.07; cortical pores 0.012, bars 0.004; length of the spines 0.2 to 0.24.

Habitat.--Central Pacific, Stations 266 to 272, surface.

2. Elatomma scoparium, n. sp.

Cortical shell thick walled, with regular, circular pores, twice as broad as the bars, connected with the medullary shell by twenty thin radial beams, which are prolonged outside into twenty large cylindrical radial spines somewhat longer than the radius; in the proximal half simple, in the distal half with six to nine dichotomous, irregular branches. Similar to Cladococcus scoparius (Pl. 27, fig. 2), but much larger, and with a large medullary shell (one-third as broad as the outer), and regular, circular pores.

Dimensions.--Diameter of the outer shell 0.12, inner 0.04; cortical pores 0.01, bars 0.005; length of the spines 0.08.

Habitat.--North Pacific, Station 240, surface.

Subgenus 2. Elatommura, Haeckel.

Definition.--Pores of the cortical shell irregular, of different size or form.

{243}3. Elatomma juniperinum, n. sp. (Pl. 28, fig. 8).

Cortical shell thin walled, with regular, polygonal, or roundish pores, twice to four times as broad as the bars, connected with the small medullary shell by about twenty thin radial beams. Inner shell only one-eighth as broad as the outer, with few irregular, polygonal meshes. Surface covered with very numerous (one hundred to one hundred and fifty or more) branched conical radial spines, one-third as long as the shell radius, with six to twelve short lateral branches.

Dimensions.--Diameter of the outer shell 0.2, inner 0.025; cortical pores 0.08 to 0.016, bars 0.004; length of the spines 0.04.

Habitat.--Central Pacific, Station 271, surface.

4. Elatomma penicillus, n. sp.

Cortical shell thin walled, with irregular, polygonal pores, twice to four times as broad as the bars, connected with the medullary shell by twenty (or more?) very thin beams. These are prolonged outside into twenty straight, three-sided prismatic, radial spines as long as the radius, with a brush-like bunch of six to nine short, irregularly ramified branches at the end. Medullary shell very delicate (half as broad as the outer), with regular, hexagonal meshes and thread-like bars.

Dimensions.--Diameter of the outer shell 0.15, inner 0.08; length of the spines 0.08.

Habitat.--West coast of Norway, Bergen, Haeckel.

5. Elatomma irregulare, n. sp.

Cortical shell thin walled, with irregular, polygonal, or roundish meshes, twice to six times as broad as the bars; the medullary shell of the same structure, half as broad, with smaller irregular pores. Forty to sixty curved, three-sided, radial spines, as long as the shell, with a bunch of very irregular, curved, and partly ramified branches at the distal end.

Dimensions.--Diameter of the outer shell 0.2, inner 0.1; length of the spines 0.2, breadth 0.01.

Habitat.--North Atlantic, Gulf Stream, Færöe Channel, surface, John Murray.

Genus 97. Leptosphæra,[132] n. gen.

Definition.--#Astrosphærida# with two extracapsular cortical shells without by-spines, connected by long prismatic radial spines.

The genus Leptosphæra, together with the three following genera, forms the very peculiar and typical small group of #Sphæroidea# which we call the Diplosphærida (with four genera and twenty-four species); their shell is composed of two concentric spheres as in the three foregoing genera; but whilst in these the inner shell is an intracapsular medullary shell and the outer an extracapsular cortical shell, in the Diplosphærida {244}both shells are extracapsular or cortical shells, therefore the inner shell of the latter corresponds to the outer of the former. The inner spherical shell of all Diplosphærida is composed of very delicate beams and large pores, which are either regular hexagonal or irregular polygonal (never roundish). From its surface arise a variable number (twenty to thirty) of stout long radial spines, which are invariably longer than the shell diameter (often two to three times as long or more), and of three-sided prismatic form, the three edges either smooth or serrate, often with three rows of lateral branches (commonly three to five branches in each row); the latter are invariably of the same form, concavely curved towards the spine, and decrease in size towards the distal end. From the three edges of each main spine in all Diplosphærida, at equal distances from the centre, arise six very thin, thread-like lateral branches (a pair from each edge) and connect the spine in a tangential direction with all neighbouring spines. In this manner the polyhedral outer shell is formed, the meshes of which therefore are always very large and triangular. Sometimes each of these primary triangular meshes becomes filled up with a secondary network, either of regular quadrangular or of irregular polygonal secondary meshes. Besides the constant twenty to thirty large main spines, in the majority of Diplosphærida bristle-shaped radial by-spines arise, either from the inner shell (Diplosphæra) or from the outer (Drymosphæra), or from both (Astrosphæra). They are absent only in Leptosphæra. Commonly the by-spines are simple, rarely forked or branched. The central capsule in the Diplosphærida is usually enclosed in the inner shell; often it completely fills up the latter, or drives out a cæcal protuberance through each mesh; but these processes rarely unite outside. The average size of the Diplosphærida, which are all pelagic organisms, is much larger than that of the other Haliommida.

Subgenus 1. Leptosphærella, Haeckel.

Definition.--Radial spines simple, without lateral branches.

1. Leptosphæra hexagonalis, n. sp. (Pl. 19, fig. 2).

Inner shell with regular, hexagonal meshes, and very thin, thread-like bars; outer shell twice as broad, with simple triangular meshes. Radial spines with three smooth edges. (Fig. 2 represents the central capsule with numerous club-shaped saccules, prominent externally through the meshes; in the centre a large simple spherical nucleus, one-third as broad as the capsule. The skeleton of this species is identical with that of Diplosphæra hexagonalis, Pl. 19, fig. 3, but has no by-spines.)

Dimensions.--Diameter of the outer shell 0.3, of the inner 0.15.

Habitat.--Cosmopolitan; Mediterranean (Corfu), North Atlantic (Canary Islands), Tropical Pacific, surface.

{245}2. Leptosphæra serrata, n. sp.

Inner shell with regular, hexagonal meshes, five to six times as broad as the bars; outer shell three times as broad, with simple triangular meshes. Radial spines with three serrated edges (of the same form as the main spines of Drymosphæra dendrophora, Pl. 20, fig. 1).

Dimensions.--Diameter of the outer shell 0.45, of the inner 0.15.

Habitat.--Central Pacific, Station 271, surface.

3. Leptosphæra polygonalis, n. sp.

Inner shell with irregular, polygonal meshes and very thin thread-like bars; outer shell twice as broad, with simple triangular meshes. Radial spines with three smooth edges. (Resembles Drymosphæra polygonalis, Pl. 19, fig. 1, but has no by-spines.)

Dimensions.--Diameter of the outer shell 0.35, inner 0.175.

Habitat.--North Pacific, Station 256, surface.

Subgenus 2. Leptosphæromma, Haeckel.

Definition.--Radial spines with three rows of lateral branches (one row on each edge).

4. Leptosphæra ciliata, n. sp.

Inner shell with regular, hexagonal meshes and very thin thread-like bars; outer shell three times as broad, with simple triangular meshes. Radial spines with smooth edges and three rows of simple, smooth, curved, lateral branches (six branches on each edge), similar to those of Diplosphæra gracilis.

Dimensions.--Diameter of the outer shell 0.6, inner 0.2.

Habitat.--South Atlantic, Station 325, surface.

5. Leptosphæra spinosa, Haeckel.

Diplosphæra spinosa, R. Hertwig, 1879, Organismus d. Radiol., p. 40, Taf. v. fig. 2.

Inner shell with regular, hexagonal meshes, five times as broad as the bars; outer shell three times as broad, with simple triangular meshes. Radial spines with three densely serrated edges, and with three rows of serrated, simple, curved, lateral branches (three branches on each edge). Differs from the preceding in the thicker bars and the elegantly denticulated spines and branches.

Dimensions.--Diameter of the outer shell 0.66, inner 0.22.

Habitat.--Mediterranean (Messina), R. Hertwig.

6. Leptosphæra stellata, n. sp.

Inner shell with regular, hexagonal meshes, six times as broad as the bars, each bar crossed by a transverse tangential rod, so that each mesh represents an elegant six-rayed star (as {246}in Astrosphæra stellata, Pl. 19, fig. 5, but without radial by-spines); outer shell twice as broad, with simple triangular meshes. Radial spines with serrated edges and three rows of simple lateral branches (four branches on each edge).

Dimensions.--Diameter of the outer shell 0.44, inner 0.22.

Habitat.--Tropical Atlantic (Ascension Island), Station 343, surface.

7. Leptosphæra reticulum, n. sp.

Inner shell with irregular, polygonal meshes and very thin thread-like bars; outer shell four times as broad, also with irregular, polygonal meshes, the sides of the triangular main meshes being connected by irregular lateral ramules, forming an extremely delicate reticulum.

Dimensions.--Diameter of the outer shell 0.64, inner 0.16.

Habitat.--South Pacific, Station 291, surface.

Genus 98. Diplosphæra,[133] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 804.

Definition.--#Astrosphærida# with two extracapsular cortical shells, connected by long, prismatic, radial spines; inner shell with thin radial by-spines.

The genus Diplosphæra differs from its ancestral form Leptosphæra in the development of radial by-spines on the surface of the inner shell, the outer shell being smooth.

Subgenus 1. Diplosphærella, Haeckel.

Definition.--Radial main spines simple, without lateral branches.

1. Diplosphæra hexagonalis, n. sp. (Pl. 19, fig. 3).

Inner shell with regular, hexagonal meshes and very thin thread-like bars; at each nodal-point one bristle-shaped by-spine; outer shell twice as broad, with simple triangular meshes. Radial spines with three smooth edges. (The radially striped central capsule, enclosed in the inner shell, envelops a large central nucleus one-third its size, fig. 3.)

Dimensions.--Diameter of the outer shell 0.36, inner 0.18.

Habitat.--Central Pacific, Stations 265 to 274, surface.

2. Diplosphæra ornata, n. sp.

Inner shell with regular, hexagonal meshes, four times as broad as the bars; outer shell three times as broad, with simple triangular meshes. Radial main spines as well as the bars of both {247}shells very elegantly denticulated; radial by-spines (very numerous in the surface of the inner shell) smooth.

Dimensions.--Diameter of the outer shell 0.7, inner 0.24.

Habitat.--Indian Ocean, Madagascar, surface, Rabbe.

3. Diplosphæra dictyota, n. sp.

Inner shell with regular, hexagonal meshes, six times as broad as the bars; at each nodal-point one radial by-spine; outer shell two and a half times as broad, with very delicate square meshes, separated by thread-like bars which arise from the sides of the triangular main meshes. Radial main spines with three serrated edges. (Differs from the similar Diplosphæra gracilis in the simple main spines, with delicate dentition of the edges.)

Dimensions.--Diameter of the outer shell 0.5, inner 0.2.

Habitat.--North Atlantic, Canary Islands, surface.

4. Diplosphæra polygonalis, n. sp.

Inner shell with irregular, polygonal meshes and very thin thread-like bars, covered with very numerous bristle-shaped by-spines; outer shell twice as broad, with simple triangular meshes. Radial main spines with three smooth edges.

Dimensions.--Diameter of the outer shell 0.44, inner 0.22.

Habitat.--South Pacific, Station 288, surface.

Subgenus 2. Diplosphæromma, Haeckel.

Definition.--Radial main spines with three rows of lateral branches (one row on each edge).

5. Diplosphæra gracilis, Haeckel.

Diplosphæra gracilis, Haeckel, 1862, Monogr. d. Radiol., p. 354, Taf. x. fig. 1.

Inner shell with regular, hexagonal meshes and very thin bars; at each nodal-point one simple bristle-shaped radial by-spine; outer shell twice as broad, with very delicate square meshes, separated by thread-like bars which arise from the sides of the triangular main meshes. Radial spines with smooth edges and with three rows of simple curved lateral branches (four to six branches on each edge).

Dimensions.--Diameter of the outer shell 0.54, inner 0.27.

Habitat.--Mediterranean (Messina).

6. Diplosphæra denticulata, n. sp.

Inner shell with regular, hexagonal meshes, four times as broad as the bars; at each nodal-point is a simple bristle-shaped by-spine; outer shell three times as broad, with simple triangular meshes. {248}Radial spines very strong, with dentated edges and with three rows of lateral branches (six dentated curved branches on each edge).

Dimensions.--Diameter of the outer shell 0.4, inner 0.13.

Habitat.--North Atlantic, Azores, surface.

7. Diplosphæra reticulata, n. sp.

Inner shell with regular, hexagonal meshes, five times as broad as the bars, which are densely covered with very numerous, simple bristle-shaped by-spines; outer shell four times as broad, with very numerous small irregular polygonal meshes, forming a very delicate network, and filling out the large triangular main meshes. Radial spines with three serrated edges and three rows of short curved branches (four to five branches on each edge).

Dimensions.--Diameter of the outer shell 0.6, inner 0.15.

Habitat.--North Atlantic, Gulf Stream, Færöe Channel, surface, John Murray.

8. Diplosphæra triglochin, n. sp.

Inner shell with irregular, polygonal meshes and very thin thread-like bars; outer shell three times as broad, with similar irregular polygonal meshes, filling out the large triangular main meshes. Radial spines with three serrated edges, each of which bears one single large lateral branch, concavely curved towards the distal end. By-spines of the inner shell very numerous.

Dimensions.--Diameter of the outer shell 0.5, inner 0.17.

Habitat.--Central Pacific, Station 264, surface.

Genus 99. Drymosphæra,[134] Haeckel, 1881, Prodromus, p. 452.

Definition.--#Astrosphærida# with two extracapsular cortical shells, connected by long prismatic, radial spines; outer shell with thin radial by-spines.

The genus Drymosphæra differs from its ancestral form Leptosphæra in the development of radial by-spines on the surface of the outer shell, the inner shell being smooth.

Subgenus 1. Drymosphærella, Haeckel.

Definition.--Radial by-spines simple, not branched (main spines simple).

1. Drymosphæra hexagonalis, n. sp.

Inner shell with regular, hexagonal meshes and very thin thread-like bars; outer shell twice as broad, with simple triangular meshes and thin thread-like bars, which bear very numerous, {249}bristle-shaped radial by-spines. Radial main spines with three smooth edges. (Differs from the first species of the other three genera of Diplosphærida in the presence of by-spines on the outer, and their absence on the inner shell.)

Dimensions.--Diameter of the outer shell 0.32, inner 0.16.

Habitat.--Central Pacific, Station 274, surface.

2. Drymosphæra polygonalis, n. sp. (Pl. 19, fig. 1).

Diplosphæra polygonalis, Haeckel, 1879, Atlas.

Inner shell with irregular, polygonal meshes and very thin thread-like bars; outer shell one and a half times as broad, with simple triangular meshes and thicker bars, which bear numerous bristle-shaped radial by-spines (in the figure the majority of these are broken off). Radial main spines with three smooth edges. (Similar to Leptosphæra polygonalis and Diplosphæra polygonalis, but differs from both in the presence of by-spines on the outer, and their absence on the inner shell.)

Dimensions.--Diameter of the outer shell 0.33, inner 0.22.

Habitat.--North Pacific, Station 236 south of Japan, surface.

Subgenus 2. Drymosphæromma, Haeckel.

Definition.--Radial by-spines forked or branched (main spines simple).

3. Drymosphæra furcata, n. sp.

Inner shell with irregular, polygonal meshes and thin bars, the former five times as broad as the latter; outer shell two and a half times as broad, with simple triangular meshes and smooth bars, bearing numerous long smooth bristle-shaped by-spines, which in the distal half are forked. Radial main spines with three smooth edges.

Dimensions.--Diameter of the outer shell 0.4, inner 0.16.

Habitat.--Indian Ocean, Ceylon, surface, Haeckel.

4. Drymosphæra cladophora, n. sp.

Inner shell with irregular, polygonal meshes, three to six times as broad as the smooth bars; outer shell twice as broad, with simple triangular meshes and very thin smooth bars, bearing numerous curved, irregularly branched, smooth by-spines. Radial main spines with three serrated edges.

Dimensions.--Diameter of the outer shell 0.4, inner 0.2.

Habitat.--Central Pacific, Station 276, surface.

5. Drymosphæra dendrophora, n. sp. (Pl. 20, figs. 1, 1_a_, 1_b_).

Inner shell with irregular, polygonal meshes and very thin thread-like bars; outer shell one and a half times as broad, with simple triangular meshes and thicker bars, which bear a forest of {250}very numerous, repeatedly dichotomous or irregularly branched, curved by-spines, longer than the diameter of the outer shell. Radial main spines with three dentated edges. All parts of the skeleton, the net bars as well as the radial beams and spines, are very elegantly denticulated (fig. 1_b_). The central capsule (fig. 1_a_) completely distends the inner shell and forces out protuberances through all its pores; in its centre lies a nucleus one-third its size.

Dimensions.--Diameter of the outer shell 0.25, inner 0.16.

Habitat.--Central Pacific, Station 271, surface.

Genus 100. Astrosphæra,[135] n. gen.

Definition.--#Astrosphærida# with two extracapsular cortical shells, connected by long, prismatic, radial spines; inner and outer shell with thin radial by-spines.

The genus Astrosphæra differs from its ancestral form, Leptosphæra, in the development of radial by-spines on the surface of both shells.

Subgenus 1. Astrosphærella, Haeckel.

Definition.--Radial main spines simple without lateral branches.

1. Astrosphæra hexagonalis, n. sp. (Pl. 19, fig. 4).

Inner shell with regular, hexagonal meshes and very thin bars, having a bristle-shaped, short radial by-spine in each hexagon-corner; outer shell twice as broad, with simple triangular meshes and thicker bars, bearing one row of simple bristle-shaped, curved, radial by-spines. Radial main spines with three smooth edges.

Dimensions.--Diameter of the outer shell 0.32, inner 0.16.

Habitat.--South Pacific (West Patagonia), Station 302, surface.

2. Astrosphæra splendens, n. sp.

Inner shell with regular, hexagonal meshes, four times as broad as the bars, and covered with numerous curved, long, bristle-shaped by-spines; outer shell three times as broad, with simple triangular meshes and thin bars, bearing a row of very long, curved, bristle-shaped by-spines. Radial main spines with three dentated edges. All parts of the skeleton elegantly denticulated, as in Drymosphæra dendrophora (Pl. 20, fig. 1).

Dimensions.--Diameter of outer shell 0.7, inner 0.24.

Habitat.--Tropical Atlantic, Station 347, surface.

{251}Subgenus 2. Astrosphæromma.

Definition.--Radial main spines with three rows of lateral branches (one row on each edge).

3. Astrosphæra sideræa, n. sp.

Inner shell with regular, hexagonal meshes, six times as broad as the bars, and covered with numerous short bristle-shaped by-spines; outer shell four times as broad, with simple triangular meshes, and rows of long bristle-shaped by-spines arising from the bars. Radial main spines with three serrated edges and three rows of lateral branches (four branches on each edge).

Dimensions.--Diameter of the outer shell 0.6, inner 0.15.

Habitat.--Central Pacific, Station 266, surface.

4. Astrosphæra stellata, n. sp. (Pl. 19, fig. 5).

Diplosphæra stellata, Haeckel, 1881, Prodrom. et Atlas.

Inner shell with regular, hexagonal, six-rayed meshes, each bar being crossed by a transverse tangential rod, at each nodal-point a long bristle-shaped by-spine; outer shell three times as broad, with simple triangular meshes and denticulated thin bars, bearing a row of bristle-shaped radial by-spines. Radial main spines in the proximal half with three serrated edges, in the distal half with three rows of curved lateral branches (five branches on each edge).

Dimensions.--Diameter of the outer shell 0.6, inner 0.2.

Habitat.--Central Pacific, Station 274, surface.

Subfamily ACTINOMMIDA,[136] Haeckel, 1862, Monogr. d. Radiol., p. 440 (sensu emendato).

Definition.--#Astrosphærida# with three concentric, spherical, lattice-shells, united by radial beams.

Genus 101. Actinomma,[137] Haeckel, 1862, Monogr. d. Radiol., p. 440.

Definition.--#Astrosphærida# with three concentric lattice-spheres and numerous simple radial spines of one kind.

The genus Actinomma is here restricted to those #Sphæroidea# which combine the possession of three concentric lattice-shells with numerous radial spines on the surface; the spines are all simple, being of one and the same kind. Commonly two of the three shells are intracapsular medullary shells, connected by radial beams (piercing {252}the central capsule) with the outer, extracapsular, cortical shell. But in some species only one medullary shell is enclosed in the central capsule, whilst both other shells lie outside it. In such case the distance between these two cortical shells is much smaller than their distance from the simple internal medullary shell. These forms correspond more to aculeate Rhodosphæræ, whilst the others resemble aculeate Thecosphæræ.

Subgenus 1. Actinommantha, Haeckel.

Definition.--Pores of the cortical shell regular, of nearly equal size and similar form; spines on the entire surface (commonly one spine at each nodal-point).

1. Actinomma hexagonium, n. sp.

Cortical shell, as well as both medullary shells, very thin walled, with regular, hexagonal pores and thread-like bars between them. Pores of the outer shell twice as broad as those of the middle, and three times as broad as those of the inner shells. Radial proportion of the three spheres = 1 : 3 : 9; about twenty thin radial beams between them. At each nodal-point of the surface arises one bristle-shaped radial spine, half as long as the radius.

Dimensions.--Diameter of the outer shell 0.22, middle 0.07, inner 0.025; meshes of the cortical shell 0.01; length of the spines 0.05.

Habitat.--Central Pacific, Stations 270 to 274, surface.

2. Actinomma facetum, n. sp.

Cortical shell thick walled, with regular, circular, hexagonally framed pores, three times as broad as the bars. Pores of both medullary shells regular, circular. Radial proportion of the three spheres = 1 : 2 : 4; about forty thin radial beams between them. At each nodal-point of the surface arises one short, three-sided pyramidal, radial spine, about one-third as long as the radius.

Dimensions.--Diameter of the outer shell 0.16, middle 0.08, inner 0.04; cortical pores 0.012, bars 0.004; length of the spines 0.03, basal breadth 0.015.

Habitat.--North Pacific, Station 253, depth 3125 fathoms.

3. Actinomma anthomma, n. sp.

Cortical shell thick walled, with regular, six-lobed pores, twice as broad as the bars. At each nodal-point of the surface is one short conical radial spine, as long as the diameter of the pores; one corresponding to each lobe, and there is therefore around each pore a regular corona of six spines, as in Haliomma lirianthus (Pl. 28, fig. 1_b_). Both medullary shells with simple, circular, regular pores. Radial proportion of the three spheres = 1 : 2.5 : 7; radial beams between them only six, opposite in pairs in the three dimensive axes.

{253}Dimensions.--Diameter of the outer shell 0.2, middle 0.075, inner 0.003; cortical pores 0.01, bars 0.005; length of the spines 0.01.

Habitat.--Central Pacific, Station 271, surface.

4. Actinomma castanomma, n. sp.

Cortical shell as well as both medullary shells thick walled, with regular, circular pores, twice as broad as the bars; between them at each nodal-point one bristle-shaped radial spine, one-third as long as the radius, with conical base. Radial proportion of the three spheres = 2 : 3 : 8; only six radial beams between them (opposed in pairs in the three dimensive axes).

Dimensions.--Diameter of the outer shell 0.15, middle 0.06, inner 0.04; cortical pores 0.008, bars 0.004; length of the spines 0.025.

Habitat.--South Atlantic, Station 333, surface.

5. Actinomma entactinia, Stöhr.

Actinomma entactinia, Stöhr, 1880, Palæontogr., vol. xxvi. p. 93, Taf. ii. fig. 12.

Cortical shell as well as both medullary shells thick walled, with regular, circular pores, of the same breadth as the bars. Radial proportion of the three spheres = 1 : 3 : 8; radial beams between them very numerous (thirty to fifty or more?). Entire surface covered with short thick conical spines, only one-fifth as long as the radius.

Dimensions.--Diameter of the outer shell 0.16, middle 0.06, inner 0.02; cortical pores and bars 0.007; length of the spines 0.015.

Habitat.--Fossil in the Tertiary rocks of Sicily, Grotte, Caltanisetta.

Subgenus 2. Actinommetta, Haeckel.

Definition.--Pores of the outer shell regular, of nearly equal size and similar form; spines not over the entire surface, but scattered at intervals (their number smaller than that of the nodal-points).

6. Actinomma japonicum, n. sp.

Cortical shell thick walled, with regular, circular, hexagonally framed pores, three times as broad as the bars. Both medullary shells with simple, circular, regular pores, of the same breadth as the bars. Radial proportion of the three spheres = 2 : 5 : 9; radial beams between them twenty, prolonged outside into twenty symmetrically disposed, three-sided pyramidal spines, as long as the radius.

Dimensions.--Diameter of the outer shell 0.18, middle 0.1, inner 0.04; cortical pores 0.01, bars 0.003; length of the spines 0.1, basal breadth 0.012.

Habitat.--North Pacific, Station 240, east of Japan, surface.

{254}7. Actinomma denticulatum, n. sp. (Pl. 29, fig. 3).

Cortical shell thick walled, with regular, circular, double-edged pores, twice as broad as the bars. Forty to fifty radial spines, three-sided pyramidal, half as long as the radius, with three elegantly denticulated edges. Radial proportion of the three spheres = 1 : 2 : 5. (Differs from Haliomma denticulatum only in the double medullary shell and larger size.)

Dimensions.--Diameter of the outer shell 0.14, middle 0.06, inner 0.03; cortical pores 0.01, bars 0.005; length of the spines 0.04, basal breadth 0.01.

Habitat.--Central Pacific, Station 271, depth 2425 fathoms.

8. Actinomma trinacrium, Haeckel.

Actinomma trinacrium, Haeckel, 1862, Monogr. d. Radiol., p. 441, Taf. xxiv. figs. 6-8.

Haliomma trinacrium, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 815.

Cortical shell as well as both medullary shells thin walled, with subregular, circular pores, twice as broad as the bars. Radial proportion of the three spheres = 1 : 3 : 9; radial beams between them twenty, prolonged outside into strong, three-sided pyramidal spines, as long as the radius; between them, on the surface, numerous similar spines. Sometimes the latter remain smaller, the pores more irregular, and then this species corresponds to Echinomma trinacrium.

Dimensions.--Diameter of the outer shell 0.09, middle 0.03, inner 0.01; cortical pores 0.008, bars 0.004; length of the spines 0.04, basal breadth 0.01.

Habitat.--Mediterranean (Messina, Corfu, Haeckel), surface.

9. Actinomma pachyderma, n. sp. (Pl. 29, figs. 4, 5).

Cortical shell very thick walled, with regular, circular, double-edged pores, twice as broad as the bars. Both medullary shells with simple, small, circular pores, of the same breadth as the bars. Radial proportion of the three spheres = 1 : 2 : 4; radial spines about twenty, conical, shorter than the radius, prolonged inside into twenty very thin connecting beams (fig. 4).

Dimensions.--Diameter of the outer shell 0.08, middle 0.04, inner 0.02; cortical pores 0.01; bars 0.005; length of the spines 0.03, basal breadth 0.01.

Habitat.--South Pacific, Station 297, depth 1775 fathoms.

Subgenus 3. Actinommilla, Haeckel.

Definition.--Pores of the cortical shell irregular, of different size and form; spines over the entire surface (commonly one spine at each nodal-point).

10. Actinomma spinigerum, Stöhr.

Actinomma spinigerum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 92, Taf. ii. fig. 10.

Cortical shell thick walled, with irregular, roundish, or subcircular pores, twice to four times as broad as the bars. Radial proportion of the three spheres = 1 : 3 : 8; between them eight (?) {255}connecting radial beams. Entire surface densely covered with small conical spines, not larger than the pores.

Dimensions.--Diameter of the outer shell 0.17, middle 0.07, inner 0.023; cortical pores 0.006 to 0.012, bars 0.003; length of the spines 0.01.

Habitat.--Fossil in Tertiary rocks of Sicily, Grotte, Stöhr.

11. Actinomma hirsutum, n. sp.

Cortical shell thick walled, with irregular, roundish pores, about the same breadth as the bars. Radial proportion of the three spheres = 1 : 2 : 8; between them numerous (twenty to thirty or more) cylindrical connecting beams. Entire surface densely covered with innumerable small bristle-shaped spines, as long as the diameter of the inner shell.

Dimensions.--Diameter of the outer shell 0.25, middle 0.06, inner 0.03; cortical pores and bars 0.004 to 0.008; length of the spines 0.03.

Habitat.--Central Pacific, Station 265, depth 2900 fathoms.

Subgenus 4. Actinommura, Haeckel.

Definition.--Pores of the cortical shell irregular, of different size and form; spines not over the entire surface, but scattered at intervals (their number smaller than that of the nodal-points).

12. Actinomma capillaceum, n. sp. (Pl. 29, fig. 6).

Cortical shell very thin walled, with irregular, polygonal meshes (sixteen to eighteen on the radius), three to six times as broad as the bars. Both medullary shells with smaller pores of the same structure. Radial proportion of the three spheres = 1 : 2.5 : 7; radial connecting beams between them very thin and numerous (one hundred and twenty to one hundred and fifty or more), each prolonged outside into a short three-sided pyramidal spine, as long as the radius of the inner shell. (Similar to Haliomma capillaceum.)

Dimensions.--Diameter of the outer shell 0.27, middle 0.1, inner 0.04; cortical pores 0.01 to 0.02, bars 0.003; length of the spines 0.02, basal breadth 0.005.

Habitat.--Central Pacific, Stations 266 to 274, surface.

13. Actinomma arcadophorum, n. sp. (Pl. 29, figs. 7, 8).

Cortical shell very thin walled, with irregular, polygonal meshes, ten to twenty times as broad as the bars; twelve to sixteen on the radius. Both medullary shells with similar delicate network. Radial proportion of the three spheres = 1 : 2 : 6; numerous thin radial beams (forty to eighty or more) connect both medullary shells and alternate with other beams, which arise from arcade-shaped {256}protuberances of the outer medullary shell, and connect it with the cortical shell. Outer prolongations of these form the bristle-shaped spines of the surface.

Dimensions.--Diameter of the outer shell 0.22, middle 0.09, inner 0.04; cortical pores 0.01 to 0.02, bars 0.001 to 0.002; length of the radial spines 0.2.

Habitat.--Central Pacific, Station 266, surface.

14. Actinomma schwageri, Stöhr.

Actinomma schwageri, Stöhr, 1880, Palæontogr., vol. xxvi. p. 92, Taf. ii. fig. 9_a_, b.

Cortical shell thick walled, with irregular, large, polygonal meshes, five to twelve times as broad as the bars; six to eight on the radius. Both medullary shells with very small, circular, regular pores. Radial proportion of the three spheres = 1 : 2 : 9; connecting radial beams between them nine, prolonged outside into nine short stout, three-sided pyramidal spines, as long as the diameter of the inner shell.

Dimensions.--Diameter of the outer shell 0.17, middle 0.04, inner 0.02; cortical pores 0.01 to 0.03, bars 0.006 and less; length of the spines 0.02, basal breadth 0.01.

Habitat.--Fossil in Tertiary rocks of Sicily, Grotte, Stöhr.

15. Actinomma dodecomma, n. sp.

Cortical shell thin walled, with irregular, roundish pores, three to six times as broad as the bars. Both medullary shells with regular, circular pores, twice as broad as the bars. Radial proportion of the three shells = 1 : 2.5 : 7; connecting radial beams between them twelve, regularly disposed, prolonged outside into twelve strong, three-sided pyramidal spines, as long as the radius.

Dimensions.--Diameter of the outer shell 0.14, middle 0.05, inner 0.02; cortical pores 0.008 to 0.018, bars 0.003; length of the spines 0.08, breadth 0.02.

Habitat.--Tropical Atlantic, Station 348, depth 2450 fathoms.

16. Actinomma pachycapsa, n. sp.

Cortical shell very thick walled, with irregular, roundish pores, twice to four times as broad as the bars; twelve to sixteen on the radius. Radial proportion of the three spheres = 1 : 3 : 12. Both medullary shells of similar irregular structure, connected with the cortical shell by twelve regularly disposed radial beams, which are prolonged outside into twelve short stout conical spines, as long as the diameter of the middle shell.

Dimensions.--Diameter of the outer shell 0.25, middle 0.06, inner 0.02; cortical pores 0.006 to 0.012, bars 0.003; length of the spines 0.05, breadth 0.02.

Habitat.--Central Pacific, Station 268, depth 2900 fathoms.

17. Actinomma giganteum, n. sp.

Cortical shell thick walled, little larger than the outer medullary shell, whilst the inner is only one-tenth as large. Pores of all three shells irregular, roundish, or subcircular, twice to three times {257}as broad as the bars, on an average twice as large in the outer and middle as in the inner shell. Sixty to eighty short conical radial spines on the surface, about as long as the diameter of the inner shell, and one-fourth as broad at the base. Radial proportion of the three spheres = 1 : 9 : 10.

Dimensions.--Diameter of the outer shell 0.4 to 0.5, middle 0.35 to 0.45, inner 0.05 to 0.06.

Habitat.--Fossil in Barbados.

Genus 102. Echinomma,[138] Haeckel, 1881, Prodromus, p. 453.

Definition.--#Astrosphærida# with three concentric lattice-spheres and numerous simple radial spines of two different kinds; larger main spines and smaller by-spines.

The genus Echinomma, differs from its ancestral form, Actinomma, in the differentiation of the radial spines. Whilst a large number of small by-spines cover the entire surface, a smaller number of large main spines are scattered over it, or limited to certain regularly distributed points. It represents Heliosoma among the Haliommida.

Subgenus 1. Echinommetta, Haeckel.

Definition.--Pores of the cortical shell regular, of nearly equal size and similar form.

1. Echinomma echinidium, n. sp.

Cortical shell thin walled, with regular, hexagonal pores, four times as broad as the bars; ten to twelve on the radius. Both medullary shells with regular, circular pores, twice as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 5. Surface covered with short bristle-shaped by-spines (one in every hexagon-corner); twenty main spines regularly disposed, three-sided pyramidal, as long as the diameter of the inner shell.

Dimensions.--Diameter of the outer shell 0.1, middle 0.045, inner 0.02; cortical pores 0.008, bars 0.002; length of the main spines 0.02, breadth 0.01.

Habitat.--South Pacific, Station 295, surface.

2. Echinomma cidaris, n. sp.

Cortical shell thin walled, with regular, circular, hexagonally framed pores, twice as broad as the bars; six to eight on the radius. Both medullary shells with simple, circular pores. Radial proportion of the three spheres = 1 : 2 : 6. Surface covered with short bristle-shaped by-spines, half as long as the forty to fifty main spines, which are three-sided pyramidal, and reach the radius of the shell.

Dimensions.--Diameter of the outer shell 0.18, middle 0.06, inner 0.03; cortical pores 0.01, bars 0.005; length of the main spines 0.08, basal breadth 0.015.

Habitat.--Central Pacific, Station 272, surface.

{258}3. Echinomma aculeatum, Haeckel.

Actinomma aculeatum, Stöhr, 1880 Palæontogr., vol. xxvi. p. 92, Taf. ii. fig. 11.

Cortical shell thick walled with regular circular pores, of the same breadth as the bars; eight to ten on the radius. Radial proportion of the three spheres = 1 : 2 : 8. Surface covered with short conical by-spines about twenty strong main spines, three-sided pyramidal, one-third as long as the shell diameter.

Dimensions.--Diameter of the outer shell 0.16, middle 0.04, inner 0.02; cortical pores and bars 0.003; length of the main spines 0.05, basal breadth 0.013.

Habitat.--Fossil in the Tertiary rocks of Sicily and Barbados; living in the Atlantic, Station 332, depth 2200 fathoms.

4. Echinomma diadema, n. sp.

Cortical shell thick walled with regular circular pores, twice as broad as the bars; sixteen to eighteen on the radius. Radial proportion of the three spheres = 1 : 3 : 11. Surface covered with short bristle-shaped by-spines one third as long as the twelve stout conical main spines, which reach in length the radius, and lie opposite in pairs in six axes.

Dimensions.--Diameter of the outer shell 0.22, middle 0.06, inner 0.02; cortical pores 0.006, bars 0.003 length of the main spines 0.12, basal breadth 0.02.

Habitat.--Central Pacific, Station 268, depth 2900 fathoms.

Subgenus 2. Echinommura, Haeckel.

Definition.--Pores of the cortical shell irregular, of different size or form.

5. Echinomma sphærechinus, n. sp. (Pl. 29, fig. 2).

Actinomma sphærechinus, Haeckel, 1879, Atlas (pl. xxix. fig. 2).

Cortical shell thin walled, with irregular, roundish pores, twice to five times as broad as the bars; five to seven on the radius. Both medullary shells with regular, circular pores, twice as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 4. Surface covered with thirty to fifty pyramidal main spines, as long as the diameter of the inner shell, and with numerous small conical by-spines of half the length.

Dimensions.--Diameter of the outer shell 0.11, middle 0.05, inner 0.025; cortical pores 0.01 to 0.02, bars 0.004; length of the main spines 0.03, basal breadth 0.005.

Habitat.--North Atlantic, Station 353, surface.

6. Echinomma trinacrium, Haeckel.

Actinomma trinacrium, Haeckel, 1862, Monogr. d. Radiol., p. 441, Taf. xxiv. figs. 6-8.

Cortical shell thin walled, with irregular, roundish pores, twice to three times as broad as the bars. Both medullary shells with regular, circular pores. Radial proportion of the three spheres {259}= 1 : 3 : 9. On the surface about twenty three-sided pyramidal main spines, as long as the radius, and numerous (forty to sixty) by-spines of half the length. (Compare with this species Actinomma trinacrium, with which it is connected by transitional forms.)

Dimensions.--Diameter of the outer shell 0.09, middle 0.03, inner 0.01; cortical pores 0.008 to 0.012, bars 0.004; length of the spines 0.02 to 0.05, basal breadth 0.01.

Habitat.--Mediterranean (Messina).

7. Echinomma toxopneustes, n. sp. (Pl. 29, fig. 1).

Cortical shell thin walled, with large, irregular roundish, polygonally framed pores, twice to four times as broad as the crested bars. Both medullary shells of similar structure. Radial proportion of the three spheres = 1 : 2.5 : 6. Numerous (thirty to fifty or more) thin radial beams connecting them, prolonged outside into strong three-sided pyramidal spines, shorter than the radius; each of the three wings with two teeth. Between these, numerous smaller angular by-spines of one-quarter to one-half the length.

Dimensions.--Diameter of the outer shell 0.12, middle 0.05, inner 0.02; cortical pores 0.01 to 0.03, bars 0.008; length of the main spines 0.05, basal breadth 0.01.

Habitat.--South-east Pacific (South of Juan Fernandez), Station 300, surface.

Genus 103. Pityomma,[139] Haeckel, 1881, Prodromus, p. 453.

Definition.--#Astrosphærida# with three concentric lattice-shells and numerous branched radial spines.

The genus Pityomma differs from its ancestral form, Actinomma, in the ramification of its radial spines, and exhibits therefore the same relation to it that Elatomma, among the Haliommida, bears to Haliomma.

1. Pityomma scoparium, n. sp.

Cortical shell thick walled, connected with both concentric medullary shells by twenty thin radial beams, which are prolonged outside into twenty large cylindrical radial spines; these are somewhat shorter than the shell radius, simple in the proximal inner half, irregularly branched in the outer half. All three spheres with regular, circular pores, twice to three times as broad as the bars; radial proportion = 1 : 2 : 6. (Similar to Cladococcus scoparius, Pl. 27, fig. 2, and Elatomma scoparium, but differs from both in the double medullary shell.)

Dimensions.--Diameter of the outer shell 0.15, middle 0.05, inner 0.025; length of the spines 0.1.

Habitat.--Central Pacific, Station 273, surface.

{260}2. Pityomma piniferum, n. sp.

Cortical shell thin walled, with irregular, roundish pores, connected with both medullary shells by twenty stout radial beams, which are prolonged outside into twenty large three-sided prismatic spines. These are longer than the shell diameter and have three dentate edges, being branched like a pine tree (with four to six ramified branches on each edge, decreasing in size towards the distal end); similar to those of Cladococcus abietinus (Pl. 27, fig. 3). Radial proportion of the three spheres = 1 : 2 : 8. Both medullary shells with regular, circular pores, twice as broad as the bars.

Dimensions.--Diameter of the outer shell 0.2, middle 0.05, inner 0.025; length of the spines 0.25.

Habitat.--South Pacific, Station 299 (Juan Fernandez), surface.

3. Pityomma drymodes, n. sp. (Pl. 29, fig. 9).

Cortical shell thin walled, connected with both medullary shells by very numerous (one hundred to two hundred or more) very thin radial beams, which are prolonged outside into thin branched radial spines, scarcely half as long as the shell radius, each spine bearing six to nine simple branches. Outer and middle shell uneven, with hill-shaped protuberances and valleys between them; the connecting radial beams, which arise from the top of the protuberances of the middle shell, are inserted into the deepest part of the valleys of the outer shell. Radial proportion of the three spheres = 1 : 3 : 8. Outer medullary shell with small, irregular, roundish, or polygonal pores, not much broader than the bars; innermost shell with polygonal pores and very thin bars.

Dimensions.--Diameter of the outer shell 0.28, middle 0.1, inner 0.033; length of the spines 0.07, breadth 0.004.

Habitat.--Central Pacific, Station 271, surface.

Subfamily CROMYOMMIDA,[140] Haeckel, 1881, Prodromus, pp. 449, 453.

Definition.--#Astrosphærida# with four concentric spherical lattice-shells.

Genus 104. Cromyomma,[141] Haeckel, 1881, Prodromus, p. 454.

Definition.--#Astrosphærida# with four concentric lattice-spheres and numerous simple radial spines of one kind.

The genus Cromyomma is the common ancestral form of the Cromyommida, or of those Astrosphærida in which the shell is composed of four concentric spheres, connected by radial beams. Usually two of these are intracapsular or medullary {261}shells, two extracapsular or cortical shells; the distance between the former and the latter is greater than the distance between either the two inner or the two outer shells. In some cases, however (e.g., Cromyomma zonaster), the distance between all four shells is equal.

Subgenus 1. Cromyommetta, Haeckel.

Definition.--Pores of the outer cortical shell regular, of nearly equal size and similar form.

1. Cromyomma villosum, n. sp. (Pl. 30, fig. 2).

Radial proportion of the four spheres = 1 : 2 : 4 : 5. Outer cortical shell thick walled, densely covered with innumerable bristle-shaped radial spines, half as long as the radius. Pores regular, circular, double-edged, of the same breadth as the bars; ten to twelve on the radius. The thick outer shell is so dark, that the outlines only of the other three shells can be seen.

Dimensions.--Diameter of the four shells--(A) outer cortical shell 0.2, (B) inner cortical shell 0.16, (C) outer medullary shell 0.08, (D) inner medullary shell 0.04; pores and bars of the outer shell 0.008; length of the spines 0.04.

Habitat.--Central Pacific, Station 267, depth 2700 fathoms.

2. Cromyomma zonaster, Haeckel.

Acanthosphæra zonaster, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 285, Taf. ii. fig. 2.

Radial proportion of the four spheres = 2 : 3 : 4 : 5. Outer cortical shell thick walled, densely covered with numerous bristle-shaped radial spines, as long as the radius. Pores regular, circular, twice as broad as the bars; eight to ten on the radius. The thick outer shell is so dark, that the outlines only of the other three shells can be seen.

Dimensions.--Diameter of the four shells--(A) 0.15, (B) 0.12, (C) 0.09, (D) 0.06; pores of the outer shell 0.01, bars 0.005; length of the spines 0.08.

Habitat.--Arctic Ocean, Greenland (depth 1000 fathoms), "Alert" Expedition.

3. Cromyomma perplexum, Stöhr.

Cromyomma perplexum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 95, Taf. iii. fig. 5.

Radial proportion of the four spheres = 1 : 2 : 3 : 4. Outer cortical shell thick walled, densely covered with short conical spines, as long as the diameter of the pores. These are regular, circular, three times as broad as the bars; six to eight on the radius. The thick outer shell is so dark, that the outlines only of the three other shells can be seen.

Dimensions.--Diameter of the four shells--(A) 0.17, (B) 0.13, (C) 0.087, (D) 0.043; pores of the outer shell 0.015, bars 0.005; length of the spines 0.02.

Habitat.--Fossil in the Tertiary rocks of Sicily (Grotte) Stöhr.

{262}Subgenus 2. Cromyommura, Haeckel.

Definition.--Pores of the outer cortical shell irregular, of different size and form.

4. Cromyomma perspicuum, n. sp. (Pl. 30, fig. 8).

Cromyosphæra perspicua, Haeckel, 1879, Atlas (pl. xxx. fig. 8).

Radial proportion of the four shells = 1 : 2.5 : 6 : 9. Outer cortical shell very thin walled, with thread-like bars, and irregular, polygonal pores; inner cortical shell with similar pores, but with thicker bars. Both medullary shells with regular, circular pores (the outer three times as broad as the inner). Numerous thin radial beams connect the latter with the former; other very thin and numerous beams connect the two cortical shells, and are prolonged outside into short bristle-shaped spines (often longer than in the figure).

Dimensions.--Diameter of the four shells--(A) 0.18, (B) 0.12, (C) 0.05, (D) 0.02; pores of the outer shell 0.01 to 0.02; length of the spines 0.01 to 0.03.

Habitat.--Central Pacific, Station 274, surface.

5. Cromyomma quadruplex, Haeckel.

Cromyomma quadruplex, Haeckel, 1862, Monogr. d. Radiol., p. 446.

Haliomma quadruplex, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 243.

Radial proportion of the four spheres = 1 : 3 : 7 : 10. Outer cortical shell thin walled, irregularly covered with numerous angular spines, as long as the radius. Pores of all four shells irregular, roundish, increasing in size from the first to the fourth.

Dimensions.--Diameter of the four shells--(A) 0.15, (B) 0.1, (C) 0.045, (D) 0.015; pores of the outer shell 0.01 to 0.02; length of the spines 0.07.

Habitat.--North Atlantic, Station 353, depth 2965 fathoms.

6. Cromyomma macroporum, Stöhr.

Cromyomma macroporum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 95, Taf. iii. fig. 4.

Radial proportion of the four spheres = 1 : 3 : 6 : 9. Outer cortical shell thick walled, densely covered with short conical spines, as long as the diameter of the pores; the latter are irregular, roundish, or polygonal, larger and smaller alternating.

Dimensions.--Diameter of the four shells--(A) 0.1, (B) 0.066, (C) 0.033, (D) 0.011; pores of the outer shell 0.033 to 0.016, bars 0.003; length of the spines 0.01.

Habitat.--Fossil in the Tertiary rocks of Sicily, Grotte, Stöhr.

7. Cromyomma circumtextum, n. sp. (Pl. 30, fig. 4).

Radial proportion of the four spheres = 1 : 2 : 5 : 7. Outer cortical shell very delicate and thin walled, with thread-like bars and large, irregular, polygonal meshes (larger than the innermost shell); {263}inner cortical shell also with irregular, polygonal pores, three to nine times as broad as the thick bars. Both medullary shells with subregular, circular pores (the outer three times as broad as the inner). Radial spines twelve to twenty, three-sided prismatic, stout, piercing the three outer shells, inserted on the innermost; their outer part pyramidal, half as long as the radius.

Dimensions.--Diameter of the four shells--(A) 0.22, (B) 0.15, (C) 0.07, (D) 0.03; meshes of the outer shell 0.02 to 0.04; length of the outer spines 0.05.

Habitat.--Central Pacific, Station 266, depth 2750 fathoms.

8. Cromyomma mucronatum, n. sp. (Pl. 30, figs. 5, 5_a_).

Radial proportion of the three spheres = 1 : 2 : 3 : 6. Outer cortical shell thin walled, with large, irregular, roundish pores and crested three-sided bars; inner cortical shell with regular, circular, hexagonally formed pores (four times as broad as the bars). Both medullary shells with simple, small, regular, circular pores (fig. 5_a_). Twelve radial spines three-sided prismatic, dagger-shaped, with three teeth, as long as the diameter of the innermost shell.

Dimensions.--Diameter of the four shells--(A) 0.24, (B) 0.12, (C) 0.08, (D) 0.04; meshes of the outer shell 0.02 to 0.04; length of the spines 0.04.

Habitat.--Central Pacific, Station 274, depth 2750 fathoms.

Genus 105. Cromyechinus,[142] Haeckel, 1881, Prodromus, p. 454.

Definition.--#Astrosphærida# with four concentric lattice-spheres and numerous simple spines of two different kinds; larger main spines and smaller by-spines.

The genus Cromyechinus differs from Cromyomma in the same way as Echinomma from Actinomma; the radial spines being differentiated into two different kinds; a larger number of small by-spines, and a smaller number of large main spines.

1. Cromyechinus icosacanthus, n. sp. (Pl. 30, fig. 1).

Radial proportion of the three spheres = 1 : 2 : 6 : 8. Outer cortical shell very delicate, with very small, regular, circular pores, covered with very numerous bristle-shaped by-spines, half as long as the radius; inner cortical shell with very large, irregular, polygonal pores, three to eight times as broad as the bars. Both medullary shells with regular, circular pores, connected with the former by twenty regularly disposed, very thin bars; these are prolonged outside into twenty very stout, three-sided prismatic main spines, as long as the radius, which arise from the inner cortical shell, and at the distal end are cuspidate.

Dimensions.--Diameter of the four shells--(A) 0.16, (B) 0.13, (C) 0.04, (D) 0.02; pores of the outer cortical shell 0.003, of the inner 0.03, bars 0.003; length of the spines 0.08.

Habitat.--Central Pacific, Station 271, depth 2425 fathoms.

{264}2. Cromyechinus dodecacanthus, n. sp. (Pl. 30, figs. 3, 3_a_).

Radial proportion of the four spheres = 1 : 3 : 10 : 12. Outer cortical shell very delicate, with very small, regular, circular pores, covered with numerous short bristle-shaped by-spines, scarcely one-fourth as long as the radius; inner cortical shell with very large, irregular, polygonal pores, twice to six times as broad as the bars. Both medullary shells with very small, regular, circular pores, connected with the former by twelve regularly disposed, thin radial beams; these are prolonged outside into twelve strong, three-sided pyramidal main spines, one-third as long as the shell diameter. (Differs from the foregoing only in the number and form of the radial spines.)

Dimensions.--Diameter of the four shells--(A) 0.12, (B) 0.1, (C) 0.03, (D) 0.01; pores of the outer cortical shell 0.002, of the inner 0.02, bars 0.002; length of the spines 0.04, basal breadth 0.01.

Habitat.--South Atlantic, Station 325, surface.

3. Cromyechinus polyacanthus, n. sp.

Radial proportion of the four spheres = 1 : 2 : 8 : 10. Outer cortical shell of the same structure as the inner, with irregular, roundish pores, twice to six times as broad as the bars. Both medullary shells with small, regular, circular pores, twice as broad as the bars. Connecting radial beams forty to sixty, thin, cylindrical, prolonged outside into forty to sixty strong conical main spines, about as long as the radius. Between these, numerous thin bristle-shaped by-spines, nearly of the same length.

Dimensions.--Diameter of the four shells--(A) 0.25, (B) 0.2, (C) 0.05, (D) 0.025; pores of both cortical shells 0.01 to 0.03; length of the spines 0.12.

Habitat.--North Pacific, Station 237, surface.

Genus 106. Cromyodrymus,[143] Haeckel, 1881, Prodromus, p. 454.

Definition.--#Astrosphærida# with four concentric lattice-spheres and numerous branched radial spines.

The genus Cromyodrymus differs from its ancestral form, Cromyomma, in the ramification of the radial spines, and exhibits therefore the same relation to it that Pityomma among the Actinommida bears to Actinomma.

1. Cromyodrymus quadricuspis, n. sp. (Pl. 30, figs. 7, 7_a_).

Radial proportion of the four shells = 1 : 3 : 6 : 12. All four shells with regular, circular pores, about twice as broad as the bars. Radial proportion of the pores in the four shells = 2 : 4 : 2 : 1. Radial spines fifty to sixty, three-sided prismatic, half as long as the radius, with three recurved teeth, each spine in this way bearing four points.

{265}Dimensions.--Diameter of the four shells--(A) 0.16, (B) 0.08, (C) 0.04, (D) 0.013; length of the spines 0.03 to 0.04, breadth 0.007.

Habitat.--Central Pacific, Station 272, depth 2600 fathoms.

2. Cromyodrymus abietinus, n. sp. (Pl. 30, fig. 6).

Radial proportion of the four shells = 1 : 2 : 5 : 11. All four shells with irregular, roundish pores, twice to four times as broad as the bars. Radial proportion of the pores in the four shells = 9 : 3 : 2 : 1. Radial spines eighty to one hundred and twenty, about as long as the radius, branched like a pine tree, with six to twelve ramified branches.

Dimensions.--Diameter of the four shells--(A) 0.22, (B) 0.1, (C) 0.04, (D) 0.02; length of the spines 0.12, breadth 0.006.

Habitat.--South-east Pacific (Juan Fernandez), Station 299, surface.

Subfamily CARYOMMIDA,[144] Haeckel.

Arachnosphærida, Haeckel, 1862, Monogr. d. Radiol., p. 354; Prodromus, 1881, p. 454.

Definition.--#Astrosphærida# with five or more concentric spherical lattice-shells.

Genus 107. Caryomma,[145] n. gen.

Definition.--#Arachnosphærida# with five to six or more concentric spherical lattice-shells; two inner (intracapsular) medullary and three or more outer (extracapsular) cortical shells, composed of ordinary lattice-work; distance between the former and the latter greater than between any other two shells.

The genus Caryomma may be regarded as a Cromyomma, in which the number of the cortical shells is increased to three, four, or more. These lie outside the central capsule, whilst two medullary shells lie within it, and are connected with the former by numerous radial spines piercing the wall of the capsule. The ordinary lattice-work is not arachnoidal, as in the three following genera.

1. Caryomma regulare, n. sp.

Radial proportion of the five shells = 1 : 2 : 6 : 8 : 10. All five shells with regular, circular pores, twice to three times as broad as the bars, and gradually increasing in size from the innermost to the outermost shell. Radial beams connecting them twenty, prolonged on the surface into twenty stout, three-sided pyramidal, radial spines, half as long as the radius, regularly disposed.

Dimensions.--Diameter of the five shells--(A) 0.25, (B) 0.2, (C) 0.15, (D) 0.05, (E) 0.025.

Habitat.--Central Pacific, Station 268, depth 2900 fathoms.

{266}2. Caryomma irregulare, n. sp.

Radial proportion of the six shells = 1 : 2.5 : 8 : 10.5 : 13 : 15. Both inner (medullary) shells with regular, circular pores, the other four (cortical) shells with irregular, roundish pores, gradually increasing in size from the innermost to the outermost shell. Radial spines sixty to eighty, pyramidal, irregularly disposed.

Dimensions.--Diameter of the six shells--(A) 0.3, (B) 0.26, (C) 0.21, (D) 0.16, (E) 0.05, (F) 0.02.

Habitat.--Central Pacific, Station 265, depth 2900 fathoms.

Genus 108. Arachnopila,[146] n. gen.

Definition.--#Astrosphærida# with five to ten or more cortical, concentric, polyhedral, or spherical lattice-shells, composed of a very thin cobweb-like network; innermost shell with hexagonal (regular) or polygonal (irregular) meshes; other shells with simple triangular meshes, without diagonal threads between them.

The genus Arachnopila, together with the two following genera, forms the peculiar small group of large Arachnosphærida, separated from the true Caryommida by the totally different structure and disposition of the numerous concentric shells; the former exhibits a similar relation to the latter that the Diplosphærida bears to the Elatommida among the dispherical Haliommida. The concentric shells (five to ten or more) lie outside the central capsule, and are composed of very delicate, cobweb-like threads. From the innermost shell arise numerous, three-sided prismatic, very long spines, from which at equal regular distances arise lateral branches (three pairs from each spine, and one pair from each corner). In Arachnopila these threads pass directly from one spine to the other, and form simple, large, triangular meshes between them. The concentric shells are not connected by interwoven diagonal threads.

1. Arachnopila hexagonella, n. sp.

Innermost shell with regular hexagonal pores; its diameter twice as long as the equal distance between every two concentric shells. Radial spines twenty to forty, each with twenty to twenty-four verticils.

Dimensions.--Diameter of the innermost shell 0.1; distance between the concentric shells 0.05.

Habitat.--Central Pacific, Station 271, surface.

2. Arachnopila polygonella, n. sp.

Innermost shell with irregular, polygonal pores; its diameter fully as long as the equal distance between every two concentric shells. Radial spines sixty to eighty, each with twelve to sixteen verticils.

Dimensions.--Diameter of the innermost shell 0.04; distance between the concentric shells 0.04.

Habitat.--Central Pacific, Station 266, surface.

{267}Genus 109. Arachnopegma,[147] Haeckel, 1881, Prodromus, p. 454.

Definition.--#Astrosphærida# with five to ten or more cortical, concentric, polyhedral, or spherical lattice-shells, composed of a very thin, cobweb-like network; innermost shell with hexagonal or polygonal meshes; other shells with simple triangular meshes, connected to one another by diagonal threads between them.

The genus Arachnopegma differs from its ancestral form Arachnopila, in the possession of peculiar diagonal threads, which connect the verticils or nodal-points of every two neighbouring radial spines in two different neighbouring concentric shells. In this case, therefore, not only do triangular meshes lie in the spherical faces of the concentric spheres, but also between them, in numerous oblique diagonal planes; a very rare and remarkable structure, and forming a transition to spongy shells.

1. Arachnopegma verticillatum, n. sp.

Innermost shell with regular, hexagonal meshes; its diameter is the same as the equal distance between each of the two shells. Threads of the network smooth. Radial spines twenty to forty, each with fifteen to twenty verticils.

Dimensions.--Diameter of the innermost shell 0.04, distance between the concentric shells 0.03 to 0.04.

Habitat.--Central Pacific, Station 266, surface.

2. Arachnopegma longispinum, n. sp.

Innermost shell with regular, hexagonal meshes; its diameter half as large as the equal distance between every two shells. Threads of the network dentated or with small knots. Radial spines fifty to sixty, each with twenty to twenty-five verticils.

Dimensions.--Diameter of the innermost shell 0.02; distance between the concentric shells 0.04 to 0.05.

Habitat.--Central Pacific, Station 272, surface.

3. Arachnopegma increscens, n. sp.

Innermost shell with regular, hexagonal meshes; its diameter quite as large as the distance between it and the second shell; only half as large as the distance between the fourth and fifth shells. Forty to fifty radial spines, each with fifteen to twenty verticils.

Dimensions.--Diameter of the innermost shell (A) 0.025; distance between the following shells--A, B = 0.025, B, C = 0.03, C, D = 0.04, D, E = 0.048, E, F = 0.056, F, G = 0.064, &c.

Habitat.--Central Pacific, Station 274, surface.

{268}Genus 110. Arachnosphæra,[148] Haeckel, 1862, Monogr. d. Radiol., p. 355.

Definition.--#Astrosphærida# with five to ten or more cortical, concentric, polyhedral, or spherical lattice-shells, composed of a very thin cobweb-like network; innermost shell with hexagonal (regular) or polygonal (irregular) meshes; other shells with larger, irregular, polygonal meshes.

The genus Arachnosphæra (accurately described by me in 1862, loc. cit.) differs from the two preceding genera in the irregular form of the large meshes in all shells (except often the innermost). This is caused by the ramification of the thin threads, which on each shell connect the neighbouring spines. In Arachnopila and Arachnopegma the threads pass directly and undivided from each spine to the neighbouring spine (three pairs from the three edges), and therefore all meshes are triangular. In Arachnosphæra they become polygonal by irregular ramification of the threads. There are here no diagonal threads.

Subgenus 1. Arachnosphærella, Haeckel.

Definition.--Pores of the innermost shell regular, hexagonal.

1. Arachnosphæra oligacantha, Haeckel.

Arachnosphæra oligacantha, Haeckel, 1862, Monogr. d. Radiol., p. 356, Taf. x. fig. 2, Taf. xi. fig. 3.

Innermost shell with regular, hexagonal meshes; its diameter three times as long as the equal distances between every two concentric shells. Fifteen to twenty radial spines scattered at wide intervals, each with six to eight verticils.

Dimensions.--Diameter of the innermost shell 0.12; distance between the concentric shells 0.04 to 0.05.

Habitat.--Mediterranean (Messina), surface, Haeckel.

2. Arachnosphæra myriacantha, Haeckel.

Arachnosphæra myriacantha, Haeckel, 1862, Monogr. d. Radiol., p. 357, Taf. x. fig. 3, Taf. xi. fig. 4.

Innermost shell with regular, hexagonal meshes; its diameter twice as long as the equal distances between every two concentric shells. At each nodal-point occurs one radial spine with six to eight verticils (spines in all one hundred to one hundred and twenty or more).

Dimensions.--Diameter of the innermost shell 0.1; distance between the concentric shells 0.04 to 0.05.

Habitat.--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface.

{269}3. Arachnosphæra dolichacantha, n. sp.

Innermost shell with regular, hexagonal meshes, very small; its diameter only as long as the equal distances between every two concentric shells. At each nodal-point occurs one radial spine with twelve to sixteen verticils (altogether thirty to forty spines).

Dimensions.--Diameter of the innermost shell 0.05; distance between the concentric shells 0.04 to 0.05.

Habitat.--Central Pacific, Station 265 to 274, surface.

4. Arachnosphæra increscens, n. sp.

Innermost shell with regular, hexagonal meshes; its diameter three times as long as the distance between it and the second shell, quite as long as the distance between the fifth and sixth shells; the distances between the concentric shells gradually increasing from the centre. Radial spines about fifty to sixty, each with six to eight verticils.

Dimensions.--Diameter of the innermost shell (A) 0.75; distances between the following shells--A, B = 0.025, B, C = 0.037, C, D = 0.05, D, E = 0.062, E, F = 0.075, &c.

Habitat.--Central Pacific, Station 271, surface.

Subgenus 2. Arachnosphæromma, Haeckel.

Definition.--Pores of the innermost shell irregular, polygonal.

5. Arachnosphæra tenuissima, n. sp.

Innermost shell with irregular, polygonal meshes; its diameter twice as long as the equal distance between every two concentric shells. Forty to fifty radial spines, each with twelve to sixteen verticils.

Dimensions.--Diameter of the innermost shell 0.1, distance between the concentric shells 0.04 to 0.05.

Habitat.--South Atlantic, Station 332, surface.

6. Arachnosphæra velaris, n. sp.

Innermost shell with irregular, polygonal meshes; its diameter twice as long as the distance between it and the second shell, quite as long as the distance between the third and fourth shells; the distance between the concentric shells gradually increasing from the centre. Radial spines twenty to thirty, each with ten to twelve verticils.

Dimensions.--Diameter of the innermost shell (A) 0.5; distances of the following shells--A, B = 0.025, B, C = 0.037, C, D = 0.05, D, E = 0.062, E, F = 0.075.

Habitat.--Tropical Atlantic, Station 347, surface.

{270}Subfamily SPONGIOMMIDA,[149] Haeckel.

Definition.--#Astrosphærida# with spongy spherical or polyhedral shell (with or without enclosed concentric lattice-shells).

Genus 111. Spongiomma,[150] n. gen.

Definition.--#Astrosphærida# with solid spongy sphere, with numerous simple radial spines, but without latticed medullary shells.

The genus Spongiomma differs from its ancestral form, Styptosphæra, in the development of simple radial spines on the surface of the solid sphere, the entire mass of which is composed of an irregular, spongy wicker-work.

Subgenus 1. Spongiommella, Haeckel.

Definition.--Radial spines on the surface of the spongy sphere all of the same shape.

1. Spongiomma radiatum, n. sp.

Spongy framework of the solid sphere of the same structure throughout, with small, irregular, polyhedral meshes and very thin thread-like bars. From the surface arise very numerous (one hundred and twenty to one hundred and sixty or more) straight, bristle-shaped radial spines, as long as the radius of the sphere (counting from the middle part of it).

Dimensions.--Diameter of the spongy sphere 0.2; length of the radial spines 0.1.

Habitat.--Central Pacific, Station 272, surface.

2. Spongiomma denticulatum, n. sp.

Spongy framework of the solid sphere of the same structure throughout, with small, almost equal meshes, four to eight times as broad as the thin, elegantly denticulated bars; from the surface arise very numerous (two hundred to three hundred or more) curved, radial spines, as long as the radius, and of the same form as the bars.

Dimensions.--Diameter of the sphere 0.25; length of the spines 0.12.

Habitat.--Central Pacific, Station 274, surface.

3. Spongiomma spathillatum, n. sp.

Spongy framework in the central part of the sphere much denser and darker, and with smaller meshes than in the peripheral part in which are very thin bars. Entire surface covered with {271}innumerable short, bristle-shaped radial spines, only one-eighth as long as the radius, of the same elegant form as in Octodendron spathillatum (Pl. 18, figs. 2, 4); each spine developed in a zig-zag fashion, with very small beards, with a delicate spathillum (or coronal of beard spines) at the distal end.

Dimensions.--Diameter of the spheres 0.16; length of the spines 0.01.

Habitat.--South Pacific, Station 295, surface.

4. Spongiomma clavatum, n. sp.

Spongy framework in the central part of the sphere much denser and darker than in the peripheral part. On the surface are sixty to eighty stout, club-shaped radial spines, as long as the radius of the sphere, in the proximal half three-sided prismatic, with three dentated edges; they begin at the middle of the radius (where the denser inner framework changes into the looser outer) and are very thin at first but increase slowly in thickness towards the truncated distal end. (Similar to Centrocubus rhopalophorus, Pl. 18, fig. 1, but without the cubical medullary shell.)

Dimensions.--Diameter of the sphere 0.4; length of the spines 0.2.

Habitat.--North Pacific, Station 241, surface.

Subgenus 2. Spongiommura, Haeckel.

Definition.--Radial spines on the surface of the spongy sphere of two different kinds; large main spines and small by-spines.

5. Spongiomma helioides, n. sp.

Spongy framework of the sphere everywhere of the same structure, with almost equal meshes, ten to twelve times as broad as the bars. Sixteen to twenty radial main spines, longer than the shell diameter, three-sided prismatic, with three serrated edges, beginning about the middle of the radius and increasing in thickness to the truncated distal end. Between them occur numerous thin, bent, bristle-shaped by-spines. (Very similar to Spongosphæra helioides, Monogr. d. Radiol., Taf. xii. figs. 11-13, but without medullary shells.)

Dimensions.--Diameter of the sphere 0.3; length of the main spines 0.4, of the by-spines 0.01.

Habitat.--Tropical Atlantic, Station 352, surface.

6. Spongiomma multiaculeum, Haeckel.

Spongechinus multiaculeatus, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 29, Taf. v. figs. 60-63.

Spongy framework of the sphere very compact, with small meshes, scarcely broader than the bars; four to eight large main spines, three-sided pyramidal, longer than the shell radius; numerous (thirty to forty) thin by-spines, scarcely half as long.

{272}Dimensions.--Diameter of the sphere 0.16; length of the main spines 0.11, of the by-spines 0.03.

Habitat.--Fossil in the Alpine Jura, Schafberg near Salzburg (Dunikowski).

7. Spongiomma asteroides, n. sp.

Spongy framework in the central part of the sphere much denser and darker than in the peripheral part. Sixty to eighty cylindro-conical main spines, as long as the radius, between them are numerous straight, bristle-shaped by-spines half that length.

Dimensions.--Diameter of the sphere 0.28; length of the main spines 0.16, of the by-spines 0.08.

Habitat.--South Atlantic, Station 325, surface.

Genus 112. Spongodrymus,[151] Haeckel, 1881, Prodromus, p. 456.

Definition.--#Astrosphærida# with solid spongy sphere, without latticed medullary shell, with numerous branched radial spines.

The genus Spongodrymus differs from the preceding Spongiomma in the ramification of the numerous radial spines, covering the surface of the solid spongy sphere.

1. Spongodrymus elaphococcus, n. sp. (Pl. 18, fig. 9).

Spongy framework of the solid sphere equal throughout, on the surface arising in the form of very numerous (sixty to eighty or more) spongy cones with rather rhomboidal meshes. Each cone is prolonged into a very thin, irregularly curved radial spine, which is twice as long as the shell diameter, simple in the proximal half, branched like a tree in the distal half; each arborescent spine has from sixteen to thirty-two terminal branches, which fall in one spherical face. The branches of neighbouring spines are partly connected by anastomoses, so that they begin to form an outer spherical shell (cortical shell) with a looser spongy framework.

Dimensions.--Diameter of the whole spherical skeleton (sphere formed by the distal ends of the dichotomous branches) 0.9, of the inner solid spongy sphere 0.02.

Habitat.--Tropical Atlantic, Station 349, surface.

2. Spongodrymus abietinus, n. sp.

Spongy framework denser and darker in the central part of the sphere than in the peripheral part, with rather coarse meshes and thick bars. From the surface arise very numerous (sixty to eighty) stout, radial branches, as long as the shell radius, branched like a pine tree (with six to twelve ramified branches). Similar in structure to Cromyodrymus abietinus (Pl. 30, fig. 6), but with a quite irregular spongy texture in the central sphere.

Dimensions.--Diameter of the sphere 0.3; length of the spines 0.015.

Habitat.--Central Pacific, Station 272, surface.

{273}Genus 113. Spongechinus,[152] Haeckel, 1881, Prodromus, p. 456.

Definition.--#Astrosphærida# with hollow, spongy sphere, without latticed medullary shell in the central cavity, and with numerous simple radial spines.

The genus Spongechinus differs from its ancestral form, Plegmosphæra, in the development of numerous radial spines on the surface of the spongy sphere, within which is enclosed a large spherical central cavity.

1. Spongechinus setosus, n. sp.

Spongy sphere three times as broad as its inner cavity, with a very delicate, equal framework. Entire surface covered with short, straight, bristle-shaped radial spines, about half as long as the radius.

Dimensions.--Diameter of the sphere 0.2, of its inner cavity 0.07; length of the spines 0.05.

Habitat.--North Atlantic, Azores, surface.

2. Spongechinus serrulatus, n. sp.

Spongy sphere twice as broad as its inner cavity, with a delicate, equal framework. Entire surface covered with short, curved, radial spines, which are elegantly denticulated, and as long as the shell radius.

Dimensions.--Diameter of the sphere 0.3, of its cavity 0.15; length of the spines 0.15.

Habitat.--Central Pacific, Station 274, surface.

3. Spongechinus cavus, n. sp.

Spongy sphere only one-fourth broader than the large inner cavity, its spongy wall being only one-fourth as thick as the radius, composed of three to four strata of irregular, small meshes. Surface covered with short, bristle-shaped, curved spines, one-third as long as the radius.

Dimensions.--Diameter of the sphere 0.5, of its inner cavity 0.4; length of the spines 0.08.

Habitat.--North Atlantic, Station 354, surface.

Genus 114. Spongothamnus,[153] n. gen.

Definition.--#Astrosphærida# with hollow, spongy sphere, without latticed medullary shell in the central cavity, and with numerous branched radial spines.

The genus Spongothamnus differs from the preceding Spongechinus in the ramification of the numerous radial spines, covering the surface of the hollow spongy sphere; {274}it therefore exhibits the same relation to the latter that Spongodrymus bears to Spongiomma.

1. Spongothamnus furcatus, n. sp.

Spongy sphere twice as broad as its inner cavity, with very delicate bars, and irregular, dense framework. From the surface arise one hundred and fifty to one hundred and eighty thin, forked, bristle-shaped spines, half as long as the radius; both fork branches one-third as long as the basal or simple part.

Dimensions.--Diameter of the sphere 0.3, of its inner cavity 0.15; length of the spines 0.08.

Habitat.--North Pacific, Station 241, surface.

2. Spongothamnus scoparius, n. sp.

Spongy sphere four times as broad as its inner cavity, with thick bars and rather loose framework. From the surface arise sixty to eighty broom-shaped radial spines, as long as the radius, each in the basal half simple, in the distal half with six to twelve irregularly ramified branches (similar to the spines of Cromyodrymus abietinus, Pl. 30, fig. 6).

Dimensions.--Diameter of the sphere 0.4, of the inner cavity 0.1; length of the spines 0.2.

Habitat.--Central Pacific, Station 271, surface.

Genus 115. Spongopila,[154] Haeckel, 1881, Prodromus, p. 456.

Definition.--#Astrosphærida# with a single, spherical, latticed medullary shell, immediately enveloped by the spongy framework of the cortical shell; on the surface of the latter are numerous radial spines.

The genus Spongopila is a Spongoplegma with radial spines. On the other hand it may be derived either from Elaphococcus, by communication of the branched spines, or from Arachnosphæra, by development of spongy branches between the concentric spheres.

1. Spongopila dichotoma, n. sp.

Medullary shell with regular, hexagonal meshes, six times as broad as the bars. From each nodal-point (between every three meshes) arises a bristle-shaped radial spine, which is dichotomously branched. By communication of the neighbouring branches the loose spongy framework of the spherical cortical shell is formed, which is four times as broad as the medullary shell. On the surface occur very numerous bristle-shaped radial spines, as long as the diameter of the medullary shell. (May be derived from Elaphococcus.)

Dimensions.--Diameter of the spongy cortical shell 0.3, of the medullary shell 0.08.

Habitat.--Tropical Atlantic, Station 347, surface.

{275}2. Spongopila verticillata, n. sp.

Medullary shell with regular, hexagonal meshes, four times as broad as the bars. From its surface arise forty to sixty, three-sided prismatic radial spines, bearing eight to ten verticils of lateral branches, each verticil with six forked branches (two from each edge). By irregular ramification of these branches, and communication in all directions, the loose spongy framework of the cortical shell originates, which is six times as broad as the medullary shell. The free distal ends of the spines are as long as the shell radius. (May be derived from Arachnosphæra.)

Dimensions.--Diameter of the spongy cortical shell 0.6, of the medullary shell 0.1.

Habitat.--Tropical Pacific, Station 200, surface.

Genus 116. Rhizoplegma,[155] Haeckel, 1881, Prodromus, p. 456.

Definition.--#Astrosphærida# with a single, spherical, latticed medullary shell, which is not armed with by-spines, but connected by stout radial main spines with the spongy cortical shell.

The genus Rhizoplegma is immediately allied to the foregoing Spongopila, but differs from it in the large interval separating both shells. In this interval lies the wall of the central capsule, which is only pierced by the radial spines connecting both shells.

Subgenus 1. Rhizoplegmarium, Haeckel.

Definition.--No free lateral branches of the radial spines between the two shells.

1. Rhizoplegma polyacanthum, n. sp.

Spongy cortical shell with a very fine dense framework and nearly smooth surface (without superficial by-spines). Its inner cavity is four times as broad as the medullary shell, which exhibits regular, hexagonal meshes. Radial spines sixty to eighty, three-sided prismatic, with three smooth edges, without lateral branches between both shells; their free outer part as long as the shell radius.

Dimensions.--Diameter of the spongy cortical shell 0.3, of its inner cavity 0.2, of the medullary shell 0.05.

Habitat.--Central Pacific, Station 274, surface.

2. Rhizoplegma spirale, n. sp.

Spongy cortical shell with a very delicate loose framework and bristly surface. Its inner cavity three times as broad as the medullary shell, which exhibits regular, hexagonal meshes. {276}Radial spines thirty to forty, prismatic, with three smooth, spirally contorted edges, without lateral branches between the two shells; their free outer part half as long as the shell radius.

Dimensions.--Diameter of the spongy cortical shell 0.2, of its inner cavity 0.12, of the medullary shell 0.04.

Habitat.--Central Pacific, Station 265, surface.

3. Rhizoplegma trigonacantha, n. sp.

Spongy cortical shell with a rather loose framework and coarse bars, with nearly smooth surface (without by-spines). Its inner cavity twice as broad as the medullary shell, which exhibits irregular, roundish pores. Radial spines forty to sixty, prismatic, with three smooth straight edges, without free branches between the two shells; their outer pyramidal part only one-third of the shell radius. (Very similar to the common Rhizosphæra trigonacantha, but with simple medullary shell.)

Dimensions.--Diameter of the spongy shell 0.2, of its inner cavity 0.16, of the medullary shell 0.08.

Habitat.--North Atlantic, Station 353, surface.

Subgenus 2. Rhizoplegmidium, Haeckel.

Definition.--Between the two shells free lateral branches arise from the three edges of the radial spines.

4. Rhizoplegma radicatum, n. sp. (Pl. 15, figs. 9, 9_a_).

Spongy cortical shell with a very loose framework; on the surface are innumerable thin, forked, or repeatedly dichotomous by-spines. Its inner cavity three times as broad as the medullary shell, which exhibits regular, hexagonal meshes (fig. 9_a_). Radial spines twelve, prismatic, with straight dentated edges, their outer pointed part as long as the shell radius. Each spine between the two shells has a verticil of three forked lateral branches (fig. 9_a_). The central capsule completely distends the medullary shell, and forces out through each mesh a hernia-shaped process (fig. 9).

Dimensions.--Diameter of the spongy shell 0.5, of its inner cavity 0.25, of the medullary shell 0.08.

Habitat.--Central Pacific, Station 271, surface.

5. Rhizoplegma lychnosphæra, n. sp. (Pl. 11, fig. 5).

Lychnosphæra rhizoplegma, Haeckel, 1879, Atlas (pl. xi. fig. 5).

Spongy cortical shell with a very loose framework, composed of long thin beams as in Lychnosphæra regina (Pl. 11, figs. 1-4). Surface covered with short bristles. Its inner cavity six times as broad as the medullary shell, which exhibits regular, hexagonal meshes. Radial spines twelve, prismatic, with three smooth edges; their outer pointed part half as long as the shell radius. Each spine has three verticils of three forked branches; the first verticil is free {277}between the two shells, while the two following verticils, by communication of their ramules, form the irregular framework. Central capsule with many herniæ, forced out through the meshes of the medullary shell (fig. 5).

Dimensions.--Diameter of the spongy shell 0.7, of its inner cavity 0.45, of the medullary shell 0.07.

Habitat.--South Pacific, Station 284, surface.

Genus 117. Lychnosphæra,[156] Haeckel, 1881, Prodromus, p. 453.

Definition.--#Astrosphærida# with a single, spherical, latticed medullary shell, which is armed with free radial by-spines, and connected by stout radial main spines with the spongy cortical shell.

The genus Lychnosphæra, known only by one single, large, and very remarkable species, mainly differs from the foregoing in the development of free radial by-spines on the surface of the medullary shell, and in the free interval between it and the cortical shell; but beyond this the loose spongy framework of the latter exhibits a very remarkable structure, figured in Pl. 11.

1. Lychnosphæra regina (Pl. 11, figs. 1-4).

Medullary shell (fig. 3) with regular, circular, hexagonally framed pores, twice as broad as the bars; from each hexagon-corner arises a radial, bristle-shaped by-spine, as long as the diameter. Twelve radial main spines each as broad as one of the meshes, three-sided prismatic, six to eight times as long as the medullary shell. From their three leaf-shaped (often somewhat denticulated or spirally contorted) edges arise four verticils of lateral branches, each composed of three forked, thin branches. The forked branches of the first verticil end free between the two shells (figs. 2, 3), while the two following verticils are ramified, and, by anastomosis of their branches, compose the loose spongy framework of the cortical shell. On the surface of the latter arise numerous radial (zig-zag-shaped) by-spines. The fourth verticil is terminal, with three shorter, thicker, dentated, simple branches, which constitute, together with the distal apex of the spine itself, a bunch of four terminal spines. The large central capsule completely distends the medullary shell, and forces out by its pores numerous club-shaped herniæ (fig. 1).

Dimensions.--Diameter of the spongy cortical shell 0.6, of its inner cavity 0.4, of the central capsule 0.22, of the medullary shell 0.06; length of the radial spines 0.4, breadth 0.01.

Habitat.--Central Pacific, Station 271, surface.

Genus 118. Centrocubus,[157] n. gen.

Definition.--#Astrosphærida# with a single, cubical medullary shell, immediately surrounded by the spongy framework of the cortical shell; from the eight corners {278}of the central cube arise eight primary radial spines, and often others from the framework between them.

The genus Centrocubus and the following closely allied Octodendron may represent a peculiar small group of Spongiommida, remarkable for the regular, cubical form of the medullary shell, which is composed of twelve thin rods, corresponding to the twelve edges of a mathematical cube; from the eight corners invariably arise eight primary radial spines, the branches of which form the spongy cortical shell.

1. Centrocubus octostylus, n. sp.

Radial spines eight, arising from the eight corners of the cubiform, regular, medullary shell, gradually increasing in thickness towards the club-shaped distal end, which is five to six times as broad as the central end. From the three denticulate edges of each spine arise six to eight lateral branches, which ramify irregularly and form by their anastomosis the spongy framework which is of nearly similar structure throughout, and with large loose meshes. The free distal part of each spine is half as long as the enclosed part.

Dimensions.--Diameter of the sphere 0.6, of the central cube 0.02; length of the spines 0.15, distal thickness 0.02.

Habitat.--Central Pacific, Station 271, surface.

2. Centrocubus cladostylus, n. sp. (Pl. 18, fig. 1).

Radial spines thirty-two, club-shaped, at the distal end eight to ten times as broad as at the basal end. Eight primary spines arise from the eight corners of the regular, cubiform medullary shell, and from these, in the form of lateral branches, twenty-four secondary spines arise with concavely curved bases (three from the three denticulate edges of each spine, at nearly equal distances from the centre). The free distal end of each of the thirty-two spines is of the same shape, about half as long as the radius of the spongy sphere; framework much looser in the outer than in the inner part.

Dimensions.--Diameter of the sphere 0.8, of the central cube 0.02; length of the spines 0.2, distal thickness 0.02.

Habitat.--North Pacific, Station 256, surface.

3. Centrocubus polystylus, n. sp.

Radial spines sixty to eighty, club-shaped, four to six times as broad at the distal as at the basal end. Eight primary spines arise from the eight corners of the regular, cubiform medullary shell, the remainder either springing as lateral branches from the three denticulate corners of the former, or arising within the spongy framework, which is much denser and darker in the central than in the peripheral part. The free distal end of each spine is one-third as long as the radius.

{279}Dimensions.--Diameter of the sphere 0.9, of the central cube 0.02; length of the spines 0.15, distal thickness 0.02.

Habitat.--South Pacific, Station 295, surface.

Genus 119. Octodendron,[158] n. gen.

Definition.--#Astrosphærida# with a single, cubical medullary shell, and eight primary radial spines arising from its eight corners; these are connected at equal distances by a latticed, spherical, cortical shell, from which the spongy framework directly springs; often from the latter secondary radial spines arise.

The genus Octodendron has the same regular, cubical medullary shell as the preceding Centrocubus, but differs from it in the wide interval separating the medullary shell from the inner spherical face of the spongy cortical shell, the two being connected only by eight radial beams, arising from the eight corners of the cube.

Subgenus 1. Octodendridium, Haeckel.

Definition.--Only eight primary radial spines, arising from the eight corners of the central cube.

1. Octodendron cubocentron, n. sp. (Pl. 18, fig. 3).

Radial spines eight, club-shaped, with three denticulate, straight edges, twice as long as the diameter of the central cavity of the cubical spongy shell; the inner face of the latter (or the "inner cortical shell") exhibits the form of a large cube, the spongy sides of which are parallel with the simple square sides of the central cube. The thin eight radial beams, connecting the corresponding corners of both cubes, are not thicker than the edge-bars of the central cube, whilst their outer prolongations are much thicker, with four to six verticils of lateral branches. Surface of the thin walled, loose, spongy shell armed with short simple thorns.

Dimensions.--Diameter of the spongy shell 0.2, of its inner cavity 0.1, of the central cube 0.02; length of the spines 0.2 (from the centre 0.3).

Habitat.--Central Pacific, Station 266, surface.

2. Octodendron spirale, n. sp.

Radial spines eight, three-sided prismatic, three times as long as the diameter of the inner shell-cavity; their three edges denticulated and spirally contorted around the spine axis. Thickness of the loose spongy shell-wall equal to the radius of the inner cavity, three times as large as the central cube. Surface covered, with numerous thin, bristle-shaped, bent spinules.

{280}Dimensions.--Diameter of the spongy shell 0.24, of its inner cavity 0.12, of the central cube 0.02; length of the spines 0.4, breadth 0.01.

Habitat.--North Pacific, Station 254, surface.

3. Octodendron pinetum, n. sp.

Radial spines eight, three-sided prismatic, three to four times as long as the diameter of the inner shell-cavity, with three spirally contorted edges. From each spine arise at equal distances (equal to the half radius of the cavity) fifteen to twenty verticils of branches which increase in size from the base of the spine. Each verticil is composed of six forked branches (two from each spine-edge); the inferior are richly branched, and form by their connection the loose network of the spongy cortical shell, the surface of which is covered with numerous bent threads. Each spine bears a resemblance to a pine tree.

Dimensions.--Diameter of the spongy shell 0.3, of its inner cavity 0.15, of the central cube 0.02; length of the spines 0.5 to 0.6, breadth 0.01.

Habitat.--Central Pacific, Station 272, surface.

4. Octodendron araucaria, n. sp.

Radial spines eight, three-sided prismatic, with three spirally contorted edges, eight to ten times as long as the diameter of the inner shell-cavity (the free distal portion twice to three times as long). From each spine arise at equal distances thirty to thirty-five verticils of branches, which decrease in size towards the distal end. Each verticil is composed of six forked branches (two from each spine-edge); the inferior are richly ramified and form by their connection the loose spongy framework; the distal branches bear on the free end elegant spathillæ (as in the following species). Surface covered with innumerable straight bristles, as long as the cavity radius, and ending with a spathilla. Diameter of the central capsule about equal to the radius of the spongy sphere, its membrane is double-edged.

Dimensions.--Diameter of the spongy shell 1.4 mm., of its inner cavity 0.14, of the central cube 0.02, of the central capsule 0.5 to 0.6; length of the spines 0.9 to 1.2, breadth 0.02.

Habitat.--South Pacific, Station 288, surface.

5. Octodendron spathillatum, n. sp. (Pl. 18, figs. 2, 4).

Radial spines eight, three-sided prismatic, with contorted edges, five to eight times as long as the diameter of the shell-cavity (the free part twice as long). From each spine arise ten to twelve verticils of lateral branches; each verticil composed of three forked branches. The proximal larger branches ramify richly, and form by their connection the loose spongy framework of the spherical shell; the distal smaller branches are simple or bifurcated, and the ramules are provided with an elegant spathillum at the end (fig. 4). Entire surface of the spongy sphere covered with innumerable bristle-shaped radial spines (half as long as the cavity radius), zig-zag, bent, with beards, and with a spathillum at the end.

{281}Dimensions.--Diameter of the spongy sphere 1 mm., of its central cavity 0.15, of the central cube 0.02; length of the spines 1 to 1.2 mm., breadth 0.008.

Habitat.--Central Pacific, Station 271, surface.

Subgenus 2. Octodendronium, Haeckel.

Definition.--Radial spines thirty-two or more, eight primary (arising from the eight corners of the central cube) and twenty-four or more secondary (between them).

6. Octodendron verticillatum, n. sp.

Radial spines thirty-two, with three denticulate straight edges, six to eight times as long as the diameter of the shell-cavity; the distal parts half free. Eight primary spines arise from the eight corners of the central cube, twenty-four secondary from the edges of these (a verticil of every three from each primary spine). Distal free parts of all thirty-two spines equal. Each spine with eight to ten verticils of forked lateral branches, without spathillæ. Surface of the spongy sphere covered with short simple bristles.

Dimensions.--Diameter of the spongy shell 0.3, of its cavity 0.12, of the central cube 0.02; length of the spines 0.7 to 1 mm., breadth 0.02.

Habitat.--South Pacific, Station 291, surface.

7. Octodendron contortum, n. sp.

Radial spines thirty-two, disposed in a similar manner to those of the former species (eight primary and twenty-four secondary); also the spongy shell of the same shape. The difference arises in the form of the spines, the three edges of which are much broader and spirally contorted around the axis; and thus the corresponding branches of the verticil do not lie in the same meridian-plane, but alternate one with another.

Dimensions.--Diameter of the spongy shell 0.4, of its cavity 0.1, of the central cube 0.02; length of the spines 0.8 to 1.2, breadth 0.04.

Habitat.--Central Pacific, Station 274, surface.

8. Octodendron arboretum, n. sp.

Radial spines sixty to ninety, three-sided prismatic, with spirally contorted and denticulate edges, six to eight times as long as the diameter of the inner shell-cavity. Eight primary arise from the eight corners of the central cube, twenty-four others from their three edges (as in the two former species); the remaining thirty to sixty spines seem to arise between the former and immediately from the dense spongy framework, which is twice as thick as the diameter of the inner shell-cavity. The numerous verticils of the free distal part are of equal shape in all the spines, composed of three forked branches in the terminal, and of more ramified branches in the inferior parts. Entire surface of the spongy shell covered with simple radial bristles, without spathillæ.

{282}Dimensions.--Diameter of the spongy shell 0.75, of its central cavity 0.15, of the central cube 0.02; length of the spines 0.9 to 1.2, breadth 0.02.

Habitat.--Tropical Pacific, Station 225, surface.

Genus 120. Spongosphæra,[159] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.--#Astrosphærida# with two concentric latticed medullary shells, connected by radial beams; the outer is immediately enveloped by the spongy framework, and bears numerous radial spines.

The genus Spongosphæra (in the definition here restricted) differs from Spongopila in the double medullary shell, which in the latter is simple; it exhibits to the latter the same relation that Spongodictyon among the Liosphærida bears to Spongoplegma. The outer medullary shell of Spongosphæra is immediately enveloped by the spongy wicker-work, which everywhere pierces the wall of the central capsule.

1. Spongosphæra streptacantha, Haeckel.

Spongosphæra streptacantha, Haeckel, 1862, Monogr. d. Radiol., p. 455, Taf. xxvi. figs. 1-3.

Spongy shell of polyhedric, irregular outline, the framework being prolonged sheath-like into the eight to twelve radial spines, which are quite irregularly distributed, very large, three-sided prismatic, with three serrated, spirally contorted edges; their length is twice to four times as great as the diameter of the spongy body; they arise with thinner bases from the outer medullary shell, which is three times as broad as the inner, both having roundish pores, twice to four times as broad as the bars; surface without radial by-spines.

Dimensions.--Diameter of the spongy shell 0.2 to 0.6, outer medullary shell 0.04 to 0.06, inner 0.012 to 0.016.

Habitat.--Cosmopolitan; common in all warmer seas, surface.

2. Spongosphæra polyacantha, J. Müller.

Spongosphæra polyacantha, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 32, Taf. iv. figs. 1-4.

Spongy shell spherical, with ten to twenty large radial spines, which arise with thinner bases from the medullary shell, and are prominent on the surface at different lengths; they are three-sided prismatic (not four-sided), with three leaf-shaped straight edges. Whilst the spongy framework is much looser than in the preceding species, both medullary shells have nearly the same shape.

Dimensions.--Diameter of the spongy shell 0.2 to 0.5, outer medullary shell 0.04 to 0.06, inner 0.012 to 0.016.

Habitat.--Mediterranean (Nice); Atlantic, Station 353, surface.

{283}Subgenus Spongosphæromma, Haeckel.

Definition.--Radial spines on the surface of the spongy shell of two different kinds; large piercing main spines and small superficial by-spines.

3. Spongosphæra helioides, Haeckel.

Spongosphæra helioides, Haeckel, 1862, Monogr. d. Radiol., p.456, Taf. xii. figs. 11-13.

Spongy shell spherical, with numerous curved, bristle-shaped by-spines on the surface, as long as the radius. Main spines ten to twenty, irregularly disposed, prismatic, with three dentated, spirally contorted edges, broader toward the distal end. Outer medullary shell three times as broad as the inner, with polygonal meshes (of the same size as those in the spongy framework) and fine bars.

Dimensions.--Diameter of the spongy shell 0.2, outer medullary shell 0.02, inner 0.007.

Habitat.--Mediterranean (Messina).

4. Spongosphæra quadricuspis, n. sp.

Spongy shell spherical, with numerous curved, bristle-shaped by-spines on the surface, half as long as the radius. Main spines twenty to thirty, irregularly disposed, prismatic, with three dentated, spirally contorted edges, and at the distal end four strong pyramidal divergent teeth (three as terminations of the edges, the fourth as end of the spine axis). Outer medullary shell twice as broad as the inner, both having circular, regular pores, twice to three times as broad as the bars.

Dimensions.--Diameter of the spongy shell 0.3, outer medullary shell 0.04, inner 0.013.

Habitat.--Central Pacific, Station 272, surface.

Genus 121. Rhizosphæra,[160] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 840.

Definition.--#Astrosphærida# with two concentric latticed medullary shells, connected by radial beams; from the outer arise numerous radial spines, which at equal distances are connected by a latticed spherical cortical shell, surrounded by a spongy framework.

The genus Rhizosphæra exhibits the same relation to Spongosphæra that Rhizoplegma bears to Spongopila; but in the latter the latticed medullary shell is simple, in the two former double. The wall of the central capsule is pierced only by the radial spines connecting the medullary and the cortical shells.

1. Rhizosphæra trigonacantha, Haeckel.

Rhizosphæra trigonacantha, Haeckel, 1862, Monogr. d. Radiol., p. 452, Taf. xxv. figs. 1-7.

Central cavity of the spongy cortical shell twice as broad as the diameter of the outer medullary shell. Bars of all three shells of the same breadth as the thirty to fifty (or more) radial spines, {284}which are three-sided prismatic; their outer free distal end only as long as the diameter of the inner medullary shell.

Dimensions.--Diameter of the spongy shell 0.25, of its inner cavity 0.2, outer medullary shell 0.1, inner 0.05.

Habitat.--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface from many Stations.

2. Rhizosphæra serrata, n. sp. (Pl. 18, figs. 5-7).

Central cavity of the spongy shell five times as broad as the diameter of the outer medullary shell. Bars of all three shells of the same breadth as the forty to sixty (or more) thin radial beams between them. These are three-sided prismatic, with denticulate edges, scarcely half as broad as their outer prolongations, which are half as long as the shell radius, and possess three spirally contorted serrated edges. (The figured specimen is a young one; in the older specimens the spongy framework of the cortical shell is much more developed.)

Dimensions.--Diameter of the spongy shell 0.3, of its central cavity 0.22, outer medullary shell 0.06, inner 0.02.

Habitat.--Central Pacific, Stations 270 to 274, surface.

3. Rhizosphæra leptomita, Haeckel.

Rhizosphæra leptomita, Haeckel, 1862, Monogr. d. Radiol., p. 453, Taf. xxv. figs. 8-10.

Central cavity of the spongy cortical shell twice as broad as the diameter of the outer medullary shell; bars of both very thin, only one-third as broad as the bars of the inner medullary shell. Radial spines thirty to fifty (or more), curved, three-sided prismatic; inside the spongy shell as thin as their bars, outside three times as broad.

Dimensions.--Diameter of the spongy shell 0.27, of its inner cavity 0.2, outer medullary shell 0.1, inner 0.05.

Habitat.--Mediterranean (Messina); Atlantic, Stations 348 to 354, surface.

----

Suborder PRUNOIDEA, Haeckel, 1883 (Pls. 13-17, 39, 40).

Definition.--SPUMELLARIA with an ellipsoidal or cylindrical central capsule, prolonged into one axis (sometimes articulate by annular transverse strictures); with an ellipsoidal or cylindrical, fenestrated siliceous shell (often articulate by annular strictures), invariably prolonged into one axis. Fundamental form monaxon, usually with the poles of the prolonged dimensive main axis equal.

The suborder #Prunoidea# comprises those SPUMELLARIA in which the fenestrated spherical shell appears prolonged into one axis. The geometric fundamental form of the shell, which in the #Sphæroidea# was a sphere, in this case therefore becomes an ellipsoid, and whilst in the former all axes originally have the same value (Homaxonia), {285}here one main axis is constantly larger than all other axes (Monaxonia). Usually both poles of this main axis are equal (Haplopola); but in some genera both poles become different (Diplopola).

In the #Sphæroidea# all planes going through the centre of the shell are circular, whereas in the #Prunoidea# only those planes are circular which are perpendicular to the main axis; all other planes going through the centre are elliptical; the largest of these are the meridian planes, in which is situated the main axis. Commonly all meridian planes are equal, as no transverse axes (or cross axes) are differentiated.

In my Monograph (1862) only very few forms of #Prunoidea#, such as Didymocyrtis and Spongurus, are described, and the greater part of them are distributed under different genera of #Sphæroidea#, such as Haliomma and Actinomma. In my Prodromus (1881) I separated them as the family Zygartida (p. 462). But it seems now much more convenient to restrict this term to a particular family and to give a wider extension to the whole suborder under the name #Prunoidea# (called after the characteristic ellipsoidal form of a plum, or Prunus, with its stone).

The suborder #Prunoidea# comprises seven different families, of which the Ellipsida constitutes the simplest and the probable common ancestral group. In all Ellipsida the fenestrated shell is simple, and never composed of concentric or twin shells. In their primitive genus Cenellipsis, the whole shell is geometrically nothing more than a simple ellipsoid (Pl. 39, figs. 1, 2). By development of radial spines it passes into Ellipsidium, by development of spongy framework into Spongellipsis. In the greater part of this family large spines are developed on both poles of the main axis of the shell, but sometimes instead of these solid spines, two opposite hollow fenestrated tubes are developed (Pipettella, Pl. 39, fig. 6).

The second family of #Prunoidea#, the Druppulida, is much richer in different forms than the simple Ellipsida. In this case the ellipsoidal shell is composed of two or three (rarely more) concentric shells. Constantly one or two of these fenestrated shells are enclosed in the central capsule, and may therefore be called "medullary shells"; and one or two (rarely more) lie outside the central capsule, "cortical shells." The inner medullary shells (one or two) are either spherical or ellipsoidal; the outer cortical shells (one or two, rarely more) are always ellipsoidal. All concentric shells are connected by radial beams. In the simplest form of the subfamily, Druppula (Pl. 39, fig. 3), one medullary shell is connected with one cortical shell. By duplication of the medullary shell arises Prunulum (Pl. 39, fig. 4), and by duplication or multiplication of the cortical shell Cromyodruppa (Pl. 15, figs. 1-4) is formed. In by far the greater portion of this subfamily large spines are developed on both poles of the main axis of the cortical shell (Pls. 16, 17), but sometimes also instead of these solid spines two opposite hollow fenestrated tubes are developed (Pipetta, Pl. 39, figs. 7, 8).

{286}A third family of #Prunoidea#, closely allied to the two preceding families, is the Spongurida, in which we include all #Prunoidea# with an ellipsoidal or cylindrical, unjointed shell, in which the lattice-work of the cortical shell is transformed into an irregular, siliceous framework. In the simplest form, Spongellipsis, the simple lattice-shell of Cenellipsis is substituted by an external spongy envelope. In other cases (Spongurus and allied genera) the whole cavity of this external spongy shell is distended with a fine spongy framework. The subfamily of Spongodruppida is distinguished by the possession of a simple or double latticed medullary shell; this lies in the midst of the central capsule, and is connected by radial beams (perforating its membrane) with the enveloping spongy cortical shell. The surface of the latter may bear either radial spines, or two opposite strong polar spines, at the poles of the main axis (Pl. 17, fig. 12).

Closely allied to the Ellipsida and Druppulida are two other families of the #Prunoidea#, the Artiscida and Cyphinida, which differ from the former by a circular constriction in the equatorial plane of the ellipsoidal shell; and in this way assume a characteristic twin form, like a figure of eight. In the Artiscida the shell is simple (as in the Ellipsida), whereas in the Cyphinida it is composed of two or more concentric shells (as in the Druppulida). The simplest form of the Artiscida is Artiscus (Pl. 39, fig. 9), differing from Cenellipsis in the ring-shaped, equatorial constriction. In other Artiscida polar appendages are developed on both poles of the main axis, either in the form of solid, strong spines (Stylartus), or hollow fenestrated tubes (Cannartus, Pl. 39, fig. 10).

The family Cyphinida differs from the Druppulida in the equatorial constriction of the shell, and from the Artiscida in the presence of two or more concentric shells. One or two of these concentric fenestrated shells are enclosed in the central capsule (and therefore may be called "medullary shells"); the others (one or two, rarely more) lie outside of the central capsule (therefore "cortical shells"). The internal "medullary shells" are always spherical or somewhat lenticular, compressed from both sides; the external "cortical shells" have constantly a ring-like constriction in the equatorial plane, and "twin-shells" are therefore like a figure of eight. The simplest form of this subfamily is Cyphanta, composed of a simple medullary shell and a simple cortical shell, the two being connected in the equatorial plane by radial beams. In Cyphonium (Pl. 39, fig. 12) the medullary shell is doubled, and in Cypassis (Pl. 39, fig. 13) the cortical shell likewise. On both poles of the main axis strong spines are often developed (Cyphinus, Pl. 39, fig. 14), or hollow fenestrated tubes (Cannartidium, Pl. 39, figs. 16-19).

The equatorial constriction of the ellipsoidal shell, which characterises the Artiscida and Cyphinida, is repeated or multiplied in the two following families, in the Panartida and Zygartida; in the former we find three ring-like strictures, in the latter five or more (lying in parallel transverse planes); therefore the fenestrated shell is composed in the one instance of four chambers, in the other of six or {287}more; all the chambers form a single series and have a common main axis. All constrictions lie in planes parallel to the equatorial plane of the original ellipsoid; in the centre of the latter constantly lies a double "medullary shell," composed of two concentric, either spherical or lenticular, compressed shells. In all Panartida we call the two inner chambers (on both sides of the equatorial constriction) "proximal chambers," the two outer chambers (on the poles of the main axis) "distal chambers." The four-chambered cortical shell of the Panartida is either simple (in Panartus, Pl. 40, figs. 1-4) or double, with an external mantle (as in Peripanartus, Pl. 40, figs. 5-7). The simplest form of the subfamily is Panartus (loc. cit.). In this case also on both poles of the main axis may be developed solid spines, or hollow fenestrated tubes (Panarium, Pl. 40, fig. 9).

The seventh and last family of the #Prunoidea#, the Zygartida is most nearly allied to the Panartida, and appears as a further developmental step from that family. Whilst in the Panartida the cortical shell is constantly four-chambered, with three parallel ring-like constrictions, in the Zygartida it is always prolonged and composed of six or more chambers, separated by five or more ring-shaped constrictions, in the middle of which is the equatorial stricture. In the centre of the latter (as also in the Panartida) always lies the double medullary shell, composed of two concentric, spherical, or lenticular shells. The number of the chambers of the cortical shells is commonly six or eight (with five to seven ring strictures), but it often mounts to ten and sometimes to twenty (with nineteen strictures), as in some species of Zygartus (Pl. 40, fig. 13). All the chambers lie in one series, one behind another, with a common main axis. The cortical shell is usually simple (in Ommatocampe, Pl. 40, fig. 10), sometimes double (in Desmocampe, Pl. 40, fig. 12), rarely triple (in ZYGOCAMPE, Pl. 40, fig. 13). In all three cases hollow fenestrated tubes may be developed on the poles of the main axis.

The morphological references and the phylogenetic affinities of all #Prunoidea# are so complex, that they seem to represent a quite natural group; all forms of it may be derived from the common ancestral form Cenellipsis. But a far more difficult question is the manner in which its pedigree may be constructed. The oldest family is probably the simplest, namely, Ellipsida. From this the Druppulida may be derived by production of medullary shells, the Artiscida by equatorial constriction. The Cyphinida can be produced either from the Druppulida by equatorial constriction or from the Artiscida by development of medullary shells. The Panartida appear as further developmental steps of the Cyphinida, by duplication of the chamber number; and the Zygartida as further productions of the Panartida, by increasing the number of the chambers.

The seven subfamilies of the #Prunoidea# can be arranged in two sections according to the presence or absence of medullary shells. The Ellipsida, Spongellipsida, and Artiscida possess a simple cortical shell, without a medullary shell; they represent the {288}section Cenoprunida. All other families possess medullary shells, and so represent the section Coccoprunida.

Another character, which can be employed in the arrangement of the seven subfamilies in some larger groups, is the presence or absence of ring-like constrictions, by which the cortical shell is divided into chambers. I. The Monoprunida comprise all forms without any constriction, of which the Ellipsida are without a medullary shell, the Druppulida with one or two medullary shells, and the Spongurida with a spongy cortical shell. II. The Dyoprunida contain all forms with a cortical twin shell, or with two chambers separated by one equatorial constriction, of which the Artiscida are without a medullary shell and the Cyphinida have one or two medullary shells. III. The Polyprunida comprise all forms with several (three or more) constrictions, which separate four or more chambers, of which the Panartida have three constrictions and four chambers, and the Zygartida five or more constrictions and six or more chambers.

The Central Capsule of the #Prunoidea# is originally ellipsoidal (monaxial), and preserves this form in the greater part of the genera. In some groups, where the axis of the ellipsoid is much prolonged, it passes over to the cylindrical form (with hemispherical vaultings on both poles), as in Spongurus and Spongocore, in many Panartida and Zygartida. Very often the ellipsoidal or cylindrical capsule gets annular transverse constrictions, corresponding to those of the enveloping cortical shell (one single, equatorial stricture in the Artiscida and Cyphinida, three strictures in the Panartida, five or more in the Zygartida). In the Cenoprunida (Ellipsida and Artiscida, also in Spongellipsis) the central capsule lies freely in the cavity of the cortical shell, separated from its inner surface by the jelly-envelope; in all other groups it contains a part of the skeleton, the medullary shell and the beams which connect it with the enveloping cortical shell.

Synopsis of the Families of #Prunoidea#.

{a. Shell simple, latticed (not { spongy), without enclosed internal { enclosed internal shells, 1. ELLIPSIDA. A. MONOPRUNIDA. { {b. Shell composed of two or more Shell without { concentric latticed shells transverse stricture { (not spongy), 2. DRUPPULIDA. { {c. Shell partially or wholly { composed of an irregular spongy { framework, 3. SPONGURIDA.

B. DYOPRUNIDA. { {d. Shell simple, without enclosed Shell bilocular, { internal shells, 4. ARTISCIDA. divided by an { equatorial stricture { into two communicating{e. Shell composed of two or more hemi-ellipsoidal { concentric shells, 5. CYPHINIDA. shells. {

C. POLYPRUNIDA. {f. Shell with three parallel { strictures and therefore four Shell multilocular, { cameræ, 6. PANARTIDA. divided by three { or more parallel {g. Shell with five or more parallel transverse strictures { strictures and therefore six into four or more { or more cameræ, 7. ZYGARTIDA. serial cameræ. {

{289}Family XI. #ELLIPSIDA#, Haeckel, 1882 (Pls. 13, 14, 39).

Definition.--#Prunoidea# with simple ellipsoidal shell, without equatorial stricture (without enclosed medullary shell); network a simple lattice lamella, not spongy. Central capsule ellipsoidal or cylindrical, without annular equatorial constriction.

The family #Ellipsida# comprises the simplest forms of #Prunoidea#, and probably represents the ancestral forms of this whole suborder. The fenestrated shell, which encloses the ellipsoidal central capsule, is a perfectly simple "cortical shell" of the same form, without enclosed "medullary shell." Its form is commonly a regular monaxial ellipsoid; sometimes a little modified by unequal growth of the two poles of the main axis. Two opposite large spines are often developed at these poles, or it may be that instead of these, two hollow fenestrated tubes are present.

The ellipsoidal fenestrated shell exhibits in the regular Ellipsida all the characters of a geometric ellipsoid; one main axis surpasses in length all other possible axes. All sections going through this main axis are "meridian sections," with elliptical periphery; all sections perpendicular to the main axis are "transverse sections," with circular periphery. The largest of these is the equatorial section, which divides the main axis into halves. The diameter of this equatorial plane is the "minor axis" of the ellipsoid.

The proportion of the two axes of the ellipsoidal shell, of the major vertical or main axis and the minor horizontal or equatorial axis, is commonly between 6 : 5 and 3 : 2. In the former case it approaches the spherical shell, from which it is derived; in the latter case it becomes almost fusiform or cylindrical. The network of silex, constituting the shell, is constantly a simple latticed lamella, never composed of concentric shells (as in Druppulida) or spongy (as in Spongurida). The network is often very regular and elegant, in other cases irregular.

The simplest genus among the Ellipsida, and probably the common ancestral form of the whole subfamily, is the genus Cenellipsis, possessing a simple ellipsoidal shell without any appendages. It is derived from Cenosphæra (the simplest spherical shell) by the prolongation of one axis. Cenellipsis passes over into Ellipsidium by the production of radial spines on the surface (corresponding to Heliosphæra). Axellipsis is a peculiar genus differing from Cenellipsis in an axial rod, which corresponds to the minor or equatorial axis. In all other genera of the subfamily both poles of the main axis are distinguished by peculiar polar prolongations, either hollow fenestrated tubes (as in Pipettella) or strong solid spines. Both polar spines are of equal size and similar form in Ellipsoxiphus, unequal in Ellipsostylus. From the latter is derived Lithapium, by reduction and loss of one spine (so that only one remains); Lithomespilus, by production of a bunch of several spines at one pole. In the three latter genera both poles of the main axis are unequal, in all others equal.

{290}The central capsule of the Ellipsida is in all cases ellipsoidal, and occupies the largest part of the shell, being separated from its inner surface by a thinner or thicker jelly-mantle.

Synopsis of the Genera of Ellipsida.

------------------------------------------------------------------------- Ellipsoidal shell without polar appendages (neither solid spines nor hollow tubes at the poles of the axis). ------------------------------------------------------------------------- Surface without {Shell cavity radial spines. { simple, without { an axial rod, 122. Cenellipsis. { {Shell cavity { with a transverse { axial rod, 123. Axellipsis.

Surface covered with radial spines, 124. Ellipsidium. ------------------------------------------------------------------------- Ellipsoidal shell with polar appendages (either solid spines or hollow fenestrated tubes) at the poles of the main axis. ------------------------------------------------------------------------- Solid spines of {Shell cavity similar shape, { simple, without at both poles of { axial rods, 125. Ellipsoxiphus. the main axis. { {Shell cavity { with a cross of { axial rods, 126. Axoprunum.

Solid spines of {Two polar spines different shape, { of different at both poles { shape, 127. Ellipsostylus. of the main { axis. {A bunch of spines { at one pole { only, 128. Lithomespilus { {Only a single { spine at one { one pole, 129. Lithapium.

Two hollow fenestrated tubes opposite, at the poles of the main axis, 130. Pipettella.

Genus 122. Cenellipsis,[161] n. gen.

Definition.--#Ellipsida# with simple ellipsoidal shell, without radial spines and without polar tubes.

The genus Cenellipsis is the simplest and most primitive form, not only among the Ellipsida, but also among the #Prunoidea#, and it may therefore be regarded as the common ancestral form of the whole family. It corresponds to Cenosphæra among the #Sphæroidea#, to Cenodiscus among the #Discoidea#, to Cenolarcus among the #Larcoidea#. Probably it is derived from Cenosphæra by prolongation of one axis.

Subgenus 1. Cenellipsium, Haeckel.

Definition.--Network of the shell regular, with meshes of equal size and similar form.

{291}1. Cenellipsis primitiva, n. sp.

Proportion of the longer axis of the ellipsoid to the shorter = 3 : 2. Network of the thin wall very delicate and regular, with hexagonal pores. All pores of nearly the same size and form, ten to twelve times as broad as the bars; nine to twelve on the half equator of the shell. Surface smooth.

Dimensions.--Longer axis of the ellipsoid 0.09 to 0.11, shorter axis 0.06 to 0.08; pores 0.01, bars between them 0.001.

Habitat.--Pacific, central area, Station 272, surface.

2. Cenellipsis faceta, n. sp. (Pl. 39, fig. 1).

Proportion of the longer axis of the ellipsoid to the shorter = 4 : 3. Network of the thin wall delicate and regular. All the pores of the same size and form, circular, with a hexagonal frame, twice to three times as broad as the bars; eight to ten on the half equator. Surface smooth or slightly spiny.

Dimensions.--Longer axis of the ellipsoid 0.12 to 0.13, shorter axis 0.09 to 0.1; pores 0.013, bars 0.005.

Habitat.--Pacific, central area. Station 274, surface.

3. Cenellipsis ehrenbergii, Haeckel.

Haliomma (?) cenosphæra, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, Taf xxvi. fig. 5.

Proportion of the longer axis to the shorter = 2 : 1. Network of the thin wall regular or subregular. All pores circular, nearly of the same size, without hexagonal frame, three to four times as broad as the bars; eight to nine on the half equator. Surface covered with small thorns.

Dimensions.--Longer axis of the ellipsoid 0.16 to 0.2, shorter axis 0.08 to 0.1; pores 0.1, bars 0.003.

Habitat.--Fossil in the Tertiary rocks of Barbados (Ehrenberg, Haeckel).

4. Cenellipsis circopora, n. sp.

Proportion of the longer axis to the shorter = 5 : 3. Network of the thin wall delicate and regular. All pores circular, nearly of the same size, without hexagonal frame, twice as broad as the bars; fifteen to twenty on the half equator. Surface quite smooth.

Dimensions.--Longer axis of the ellipsoid 0.15 to 0.2, shorter axis 0.09 to 0.12; pores 0.08, bars 0.4.

Habitat.--North Pacific, Station 236, surface.

5. Cenellipsis micropora, n. sp.

Proportion of the longer axis to the shorter = 5 : 4. Network of the thick wall quite regular. All pores circular, without hexagonal frame, very small, scarcely half as broad as the bars; six to eight on the half equator. Surface quite smooth.

{292}Dimensions.--Longer axis of the ellipsoid 0.1, shorter axis 0.08; pores 0.004, bars 0.01.

Habitat.--South Pacific, Station 289, surface.

Subgenus 2. Cenellipsula, Haeckel.

Definition.--Network of the shell irregular, with meshes of different size or form.

6. Cenellipsis heteropora, n. sp.

Proportion of the longer axis to the shorter = 3 : 2 or = 5 : 3. Network of the thin wall very irregular, with polygonal meshes of different size and form (for the most part pentagonal or hexagonal, but also many tetragonal or heptagonal). The largest pores four to six times as broad as the smallest; ten to twenty pores on the half equator; bars between them thin. Surface smooth or somewhat spiny.

Dimensions.--Longer axis of the ellipsoid 0.18 to 0.22, shorter axis 0.1 to 0.12; pores 0.004 to 0.008, bars 0.001.

Habitat.--Indian Ocean, near the Cocos Islands, surface, Rabbe.

7. Cenellipsis maxima, n. sp.

Proportion of the longer axis to the shorter = 3 : 2. Network of the thin wall very irregular, with polygonal meshes of very different size and form, twice to eight times as broad as the bars; fifty to sixty on the half equator. Surface smooth.

Dimensions.--Longer axis of the ellipsoid 0.36, shorter axis 0.25; pores 0.004 to 0.015, bars 0.002.

Habitat.--Equatorial Atlantic, Station 347, surface.

8. Cenellipsis ovulum, n. sp.

Proportion of the longer axis to the shorter = 3 : 2. Network of the thin wall very irregular, with roundish or longish pores of very different size and form. Pores flat, with even margins, thirty to forty on the half equator, twice to six times as broad as the bars. Surface smooth. (This species being observed alive, showed a transparent central capsule of ellipsoidal form, two-thirds as large as the shell.)

Dimensions.--Longer axis of the ellipsoid 0.3, shorter axis 0.2; pores 0.04 to 0.012, bars 0.002.

Habitat.--Indian Ocean, Ceylon, Haeckel; Pacific, central area, Station 266, surface.

9. Cenellipsis infundibulum, n. sp. (Pl. 39, fig. 2).

Proportion of the longer axis to the shorter = 3 : 2. Network of the thick wall irregular, with roundish pores of different size and form. Pores funnel-like, with prominent, irregular, spiny {293}crests between them, their outer aperture three to four times as broad as the inner; twelve to fifteen pores on the half equator. Surface prickly.

Dimensions.--Longer axis of the ellipsoid 0.14, shorter axis 0.11; outer aperture of the pores 0.01 to 0.012, inner aperture 0.003 to 0.004.

Habitat.--South Atlantic, Station 332, depth 2200 fathoms.

10. Cenellipsis oblonga, n. sp.

Proportion of the longer axis to the shorter = 2 : 1. Network of the thick wall irregular, with roundish pores of different size and form. Pores with prominent conical edges, about as broad as the bars; twenty to twenty-five on the half equator. Sometimes each pore is prolonged into a short conical tubulus.

Dimensions.--Longer axis of the ellipsoid 0.22, shorter axis 0.12; pores and bars 0.008 to 0.012.

Habitat.--Pacific, central area, Station 265, depth 2900 fathoms.

Genus 123. Axellipsis,[162] n. gen.

Definition.--#Ellipsida# with simple ellipsoidal shell, without radial spines or polar tubes, but with an inner transverse axial rod, which corresponds to the shorter axis of the ellipsoid.

The genus Axellipsis differs from the simple Cenellipsis in a very peculiar character, namely, the presence of an inner siliceous bar marking the minor axis of the ellipsoidal shell. If in some forms of Druppula (e.g., Pl. 39, fig. 3) we remove the central medullary shell and prolong both beams (connecting it with the cortical shell) till they unite in the centre, we shall arrive at Axellipsis. Therefore Axellipsis may be derived in the same way from Druppula as Axoprunum is from Lithatractus, by phyletic loss of the medullary shell.

1. Axellipsis perforata, n. sp.

Proportion of the major axis of the ellipsoid to the minor = 3 : 2. Pores of the shell regular, circular, twice as broad as the bars; ten to twelve on the half equator. Surface smooth.

Dimensions.--Longer axis of the shell 0.12, shorter axis 0.08; pores 0.006, bars 0.003.

Habitat.--Central area of the Pacific, Station 266, depth 2750 fathoms.

2. Axellipsis lobata, n. sp.

Proportion of the major axis to the minor = 5 : 4. Meshes of the shell irregular, roundish, lobed, with three to six indentations (each mesh formed by the confluence of three to six, commonly {294}four or five, smaller pores); eight to nine meshes on the half equator, these being twice to four times as broad as the bars.

Dimensions.--Longer axis of the shell 0.1, shorter axis 0.08; pores 0.007 to 0.01, bars 0.003.

Habitat.--Tropical zone of the Western Pacific, Station 225, surface.

Genus 124. Ellipsidium,[163] n. gen.

Definition.--#Ellipsida# with simple ellipsoidal shell, with numerous radial spines on the surface, without polar spines or tubes.

The genus Ellipsidium differs from Cenellipsis solely in the development of numerous radial spines on the surface, and exhibits the same phylogenetic relation to it that Heliosphæra bears to Cenosphæra.

1. Ellipsidium pandanidium, n. sp.

Proportion of the longer axis of the ellipsoid to the shorter = 5 : 4. Shell thick walled, with regular and hexagonal meshes, twice as broad as the bars; eighteen to twenty on the half equator. In each hexagon-corner (between three pores) arises a short, three-sided pyramidal spine, half as long as the equatorial radius, and as thick at the base as a single mesh.

Dimensions.--Major axis of the ellipsoid 0.15, minor 0.12; pores 0.006, bars 0.003; length of the radial spines 0.03, basal breadth 0.006.

Habitat.--Fossil in the Tertiary rocks of Barbados (Haeckel).

2. Ellipsidium datura, n. sp.

Proportion of the longer axis of the ellipsoid to the shorter = 4 : 3. Shell thick walled, with regular, circular meshes, twice as broad as the thick bars between them eight to ten meshes on the half equator. Outer surface of the shell thorny, covered with short, conical, radial spines, which are regularly distributed (one spine between every three meshes), and about as long as the diameter of the meshes. (The shell is similar to the outer shell of Haliomma castanea, Haeckel, Monogr. d. Radiol., Taf. xxiv. fig. 4.)

Dimensions.--Major axis of the ellipsoid 0.12, minor axis 0.09; meshes 0.012, bars 0.006.

Habitat.--Western part of the Tropical Pacific, Station 225, depth 4475 fathoms.

3. Ellipsidium artocarpus, n. sp.

Proportion of the longer axis to the shorter = 3 : 2. Shell thick walled, with regular, circular meshes, separated by deep furrows, which represent a regular, hexagonal framework; on the half equator twelve to fifteen meshes, scarcely broader than the broad bars between them. Outer {295}surface spiny; between every three meshes arises a strong radial spine, twice to three times as long as the diameter of the meshes; the base of the spine is like a three-sided pyramid.

Dimensions.--Major axis of the ellipsoid 0.12, minor axis 0.08; meshes 0.006, bars 0.005.

Habitat.--Central area of the Pacific, Station 268, depth 2900 fathoms.

4. Ellipsidium opuntia, n. sp.

Proportion of the longer axis to the shorter = 5 : 4. Shell thin walled, with irregular, roundish meshes of different size and form, about twice to three times as broad as the irregular, thin bars between them; ten to fifteen meshes on the half equator. Between the meshes arise numerous thin, bristle-like, radial spines, about as long as the shorter radius of the shell. The number of the meshes may be three to four times as great as the number of the spines.

Dimensions.--Major axis of the ellipsoid 0.15, minor axis 0.12; pores 0.006 to 0.01, bars 0.003 to 0.004.

Habitat.--Southern Pacific, Station 284, surface.

5. Ellipsidium echinidium, n. sp.

Proportion of the longer axis to the shorter = 4 : 3. Shell thick walled, with irregular, roundish pores of different size and form, about as large or somewhat smaller than the broad bars; twelve to sixteen pores on the half equator. On the surface, irregularly scattered, twenty to thirty strong, three-sided pyramidal, radial spines, one-fourth to one-half as long as the main axis.

Dimensions.--Major axis of the ellipsoid 0.16, minor 0.12; pores and bars 0.002 to 0.008; length of the radial spines 0.04 to 0.08, basal breadth 0.01.

Habitat.--Equatorial Atlantic, Station 347, depth 2250 fathoms.

Genus 125. Ellipsoxiphus,[164] Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, vol. xlv. p. 25.

Definition.--#Ellipsida# with simple ellipsoidal shell, the main axis of which is prolonged at both poles into two strong opposite spines of equal size and similar form.

The genus Ellipsoxiphus was established by Dunikowski (in 1882, loc. cit.) for those simple amphistylous fenestrated shells, formerly united with Xiphosphæra, in which the mathematical form of the shell itself is not a true sphere, but an ellipsoid. It may therefore be derived from Xiphosphæra by prolongation of the axis in which lie both polar spines; but it may also be derived from Cenellipsis by the production of two equal spines at the poles of the main axis.

{296}Subgenus 1. Ellipsoxiphetta, Haeckel.

Definition.--Network of the shell regular, with pores of equal size and similar form.

1. Ellipsoxiphus elegans, n. sp. (Pl. 14, fig. 7).

Proportion of the major axis of the ellipsoid to the minor = 5 : 4. Shell thick walled, with regular, circular meshes, separated by a regular, hexagonal elevated framework. From each hexagon-corner arises (between every three meshes) a short thin spine, about as long as the diameter of a mesh; twelve to fourteen meshes on the half equator, of the same breadth as the bars. Polar spines three-sided prismatic, cuspidate, about as long as the axis of the shell. (This elegant and not uncommon species is remarkable for its variations. By unequal development of both spines it passes over to Ellipsostylus.) In the figured variety (Pl. 14, fig. 7) the ends of the surface spines are connected by a very delicate network, so as to form an outer veil. This may further be separated as a peculiar genus Ellipsoxiphium palliatum.

Dimensions.--Longer axis 0.08 to 0.13, shorter axis 0.06 to 0.11; pores and bars 0.008; length of the polar spines 0.06 to 0.12, basal breadth 0.01.

Habitat.--Pacific, central area, Stations 270 to 274, from 2350 to 2925 fathoms.

2. Ellipsoxiphus flosculus, n. sp.

Proportion of the major axis to the minor = 6 : 5. Shell very thick walled, with regular, hexagonal meshes, eight to nine on the half equator, three to four times as broad as the bars. The inner contour of the meshes is circular, the outer six-lobed (similar to Xiphostylus phasianus, Pl. 13, fig. 9). Polar spines three-sided pyramidal, about as long as the major axis of the shell; their basal thickness equals one mesh.

Dimensions.--Longer axis 0.12, shorter axis 0.1; pores 0.012 to 0.015, bars 0.004; length of the polar spines 0.12 to 0.15, basal breadth 0.015.

Habitat.--Fossil in the Tertiary rocks of Barbados (Teuscher).

3. Ellipsoxiphus fragilis, n. sp.

Proportion of the major axis to the minor = 4 : 3. Shell thin walled, with regular, circular meshes, twice as broad as the bars; ten to twelve on the half equator. Surface smooth. Polar spines cylindrical, at the apex conical, half as long as the major axis.

Dimensions.--Longer axis 0.16, shorter axis 0.12; pores 0.008, bars 0.004; length of the polar spines 0.09, basal breadth 0.008.

Habitat.--South Atlantic, Station 325, surface.

Subgenus 2. Ellipsoxiphilla, Haeckel.

Definition.--Network of the shell irregular, with pores of different size or form.

{297}4. Ellipsoxiphus claviger, n. sp. (Pl. 14, fig. 3).

Xiphosphæra clavigera, Haeckel, 1881, Prodromus et Atlas.

Proportion of the major axis to the minor = 5 : 4. Shell thick walled, with irregular network; meshes roundish or circular, double contoured, of unequal size, twice to four times as broad as the bars; eight to ten on the half equator. Polar spines club-shaped, with prominent edges, about as long as the minor axis; thicker in their middle part than at both ends (differs from Xiphosphæra clavigera by the ellipsoidal form of the shell, and the double length of the spines).

Dimensions.--Longer axis 0.15. shorter axis 0.12; pores 0.007 to 0.015, bars 0.004; length of the polar spines 0.12, thickness in the middle part 0.02.

Habitat.--Central area of the Pacific, Station 272, depth 2600 fathoms.

5. Ellipsoxiphus suessi, Dunikowski.

Ellipsoxiphus suessi, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 26, Taf. v. fig. 50.

Proportion of the major axis to the minor = 7 : 5. Shell thick walled, with irregular, roundish meshes, six to eight on the half equator, twice to three times as broad as the bars. Polar spines nearly cylindrical, blunt, as long as the major axis.

Dimensions.--Longer axis 0.14; shorter axis 0.1; pores 0.018 to 0.023, bars 0.01; length of the polar spines 0.12; thickness of them 0.035.

Habitat.--Fossil in the Alpine Lias, Schafberg near Salzburg, Dunikowski.

6. Ellipsoxiphus parvoforaminus, Dunikowski.

Ellipsoxiphus parvoforaminus, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 26, Taf. v. fig. 51.

Proportion of the major axis to the minor = 7 : 6. Shell thick walled, with irregular, roundish or oval meshes, ten to twelve on the half equator, scarcely as broad as the bars. Polar spines conical, shorter than the minor axis.

Dimensions.--Longer axis 0.14, shorter axis 0.12; pores 0.016 to 0.01, bars 0.01 to 0.02; length of the polar spines 0.1, basal thickness 0.045.

Habitat.--Fossil in the Alpine Lias, Schafberg near Salzburg, Dunikowski.

7. Ellipsoxiphus bipolaris, n. sp. (Pl. 14, fig. 11).

Xiphosphæra bipolaris, 1881, Prodromus et Atlas.

Proportion of the major axis to the minor = 8 : 7. Shell thick walled, with irregular, roundish meshes, twice to three times as broad as the bars; sixteen to twenty on the half equator. Polar spines short and thick, three-sided pyramidal, scarcely half as long as the shorter radius of the shell; surrounding the base of every spine is a circle of eight to nine shorter spines.

Dimensions.--Longer axis 0.08, shorter axis 0.07; pores 0.003 to 0.007, bars 0.002; length of the polar spines 0.02 to 0.03, basal thickness 0.02.

Habitat.--Tropical part of the Western Pacific, Station 225, depth 4475 fathoms.

{298}8. Ellipsoxiphus atractus, n. sp. (Pl. 14, fig. 1).

Proportion of the major axis to the minor = 3 : 2. Shell spindle-shaped, very thick walled, with roundish, very irregular meshes, twice to five times as broad as the bars; eight to twelve on the half equator. The meshes are partly simple, oblong, partly lobed or composed of two to four (commonly three) confluent meshes. Surface smooth. Polar spines very short and thick, shorter than the minor radius of the shell, three-sided pyramidal, with prominent, somewhat contorted edges.

Dimensions.--Longer axis 0.15, shorter axis 0.1; meshes 0.007 to 0.02, bars 0.004; length of the polar spines 0.04, basal thickness 0.03.

Habitat.--Central area of the Pacific, Station 268, depth 2900 fathoms.

Genus 126. Axoprunum,[165] n. gen.

Definition.--#Ellipsida# with simple ellipsoidal shell, the main axis of which is prolonged at both poles into two opposite spines of equal size and similar form. Within the cavity of the shell four radial rods arise from its inner surface, two in the main axis, two in the smallest axis, perpendicular to the former; their free inner ends are at the same distance from the centre.

The genus Axoprunum possesses precisely the same shell as the foregoing Ellipsoxiphus, but differs from it in a very remarkable peculiarity. The two polar spines are centripetally prolonged into two internal beams, and perpendicular to these are two other, opposite, transverse beams, marking the minor axis of the ellipsoid. The free inner ends of all four radial rods bear little thickened knobs, and are at the same distance from the centre. It therefore appears as though a central, spherical, medullary shell had been lost, and this gives a strong support to the important hypothesis, that in many #Sphærellaria#, where the medullary shell is absent, it may have been lost by phylogenetic reduction or retrograde metamorphosis. In this case Axoprunum (and Ellipsoxiphus) would arise from Lithatractus.

1. Axoprunum stauraxonium, n. sp. (Pl. 48, fig. 4).

Shell ellipsoidal, one and one-third times as long as broad, with smooth surface. Network regular, with circular meshes four times as broad as the bars. Two polar spines three-sided pyramidal, half as long as the shell, as thick at the base as a single mesh. Four inner radial beams (lying, two in the major and two in the minor axis of the ellipsoid) very thin, at the central free ends knob-like, thickened. The distance between two opposite beams equals one-third of the minor axis, and indicates probably the diameter of the lost spherical medullary shell. (Three perfect and complete specimens of the same size and shape were observed.)

{299}Dimensions.--Major axis of the ellipsoid 0.14, minor axis 0.11; pores 0.012, bars 0.003; length of the polar spines 0.07, basal breadth 0.012. (Diameter of the lost medullary shell 0.03?)

Habitat.--South Atlantic, Station 338, depth 1990 fathoms.

Genus 127. Ellipsostylus,[166] n. gen.

Definition.--#Ellipsida# with simple ellipsoidal shell, the main axis of which is prolonged at both poles into two opposite spines of different size or form.

The genus Ellipsostylus differs from Ellipsoxiphus only in the unequal size or different form of the polar spines, which in the former are equal. This difference does not seem important at first, but in the further development it produces very singular and strange forms. Theoretically it is always important, because the fundamental haplopolar form of the monaxon body becomes diplopolar by this differentiation.

Subgenus 1. Ellipsostyletta, Haeckel.

Definition.--Network of the shell regular, with pores of equal size and similar form.

1. Ellipsostylus ornithoides, n. sp.

Proportion of the major axis of the ellipsoid to the minor = 4 : 3. Shell thin walled, with regular, circular meshes and hexagonal framework between them, like that of Xiphostylus favosus (Pl. 13, fig. 4). Circular pores about as broad as the bars; eight to nine on the half equator. Surface smooth. Polar spines three-sided pyramidal, as broad at the base as a single hexagon; the longer spine as long as the major axis, the shorter half as long.

Dimensions.--Longer axis of the ellipsoidal shell 0.16, shorter axis 0.12; pores and bars 0.006; length of the longer polar spine 0.16, of the shorter 0.08.

Habitat.--North Pacific, Station 241, depth 2300 fathoms.

2. Ellipsostylus avicularis, n. sp.

Proportion of the major axis to the minor = 3 : 2. Shell thick walled, with regular, rosette-shaped meshes, three times as broad as the bars; ten to twelve on the half equator. Every mesh on the outer margin with five to six rounded lobes, as in Xiphostylus phasianus (Pl. 13, fig. 9). Surface smooth. Polar spines sharp edged, thick; the longer straight and equal to the longer axis, the shorter half as long, shaped like a bird's head.

Dimensions.--Longer axis 0.18, shorter axis 0.12; pores 0.015, bars 0.005.

Habitat.--South Pacific, Station 300, depth 1375 fathoms.

{300}3. Ellipsostylus psittacus, n. sp. (Pl. 13, fig. 6).

Proportion of the major axis to the minor = 4 : 3. Shell thin walled, with regular or subregular rosette-shaped meshes, twice as broad as the bars; eight to nine on the half equator; each mesh with three to four rounded lobes. Surface smooth. Polar spines sharp edged, very unequal; longer spine about twice as long as the major axis, somewhat curved; shorter spine scarcely longer than the radius, shaped like a bird's head.

Dimensions.--Longer axis 0.08, shorter axis 0.06; pores 0.01, bars 0.005; length of the polar spines--longer 0.15, shorter 0.05.

Habitat.--Central area of the Pacific, Station 266, depth 2750 fathoms.

4. Ellipsostylus aquila, n. sp. (Pl. 13, fig. 1).

Proportion of the major axis to the minor = 7 : 6. Shell thick walled, with subregular, circular meshes, five to six times as broad as the bars; ten to twelve on the half equator. Surface smooth. Polar spines sharp edged (six-sided?), very unequal; longer spine straight, about equal to the minor axis; shorter spine obliquely inserted, scarcely half as long, shaped like a bird's head.

Dimensions.--Longer axis 0.15, shorter axis 0.13; pores 0.02, bars 0.004; length of the polar spines--longer 0.1, shorter 0.05.

Habitat.--Central area of the Pacific, Station 272, depth 2600 fathoms.

5. Ellipsostylus columba, n. sp. (Pl. 13, fig. 3).

Proportion of the major axis to the minor = 4 : 3. Shell egg-shaped, thin walled, with regular, circular meshes, three times as broad as the bars; ten to twelve on the half equator. Surface somewhat thorny. Polar spines nearly of equal length (equal to the major axis), but of very different form; one straight, pyramidal, and obliquely inserted, the other like a bird's head.

Dimensions.--Longer axis 0.08, shorter 0.06; pores 0.003, bars 0.01; length of the spines 0.09.

Habitat.--South Atlantic, Station 332, surface.

6. Ellipsostylus ciconia, n. sp. (Pl. 13, fig. 8).

Proportion of the major axis to the minor = 7 : 5. Shell egg-shaped, thick walled; the meshes very small, regular, circular, three times as broad as the bars; sixteen to twenty on the half equator. Surface uneven. Polar spines nearly cylindrical, pointed; the smaller obliquely inserted, equal to the major axis; the larger more than twice as long and thick, furrowed at its base. (Compare with this and the allied species Rhabdolithis pipa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. i. fig. 27.)

Dimensions.--Longer axis 0.07, shorter 0.05; pores 0.003, bars 0.001; length of the polar spines--longer 0.2, shorter 0.08.

Habitat.--North Pacific, Station 253, depth 3125 fathoms.

{301}Subgenus 2. Ellipsostylissa, Haeckel.

Definition.--Network of the shell irregular, with pores of different size or form.

7. Ellipsostylus megadictya, Haeckel.

Stylosphæra megadictya, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 299, Taf. viii. fig. 13.

Proportion of the major axis to the minor = 5 : 4. Shell thin walled, with irregular, roundish, large meshes, four to five times as broad as the bars; only four to five on the half equator. Surface smooth. Polar spines straight, thin, angular; the shorter equal to the minor axis, the longer four times as large.

Dimensions.--Longer axis 0.05, shorter axis 0.04; meshes 0.01, bars 0.002; length of the polar spines--longer 0.12, shorter 0.03.

Habitat.--Philippine Sea, 3300 fathoms, Ehrenberg.

8. Ellipsostylus gallinula, n. sp.

Proportion of the major axis to the minor = 3 : 2. Shell thick walled, with irregular, roundish meshes, twice to four times as broad as the bars; eight to ten on the half equator. Surface thorny. Polar spines conical, straight; the longer twice as long as the major axis, the minor scarcely half as long.

Dimensions.--Longer axis 0.15, shorter 0.12; pores 0.01 to 0.02, bars 0.002 to 0.004.

Habitat.--North Pacific, Station 253, surface.

9. Ellipsostylus hirundo, n. sp. (Pl. 13, fig. 2).

Proportion of the major axis to the minor = 4 : 3. Shell thick walled, with irregular, roundish meshes, three to five times as broad as the bars; eight to ten on the half equator. The inner aperture of every mesh is fenestrated by a delicate lamella of silex, perforated by six to eight very small circular pores. Polar spines sharp edged, more or less curved, the shorter equal to the minor axis, the longer twice as long.

Dimensions.--Longer axis 0.16, shorter 0.12; pores 0.01 to 0.02, bars 0.003 to 0.006; length of the polar spines--longer 0.24, shorter 0.12.

Habitat.--Pacific, central area, Station 268, depth 2900 fathoms; the same form also fossil in the rocks of Barbados.

Genus 128. Lithomespilus,[167] Haeckel, 1881, Prodromus, p. 450.

Definition.--#Ellipsida# with simple ellipsoidal or oviform shell, the main axis of which bears at one pole a single spine, at the other a bunch of several spines.

{302}The genus Lithomespilus differs from the closely allied Ellipsoxiphus in the further differentiation of both poles of the main axis. One pole exhibits only a single polar spine, the other pole a group of several spines, peculiarly grouped together. It differs from the similar Sphæromespilus (Pl. 14, figs. 12, 13) in the ellipsoidal form of the shell.

1. Lithomespilus phloginus, n. sp. (Pl. 14, fig. 16).

Proportion of the major axis of the ellipsoid to the minor = 4 : 3. Shell thick walled, with circular pores of different size, the breadth of which equals that of the bars; twelve to fifteen pores on the half equator. Surface smooth, with the exception of a circumpolar region covered with numerous thick spines of unequal size, which surround the large single polar spine and are curved like a bow against its axis. This larger polar spine is straight, and equals in length the major axis of the shell. The other and opposite polar spine is scarcely one-fourth as long, perfectly simple, very stout, and of a three-sided pyramidal shape.

Dimensions.--Longer axis of the ellipsoidal shell 0.08, shorter axis 0.06; pores 0.002 to 0.006, bars 0.003 to 0.005; length of the polar spines--longer 0.08, shorter 0.02.

Habitat.--Indian Ocean, near Madagascar, depth 1200 fathoms, Smith.

2. Lithomespilus phlogoides, n. sp. (Pl. 14, fig. 17).

Proportion of the major axis to the minor = 5 : 4. Shell very thick walled, with roundish, double-contoured pores of different size and form, twice to three times as broad as the bars; sixteen to eighteen pores on the half equator. Surface smooth, with the exception of a circumpolar region covered with numerous thin spines of unequal size, which surround the large single polar spine and are curved like a bow against its axis. This larger polar spine is straight, and equals half the size of the major axis of the shell; the other polar spine (sometimes double, as in the figured specimen) is much shorter, being scarcely one-fourth as long.

Dimensions.--Longer axis of the shell 0.08, shorter axis 0.065; pores 0.003 to 0.006, bars 0.002 to 0.004; length of the polar spines--longer 0.04, shorter 0.01.

Habitat.--Central area of the Pacific, Stations 270 to 272, depth 2425 to 2925 fathoms.

3. Lithomespilus flammeus, n. sp.

Stylosphæra species, Bury, 1862, Polycystins of Barbados, pl. xi. fig. 3.

Proportion of the major axis to the minor = 4 : 3. Shell thick walled, with irregular, roundish pores, about as broad as the bars; ten to twelve pores on the half equator. Surface spiny. Length of the conical straight spines increasing towards the poles; each polar spine surrounded by a circumpolar group of larger, somewhat curved spines. The larger polar spine equals in length the major axis; the smaller is scarcely half as long. (The figure, given by Bury, is not quite exact; there the spines are situated in the pores, instead of between them. In my specimen the polar spines were not branched.)

{303}Dimensions.--Longer axis of the shell 0.12, shorter axis 0.09; pores and bars 0.004 to 0.006; length of the polar spines--longer 0.12, shorter 0.06.

Habitat.--Fossil in Barbados.

4. Lithomespilus flammabundus, n. sp. (Pl. 14, fig. 14).

Proportion of the major axis to the minor = 4 : 3. Shell thin walled, with irregular, roundish pores, partly simple, partly composed of three to six confluent pores; only six to eight pores on the half equator, twice to four times as broad as the bars. Surface spiny. Length of the conical irregular spines increasing towards the poles; each polar spine surrounded by a flame-shaped, circumpolar area of longer spines; all large spines (also the polar spines) curved or contorted at one pole and much stronger and more numerous than at the other; length variable, often equal to the longer axis.

Dimensions.--Longer axis of the shell 0.12, shorter axis 0.09; pores 0.005 to 0.015, bars 0.003 to 0.005; length of the polar spines 0.1 to 0.15.

Habitat.--Western part of the Tropical Atlantic, Station 347, depth 2250 fathoms.

Genus 129. Lithapium,[168] n. gen.

Definition.--#Ellipsida# with simple ellipsoidal or pear-shaped shell; with a single spine only situated at one pole of the main axis.

The genus Lithapium represents a peculiar modification of Ellipsoxiphus; one of the two opposite polar spines disappears by reduction, and in this way only a single spine remains, at one pole of the main axis. For this reason the shell assumes a characteristic pear-shape, and may easily be confounded with some similar Monocyrtida (Halicapsa).

1. Lithapium pyriforme, n. sp. (Pl. 14, fig. 9).

Proportion of the longer axis to the shorter = 6 : 5. Shell thin walled, with regular, circular pores, four times as broad as the bars; six to eight on the half equator. Surface a little thorny. The single polar spines three-sided pyramidal, as broad at the base as one mesh, about as long as the radius of the shell. (In the specimen figured, there was on the opposite pole a little rudiment of the other lost polar spine; it is missing in other specimens.)

Dimensions.--Major axis of the ellipsoidal shell 0.12, minor axis 0.1; pores 0.02, bars 0.005; length of the single polar spine 0.05, basal thickness 0.02.

Habitat.--Central area of the Pacific, Station 266, depth 2750 fathoms.

2. Lithapium halicapsa, n. sp. (Pl. 14, fig. 8).

Proportion of the longer axis to the shorter = 6 : 5. Shell thin walled, with irregular, lobed meshes, six to eight on the half equator, twice to five times as broad as the bars; each mesh {304}composed of two to five confluent roundish pores. Surface a little thorny. The single polar spine pyramidal, as broad at the base as one mesh, one-third as long as the axis.

Dimensions.--Major axis 0.12, minor axis 0.1; pores 0.01 to 0.02, bars 0.002 to 0.006; length of the single polar spine 0.03, basal thickness 0.02.

Habitat.--Central area of the Pacific, Station 270, depth 2925 fathoms.

3. Lithapium monocyrtis, n. sp. (Pl. 14, fig. 10).

Proportion of the longer axis to the shorter = 7 : 6. Shell thick walled, with irregular, lobed meshes, four to six on the half equator, three to six times as broad as the bars; each mesh composed of three to six confluent roundish pores. Surface quite smooth, without thorns. The single polar spine pyramidal, as broad at the base as the largest mesh, half as long as the radius. (This species is closely allied to the foregoing, but differs in the smooth surface and the larger meshes.)

Dimensions.--Major axis 0.15, minor axis 0.13; pores 0.01 to 0.03, bars 0.003 to 0.01; length of the single spine 0.04, basal thickness 0.03.

Habitat.--Central area of the Pacific, Station 268, depth 2900 fathoms.

Genus 130. Pipettella,[169] n. gen.

Definition.--#Ellipsida# with simple ellipsoidal shell, the main axis of which is prolonged at the pole into two opposite hollow fenestrated tubes of equal size and similar form.

The genus Pipettella is distinguished from the other Ellipsida by two hollow perforated tubes, which are directed in the longer axis of the ellipsoidal shell and arise from opposite poles of this axis. It may be derived from Cenellipsis by prolongation of both poles of the main axis. As the same peculiar production of two opposite latticed tubuli at the poles of the main axis obtains in nearly all families of #Prunoidea# (Pipetta, Cannartus, Panarium, Zygartus, &c.), it may possess a peculiar value in this group.

1. Pipettella fusiformis, n. sp.

Shell spindle-shaped, thin walled, the two opposite tubes being conical and not longer than the short transverse axis of the ellipsoidal shell; no sharp demarcation between them. The two axes of the ellipsoid bear the proportion of 3 : 2. Network of the shell and of the tubes equal, delicate, regular, hexagonal, with circular apertures of equal size; fourteen to sixteen on the half equator of the shell. Bars very thin. The shell of this species is similar to that of Cannartiscus amphiconiscus (Pl. 39, fig. 19), but possesses no equatorial stricture and no medullary shell.

Dimensions.--Longer axis of the ellipsoid 0.18, shorter axis 0.12; length of the tubes 0.1, their basal breadth 0.05; pores of the network 0.01, bars 0.001.

Habitat.--Northern Pacific, Station 244, depth 2900 fathoms.

{305}2. Pipettella tubulosa, n. sp.

Shell ellipsoidal, thin walled, distinctly separated from the two opposite tubes, which are cylindrical, longer than the main axis of the ellipsoid, and one-sixth as broad as the shorter axis. The longer axis of the ellipsoid bears to the shorter the proportion of 5 : 4. Network of the shell and of the tubes equal, regular, with very small circular pores, about as broad as the bars; sixteen to eighteen pores on the half equator of the shell.

Dimensions.--Longer axis of the ellipsoid 0.15, shorter axis 0.12; length of the tubes 0.16 to 0.2, breadth of them 0.02; pores of the network 0.003, bars 0.003.

Habitat.--Western Tropical Pacific, Station 225, depth 4475 fathoms.

3. Pipettella elongata, n. sp.

Shell ellipsoidal, thick walled, distinctly separated from both opposite tubes, which are cylindrical, much prolonged, twice to three times as long as the main axis of the ellipsoid, and one-fifth as broad as the shorter axis. Both axes of the ellipsoid bear the proportion of 3 : 2. Network of the shell and of the tubes irregular with small rounded pores of different size, separated by broader bars (often twice to three times as broad), four to six pores on the half equator of the shell. (This species somewhat recalls Solenosphæra serpentina, Pl. 7, fig. 7; but the tubes are straight, not contorted.)

Dimensions.--Longer axis of the ellipsoid 0.2, shorter axis 0.14; length of the tubes 0.4 to 0.5, breadth 0.03; pores of the network 0.001 to 0.002, bars 0.003 to 0.004.

Habitat.--Central area of the Pacific, Station 271, depth 2425 fathoms.

4. Pipettella prismatica, n. sp. (Pl. 39, fig. 6).

Shell ellipsoidal, thick walled, distinctly marked off from the two opposite tubes, which are longer than its main axis and as broad as one-fifth of it; they are nearly four-sided prismatic, with four strong ribs or edges; these are directed parallel to the main axis, in two meridian planes, perpendicular to one another. The wall of the shell is thickened in the equatorial plane, so as to form a slight stricture on the inside, separating its two halves. Both axes of the ellipsoid bear the proportion of 7 : 6. Network regular, with circular pores, somewhat broader than the bars. The meshes of the shell (fourteen to sixteen on the half equator) are twice as great as those of the tubes, which are arranged in two longitudinal rows between every two ribs (there being eight longitudinal rows on the whole tube). This species is very remarkable for the rudimentary internal equatorial stricture of the shell (transition to the genus Cannartus, Pl. 39, fig. 10), and by the four edges of the tubes, which indicate two of the dimensive axes, the third being represented by the main axis.

Dimensions.--Longer axis of the ellipsoid 0.14, shorter axis 0.12; length of the tubes 0.15 to 0.16, breadth 0.03; pores of the shell 0.008 to 0.01, pores of the tubes 0.004.

Habitat.--Western Tropical Pacific, Station 225, depth 4475 fathoms.

{306}Family XII. #DRUPPULIDA#, Haeckel, 1882 (Pls. 15, 16, 17, 39).

Definition.--#Prunoidea# with ellipsoidal, latticed (not spongy) shell, composed of two or more concentric shells; a simple or double cortical shell enclosing one or two internal concentric shells (medullary shells), without equatorial stricture. Central capsule ellipsoidal or cylindrical, without annular equatorial constriction.

The family #Druppulida# differs from the Ellipsida only in the possession of a simple or double medullary shell, which is enclosed in the centre of the central capsule, and connected with the ellipsoidal cortical shell (lying outside it) by radial beams, perforating the membrane of the capsule. The Druppulida exhibit therefore the same relation to the Ellipsida that the Dyosphærida among the #Sphæroidea# bear to the Monosphærida. The cortical shell may be simple or multiple. The whole fenestrated shell is thus composed of a variable number (two at least) of concentric shells, which are connected by radial beams.

The Medullary Shell--enclosed in the centre of the central capsule--is either simple or double, and composed of two small concentric shells. Their form is either spherical, or ellipsoidal, or lenticular. If the medullary shell be ellipsoidal, the main axis of the ellipsoid is the same as in the cortical shell. Sometimes the inner medullary shell is spherical, the outer ellipsoidal or lenticular. If the medullary shell be lenticular (arising from both poles of the main axis) its vertical axis is also identical with that of the cortical shell (Pl. 39, fig. 5).

The Radial Beams, which connect the medullary and cortical shell, are either developed in all possible directions (Pls. 16, 17), or limited to the equatorial plane, more rarely to the meridional plane. Sometimes the connection is produced only by two opposite beams which lie in the minor or equatorial axis (Pl. 39, figs. 3, 7, 8); more rarely in the major or meridional axis (Pl. 17, figs. 7, 8).

The Cortical Shell is constantly ellipsoidal, rarely with modifications, similar to those which appear in the simple shell of some Ellipsida. As a rule it is simple, rarely composed of two or more (sometimes six or more) concentric ellipsoidal shells (in Cromyodruppa and Cromyocarpus). The outer surface is commonly smooth, more rarely covered with radial spines (in Druppocarpus, Prunocarpus, &c.). In the majority peculiar polar appendages are developed at both poles of the main axis, these being prolongations of them, either in the form of hollow fenestrated tubes (Pipetta, Pipettaria, Pl. 39, figs. 7, 8), or solid strong spines. The two polar spines are either equal in size and similar in form (as in Lithatractus, Stylatractus) or unequal (as in Druppatractus, Xiphatractus, Pls. 16, 17).

The most primitive of all Druppulida is Druppula, with simple medullary shell and simple cortical shell (Pl. 39, fig. 3); Prunulum differs from it only in the possession {307}of a double medullary shell (Pl. 39, fig. 4). From these two genera all other forms of the subfamily may be derived.

The Central Capsule of the Druppulida is constantly ellipsoidal, larger than the concentric enclosed medullary shells, smaller than the surrounding cortical shell; it is separated from the inner surface of the latter by a thinner or thicker jelly-mantle.

Synopsis of the Genera of the Druppulida.

------------------------------------------------------------------------- Cortical shell without polar appendages (neither solid spines nor hollow tubes at the poles of the main axis). ------------------------------------------------------------------------- { {Surface {Medullary { smooth, 131. Druppula. { shell simple.{ { {Surface Cortical shell { { spiny, 132. Druppocarpus. simple, { ellipsoidal. { {Surface {Medullary { smooth, 133. Prunulum. { shell double.{ { {Surface { { spiny, 134. Prunocarpus.

Cortical shell }Medullary {Surface composed of } shell { smooth, 135. Cromyodruppa. two or more } double. { concentric } {Surface shells. } { spiny, 136. Cromyocarpus. ------------------------------------------------------------------------- Two opposite solid spines, arising from the poles of the main axis. ------------------------------------------------------------------------- { {Both polar {Medullary { spines equal, 137. Lithatractus. { shell { { simple. {Both polar Cortical { { spines shell { { unequal, 138. Druppatractus. simple, { ellipsoidal.{ {Both polar { { spines equal, 139. Stylatractus. {Medullary { { shell {Both polar { double. { spines { { unequal, 140. Xiphatractus.

Cortical shell composed of two or more concentric shells; medullary shell double; both polar spines equal, 141. Cromyatractus. ------------------------------------------------------------------------- Two opposite hollow fenestrated tubes, arising from the poles of the main axis. ------------------------------------------------------------------------- Medullary shell simple, 142. Pipetta.

Medullary shell double, 143. Pipettaria.

Genus 131. Druppula,[170] n. gen.

Definition.--#Druppulida# with simple ellipsoidal, cortical shell, and simple medullary shell, without spines or polar tubes.

The genus Druppula, as the simplest form of the Druppulida, may be regarded as the common ancestral form of this subfamily. It may be derived phylogenetically either {308}from Carposphæra by prolongation of one axis, or from Cenellipsis by duplication of the fenestrated shell. The outer (or cortical) shell is always more or less ellipsoidal; the inner (or medullary) shell also is sometimes ellipsoidal, sometimes spherical. Both shells are concentric, connected by a variable number of radial beams. Compare Haliomma oblongum, Harting, 1863, L. N. 18, p. 15, pl. 2, fig. 42.

Subgenus 1. Druppuletta, Haeckel.

Definition.--Pores of the cortical shell regular, hexagonal, or circular.

1. Druppula drupa, n. sp.

Cortical shell thin walled, with smooth surface and regular network; both its axes bear the proportion of 4 : 3. Pores regular, hexagonal, three times as broad as the bars; twelve to fifteen on the half equator. Medullary shell spherical, about one-third as broad as the cortical shell.

Dimensions.--Major axis of the ellipsoidal cortical shell 0.1 to 0.12, minor axis 0.08 to 0.09; pores 0.06, bars 0.02; diameter of the medullary shell 0.03.

Habitat.--Western Tropical Pacific, Station 225, depth 4475 fathoms; also fossil in Barbados.

2. Druppula pandanus, n. sp. (Pl. 39, fig. 3).

Cortical shell thin walled, somewhat rough, with regular network; both its axes bear the proportion of 3 : 2. Pores subregular, circular, hexagonally framed, one and a half times as broad as the elevated bars; ten to twelve on the half equator. Medullary shell spherical, one-fourth as broad as the cortical shell.

Dimensions.--Major axis of the cortical shell 0.16 to 0.17, minor axis 0.11 to 0.12; pores 0.01, bars 0.007; diameter of the medullary shell 0.035.

Habitat.--Pacific, central area, Station 268, depth 2900 fathoms.

3. Druppula cocos, n. sp.

Cortical shell thick walled, somewhat rough, with regular network; proportion of both axes = 6 : 5. Pores regular, circular, hexagonally framed, quite as broad as the elevated bars; fourteen to sixteen on the half equator. Medullary shell ellipsoidal (with longitudinal main axis), nearly half as large as the cortical shell.

Dimensions.--Major axis of the cortical shell 0.07 to 0.08, minor axis 0.6 to 0.65; pores and bars 0.003 to 0.004; diameter of the medullary shell 0.03 and 0.035.

Habitat.--Western Tropical Pacific, Station 222, surface, Indian Ocean, Ceylon, Haeckel.

4. Druppula phoenix, n. sp.

Cortical shell thick walled, smooth, with regular network; proportion of both axes = 5 : 4. Pores regular, circular, hexagonally lobulate (in the same manner as in Stauroxiphus gladius, {309}Pl. 15, fig. 7), three times as broad as the bars; ten to twelve on the half equator. Medullary shell ellipsoidal (with longitudinal main axis), one-third as broad as the cortical shell.

Dimensions.--Major axis of the cortical shell 0.1, minor axis 0.08; pores 0.009, bars 0.003; axis of the medullary shell 0.03 and 0.025.

Habitat.--Mediterranean, Smyrna, Haeckel, surface.

5. Druppula areca, n. sp.

Cortical shell thin walled, with smooth surface and regular network; both its axes bear the proportion of 4 : 3. Pores regular, circular, four times as broad as the bars; fifteen to eighteen on the half equator. Medullary shell spherical, half as broad as the cortical shell.

Dimensions.--Major axis of the ellipsoidal cortical shell 0.12 to 0.14, minor axis 0.1 to 0.11; pores 0.008, bars 0.002; diameter of the medullary shell 0.05 to 0.06.

Habitat.--Indian Ocean, off Bombay, Haeckel.

6. Druppula ovata, Haeckel.

Haliomma ovatum, Ehrenberg, 1854, Mikrogeol., pl. xx. I. fig. 20.

Haliomma ovatum, Haeckel, 1862, Monogr. d. Radiol., p. 432.

Cortical shell thin walled, with smooth surface and regular network; proportion of both axes = 3 : 2. Pores regular, circular, three times as broad as the bars; nine to ten on the half equator. Medullary shell spherical, one-third as broad as the cortical shell.

Dimensions.--Major axis 0.08 to 0.1, minor axis 0.05 to 0.06; pores 0.003, bars 0.001; diameter of the medullary shell 0.02.

Habitat.--Fossil in the Tertiary rocks of the Mediterranean coast, Greece (Zante), Ehrenberg; Sicily (Caltanisetta), Haeckel.

7. Druppula caryota, n. sp.

Cortical shell thick walled, with rough surface and regular network; proportion of both axes = 5 : 4. Pores regular, circular, twice as broad as the bars; sixteen to twenty on the half equator. Medullary shell ellipsoidal, one-third as large as the cortical shell.

Dimensions.--Major axis 0.2 to 0.22, minor 0.16 to 0.18, pores 0.008, bars 0.004; axes of the medullary shell 0.07 and 0.055.

Habitat.--Pacific, central area, Stations 266 to 268, depth 2700 to 2900 fathoms.

Subgenus 2. Druppulissa, Haeckel.

Definition.--Pores of the cortical shell irregular, of different form or size, usually subcircular or roundish, sometimes lobed or compound.

{310}8. Druppula nucula, n. sp.

Cortical shell thin walled, smooth, with irregular network; its two axes bear the proportion 3 : 2. Pores subcircular or irregular, roundish, twice to four times as broad as the bars; fifteen to twenty on the half equator. Medullary shell spherical, about one-third as broad as the cortical shell.

Dimensions.--Major axis of the cortical shell 0.15 to 0.2, minor axis 0.1 to 0.14; pores 0.006 to 0.012, bars 0.03; diameter of the medullary shell 0.04.

Habitat.--Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.

9. Druppula elliptica, Haeckel.

Haliomma ellipticum, Stöhr, 1880, Palæontogr., loc. cit., p. 88, Taf. i. fig. 11.

Cortical shell thin walled, rough, or thorny, with irregular network; proportion of the axes = 3 : 2. Pores subcircular or irregular, roundish, about as broad as the bars; ten to twelve on the half equator. Medullary shell half as broad as the cortical shell, irregularly polyhedral (with crooked beams in its interior).

Dimensions.--Major axis 0.15, minor 0.06; pores and bars 0.006; diameter of the medullary shell 0.03.

Habitat.--Fossil in the Tertiary rocks of Sicily: Grotte (Stöhr), Caltanisetta (Haeckel).

10. Druppula prunum, n. sp.

Cortical shell thick walled, smooth, with irregular network; proportion of the axes = 5 : 4. Pores subcircular or irregular, roundish, three to four times as broad as the bars; seven to eight on the half equator; every pore is closed at the bottom by a thin membrane, perforated by four to six irregular pores (like Stylatractus sethoporus, Pl. 17, fig. 3). Medullary shell spherical, one-third as broad as the cortical shell.

Dimensions.--Major axis 0.2, minor axis 0.16; pores 0.03, bars 0.01; small enclosed porules 0.01; diameter of the medullary shell 0.05.

Habitat.--Mediterranean, surface, Portofino near Genoa, Haeckel.

11. Druppula oliva, n. sp.

Cortical shell thick walled, rough, with irregular network; proportion of the axes = 5 : 4. Pores irregular, roundish, three to four times as broad as the bars; lobed or composed of several conjugated porules (as in Lithapium halicapsa, Pl. 14, fig. 8); five to six large pores on the half equator. Medullary shell ellipsoidal, about one-third as broad as the cortical shell.

Dimensions.--Major axis of the cortical shell 0.15, minor 0.12; pores 0.02 to 0.03, bars 0.007; diameter of the medullary shell 0.04.

Habitat.--Mediterranean (Corfu), Canary Islands (Lanzerote), Haeckel.

{311}Genus 132. Druppocarpus,[171] n. gen.

Definition.--#Druppulida# with simple ellipsoidal cortical shell and simple medullary shell, with numerous radial spines, without polar tubes.

The genus Druppocarpus differs from Druppula only in the radial spines, which arise between the pores of the cortical shell, and therefore exhibits the same relation to it that Ellipsidium bears to Cenellipsis, or Prunocarpus to Prunulum.

Subgenus 1. Druppocarpetta, Haeckel.

Definition.--Network of the cortical shell regular, with meshes of equal size and similar form.

1. Druppocarpus ananassa, n. sp.

Cortical shell thin walled, with regular, circular, hexagonally framed pores, of about the same breadth as the elevated bars; fourteen to sixteen on the half equator. From each hexagon-corner (between every three pores) arises a short thin radial spine, about as long as two pores, three-sided pyramidal at the base. Proportion of both cortical axes = 4 : 3. Medullary shell spherical, half as broad as the cortical shell. (Greatly resembles Druppula pandanus, Pl. 39, fig. 3, but differs in the larger medullary shell and the spines on the surface.)

Dimensions.--Major axis of the ellipsoidal cortical shell 0.16, minor 0.12; pores and bars 0.006; length of the radial spines 0.02; diameter of the medullary shell 0.06.

Habitat.--South Pacific, Station 289, surface.

2. Druppocarpus castanea, n. sp.

Cortical shell thin walled, with regular circular pores (without hexagonal frames), of about the same breadth as the bars; twelve to fourteen on the half equator. Between every three meshes arise a short conical spine with bristle-like apex, twice to four times as long as one pore. Proportion of both cortical axes = 3 : 2. Medullary shell spherical, one-third as broad as the cortical. (Resembles very closely the spherical Haliomma castanea, Haeckel, figured in my Monograph. pl. xxiv. fig. 4.)

Dimensions.--Major axis 0.15, minor axis 0.1; pores and bars 0.005; length of the radial spines 0.01 to 0.02; medullary shell 0.035.

Habitat.--North Atlantic, surface; Canary Islands, Lanzerote, Haeckel.

Subgenus 2. Druppocarpissa, Haeckel.

Definition.--Network of the cortical shell irregular, with meshes of different size or form.

{312}3. Druppocarpus chamaerops, n. sp.

Cortical shell thin walled, with irregular, roundish, or subcircular pores of very different size, twice to six times as broad as the thin bars; eight to twelve on the half equator. Between them arise numerous thin, bristle-like radial spines, about half as long as the equatorial axis, and equal to the diameter of the spherical medullary shell; pores of the latter subregular, circular, very small. (Resembles Prunocarpus artocarpus, Pl. 39, fig. 5, but differs in the simple spherical medullary shell.)

Dimensions.--Major axis 0.12, minor 0.09; meshes 0.005 to 0.02, bars 0.003; length of the radial spines 0.05; diameter of the medullary shell 0.04.

Habitat.--Mediterranean, in the Strait of Gibraltar, Algesiras, Haeckel, surface.

4. Druppocarpus borassus, n. sp.

Cortical shell thick walled, with irregular, roundish, or subcircular pores, three to five times as broad as the bars; twelve to fifteen on the half equator. Irregularly scattered on the surface about twenty to thirty short conical spines; their length equals their basal breadth and the diameter of the largest pores. Medullary shell ellipsoidal, half as large as the cortical.

Dimensions.--Major axis 0.1, minor 0.08; pores 0.006 to 0.01, bars 0.002; length and thickness of the radial spines 0.01; axes of the medullary shell 0.05 and 0.04.

Habitat.--Pacific, central area, Station 268, depth 2900 fathoms.

5. Druppocarpus corypha, n. sp.

Cortical shell thick walled, with irregular, funnel-like, roundish pores, scarcely as broad as the bars; sixteen to twenty on the half equator. Irregularly scattered on the surface about fifteen to twenty three-sided pyramidal radial spines, half as long as the equatorial axis, and as the diameter of the medullary shell.

Dimensions.--Major axis 0.17, minor 0.14; pores and bars 0.003 to 0.009; length of the radial spines 0.08; diameter of the medullary shell 0.09.

Habitat.--Fossil in the Tertiary rocks of the Nicobars, Haeckel.

Genus 133. Prunulum,[172] n. gen.

Definition.--#Druppulida# with simple ellipsoidal cortical shell and double medullary shell; without spines or polar tubes.

The genus Prunulum differs from Druppula in the double (not simple) medullary shell, which is sometimes spherical, sometimes ellipsoidal; it may be derived either from Druppula by duplication of the medullary shell, or from Thecosphæra by prolongation of one axis.

{313}Subgenus 1. Prunuletta, Haeckel.

Definition.--Network of the cortical shell regular, with meshes of equal size and similar form.

1. Prunulum frugulum, n. sp.

Cortical shell thin walled, smooth, with regular, hexagonal pores, three times as broad as the bars; ten to twelve on the half equator. Proportion of the major axis of the ellipsoid to the minor = 4 : 3. Both medullary shells spherical. (Differs from Druppula drupa almost entirely in the double medullary shell.)

Dimensions.--Major axis of the ellipsoidal cortical shell 0.12, minor 0.09; pores 0.006, bars 0.002; diameter of both medullary shells 0.05 and 0.03.

Habitat.--Pacific, central area, Station 266, depth 2750 fathoms.

2. Prunulum cerasum, n. sp.

Cortical shell thick walled, smooth, with circular, hexagonally framed pores, of the same breadth as the bars; sixteen to eighteen on the half equator. Proportion of the two axes of the ellipsoid = 5 : 4. Both medullary shells spherical. (The cortical shell resembles that of Pipetta tuba, Pl. 39, fig. 7, without the polar tubes.)

Dimensions.--Major axis 0.15, minor 0.12; pores and bars 0.007; diameter of the medullary shells 0.08 and 0.04.

Habitat.--South Atlantic, Station 332, depth 2200 fathoms.

3. Prunulum amygdalum, n. sp.

Cortical shell thick walled, smooth, with regular, circular, hexagonally lobulated pores, three times as broad as the bars; twelve to fourteen on the half equator (of the same form as in Druppula phoenix and in Stauroxiphos gladius, Pl. 15, fig. 7). Proportion of the two axes = 6 : 5. Inner medullary shell spherical, outer ellipsoidal.

Dimensions.--Major axis 0.12, minor 0.1; pores 0.009, bars 0.003; diameter of the medullary shells 0.07 and 0.04.

Habitat.--Mediterranean (Corfu), surface.

4. Prunulum coccymelium (Pl. 39, fig. 4).

Cortical shell thin walled, slightly rough, with regular, circular pores, twice as broad as the bars; twelve to fifteen on the half equator. Proportion of both axes = 4 : 3. Both medullary shells spherical.

Dimensions.--Major axis 0.12, minor 0.09; pores 0.006, bars 0.003; diameter of the medullary shells 0.06 and 0.03.

Habitat.--Pacific, central area, Station 273, depth 2350 fathoms.

{314}5. Prunulum crenatum, Haeckel.

? Haliomma crenatum, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 36.

Actinomma crenatum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 94, Taf. iii. fig. 3.

Caryolithis crenata, Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 43.

Cortical shell thick walled, slightly rough or thorny, with small, regular, circular pores, of the same breadth as the bars; sixteen to eighteen on the half equator. Proportion of the two axes = 4 : 3. Both medullary shells ellipsoidal. (The figure of Stöhr represents exactly the fossil form, as I have observed it myself in the Caltanisetta rocks, whilst the figure of Ehrenberg is inaccurate and doubtful. The same form, somewhat variable in size and in the number of the pores, I have also observed in the Pacific ooze.)

Dimensions.--Major axis 0.14 to 0.17, minor 0.1 to 0.13; pores and bars 0.006; main axes of the medullary shells 0.09 and 0.03.

Habitat.--Fossil in the Tertiary rocks of Sicily (Grotte and Caltanisetta); living in the Central Pacific, Station 268, depth 2900 fathoms.

6. Prunulum triplex, Haeckel.

Haliomma triplex, Ehrenberg, 1854, Microgeol., Taf. xxxvB. fig. Biv., q.

Actinomma triplex, Haeckel, 1862, Monogr. d. Radiol., p. 444.

Cortical shell thin walled, covered with numerous very thin, short, bristle-like spines. Pores small, regular, circular, of the same breadth as the bars; fourteen to sixteen on the half equator. Proportion of the two axes = 3 : 2. Both medullary shells ellipsoidal. The description of Ehrenberg--as is very often the case--is quite incongruent with his figure. From a combination of both I give here the diagnosis of a deep-sea species, which is possibly identical with it. The velvet-like covering of very short and thin bristles is peculiarly characteristic of this species.

Dimensions.--Major axis 0.1, minor 0.065; pores and bars 0.004; main axes of the medullary shells 0.04 and 0.02.

Habitat.--North Atlantic, 1800 fathoms, Ehrenberg; Station 353, depth 2965 fathoms.

Subgenus 2. Prunulissa, Haeckel.

Definition.--Network of the cortical shell irregular, with meshes of different form or size (usually roundish, but sometimes lobed or compound).

7. Prunulum persicum, n. sp.

Cortical shell thick walled, with smooth surface and irregular, roundish, double-contoured pores, twice to four times as broad as the bars; eight to ten on the half equator. Some of the pores are simple, often subcircular, others lobed, i.e., composed of from two to three confluent pores as in Amphisphæra pluto (Pl. 17, fig. 7). Proportion of the two axes = 3 : 2. Both medullary shells ellipsoidal (or the inner spherical).

{315}Dimensions.--Major axis 0.12, minor 0.08; pores 0.06 to 0.012, bars 0.003; main axes of the medullary shells 0.05 and 0.025.

Habitat.--Indian Ocean, between Socotra and Ceylon, surface, Haeckel.

8. Prunulum fenestratum, Haeckel.

Actinomma fenestratum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 94, Taf. iii. fig. 2.

Cortical shell thick walled, rough, with irregular, roundish pores, once to three times as broad as the bars; twelve to fourteen on the half equator. Proportion of the two axes = 9 : 8. Both medullary shells ellipsoidal. (The pores in Stöhr's description are by mistake called "regular"; in the figure they are very irregular, as also in the fossil specimens observed by myself. Between the cortical pores arise very short irregular thorns.)

Dimensions.--Major axis 0.12 to 0.15, minor 0.1 to 0.12; pores 0.003 to 0.01, bars 0.003; main axis of the outer medullary shell 0.07 to 0.09, of the inner 0.03 to 0.04.

Habitat.--Fossil in the Tertiary rocks of Sicily; Grotte, Stöhr, Caltanisetta, Haeckel.

9. Prunulum pyrenium, n. sp.

Cortical shell very thick walled, smooth, with large irregular, roundish pores, three to four times as broad as the bars; six to eight on the half equator. The bottom of each funnel-like pore is closed by a thin siliceous membrane, perforated by three to five irregular roundish pores. Proportion of the two axes = 4 : 3. Both medullary shells ellipsoidal. (Closely resembles Stylatractus sethoporus, Pl. 17, figs. 2, 3, but is devoid of the polar spines.)

Dimensions.--Major axis 0.16, minor 0.12; pores 0.015 to 0.02, bars 0.005; porules 0.01; main axes of the medullary shells 0.07 and 0.03.

Habitat.--Western Tropical Pacific, Station 225, depth 4475 fathoms.

Genus 134. Prunocarpus,[173] n. gen.

Definition.--#Druppulida# with simple ellipsoidal cortical shell and double medullary shell, with numerous radial spines, but without polar tubes.

The genus Prunocarpus differs from Prunulum only in the radial spines of the cortical shell, and exhibits therefore the same relation to it that Druppocarpus bears to Druppula. While in the latter the medullary shell is simple, in the former it is double.

Subgenus 1. Prunocarpetta, Haeckel.

Definition.--Network of the cortical shell regular, with meshes of equal size and similar form.

{316}1. Prunocarpus datura, n. sp.

Cortical shell thick walled, with regular, circular pores, twice as broad as the bars; ten to twelve on the half equator. Between every three meshes arises a short conical spine, twice to three times as long as one pore. Both medullary shells spherical. (Differs mainly from Ellipsidium datura and from Druppocarpus castanea in the double medullary shell. The outer network resembles Haliomma castanea, figured 1862 in my Monograph, Taf. xxiv. fig. 4.)

Dimensions.--Major axis of the ellipsoid 0.16, minor 0.12; pores 0.012, bars 0.006; length of the radial spines 0.03; diameter of the medullary shells 0.06 and 0.04.

Habitat.--North Atlantic, Færöe Channel, John Murray, surface.

2. Prunocarpus sparganium, n. sp.

Cortical shell thick walled, with very small, numerous, regular, circular pores, of the same size as the bars; forty to fifty on the half equator. Between them over the entire surface occur small conical spines. Irregularly scattered over the surface ten to twenty larger conical spines, three to six times as thick at the base as one pore, one-fourth to one-half as long as the main axis. Both medullary shells ellipsoidal.

Dimensions.--Major axis of the cortical shell 0.16, of the outer medullary shell 0.11, of the inner 0.06; equatorial axis of the first shell 0.12, of the second 0.08, of the third 0.04; pores and bars on an average 0.005; length of the spines 0.05 to 0.1, basal breadth 0.02 to 0.03.

Habitat.--Fossil in the Barbados deposits (Haeckel).

Subgenus 2. Prunocarpilla, Haeckel.

Definition.--Network of the cortical shell irregular, with meshes of different size or form.

3. Prunocarpus artocarpium, n. sp. (Pl. 39, fig. 5).

Cortical shell thin walled with irregular, roundish pores of very different sizes, twice to nine times as broad as the thin bars; ten to fifteen on the half equator. Between them arise numerous bristle-shaped, radial spines, with conical base, on an average one-fourth to two-thirds as long as the equatorial axis. The outer medullary shell, with irregular, roundish pores, presents a transverse ellipsoid, its main axis lying in the equatorial axis of the cortical shell, whilst its equatorial axis corresponds to the main axis of the latter. Inner medullary shell very small, spherical, with very small pores.

Dimensions.--Major axis of the cortical shell 0.14, of the outer medullary shell 0.05; minor axis of the former 0.1, of the latter 0.035; diameter of the inner medullary shell 0.014; pores of the cortical shell 0.005 to 0.02, bars 0.002; length of the radial spines 0.02 to 0.06.

Habitat.--Indian Ocean, surface; Ceylon, Belligemma, Haeckel.

{317}4. Prunocarpus melocactus, n. sp.

Cortical shell thick walled, with irregular, roundish pores, twice to five times as broad as the bars; eighteen to twenty-four on the half equator. Between them arise over the entire surface small conical thorns, not longer than the largest pores. Irregularly scattered over the surface twenty to thirty strong, conical, radial spines, about half as long as the main axis, as broad at the base as a large pore. Both medullary shells ellipsoidal, their main axis identical with that of the cortical shell.

Dimensions.--Major axis of the outer shell 0.18, of the middle 0.09, of the inner 0.05; minor axis of the first 0.14, of the second 0.07, of the third 0.04; pores of the cortical shell 0.006 to 0.02, bars 0.004; length of the spines 0.1, basal breadth 0.01.

Habitat.--Pacific, central area, Station 268, depth 2900 fathoms; also fossil in the Tertiary rocks of Sicily; Caltanisetta, Haeckel.

Genus 135. Cromyodruppa,[174] n. gen.

Definition.--#Druppulida# with four or more concentric shells (two medullary and two or more cortical shells), without spines or polar tubes.

The genus Cromyodruppa is characterised by the multiplication of the concentric fenestrated shell, which is composed of two medullary shells (enclosed in the central capsule) and two or more cortical shells (outside it). The former may be either spherical or ellipsoidal. The latter are always ellipsoidal, and in this it differs from Cromyosphæra. Probably Cromyodruppa has arisen from Prunulum by secondary apposition of more cortical envelopes.

Subgenus 1. Cromyodruppium, Haeckel.

Definition.--Shell composed of four concentric shells, two medullary and two cortical.

1. Cromyodruppa cepa, n. sp.

Shell composed of two ellipsoidal, cortical, and two spherical medullary shells. Proportion of the main axes of the four shells = 1 : 2 : 4 : 5. Network of all four shells nearly of the same form, subregular, with circular pores of almost equal size in every shell. The absolute size of the pores increases from the innermost to the outermost shell, but the breadth of the bars does not increase in a similar degree. The bars of the outermost shell are only twice as broad as those of the innermost; but the pores are three to four times larger. Surface of all four shells smooth. (The shell greatly resembles that of Cromyatractus tetraphractus, Pl. 15, fig. 2, but is devoid of polar spines; it differs also in the spherical form of both medullary shells and their relative size.)

{318}Dimensions.--Main axes of the four shells--(A) innermost 0.035, (B) second 0.08, (C) third 0.15, (D) outermost 0.2; their equatorial axes--(A) 0.03, (B) 0.08, (C) 0.12, (D) 0.16; pores 0.004 to 0.016, bars 0.002 to 0.004.

Habitat.--Western Tropical Pacific, Station 198, depth 2150 fathoms.

Subgenus 2. Caryodruppula, Haeckel.

Definition.--Shell composed of five or more concentric shells (two medullary and three or more cortical).

2. Cromyodruppa mango, n. sp.

Shell composed of six ellipsoidal, concentric shells, two medullary and four cortical. Proportion of their main axes = 2 : 3 : 8 : 11 : 14 : 18. Network of the two medullary shells and of the innermost cortical shell subregular, with subcircular pores, about the same breadth as the bars. Network of the three outer cortical shells more lax, with larger, irregular, roundish pores, twice to six times as broad as the bars. The size of the pores and bars increases gradually from the innermost to the outermost shell. Surface smooth.

Dimensions.--Main axis of the six shells--(A) innermost 0.04, (B) 0.06, (C) 0.16, (D) 0.22, (E) 0.28, (F) 0.35; their equatorial axes--(A) innermost 0.03, (B) 0.05, (C) 0.12, (D) 0.16, (E) 0.2, (F) 0.25; pores 0.003 to 0.02, bars 0.003 to 0.005.

Habitat.--Indian Ocean, surface; Matura, Ceylon, Haeckel.

Genus 136. Cromyocarpus,[175] n. gen.

Definition.--#Druppulida# with four or more concentric shells (two medullary and two or more cortical shells), with numerous radial spines, but without polar tubes.

The genus Cromyocarpus differs from Cromyodruppa only in the development of numerous large radial spines which start from the outer surface of the shell. It exhibits therefore the same relation to the latter that Prunocarpus bears to Prunulum, or Druppocarpus to Druppula. It differs from both in the multiplication of the cortical shell.

1. Cromyocarpus quadrifarius, n. sp.

Shell composed of four concentric shells, two ellipsoidal cortical shells, and two spherical medullary shells. Proportion of their main axes = 10 : 8 : 3 : 2. Pores of the two cortical shells irregular, roundish, twice to four times as broad as the bars. Pores of the two medullary shells subregular, circular, about the same size as the bars. Outer surface covered with numerous conical radial spines, about half as long as the main axis, half as broad at the base as the innermost shell.

{319}Dimensions.--Major axis of the outer cortical shell 0.2, of the inner 0.15; equatorial axis of the former 0.16, of the latter 0.12; diameter of the outer medullary shell 0.06, of the inner 0.04; pores of the cortical shells 0.01 to 0.02, of the medullary shells 0.004 to 0.008, bars 0.003 to 0.006; length of the radial spines 0.1, basal breadth 0.02.

Habitat.--Indian Antarctic Ocean, Station 157, depth 1950 fathoms.

Genus 137. Lithatractus,[176] n. gen.

Definition.--#Druppulida# with simple ellipsoidal cortical shell and simple medullary shell, with two large opposite polar spines in the main axis of equal size and similar form.

The genus Lithatractus, rich in common and widely distributed species, begins the series of those Druppulida which are characterised by peculiar polar spines at both poles of the main axis. It repeats the formation of Stylosphæra and Ellipsostylus, and differs from the former in the ellipsoidal form of the cortical shell, from the latter in the possession of a medullary shell. Formerly all these forms were united in the one genus Stylosphæra (see above, p. 121).

Subgenus 1. Lithatractara, Haeckel.

Definition.--Network of the outer shell regular or subregular, with meshes of nearly equal size and similar form; surface smooth, without thorns or papillæ.

1. Lithatractus hexagonalis, n. sp.

Outer shell thin walled, smooth, without thorns or papillæ, with regular delicate network; the meshes hexagonal, three to four times as broad as the thin bars; ten to twelve on the half equator. Proportion of the major axis of the ellipsoid to the minor = 4 : 3. Minor axis three times as large as that of the inner spherical shell; pores of the latter, small, circular. Two spines three-sided pyramidal, as long as the radius of the outer shell, each as broad at its base as one mesh.

Dimensions.--Longer axis of the ellipsoidal cortical shell 0.16, shorter axis 0.12; pores 0.011, bars 0.003; diameter of the spherical medullary shell 0.04; length of the polar spines 0.07; basal breadth 0.01.

Habitat.--North Pacific, Station 253, depth 3125 fathoms.

2. Lithatractus fragilis, n. sp. (Pl. 16, fig. 3).

Stylosphæra fragilis, Haeckel, 1881, Prodromus et Atlas, pl. xvi. fig. 3.

Outer shell thin walled, smooth, without thorns or papillæ, with regular network; the meshes circular, of equal size, eight to ten times as broad as the thin bars; six to eight on the half equator. {320}Proportion of the major axis of the ellipsoid to the minor = 5 : 4. Minor axis once and one-third as broad as that of the ellipsoidal inner shell, the pores of which are also circular, but of half the size. Two spines strong, three-sided pyramidal, acute, as broad as a large mesh, as long as the equatorial axis. The stout inner prolongations of these form the only connection between the two shells.

Dimensions.--Longer axis of the ellipsoidal cortical shell 0.12, shorter axis 0.1; pores 0.02, bars 0.002; longer axes of the ellipsoidal medullary shell 0.09, shorter axis 0.07; pores 0.01, bars 0.002; length of the polar spines 0.1, basal breadth 0.002.

Habitat.--Central area of the Pacific, Station 272, depth 2600 fathoms.

3. Lithatractus leptostylus, n. sp.

Outer shell thin walled, smooth, with regular, circular pores of equal size, three to four times as broad as the thin bars; ten to twelve on the half equator. Proportion of the major axis to the minor = 7 : 6. Minor axis three times as large as that of the inner spherical shell; pores of the latter half as large. Polar spines cylindrical, blunt, longer than the major axis, scarcely half as broad as one larger pore.

Dimensions.--Longer axis of the cortical shell 0.14, shorter axis 0.12; pores 0.015 to 0.02, bars 0.004; diameter of the medullary shell 0.04; length of the polar spines 0.15 to 0.2, its thickness 0.01.

Habitat.--Central area of the Pacific, Stations 270 to 272, depth 2425 to 2925 fathoms.

4. Lithatractus pachystylus, n. sp.

Outer shell thick walled, smooth, with regular, circular pores of equal size; twelve to fifteen on the half equator. Each pore is deep, funnel-shaped, its outer aperture double the size of the inner, its breadth about three times that of the high bars. Proportion of the major axis to the minor = 6 : 5. Major axis double as long as the diameter of the spherical medullary shell. Polar spines very thick and short, tetrahedral, one-fourth as long and broad as the major axis.

Dimensions.--Longer axis of the cortical shell 0.17, shorter axis 0.14; pores 0.01, bars 0.003; diameter of the medullary shell 0.08; length and thickness of the polar spines 0.04.

Habitat.--Central area of the Pacific, Station 271, depth 2425 fathoms.

5. Lithatractus convallaria, n. sp.

Outer shell thick walled, smooth, with elegant regular network; the meshes circular, six-lobed, rosette-like (of the same form as Stauroxiphos gladius, Pl. 15, fig. 7), twice to three times as broad as the bars; six to eight on the half equator. Proportion of the major axis of the ellipsoid to the minor = 4 : 3. Minor axis twice as long as the diameter of the inner spherical shell, which has regular, simple, circular pores of half the size. Polar spines short and thick, conical, only one-fourth to one-sixth as long as the minor axis, and quite as thick.

Dimensions.--Longer axis of the cortical shell 0.16, shorter axis 0.12; pores 0.016, bars 0.006; diameter of the medullary shell 0.06; length of the polar spines 0.02 to 0.03, basal thickness the same.

Habitat.--Central area of the Pacific, Station 268, depth 2900 fathoms.

{321}Subgenus 2. Lithatractylis, Haeckel.

Definition.--Network of the outer shell regular, with meshes of equal size and similar form; surface thorny or papillose, covered with small conical spines or tubercles.

6. Lithatractus echiniscus, n. sp.

Outer shell thorny, thin walled, with regular network; meshes circular, with hexagonal frame, four to five times as broad as the thin bars; eighteen to twenty on the half equator. From every corner between the three meshes, where three hexagons unite, starts one short, straight, triangular thorn (as in Ellipsoxiphus elegans, Pl. 14, fig. 7). Proportion of the major axis of the ellipsoid to the minor = 4 : 3. Minor axis twice the diameter of the inner spherical shell, the pores of which are half as broad, circular. Polar spines three-sided pyramidal, about as long as the minor axis, as broad at the base as one hexagonal frame.

Dimensions.--Longer axis of the cortical shell 0.08, shorter axis = 0.06; pores 0.004, bars 0.001; length of the polar spines 0.05, basal thickness 0.005; diameter of the inner shell 0.03.

Habitat.--South Atlantic, off Tristan da Cunha, Station 334, surface.

7. Lithatractus carduelis, n. sp.

Outer shell thin walled, thorny, with regular network; meshes circular, simple, four to six times as broad as the thin bars; ten to twelve on the half equator. Between every three meshes is one short conical spine. Proportion of the major axis to the minor = 6 : 5. Minor axis equals three times the diameter of the inner spherical shell. Polar spines conical, thick, half as long as the major axis, thicker at the base than one pore. (This species differs from Stylatractus carduus only by the simple medullary shell.)

Dimensions.--Longer axis of the ellipsoid 0.12 to 0.16, shorter axis 0.1 to 0.14; pores 0.02 to 0.03, bars 0.005; length of the polar spines 0.05 to 0.10, basal breadth 0.04; diameter of the medullary shell 0.03 to 0.04.

Habitat.--Central area of the Pacific, Stations 268 to 274, depth 2350 to 2900 fathoms; also fossil in the rocks of Barbados.

8. Lithatractus cirsium, n. sp.

Outer shell thin walled, thorny, with regular network; pores circular, simple, small, two to three times as broad as the thin bars; eighteen to twenty-four on the half equator. Proportion of the major axis to the minor = 4 : 3. Inner shell ellipsoidal, half as large as the outer. Polar spines cylindrical, blunt, thin, very variable in length (one-fourth to three-fourths of the major axis, not thicker than a mesh).

Dimensions.--Longer axis of the ellipsoid 0.07 to 0.09, shorter axis 0.05 to 0.07; pores 0.005 to 0.006, bars 0.002; length of the polar spines 0.02 to 0.06, basal breadth 0.004; length of the inner shell 0.04, breadth 0.03.

Habitat.--North Pacific, Station 244, surface.

{322}9. Lithatractus rosetta, n. sp.

Outer shell thick walled, thorny, with regular network; meshes circular, funnel-shaped, its outer aperture elegant, rosette-like, with eight to ten incisions (like Stylosphæra calliope, Pl. 16, fig. 6); eight to ten meshes on the half equator, three to four times as broad as the bars. Proportion of the longer axis to the shorter = 5 : 4. Shorter axis equals three times the diameter of the inner spherical shell. Polar spines three-sided pyramidal, about half as long as the shorter axis, as broad at the base as a mesh.

Dimensions.--Longer axis of the cortical shell 0.15, shorter 0.12; pores 0.02, bars 0.005; length of the polar spines 0.05, basal breadth 0.02; diameter of the inner shell 0.04.

Habitat.--South-eastern part of the Pacific, Station 302, depth 1450 fathoms.

Subgenus 3. Lithatractona, Haeckel.

Definition.--Network of the outer shell irregular, with meshes of unequal size or dissimilar form; surface smooth, without thorns or papillæ.

10. Lithatractus conifer, n. sp.

Outer shell thin walled, smooth, with irregular, roundish pores, two to four times as broad as the thin bars; fifteen to twenty on the half equator. Margin of the pores simple. Proportion of the major axis to the minor = 3 : 2. Minor axis twice as large as the diameter of the inner spherical shell, the pores of which are also irregular, roundish, but of half the size. Polar spines conical, somewhat shorter than the main axis, on the base two to three times as thick as a large pore.

Dimensions.--Longer axis of the outer shell 0.15, shorter axis 0.1; pores 0.002 to 0.004, bars 0.001; diameter of the inner shell 0.05; length of the polar spines 0.12, basal breadth 0.012.

Habitat.--South Atlantic, Station 325, surface.

11. Lithatractus lobatus, n. sp.

Outer shell thick walled, smooth, with irregular, roundish pores, four to eight times as broad as the bars; six to eight on the half equator. Margin of the pores lobed, very irregular, bluntly dentate, by five to twenty slight incisions. Proportion of the major axis to the minor very variable, between 3 : 2 and 9 : 8. Diameter of the inner shell also variable, between one-third and one-half of the outer; pores of the former scarcely half the size of the latter, simple, roundish, or circular. The inner shell is at some parts quite spherical, at other parts more or less ellipsoidal. Polar spines conical, very variable in size and form, sometimes in the basal half triangular; they are sometimes somewhat longer than the main axis, at other times considerably shorter; their basal breadth is occasionally the same as that of the largest pores, sometimes, however, scarcely half as large. This deep-sea species is very common in the central area of the Tropical Pacific (Stations 266 to 272), and occurs also fossil in the Barbados deposits. It is interesting from its great variability, and sometimes constitutes a transitional form to Stylosphæra.

{323}Dimensions.--Longer axis of the outer shell 0.1 to 0.15, shorter axis 0.05 to 0.12; pores 0.018 to 0.024, bars 0.002 to 0.004; diameter of the inner shell 0.04 to 0.08; length of the polar spines 0.08 to 0.2, basal thickness 0.01 to 0.02.

Habitat.--Central area of the Pacific, common; Stations 266 to 272, depth 2425 to 2900 fathoms; also fossil in Barbados.

12. Lithatractus jugatus, n. sp. (Pl. 16, fig. 2).

Stylosphæra jugata, Haeckel, 1881, Prodromus et Atlas (pl. xvi. fig. 2).

Outer shell thick walled, smooth, or somewhat reticulated, with a peculiar, irregular, double network. The pores are roundish, of very different sizes, with double margin of the outer aperture, and so irregularly distributed in polygonal groups that every group contains two to six pores immediately touching each other; the groups are separated by broader bars. On the half equator of the shell are about six to eight groups and twelve to eighteen pores. Proportion of the longer axis of the ellipsoidal shell to the shorter = 6 : 5 or 5 : 4. Inner ellipsoidal shell about half the size; its pores are not easy to make out. Polar spines three-sided pyramidal, with prominent edges, about half as long as the major axis, as broad at the base as a group of pores. (Nearly allied to Stylosphæra jugata, p. 137.)

Dimensions.--Longer axis of the cortical shell 0.12 to 0.16, shorter axis 0.1 to 0.13; pores 0.01 to 0.02; length of the polar spines 0.06 to 0.08, basal breadth 0.03 to 0.4.

Habitat.--Central area of the Pacific, Stations 266 to 272, depth 2425 to 2900 fathoms.

Subgenus 4. Lithatractium, Haeckel.

Definition.--Network of the outer shell irregular, with meshes of unequal size or dissimilar form; surface thorny or papillose, covered with small conical spines or tubercles.

13. Lithatractus conostylus, n. sp.

Outer shell thorny, thin walled, with irregular network; pores roundish, of unequal size, twice to four times as broad as the thin bars; sixteen to twenty on the half equator. Proportion of the longer axis to the shorter = 5 : 4. Shorter axis twice the diameter of the inner spherical shell. Polar spines conical, very stout, longer than the main axis, its base equals one-third of the minor axis.

Dimensions.--Major axis of the cortical shell 0.1, shorter axis 0.08; pores 0.004 to 0.002, bars 0.001; diameter of the medullary shell 0.04; polar spines--length 0.12, thickness 0.03.

Habitat.--Central area of the Pacific, Station 271, depth 2425 fathoms.

14. Lithatractus gamoporus, n. sp.

Outer shell thorny, thick walled, with irregular network; pores roundish, of unequal size, so irregularly distributed in polygonal groups that in every group two to six pores (commonly three to four) are near together; the groups are separated by broader bars. On the half equator {324}six to eight groups and eighteen to twenty-four pores. Proportion of the longer axis to the shorter = 6 : 5. Shorter axis equals twice the diameter of the inner ellipsoidal shell. Polar spines three-sided pyramidal, about as long as the equatorial axis, as broad at the base as a group of pores.

Dimensions.--Major axis of the cortical shell 0.12, minor axis 0.1; pores 0.004 to 0.012, bars 0.003; length of the polar spines 0.1, basal breadth 0.03.

Habitat.--Central area of the Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms.

Genus 138. Druppatractus,[177] n. gen.

Definition.--#Druppulida# with simple ellipsoidal cortical shell and simple medullary shell, with two large opposite polar spines in the main axis of different size or dissimilar form.

The genus Druppatractus differs from its near relation Lithatractus in the differentiation of the two polar spines, which are different in size or form, often to a very considerable degree. It has therefore the same relation to the latter that Ellipsoxiphus bears to Ellipsostylus.

Subgenus 1. Druppatractara, Haeckel.

Definition.--Network of the cortical shell regular or subregular, with meshes of nearly equal size and similar form; surface smooth, without thorns or papillæ.

1. Druppatractus ichthydium, n. sp.

Cortical shell thin walled, with smooth surface and regular network. Proportion of the major axis to the minor = 3 : 2. Pores circular, hexagonally framed, twice as broad as the bars; seven to eight on the half equator (as in Xiphostylus alcedo, Pl. 13, fig. 4). Medullary shell spherical, one-third as broad as the cortical shell. Polar spines straight, three-sided pyramidal, as broad at the base as one mesh; the longer equals the main axis of the cortical shell, the shorter only its half.

Dimensions.--Major axis of the ellipsoidal cortical shell 0.18, minor axis 0.12; pores 0.01, bars 0.005; diameter of the medullary shell 0.04; length of the major polar spine 0.16 to 0.2, of the minor 0.01 to 0.12, basal breadth 0.01.

Habitat.--Mediterranean (Corfu), surface, Haeckel.

2. Druppatractus hippocampus, n. sp. (Pl. 16, figs. 10, 11).

Stylosphæra hippocampus, Haeckel, 1881, Atlas, pl. xvi. figs. 10, 11.

Cortical shell thick walled, with smooth surface and regular network. Proportion of both axes = 7 : 6. Pores circular, hexagonally lobed, three times as broad as the bars; nine to ten on the half {325}equator. Medullary shell ellipsoidal, nearly half as large as the cortical. Larger polar spine horn-like curved, as long as the main axis, smaller scarcely half as long, pommel-shaped.

Dimensions.--Major axis 0.09, minor 0.075; pores 0.01, bars 0.003; axes of the medullary shell 0.04 and 0.03; length of the larger polar spine 0.06 to 0.09, of the smaller 0.04, basal breadth 0.02.

Habitat.--Pacific, central area, Stations 270 to 272, surface.

3. Druppatractus belone, n. sp.

Cortical shell thin walled, with smooth surface and regular network. Proportion of both axes = 4 : 3. Pores circular, twice as broad as the bars; ten to twelve on the half equator. Medullary shell spherical, one-third as broad as the cortical shell. Polar spines strong, straight, cylindrical, with conical apex, as broad at the base as two pores; the larger once and a half to twice as long as the main axis, the smaller only one-third to one-fourth as long.

Dimensions.--Major axis 0.1 to 0.12, minor 0.08 to 0.09; pores 0.008, bars 0.004; diameter of the medullary shell 0.03; length of the larger polar spine 0.15 to 0.2, of the minor 0.04 to 0.05, basal thickness of them 0.02.

Habitat.--Cosmopolitan; Atlantic, Indian, and Pacific, surface.

4. Druppatractus testudo, Haeckel.

Stylosphæra testudo, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 299, Taf. viii. fig. 16.

Cortical shell thick walled, spindle-shaped, with smooth surface and regular network. Proportion of the two axes = 3 : 2. Pores circular, five times as broad as the bars; only six to seven on the half equator. Medullary shell ellipsoidal, about one-third as large as the cortical shell. Polar spines strong, short, three-sided pyramidal; the larger as long as half the transverse axis, the smaller only one-fourth as long.

Dimensions.--Major axis 0.12, minor 0.8; pores 0.015, bars 0.003; axes of the medullary shell 0.04 and 0.03; length of the larger polar spine 0.04, of the smaller 0.02, basal thickness 0.01.

Habitat.--Pacific, Philippine and Californian Sea (Ehrenberg), Stations 244, 266, 289, &c., depth 2550 to 2900 fathoms.

Subgenus 2. Druppatractylis, Haeckel.

Definition.--Network of the cortical shell regular or subregular, with meshes of nearly equal size and similar form; surface thorny or papillose, covered with small conical spines or tubercles.

5. Druppatractus accipenser, n. sp.

Cortical shell thick walled, thorny, with regular network. Proportion of the two axes = 6 : 5. Pores circular, each with a six-lobed outer opening, funnel-shaped, twice as broad as the bars; nine {326}to ten on the half equator. Medullary shell spherical, one-third as broad as the cortical shell. Polar spines very strong, three-sided pyramidal, as broad at the base as three pores; the larger about as long as the main axis, the smaller only one-third as long.

Dimensions.--Major axis 0.12, minor 0.1; pores 0.01, bars 0.005; medullary shell 0.035; length of the larger polar spine 0.11, of the smaller 0.04, basal breadth 0.03.

Habitat.--Indian Ocean, Madagascar, surface, Rabbe.

6. Druppatractus ostracion, n. sp. (Pl. 16, figs. 8, 9).

Cortical shell thick walled, thorny, with regular network. Proportion of the two axes = 4 : 3. Pores circular, hexagonally framed, three to four times as broad as the crested bars; from every corner of the hexagon (between three meshes) arises a short papilla; the bottom of every funnel-like mesh is closed by a very thin plate with three regular, circular pores (occasionally four), sometimes confluent, at other times separate. Medullary shell (fig. 9) half as large as the cortical, ellipsoidal and papillate, with regular, circular pores. Polar spines very strong, three-sided prismatic, often somewhat irregular, with short apex; the larger once to twice as long as the main axis, the smaller scarcely half as long.

Dimensions.--Major axis 0.16, minor 0.12; pores 0.02 (porules at their base 0.01), bars 0.006; axes of the medullary shell 0.07 and 0.06, its pores 0.01, bars 0.003; length of the larger polar spine 0.15 to 0.3, of the smaller 0.07 to 0.09, basal thickness 0.03.

Habitat.--Pacific, central area, Station 265, depth 2900 fathoms.

7. Druppatractus coronatus, Haeckel.

Stylosphæra coronata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xxv. fig. 4.

Cortical shell thick walled, thorny, with regular network. Proportion of the two axes = 5 : 4. Pores circular, simple, twice as broad as the bars; eight to ten on the half equator. Medullary shell circular, one-third as broad as the cortical shell. Polar spines furrowed and angular; the longer and thinner pyramidal about as long as the main axis, the shorter and thicker scarcely half as long, thickened towards the short conical apex.

Dimensions.--Major axis 0.08 to 0.1, minor 0.06 to 0.08; pores 0.01, bars 0.005; diameter of the medullary shell 0.03; length of the large polar spine 0.08 to 0.12, of the shorter 0.04 to 0.05.

Habitat.--Fossil in the Tertiary rocks of Barbados; also living in the depths of the Pacific, central area, Stations 265 to 268, depth 2700 to 2900 fathoms.

Subgenus 3. Druppatractona, Haeckel.

Definition.--Network of the cortical shell irregular, with meshes of unequal size or dissimilar form; surface smooth, without thorns or papillæ.

{327}8. Druppatractus lævis, Haeckel.

Stylosphæra lævis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xxv. fig. 6.

Cortical shell thin walled, smooth, with irregular network. Proportion of the two axes = 3 : 2. Pores roundish or subcircular, of different size, one-half to twice as broad as the bars; eight to ten on the half equator. Medullary shell ellipsoidal, one-third as large as the cortical shell. Polar spines conical, the larger and thinner nearly as long as the main axis, the shorter and thicker scarcely one-third as long.

Dimensions.--Major axis 0.07 to 0.1, minor 0.05 to 0.07; pores and bars 0.005 to 0.01; axes of the medullary shell 0.03 and 0.02; length of the major polar spine 0.06 to 0.09, of the shorter 0.03 to 0.04.

Habitat.--Cosmopolitan; Atlantic, Indian, Pacific, surface.

9. Druppatractus xiphias, n. sp.

Cortical shell thick walled, smooth, with irregular network. Proportion of the two axes = 6 : 5. Pores funnel-shaped, composed of two to four confluent smaller porules, twice to four times as broad as the bars; ten to twelve on the half equator. Medullary shell spherical, half as broad. Polar spines three-sided pyramidal, the larger about as long as the main axis, the shorter one-third to one-half as long.

Dimensions.--Major axis 0.12, minor 0.1; pores 0.012 to 0.018, bars 0.004; diameter of the medullary shell 0.05; length of the major polar spine 0.1, of the minor 0.03 to 0.05.

Habitat.--Pacific, central area, Station 268, depth 2900 fathoms.

Subgenus 4. Druppatractium, Haeckel.

Definition.--Network of the cortical shell irregular, with meshes of unequal size or dissimilar form; surface thorny or papillose, covered with small spines or tubercles.

10. Druppatractus diodon, n. sp.

Cortical shell thin walled, thorny, with irregular network. Proportion of the two axes = 5 : 4. Pores simple, irregular, roundish, twice to four times as broad as the bars; eight to ten on the half equator. Medullary shell spherical, half as broad. Polar spines conical, more or less curved; the major longer than the main axis, the minor scarcely half as long. (Resembles Sphærostylus ophidium, Pl. 16, figs. 14, 15, but differs from it in the prolongation of the main axis.)

Dimensions.--Major axis 0.15, minor 0.12; pores 0.01 to 0.02, bars 0.005; diameter of the medullary shell 0.06; length of the larger polar spine 0.12 to 0.18, of the shorter 0.06 to 0.08, basal thickness 0.003.

Habitat.--Pacific, central area, Station 274, surface.

{328}11. Druppatractus pisciculus, n. sp.

Cortical shell thick walled, spiny, with irregular network. Proportion of the two axes = 3 : 2. Pores irregular, roundish, lobed, or composed of three to five confluent porules, twice to six times as broad as the bars; six to eight on the half equator. (Similar to Ellipsoxiphus atractus, Pl. 14, fig. 1.) Medullary shell ellipsoidal, nearly half as large as the cortical shell. Polar spines three-sided pyramidal, the major longer than the main axis, the minor scarcely one-third to one-fourth as long.

Dimensions.--Major axis 0.18, minor 0.12; pores 0.01 to 0.03, bars 0.004; axes of the medullary shell 0.08 and 0.05; length of the major polar spine 0.2, of the minor 0.05, basal breadth 0.02.

Habitat.--South Atlantic, Station 332, depth 2200 fathoms.

Genus 139. Stylatractus,[178] n. gen.

Definition.--#Druppulida# with simple ellipsoidal cortical shell and double medullary shell, in the main axis with two large opposite polar spines of equal size and similar form.

The genus Stylatractus differs from Lithatractus in the double medullary shell, from Amphisphæra in the ellipsoidal form of the cortical shell. As in these two genera, both opposite polar spines have the same shape and size.

Subgenus 1. Stylatractara, Haeckel.

Definition.--Network of the cortical shell regular or subregular, with meshes of nearly equal size and similar form; surface smooth, without thorns or papillæ.

1. Stylatractus neptunus, n. sp. (Pl. 17, fig. 6).

Amphistylus neptunus, Haeckel, 1878, Atlas, pl. xvii. fig. 6.

Cortical shell thick walled, smooth, with subregular, circular, polygonally framed pores, quite as broad as the bars; ten to twelve on the half equator. Polar spines three-sided pyramidal, about as long as the half main axis, three times as broad at the base as the pores. (Much resembles Amphisphæra neptunus, p. 142, but differs from it by the prolongation of the main axis, which equals one and a half or one and a fourth the equatorial axis, and by the somewhat irregular formation of the cortical hexagonal network. Sometimes also, as in the figured specimen, the length of both polar spines is somewhat different.)

Dimensions.--Major axis of the cortical shell 0.15, minor axis 0.12; pores and bars 0.007; main axes of both ellipsoidal medullary shells 0.08 and 0.05; length of the polar spines 0.08 to 0.1, basal breadth 0.02.

Habitat.--Pacific, central area, Stations 266 to 268, depth 2700 to 2900 fathoms.

{329}2. Stylatractus fusiformis, n. sp.

Cortical shell thick walled, smooth, with regular, simple, circular pores, quite as broad as the bars; fourteen to sixteen on the half equator. Polar spines three-sided pyramidal, half as long as the main axis, as broad at the base as the inner medullary shell. (Resembles very nearly Xiphatractus armadillo, Pl. 17, fig. 11, but differs in the regular form and equal length of the polar spines.)

Dimensions.--Major axis 0.17, minor axis 0.13; pores and bars 0.007; main axes of both ellipsoidal medullary shells 0.09 and 0.05; length of the polar spines 0.08, basal breadth 0.04.

Habitat.--Cosmopolitan; Atlantic, Indian, Pacific, at various depths.

3. Stylatractus compactus, n. sp. (Pl. 17, fig. 4).

Cortical shell thick walled, smooth, with subregular, circular, double-contoured pores, smaller than the bars; sixteen to eighteen on the half equator. The thickness of the shell-wall equals the radius of the inner medullary shell. Polar spines short, three-sided pyramidal; their length and basal thickness variable, but commonly equal to the diameter of the inner medullary shell.

Dimensions.--Major axis 0.16, minor axis 0.13; pores 0.007, bars 0.01; main axes of both ellipsoidal medullary shells 0.09 and 0.04; length and basal breadth of the polar spines 0.04 to 0.05.

Habitat.--Pacific, central area, Stations 270 to 272, depth 2425 to 2925 fathoms.

Subgenus 2. Stylatractylis, Haeckel.

Definition.--Network of the outer shell regular, with meshes of equal size and similar form; surface thorny or papillose, covered with small spinules or tubercles.

4. Stylatractus giganteus, n. sp. (Pl. 17, fig. 1).

Amphistylus giganteus, Haeckel, 1879, Atlas (pl. xvii. fig. 1).

Cortical shell papillose, very thick walled, with regular network; pores circular, with double margin, about twice as broad as the bars; ten to twelve on the half equator. The cortical shell is connected with the outer medullary shell by numerous strong beams, and the inner prolongations of both polar spines are much stronger. The circular pores of the outer medullary shell are three times as large as those of the inner, and equal to those of the cortical shell, but the bars are much thinner. Polar spines very strong, three-sided pyramidal, with spirally contorted edges, as long as the main axis, as broad at the base as the inner medullary shell.

Dimensions.--Major axis of the cortical shell 0.3, minor axis 0.22; pores 0.02, bars 0.01; main axes of the ellipsoidal medullary shells 0.14 and 0.07; length of the polar spines 0.3, basal thickness 0.06.

Habitat.--Western Tropical Pacific, Station 225, depth 4475 fathoms.

{330}5. Stylatractus carduus, Haeckel.

Stylosphæra carduus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xxv. fig. 7.

Cortical shell thin walled, spiny, with regular, circular pores, five times as broad as the bars; ten to twelve on the half equator. Polar spines conical, half as long as the main axis, at the base broader than the pores. (The cortical shell is ellipsoidal as well as both medullary shells; the figure of Ehrenberg, as is generally the case, is more correct than his description. This interesting species occurs in the Barbados rocks, with double as well as with simple medullary shell, and may in the latter case be distinguished as Lithatractus carduelis.)

Dimensions.--Major axis of the cortical shell 0.12 to 0.16, minor 0.1 to 0.14; pores 0.01 to 0.02, bars 0.002 to 0.005; main axes of the ellipsoidal medullary shells 0.05 and 0.03; length of the polar spines 0.06, basal breadth 0.02.

Habitat.--Fossil in the Tertiary rocks of Barbados.

Subgenus 3. Stylatractona, Haeckel.

Definition.--Network of the outer shell irregular, with meshes of different size or form; surface smooth, without thorns or papillæ.

6. Stylatractus variabilis, n. sp.

Cortical shell thin walled, smooth, with irregular, roundish pores, twice to six times as broad as the bars; twelve to sixteen on the half equator. Polar spines conical, about half as long as the main axis, and as broad at the base as the inner medullary shell. (The size and form of the pores and of the polar spines in this species are very variable, so that the proportions given are to be understood as averages.)

Dimensions.--Major axis 0.13, minor axis 0.11; pores 0.004 to 0.012, bars 0.002; main axes of the ellipsoidal medullary shells 0.07 and 0.04; length of the polar spines 0.06, basal breadth 0.03.

Habitat.--Pacific, central area. Stations 272 to 274, depth 2350 to 2750 fathoms.

7. Stylatractus sethoporus, n. sp. (Pl. 17, figs. 2, 3).

Cortical shell thick walled, smooth, with large irregular, roundish pores, twice to four times as broad as the bars; seven to eight on the half equator. At the bottom of each pore a thin lamella of silex, perforated by four to six irregular, roundish, double-contoured porules. Medullary shells resemble those of Stylatractus giganteus. Polar spines three-sided pyramidal; their length and basal thickness scarcely equal the diameter of the inner medullary shell.

Dimensions.--Major axis 0.15, minor axis 0.13; pores 0.02, bars 0.005, porules 0.01; length of the polar spines 0.04.

Habitat.--Pacific, central area, Station 272, depth 2600 fathoms.

{331}Subgenus 4. Stylatractium, Haeckel.

Definition.--Network of the outer shell irregular, with meshes of different size and form; surface thorny or papillose, covered with small spinules or tubercles.

8. Stylatractus papillosus, n. sp.

Cortical shell thin walled, with papillose surface, and irregular, simple, roundish pores, ten to sixteen on the half equator, twice to three times as broad as the bars. Conical papillæ of the surface irregularly scattered. Polar spines conical, about as long as the main axis, at the base half as broad as the inner medullary shell.

Dimensions.--Major axis 0.12, minor 0.1; pores 0.006 to 0.01, bars 0.003; main axes of the medullary shells 0.09 and 0.06; length of the polar spines 0.13, basal breadth 0.04.

Habitat.--Indian Ocean, surface (between Socotra and Ceylon), Haeckel.

9. Stylatractus disetanius, n. sp.

Cortical shell thin walled, with spiny surface, and irregular, roundish pores, eight to ten on the half equator, twice to three times as broad as the bars. Every pore is divided by thinner bars into four to six small roundish porules. Polar spines three-sided pyramidal, nearly as long as the main axis, as broad at the base as the inner medullary shell. (Resembles Xiphatractus glyptodon, Pl. 17, figs. 9, 10, but differs from it by the irregular network and the equal size of both polar spines.)

Dimensions.--Major axis 0.14, minor 0.1; pores 0.02, bars 0.008, porules 0.007; main axes of the two medullary shells 0.08 and 0.05; length of the polar spines 0.13, basal breadth 0.04.

Habitat.--South Pacific, near New Zealand, Station 169, surface.

Genus 140. Xiphatractus,[179] n. gen.

Definition.--#Druppulida# with a simple ellipsoidal cortical shell and double medullary shell, in the main axis with two large opposite polar spines of different size or form.

The genus Xiphatractus differs from the nearly related Stylatractus in the differentiation of two polar spines (in the same manner as Druppatractus differs from Lithatractus). From the spherical Amphistylus it differs in the ellipsoidal form of the cortical shell.

Subgenus 1. Xiphatractara, Haeckel.

Definition.--Network of the cortical shell regular or subregular, with meshes of nearly equal size and similar form; surface smooth, without thorns or papillæ.

{332}1. Xiphatractus armadillo, n. sp. (Pl. 17, fig. 11).

Cortical shell thick walled, smooth, with regular, circular pores, about as broad as the bars; fifteen to sixteen on the half equator. Polar spines three-sided pyramidal, with thick, prominent edges, of irregular form; the longer about as long as the main axis, the shorter scarcely one-third as long; their basal breadth equals the diameter of the inner medullary shell.

Dimensions.--Major axis of the cortical shell 0.13, minor axis 0.1, thickness of its wall 0.01; pores and bars 0.005; main axes of the two medullary shells 0.07 and 0.03; length of the major polar spine 0.12, of the minor 0.04, basal thickness 0.04.

Habitat.--Pacific, central area, Station 272, depth 2600 fathoms.

2. Xiphatractus euphractus, n. sp.

Cortical shell thick walled, smooth, with regular, circular pores, twice as broad as the bars; eight to nine on the half equator. Each pore has six to nine excisions (commonly eight), elegantly lobed, flower-like (as in Xiphostylus phasianus, Pl. 13, fig. 9). Polar spines strong, angulate; the major pyramidal, longer than the main axis, the shorter elegantly pommel-like, scarcely one-third as long.

Dimensions.--Major axis 0.15, minor 0.12; pores 0.014, bars 0.007; main axes of the two medullary shells 0.09 and 0.05; length of the larger polar spine 0.16, of the shorter 0.05, greatest thickness 0.03.

Habitat.--South Atlantic, Station 332, depth 2200 fathoms.

Subgenus 2. Xiphatractylis, Haeckel.

Definition.--Network of the cortical shell regular or subregular, with meshes of nearly equal size and similar form; surface thorny or papillose.

3. Xiphatractus spinulosus, Haeckel.

Stylosphæra spinulosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xxv. fig. 8.

Cortical shell thin walled, with spiny surface, and large, regular, circular pores, four times as broad as the bars; seven to eight on the half equator. Spines between the pores of the same size, conical. Polar spines also conical, but much larger; the major about as long as the main axis, the minor scarcely half as long; their basal thickness equals the largest pores.

Dimensions.--Major axis 0.1, minor 0.08; pores 0.012, bars 0.003; diameter of the spherical medullary shells 0.06 and 0.03; length of the major polar spine 0.09, of the minor 0.04, basal thickness 0.02.

Habitat.--Fossil in the Tertiary rocks of Barbados.

{333}4. Xiphatractus sulcatus, Haeckel.

Stylosphæra sulcata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xxiv, fig. 6.

Cortical shell thick walled, with thorny surface, and regular, circular pores, quite as broad as the bars; nine to ten on the half equator. Polar spines cylindrical, with longitudinal basal furrows and conical apex, three times as broad as the pores; the larger about as long as the main axis, the shorter only one-half or two-thirds as long.

Dimensions.--Major axis 0.01, minor 0.08; pores and bars 0.007; main axes of the two medullary shells 0.08 and 0.04; length of the major polar spine 0.1, of the minor 0.06, breadth of them 0.02.

Habitat.--Fossil in the Barbados deposits.

5. Xiphatractus dasypus, n. sp.

Cortical shell thick walled, with spiny surface, and regular, elegant network; pores circular, hexagonally framed, about as broad as the bars; from every corner of the network (between three pores) arises a short bristle-like spine. Polar spines three-sided prismatic, as broad as one hexagon; the major once to twice as long as the main axis, the minor only one-half to one-fourth as long. (The cortical shell much resembles Ellipsoxiphus elegans, Pl. 14, fig. 7.)

Dimensions.--Major axis 0.15, minor 0.13; pores and bars 0.01; main axes of the two medullary shells 0.1 and 0.06; length of the major polar spine 0.1 to 0.3, of the minor 0.05 to 0.1, thickness 0.01.

Habitat.--Tropical Western Pacific, Station 222, surface.

Subgenus 3. Xiphatractona, Haeckel.

Definition.--Network of the cortical shell irregular, with meshes of different size or form; surface smooth, without thorns or papillæ.

6. Xiphatractus chlamydophorus, n. sp.

Cortical shell thin walled, smooth, with irregular, roundish pores, twice to four times as broad as the bars; eight to twelve on the half equator. Polar spines angular, irregularly curved or contorted; the larger once to twice as long as the main axis, the shorter and thicker pommel-shaped, only one-third to one-half as long; their basal breadth equals two pores.

Dimensions.--Major axis 0.14, minor 0.1; pores 0.006 to 0.012, bars 0.003; main axis of the two ellipsoidal medullary shells 0.09 and 0.04; length of the major polar spine 0.1 to 0.2, of the minor 0.05 to 0.08, breadth 0.02.

Habitat.--Cosmopolitan; Atlantic, Pacific, many Stations, surface.

{334}Subgenus 4. Xiphatractium, Haeckel.

Definition.--Network of the cortical shell irregular, with meshes of unequal size or dissimilar form; surface thorny or papillose.

7. Xiphatractus radiosus, Haeckel.

Stylosphæra radiosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xxiv. fig. 5.

Cortical shell very thick walled, with thorny surface, and irregular, roundish pores, once to three times as broad as the bars; nine and ten on the half equator. Polar spines conical, on the base about as broad as the largest pores; the larger as long as the main axis, the smaller scarcely one-fourth as long. (The radial striation, figured by Ehrenberg and applied to the name of this species, is produced by the contours of the funnel-shaped pores in the thick walls seen in optical section; the ellipsoidal cortical shell is double.)

Dimensions.--Major axis 0.13, minor 0.09; pores 0.003 to 0.01, bars 0.003; main axes of the two medullary shells 0.05 and 0.03; length of the major polar spine 0.12, of the minor 0.03, basal breadth 0.01.

Habitat.--Fossil in the Tertiary rocks of Barbados.

8. Xiphatractus glyptodon, n. sp. (Pl. 17, figs. 9, 10).

Cortical shell thick walled, covered with radial spines of the size of the pores; on the half equator eight to ten irregular or subregular roundish pores, twice to four times as broad as the bars. In the bottom of each pore a thin lamella of silex, perforated by four to six smaller roundish pores. Both medullary shells (fig. 10) spherical, with smaller, regular, circular pores. Larger polar spine three-sided pyramidal, in length equals the main axis; shorter spine only half as long, but twice as thick, of elegant pommel-form (fig. 9), with nine prominent edges.

Dimensions.--Major axis 0.12, minor, 0.1; pores and spines 0.01 to 0.02, bars and porules 0.005; diameter of the two medullary shells 0.05 and 0.02; length of the major polar spine 0.1, of the minor 0.06, greatest thickness 0.04.

Habitat.--Pacific, central area, Station 263, surface.

Genus 141. Cromyatractus,[180] n. gen.

Definition.--#Druppulida# with four or more concentric shells (two medullary shells and two or more cortical shells), in the main axis with two large opposite polar spines of equal size and similar form.

The genus Cromyatractus is very nearly allied to all the foregoing genera, which bear two equal spines opposite to one another on the poles of the main axis; it differs {335}from them in the multiplication of the cortical shell, and may be considered as the most highly developed form of this amphistylous series, which proceeds from Ellipsoxiphus to Lithatractus and Stylatractus.

Subgenus 1. Cromyatractium, Haeckel.

Definition.--Shell composed of two medullary shells and two cortical shells.

1. Cromyatractus tetraphractus, n. sp. (Pl. 15, fig. 2).

Stylocromium tetraphractum, Haeckel, 1879, Atlas (pl. xv. fig. 2).

Proportion of the main axes of the four concentric shells about = 1 : 3 : 5 : 7. Network of all four shells nearly of the same structure, subregular, with circular pores of equal size (in one and the same shell). The absolute size of the pores increases gradually from the innermost to the outermost shell. The bars between the pores are smaller and quite smooth. Surface of the outermost shell smooth. Polar spines cylindrical, with conical apex, of variable length, nearly as broad as the innermost shell.

Dimensions.--Main axes of the four shells--(A) inner medullary shell 0.03, (B) outer medullary shell 0.08, (C) inner cortical shell 0.15, (D) outer cortical shell 0.2; equatorial axes of them--(A) 0.025, (B) 0.06, (C) 0.12, (D) 0.15; pores of (A) 0.004, (B) 0.007, (C) 0.01, (D) 0.013, bars 0.002 to 0.004; length of the polar spines 0.1 to 0.3 (and more), breadth 0.015.

Habitat.--Antarctic (Indian) Ocean, Station 157, depth 1950 fathoms.

2. Cromyatractus tetralepas, n. sp.

Proportion of the main axes of the four concentric shells about = 1 : 2 : 4 : 6. Network of the two medullary shells regular, with small circular pores, little larger than the bars. Network of the two cortical shells irregular, with much larger polygonal pores, three to nine times as broad as the thin bars. (Somewhat similar to Cromyatractus ceparius, Pl. 15, fig. 4.) Surface of the outermost shell smooth or a little thorny. Polar spines cylindrical, very large, twice to three times as long as the main axis of the outermost shell, about as broad as the innermost shell, with conical apex; smooth or a little thorny.

Dimensions.--Main axes of the four shells--(A) 0.03, (B) 0.05, (C) 0.13, (D) 0.18; equatorial axes of them--(A) 0.2, (B) 0.45, (C) 0.11, (D) 0.14; pores of the two medullary shells 0.004 and 0.006, of both cortical shells 0.01 to 0.03, bars 0.003.

Habitat.--Indian Ocean, Zanzibar, Pullen, 2200 fathoms.

3. Cromyatractus tetracelyphus, n. sp. (Pl. 15, figs. 1, 1_a_).

Proportion of the main axes of the four concentric shells about = 1 : 3 : 10 : 11. Network of the two spherical medullary shells (fig. 1_a_) regular, with small circular pores, twice as broad as {336}the bars. Network of the inner cortical shell regular with circular, hexagonally-framed pores, twice as broad as the bars. From every corner of the hexagons (between three pores) arises a very thin, hair-like, short radial spinule. These spinules communicate with one another by tangential branches (at equal distances from the inner cortical shell), and form thereby an outer, delicate cortical network, with large polygonal meshes and very thin bars. Polar spines very strong, pyramidal, with prominent edges, as long as the main radius of the cortical shell, and half as broad at the base.

Dimensions.--Main axes of the four shells--(A) 0.02, (B) 0.06, (C) 0.2, (D) 0.22; equatorial axes of them--(A) 0.02, (B) 0.06, (C) 0.13, (D) 0.15; pores of the four shells--(A) 0.002, (B) 0.004, (C) 0.008, (D) 0.02; bars 0.001 to 0.003; length of the polar spines 0.1, basal breadth 0.05.

Habitat.--South Atlantic, Station 335, depth 1425 fathoms.

Subgenus 2. Caryatractus, Haeckel.

Definition.--Shell composed of two medullary shells and three or more cortical shells.

4. Cromyatractus cepicius, n. sp. (Pl. 15, fig. 3).

Caryostylus cepicius, Haeckel, 1879, Atlas (pl. xv. fig. 3).

Caryodoras cepicius, Haeckel, 1881, Prodromus, p. 454.

Proportion of the main axes of the five concentric shells about = 1 : 2 : 5 : 7 : 8. Network of both spherical medullary shells regular, with small circular pores, about as broad as the bars. Network of the three ellipsoidal cortical shells irregular, with large polygonal meshes, five to ten times as broad as the thin bars. Surface of the outermost shell smooth. Polar spines cylindrical, thorny, about as thick as the innermost shell and as long as the outermost shell, against the apex with a spindle-like intumescence, formed by delicate spongy framework (fig. 3).

Dimensions.--Main axes of the five concentric shells--(A) 0.03, (B) 0.05, (C) 0.16, (D) 0.2, (E) 0.25; equatorial axes of them--(A) 0.03, (B) 0.05, (C) 0.12, (D) 0.16, (E) 0.2; pores of the two medullary shells 0.002 to 0.004, of the three cortical shells 0.02 to 0.04, bars 0.002; length of the polar spines 0.3, breadth 0.03.

Habitat.--Pacific, central area, Station 268, depth 2900 fathoms.

5. Cromyatractus ceparius, n. sp. (Pl. 15, fig. 4).

Caryostylus ceparius, Haeckel, 1881, Prodromus et Atlas (pl. xv. fig. 4).

Proportion of the main axes of the six concentric shells about = 1 : 2 : 7 : 10 : 13 : 18. Network of the three inner shells regular, with small, circular pores, which are about as broad as the bars and in the third shell hexagonally framed. Network of the three outer shells irregular, with large polygonal meshes, six to twelve times as broad as the bars. Surface smooth. Polar spines strong, spindle-shaped, thorny, outside of the sixth shell about as long as inside of it; broader than {337}the innermost shell; the thorns of their outer free part (arising at equal distances) represent perhaps the beginnings of three to four further shells.

Dimensions.--Main axes of the six concentric shells--(A) 0.02, (B) 0.05, (C) 0.14, (D) 0.2, (E) 0.26, (F) 0.37; equatorial axes--(A) 0.02, (B) 0.05, (C) 0.09, (D) 0.15, (E) 0.21, (F) 0.3; pores of the three inner shells 0.003 to 0.006, of the three outer shells 0.02 to 0.04, bars 0.003 to 0.005; length of the polar spines, from the base of the innermost shell to the apex, 0.35, greatest breadth 0.03.

Habitat.--South Pacific, Station 285, depth 2375 fathoms.

Genus 142. Pipetta,[181] n. gen.

Definition.--#Druppulida# with simple ellipsoidal cortical shell and simple medullary shell, with two hollow fenestrated tubes opposite on both poles of the main axis.

The genus Pipetta differs from Pipettella (p. 304) in the possession of an inner (medullary) shell; it exhibits the same tubular prolongations of the cortical shell at both poles of the main axis.

1. Pipetta fusus, n. sp. (Pl. 39, figs. 8, 8_a_).

Cortical shell spindle-shaped, the middle ellipsoidal part gently passing over on both poles into the conical tubes, which attain about the same length. Network regular, with circular, hexagonally-framed pores, twice as broad as the bars, sixteen to eighteen on the half equator. In the middle part of the shell the pores arise from their hexagonal bases in the form of short conical funnels; on both tubes they are much smaller and simple, without frame. Medullary shell (fig. 8_a_) spherical, scarcely one-third as broad as the cortical, with regular, circular pores, twice as broad as the bars, eight to nine on the half equator. The two shells are connected only by two opposite beams, lying in the equatorial axis and ramified at the distal insertion (fig. 8_a_).

Dimensions.--Middle ellipsoidal part of the cortical shell 0.13 to 0.15; polar tubes 0.15 long, 0.06 broad at the base; pores of the former 0.01, bars 0.005; pores of the tubes 0.06, bars 0.003. Medullary shell 0.04, pores 0.004, bars 0.002.

Habitat.--Pacific, central area, Station 268, depth 2900 fathoms.

2. Pipetta tuba, n. sp. (Pl. 39, fig. 7).

Cortical shell nearly spherical in the middle part, which is sharply separated at both poles from the long, nearly cylindrical tubes; these are longer than the main axis, at the distal end open (always broken off). Network regular, with circular, hexagonally-framed pores, of the same breadth as the bars, eighteen to twenty on the half equator. The pores of the polar tubes are of the same shape, only much smaller, and arranged in sixteen to eighteen longitudinal rows. Medullary shell {338}spherical, about one-third as broad as the cortical, with simple circular pores. The connection between the two shells is only made by two simple opposite beams, lying in the equatorial axis.

Dimensions.--Middle spheroidal part of the cortical shell 0.14 to 0.16; polar tubes 0.15 to 0.2 or longer, 0.03 broad; pores and bars of the former 0.007, of the latter 0.003. Medullary shell 0.04, pores 0.006, bars 0.003.

Habitat.--Western Tropical Pacific, Station 225, depth 4475 fathoms.

3. Pipetta salpinx, n. sp.

Cortical shell ellipsoidal, sharply separated from the cylindrical polar tubes, which reach about the same length (or more). Network regular, with circular pores, three times as broad as the bars, without hexagonal frames, fourteen to fifteen on the half equator. Pores of the polar tubes smaller, arranged in eight to ten longitudinal rows. Medullary shell spherical, one-fourth as broad as the cortical, connected with it by a circle of four to six radial beams, lying in the equatorial plane. Differs from Pipettella prismatica (Pl. 39, fig. 6) in the possession of a medullary shell and the absence of the tube edges.

Dimensions.--Main axis of the ellipsoid 0.14, equatorial axis 0.12, pores 0.01, bars 0.003; length of the tubes 0.15 or more, breadth 0.03. Medullary shell 0.03, pores 0.002, bars 0.001.

Habitat.--Pacific, central area, Stations 265 to 268, depth 2700 to 2900 fathoms.

4. Pipetta conus, n. sp.

Cortical shell spindle-shaped, the middle ellipsoidal part gently passing over at both poles into the conical tubes, which attain only half its length. Network irregular, with roundish or subcircular pores, twice to three times as broad as the bars, twelve to sixteen on the half equator. Medullary shell spherical, one-fourth as broad as the cortical. (Differs from the foregoing species in the short conical tubes and the irregular reticulation.)

Dimensions.--Middle part of the cortical shell 0.16 long, 0.13 broad; tubes 0.09 long, 0.05 on the base broad; pores 0.005 to 0.01, bars 0.003. Medullary shell 0.04.

Habitat.--North Pacific, Station 241, depth 2300 fathoms.

Genus 143. Pipettaria,[182] n. gen.

Definition.--#Druppulida# with simple ellipsoidal cortical shell and double medullary shell, with two hollow fenestrated tubes opposite on both poles of the main axis.

The genus Pipettaria differs from the foregoing Pipetta only in the duplication of the medullary shell; as in this, the tubular prolongations of the main axis of the cortical shell may be either conical (with closed apex) or cylindrical (with apical opening?).

{339}1. Pipettaria fusaria, n. sp.

Cortical shell spindle-shaped, the middle ellipsoidal part gently passing over on both poles into the conical tubes, which attain about half its length. Pores regular, circular, twice as broad as the bars, sixteen to eighteen on the half equator; pores of the tubes smaller. Both medullary shells spheroidal, compressed. (The appearance of the cortical shell resembles that of Cannartiscus amphiconus, Pl. 39, fig. 19, but without the equatorial constriction.)

Dimensions.--Main axis of the ellipsoid 0.15, equatorial axis 0.13; length of the polar tubes 0.08, basal breadth 0.05; pores of the former 0.008, bars 0.004; diameter of the medullary shells 0.04 and 0.02.

Habitat.--South Pacific, Station 300, depth 1375 fathoms.

2. Pipettaria tubaria, n. sp. (Pl. 39, fig. 15).

Cannartidium tubarium, Haeckel, 1882, Atlas (pl. xxxix. fig. 15).

Cortical shell ellipsoidal, on both poles distinctly separated from the short conical tubes, the length and breadth of which equal the outer medullary shell. In the equatorial plane arises a circle of four to six short conical protuberances, similar to the polar tubes. Pores subregular, circular, or roundish, scarcely broader than the bars, sixteen to twenty on the half equator. Both medullary shells spheroidal, somewhat compressed in the direction of the two poles (as in fig. 18_a_).

Dimensions.--Main axis of the ellipsoid 0.12, equatorial axis 0.09; pores 0.005, bars 0.004; size of the equatorial protuberances and of the polar tubes 0.02.

Habitat.--Pacific, central area, Station 265, depth 2900 fathoms.

Family XIII. #SPONGURIDA#, Haeckel (Pl. 48, figs. 6, 7).

Spongurida, Haeckel, 1862, Monogr. d. Radiol., p. 447 (sensu emendato).

Definition.--#Prunoidea# with spongy ellipsoidal or cylindrical shell, composed wholly or partially of a spongy framework, without equatorial stricture, with or without an enclosed medullary shell.

The family #Spongurida# comprises, in the sense here restricted, all those #Prunoidea# in which the ellipsoidal or cylindrical shell is composed wholly or partially of an irregular siliceous framework, not of simple lattice-work. It contains two subfamilies, differing in the absence or presence of a latticed medullary shell in the middle of the central capsule; in the Spongellipsida it is absent, in the Spongodruppida present; the former are most nearly related to the Ellipsida, the latter to the Druppulida, the difference consisting only in the spongy structure of the cortical shell.

In my Monograph (1862, p. 447) the family Spongurida had a much wider extent, comprising also a number of #Sphæroidea# and #Discoidea#, agreeing in the spongy {340}structure of the shell. Here we restrict the definition to those spongy #Sphærellaria# in which the central capsule and the enclosing spongy cortical shell are ellipsoidal or cylindrical, therefore each transverse section is a circle, and each meridional section an ellipse, as in all #Prunoidea#.

The Cortical Shell in all Spongurida is composed of a delicate framework of irregularly branched and interwoven siliceous threads; commonly this spongy structure is rather dense or compact, but sometimes also very loose. In the simplest form, Spongellipsis, the spongy cortical shell contains a large cavity, in which lies freely the central capsule. In Spongurus this cavity is completely distended by a spongy framework. In this case the solid spongy shell becomes often prolonged, and its original ellipsoidal form passes over into a cylindrical one (as in many Zygartida). Sometimes (particularly in Spongocore, Pl. 48, fig. 6) the cylinder becomes three-jointed by two more or less distinct annular constrictions. Spongocore is distinguished by an outer veil, a thin lattice-lamella, which envelops the spongy shell and is connected with it by radial beams.

The Medullary Shell, absent in the Spongellipsida, is constant in the second subfamily Spongodruppida. It is either a simple latticed shell (Spongodruppa) or double, composed of two concentric latticed shells (Spongoliva); its form is either spherical or ellipsoidal. It lies in the middle of the central capsule, and is connected by radial beams (perforating the membrane of the latter) with the enveloping spongy cortical shell.

In many Spongurida the surface of the shell is armed with radial spines, and in some genera (Spongoprunum, Spongatractus, &c., Pl. 17, fig. 12), on both poles of the main axis, are developed two strong opposite polar spines, as in many other #Prunoidea#.

The Central Capsule of the Spongurida is either ellipsoidal or cylindrical. Only in Spongellipsis it lies freely in the internal cavity of the spongy shell. In all other genera it is perforated by a part of the skeleton; in the Spongodruppida it contains the simple or double medullary shell, and the radial beams which perforate its membrane and connect the latter with the external spongy cortical shell. In Spongurus and the allied genera (Spongocore, Spongoprunum) the whole central capsule is filled with a spongy framework which also envelops its surface.

{341}Synopsis of the Genera of Spongurida.

------------------------------------------------------------------------- I. Subfamily Spongellipsida. (Ellipsoidal shell composed only of a spongy framework without a latticed medullary shell in the centre.) ------------------------------------------------------------------------- Spongy shell }No polar spines, 144. Spongellipsis. with internal } cavity. }

{Without lattice Spongy shell { mantle. No polar solid, without { spines, 145. Spongurus. internal { cavity. {With lattice { mantle. { No polar spines, 146. Spongocore. { {Without lattice { mantle. Two { opposite spines { on the poles of { the axis, 147. Spongoprunum ------------------------------------------------------------------------- II. Subfamily Spongodruppida. (Ellipsoidal shell composed of an outer spongy cortical shell and an inner latticed medullary shell.) ------------------------------------------------------------------------- Medullary shell {No polar spines, 148. Spongodruppa. simple. { {Two opposite spines { on the poles of { the axis, 149. Spongatractus.

Medullary shell {No polar spines, 150. Spongoliva. double. { { {Two opposite spines { on the poles of { the axis, 151. Spongoxiphus.

Subfamily 1. SPONGELLIPSIDA, Haeckel.

Definition.--#Spongurida# with a spongy ellipsoidal or cylindrical shell, without an internal latticed medullary shell.

Genus 144. Spongellipsis,[183] n. gen.

Definition.--#Spongurida# with an ellipsoidal or cylindrical spongy shell, containing an internal cavity, without a latticed medullary shell. Polar spines absent.

The genus Spongellipsis embraces those very simple Spongurida in which the ellipsoidal central capsule is enclosed in a spongy cortical shell of the same form. It corresponds, therefore, to Plegmosphæra among the #Sphæroidea#, to Plegmodiscus among the #Discoidea#, and to Spongolarcus among the #Larcoidea#. In some species the ellipsoidal form is prolonged and passes into a cylindrical one.

Subgenus 1. Spongellipsarium, Haeckel.

Definition.--Surface of the shell smooth or rough, without radial spines.

{342}1. Spongellipsis lævis, n. sp.

Shell ellipsoidal, with smooth surface, its spongy wall scarcely one-tenth as thick as the minor axis of the inner cavity. Spongy framework very compact, with small meshes, three to six times as broad as the bars. Proportion of the major axis to the minor = 3 : 2.

Dimensions.--Major axis (or length) of the shell 0.36, minor axis (or breadth) 0.24.

Habitat.--Pacific, central area, Station 265, surface.

2. Spongellipsis aspera, n. sp.

Shell ellipsoidal, with rough surface, its spongy wall nearly half as thick as the minor axis of the inner cavity. Spongy framework very loose, with large meshes, ten to twenty times as broad as the bars. Proportion of the major axis to the minor = 4 : 3.

Dimensions.--Length of the shell 0.24, breadth 0.18.

Habitat.--North Pacific, Station 253, surface.

3. Spongellipsis aplysina, n. sp.

Shell nearly cylindrical, with rough surface, its spongy wall about one-fourth as thick as the minor axis of the internal cavity. Spongy framework loose, with large meshes, four to eight times as broad as the bars. Proportion of both axes = 6 : 1. (Similar to a spongy cylinder of Aplysina.)

Dimensions.--Length of the shell 0.3, breadth 0.05.

Habitat.--North Atlantic, Station 64, surface.

Subgenus 2. Spongellipsidium, Haeckel.

Definition.--Surface of the shell covered with radial spines.

4. Spongellipsis setosa, n. sp.

Shell ellipsoidal, covered with numerous (sixty to eighty) thin, bristle-shaped, radial spines, about half as long as the major axis. Spongy framework loose, with large meshes, ten to twenty times as broad as the bars. Minor axis of the inner cavity twice as long as the thickness of the spongy wall. Proportion of both axes = 5 : 3.

Dimensions.--Length of the shell 0.2, breadth 0.12.

Habitat.--South Atlantic, Station 325, surface.

5. Spongellipsis spinosa, n. sp.

Shell nearly cylindrical, covered with numerous thorns and thirty to forty larger conical radial spines, somewhat longer than the major axis. Spongy framework compact, with small meshes, four {343}to eight times as broad as the bars. Minor axis of the inner cavity about six times as large as the thickness of the spongy wall. Proportion of both axes = 4 : 1.

Dimensions.--Length of the shell 0.24, breadth 0.06.

Habitat.--South Pacific, Station 300, surface.

Genus 145. Spongurus,[184] Haeckel, 1862, Monogr. d. Radiol., p. 465.

Definition.--#Spongurida# with ellipsoidal or cylindrical (sometimes three-jointed) shell, of solid spongy framework, without internal cavity and without latticed medullary shell. Polar spines and outer lattice-mantle absent.

The genus Spongurus was founded by me in 1862 for the common cosmopolitan Spongurus cylindricus, a massive spongy cylinder with radial spines. I enlarge here the conception of the genus, in receiving also ellipsoidal, massive spongy #Prunoidea#, with or without radial spines. Sometimes the cylindrical shell is more or less distinctly three-jointed, with two annular strictures, as also in the following and nearly allied genus.

Subgenus 1. Spongurantha, Haeckel.

Definition.--Spongy framework everywhere of the same structure; surface smooth or rough, but without radial spines.

1. Spongurus stuparius, n. sp.

Shell ellipsoidal, one and a half times as long as broad, with nearly smooth surface. Spongy framework everywhere of equal structure, with small meshes, four to six times as broad as the bars.

Dimensions.--Length of the shell (or major axis) 0.2, breadth of it (or minor axis) 0.14.

Habitat.--South Pacific, Station 295, depth 1500 fathoms.

2. Spongurus stypticus, n. sp.

Shell ellipsoidal, twice as long as broad, with thorny surface. Spongy framework everywhere of equal structure, with large meshes, ten to twenty times as broad as the bars.

Dimensions.--Length of the shell 0.3, breadth 0.15.

Habitat.--Pacific, central area, Station 274, depth 2750 fathoms.

3. Spongurus phalanga, Haeckel.

Spongurus cylindricus, Stöhr, 1880, Palæontogr., vol. xxvi. p. 119, Taf. vii. fig. 3.

Shell nearly cylindrical, five times as long as broad, with thorny surface. Spongy framework compact, everywhere of equal structure, with small meshes, scarcely broader than the bars.

{344}Dimensions.--Length of the shell 0.24, breadth 0.05.

Habitat.--Pacific, central area, Station 268, depth 2600 fathoms; fossil in the Tertiary rocks of Sicily, Stöhr.

Subgenus 2. Spongurella, Haeckel.

Definition.--Spongy framework everywhere of the same structure; surface armed with radial spines.

4. Spongurus asper, Haeckel.

Haliomma asperum, Joh. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 40, Taf. ii. fig. 2.

Haliomma asperum, Haeckel, 1862, Monogr. d. Radiol., p. 431.

Shell ellipsoidal, one and a third times as long as broad, with thorny surface and twenty symmetrically disposed, thin, bristle-shaped, radial spines, about as long as the shell. Spongy framework everywhere of the same structure, very compact, with small meshes, three to four times as broad as the bars.

Dimensions.--Length of the shell 0.11, breadth 0.08.

Habitat.--Mediterranean, Ligurian coast (J. Müller), Portofino (Haeckel).

5. Spongurus cylindricus, Haeckel.

Spongurus cylindricus, Haeckel, 1862, Monogr. d. Radiol., p. 465, Taf. xxvii. fig. 1.

Shell cylindrical, four to five times as long as broad, with nearly smooth surface, and twenty to thirty thin, bristle-shaped, radial spines, about half as long as the shell. Spongy framework everywhere of the same structure, very compact, with small meshes, scarcely broader than the bars.

Dimensions.--Length of the shell 0.2, breadth 0.04 to 0.05.

Habitat.--Cosmopolitan; Mediterranean, Atlantic, and Pacific, surface.

6. Spongurus tricolus, n. sp.

Shell nearly cylindrical, with two slight annular transverse strictures; its middle part is somewhat broader. Surface thorny, with numerous (forty to sixty or more) short, thin, radial spines, not longer than the breadth of the shell. Spongy framework everywhere of the same structure, compact, with small meshes, twice to three times as broad as the bars.

Dimensions.--Length of the shell 0.24, breadth 0.04 to 0.06.

Habitat.--Pacific, central area, Station 272, 2600 fathoms.

Subgenus 3. Sponguroma, Haeckel.

Definition.--Spongy framework in the inner part of the shell very compact, in the outer part very loose; surface armed with radial spines.

{345}7. Spongurus radians, n. sp.

Shell ellipsoidal, one and a half times as long as broad, with thorny surface, and eighty to one hundred and twenty (or more) thin, bristle-shaped, radial spines, somewhat longer than the shell. Spongy framework in the inner part very compact, in the outer part very loose, with a gradual transition between the two parts. Meshes in the central part not broader than the bars, in the superficial part ten to twenty times as broad.

Dimensions.--Length of the shell 0.24, breadth 0.16.

Habitat.--Mediterranean, Portofino, near Genoa, Haeckel, surface.

8. Spongurus spongechinus, n. sp.

Shell ellipsoidal, one and a third times as long as broad, with thorny surface, and thirty to forty thick, conical radial spines, about half as long as the shell. Spongy framework in the inner part of the shell compact, in the outer loose, with a gradual transition between the two parts. Meshes in the central part smaller than the bars, in the superficial part four to eight times as broad.

Dimensions.--Length of the shell 0.18, breadth 0.14.

Habitat.--North Atlantic, Station 353, surface.

Genus 146. Spongocore,[185] n. gen.

Definition.--#Spongurida# with ellipsoidal or cylindrical (sometimes three-jointed) shell of solid spongy framework, without internal cavity and without latticed medullary shell. Polar spines absent. An outer lattice-mantle is connected with the spongy shell by radial beams.

The genus Spongocore contains some widely distributed Spongurida, which are distinguished from the nearly related Spongurus by the development of a peculiar veil or mantle of delicate lattice-work, which envelops either the whole shell or only the middle part of it, and is connected with it by numerous radial beams. The distance of the simple fine lattice-lamella from the spongy shell is everywhere the same. Often the cylindrical shell is three-jointed, with two annular strictures, as also in the foregoing Spongurus. It is derived from the latter by development of the veil connecting the points of the radial spines.

Subgenus 1. Spongocorina, Haeckel.

Definition.--Shell without distinct annular strictures, not evidently three-jointed.

{346}1. Spongocore velata, n. sp.

Shell ellipsoidal, one and a half times as long as broad, without annular strictures. Spongy framework loose, with rather large meshes, four to six times as broad as the bars. The whole spongy shell enveloped by a delicate veil with smooth surface, connected with it by numerous thin radial beams. Breadth of the spongy ellipsoid (or minor axis) six times as large as its distance from the veil.

Dimensions.--Length of the whole shell (with veil) 0.3, breadth 0.2; distance of the veil from the spongy ellipsoid 0.035.

Habitat.--South Atlantic, Station 325, surface.

2. Spongocore diplocylindrica, n. sp.

Shell cylindrical, three times as long as broad, without annular strictures. Spongy framework compact, with small meshes, twice to three times as broad as the bars. The whole surface of the spongy cylinder, with exception of both rounded polar faces, enveloped by a delicate cylindrical veil with smooth surface, connected with it by numerous radial beams. Diameter of the spongy cylinder twice as large as its distance from the veil.

Dimensions.--Length of the shell 0.3, breadth (with veil) 0.1; distance of the veil 0.025.

Habitat.--South Pacific, Station 302, surface.

Subgenus 2. Spongocorisca, Haeckel.

Definition.--Shell distinctly three-jointed, with two transverse annular strictures.

3. Spongocore chrysalis, n. sp.

Spongy shell cylindrical, without the veil six times as long as broad, three-jointed, with two annular strictures; all three joints of the same length. The whole spongy shell enveloped by a thin veil with thorny surface, connected with it by numerous radial beams. Breadth of the spongy cylinder three times as large as its distance from the veil.

Dimensions.--Length of the shell (with veil) 0.4, breadth 0.1; distance of the veil from the spongy shell 0.02.

Habitat.--South Atlantic (off Patagonia), Station 318, surface.

4. Spongocore cincta, n. sp.

Spongy shell cylindrical, without the veil four times as long as broad, three-jointed, with two annular strictures; all three joints of the same length. Only the middle joint enveloped by a thin veil with smooth surface, connected with it by radial beams. Both terminal joints with long, {347}bristle-shaped, radial spines. Breadth of the spongy cylinder twice as large as its distance from the veil.

Dimensions.--Length of the shell 0.24, breadth (with veil) 0.12; distance of the veil 0.03.

Habitat.--Indian Ocean, Madagascar, Rabbe, surface.

5. Spongocore pupula, n. sp.

Spongy shell cylindrical, without the veil six times as long as broad, three-jointed, with two annular strictures; the middle joint half as long as either terminal joint. Only the middle joint enveloped by a thin veil with spiny surface, connected with it by twenty to thirty radial beams, which are prolonged on the outside into short radial spines. Breadth of the spongy cylinder about equal to its distance from the veil.

Dimensions.--Length of the shell 0.2, breadth (with veil) 0.1; distance of the veil 0.033.

Habitat.--North Pacific, Station 244, surface.

6. Spongocore puella, n. sp. (Pl. 48, fig. 6).

Spongy shell cylindrical, without the veil five times as long as broad, three-jointed, with two annular strictures; the middle joint twice as long as either terminal joint. Only the middle joint enveloped by a thin veil with delicate lattice-work and smooth surface; both terminal joints armed with numerous thin, bristle-shaped, radial spines. Breadth of the spongy cylinder twice as large as the distance from the veil.

Dimensions.--Length of the shell 0.25 to 0.3, breadth (with veil) 0.1 to 0.12; distance of the veil 0.028 to 0.032.

Habitat.--South Pacific, Stations 295 to 304, surface.

Genus 147. Spongoprunum,[186] n. gen.

Definition.--#Spongurida# with ellipsoidal or cylindrical shell of solid spongy framework, without internal cavity and without latticed medullary shell. On the poles of the axis occur two opposite strong spines.

The genus Spongoprunum differs from the most nearly allied Spongurus by the possession of two strong solid spines, lying in the axis of the ellipsoidal or cylindrical massive spongy shell, on its two opposite poles. Spongoprunum bears therefore the same relation to Spongurus that Ellipsoxiphus does to Cenellipsis.

1. Spongoprunum amphilonche, n. sp. (Pl. 48, fig. 7).

Shell ellipsoidal, two and a third times as long as broad, with nearly smooth surface. Spongy framework very compact, in the whole solid shell of the same structure, with very small meshes, {348}scarcely broader than the bars. Two polar spines conical, very strong, about half as long as the main axis of the shell and three times as long as broad.

Dimensions.--Length of the shell (without spines) 0.2, breadth 0.08.

Habitat.--Central Pacific, Station 265, depth 2900 fathoms; fossil in the rocks of Barbados.

2. Spongoprunum atractus, n. sp.

Shell spindle-shaped, twice as long as broad, with thorny surface. Spongy framework loose, in the whole shell of the same structure, with large meshes, eight to twelve times as broad as the bars. Two polar spines angular, pyramidal, very strong, about one-third as long as the shell, and twice as long as broad.

Dimensions.--Length of the shell 0.2, breadth 0.11.

Habitat.--Western Tropical Pacific, Station 225, depth 4475 fathoms.

3. Spongoprunum amphicylindrus, n. sp.

Shell nearly cylindrical, four times as long as broad, with rough surface. Spongy framework compact, in the whole shell of equal structure, with small meshes, twice to three times as broad as the bars. Two polar spines cylindrical, very large, longer than the shell, and about one-fourth as thick as its diameter.

Dimensions.--Length of the shell 0.2, breadth 0.05.

Habitat.--South Atlantic, Station 333, surface.

Subfamily SPONGODRUPPIDA, Haeckel.

Definition.--#Spongurida# with latticed medullary shell, enclosed by a spongy cortical shell.

Genus 148. Spongodruppa,[187] n. gen.

Definition.--#Spongurida# with spongy ellipsoidal cortical shell, enclosing a simple, spherical or ellipsoidal, latticed medullary shell. Polar spines absent.

The genus Spongodruppa opens the series of Spongodruppida, or of those Spongurida in which the ellipsoidal spongy cortical shell encloses a simple or double, latticed, medullary shell. In Spongodruppa, the simplest and probably the ancestral form of this subfamily, the medullary shell is simple and the polar spines absent. It may be derived from Druppula by a spongy thickening of the simple latticed cortical shell.

{349}Subgenus 1. Spongodruppula, Haeckel.

Definition.--Surface of the shell smooth or rough, without radial spines.

1. Spongodruppa terebintha, n. sp.

Cortical shell one and a third times as long as broad, with smooth surface, three times as broad as the spherical medullary shell. Spongy framework very compact, with small meshes of the same breadth as the bars. Thickness of the spongy wall equal to the radius of the medullary shell.

Dimensions.--Length of the cortical shell (or major axis of the ellipsoid) 0.16, breadth (or minor axis) 0.12; thickness of its wall 0.02; medullary shell 0.04.

Habitat.--Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Spongodruppa pistacia, n. sp.

Cortical shell one and a half times as long as broad, with thorny surface, nearly five times as broad as the spherical medullary shell. Spongy framework compact, its thickness equal to the diameter of the medullary shell.

Dimensions.--Length of the cortical shell 0.2, breadth 0.14; thickness of its wall 0.03; medullary shell 0.03.

Habitat.--Fossil in the rocks of Barbados.

3. Spongodruppa lentisca, n. sp.

Cortical shell twice as long as broad, with rough surface, four times as large as the ellipsoidal medullary shell. Spongy framework loose, with large meshes, its thickness equal to the length of the medullary shell.

Dimensions.--Length of the cortical shell 0.25, breadth 0.13; thickness of its wall 0.06; length of the medullary shell 0.06, breadth 0.04.

Habitat.--Pacific, central area, Station 266, surface.

Subgenus 2. Spongodruppium, Haeckel.

Definition.--Surface of the shell armed with radial spines.

4. Spongodruppa frangula, n. sp.

Cortical shell one and a third times as long as broad, three times as broad as the spherical medullary shell. Spongy framework loose, with large meshes, its thickness half as large as the diameter of the medullary shell. Surface covered with numerous (forty to fifty) thin, bristle-shaped, radial spines, about as long as the cortical shell.

{350}Dimensions.--Length of the cortical shell 0.24, breadth 0.18; thickness of its wall 0.035; diameter of the medullary shell 0.06.

Habitat.--North Pacific, Station 244, depth 2900 fathoms.

5. Spongodruppa elliptica, Haeckel.

Acanthosphæra elliptica, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 285, Taf. vii. fig. 4.

Cortical shell nearly twice as long as broad, four times as broad as the ellipsoidal medullary shell. Spongy framework compact, with small meshes. Surface covered with very numerous short radial spines, about as long as the medullary shell.

Dimensions.--Length of the cortical shell 0.2, breadth 0.11; length of the medullary shell 0.04, breadth 0.03.

Habitat.--Philippine Sea, Ehrenberg, Station 206, depth 2100 fathoms.

6. Spongodruppa polyacantha, Haeckel.

Haliomma polyacanthum, J. Müller, 1858, Abhandl., p. 36, Taf. i. figs. 10, 11.

Haliomma polyacanthum, Haeckel, 1862, Monogr. d. Radiol., p. 430.

Cortical shell one and a third times as long as broad, twice as broad as the ellipsoidal medullary shell. Spongy framework loose on the surface, with large regular meshes. Surface covered with fifteen to twenty thick, conical spines, about as long as the radius of the shell.

Dimensions.--Length of the cortical shell 0.12, of the medullary shell 0.09; diameter of the medullary shell 0.05 to 0.06.

Habitat.--Mediterranean (south coast of France); Atlantic (Canary Islands), Station 354, surface.

Genus 149. Spongatractus,[188] n. gen.

Definition.--#Spongurida# with spongy ellipsoidal cortical shell, enclosing a simple, spherical or ellipsoidal, latticed medullary shell. On the poles of the axis occur two opposite strong spines.

The genus Spongatractus differs from Spongodruppa by development of two strong spines in the axis of the shell, on its two opposite poles; therefore it bears the same relation to the latter that Lithatractus does to Druppula, and can be derived from Lithatractus by a spongy thickening of the cortical shell.

1. Spongatractus pachystylus, Haeckel.

Spongosphæra pachystyla, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xxvi. fig. 3.

Cortical shell one and a half times as long as broad, with rough surface. Spongy framework compact, with small meshes, about as thick as the spherical medullary shell. Polar spines very {351}stout, conical, slightly sulcated, about as long as the breadth of the cortical shell, as broad at the base as the medullary shell.

Dimensions.--Length of the cortical shell 0.2, breadth 0.13; thickness of the spongy wall 0.045; diameter of the medullary shell 0.04.

Habitat.--Fossil in the rocks of Barbados, Ehrenberg; living in the Equatorial Atlantic, Station 348, depth (2450) fathoms.

2. Spongatractus fusiformis, n. sp.

Cortical shell one and a third times as long as broad, with nearly smooth surface. Spongy framework very compact, with very small meshes, about as thick as the radius of the spherical medullary shell. Polar spines very strong, three-sided pyramidal, about as long as the breadth of the cortical shell, as broad at the base as the medullary shell.

Dimensions.--Length of the cortical shell 0.16 to 0.18, breadth 0.12 to 0.14; thickness of the spongy wall 0.02; diameter of the medullary shell 0.04.

Habitat.--Pacific, central area, Station 268, depth 2900 fathoms.

3. Spongatractus streptacanthus, n. sp.

Cortical shell twice as long as broad, with thorny surface. Spongy framework loose, with large meshes, about as thick as the ellipsoidal medullary shell. Polar spines very long, three-sided prismatic, with three spirally contorted edges, much longer than the cortical shell, half as broad as the medullary shell.

Dimensions.--Length of the cortical shell 0.25, breadth 0.13; thickness of the spongy wall 0.03; diameter of the medullary shell 0.03 to 0.04.

Habitat.--North Atlantic, off Canary Islands, Haeckel.

Genus 150. Spongoliva,[189] n. gen.

Definition.--#Spongurida# with spongy ellipsoidal cortical shell, enclosing a double, spherical or ellipsoidal, latticed medullary shell. Polar spines absent.

The genus Spongoliva differs from the nearest Spongodruppa by duplication of the medullary shell; it bears therefore the same relation to this that Prunulum does to Druppula, and can be regarded as a Prunulum, in which the simple latticed cortical shell is replaced by a spongy framework.

Subgenus 1. Spongolivetta, Haeckel.

Definition.--Surface of the shell smooth or rough, without radial spines.

{352}1. Spongoliva cerasina, n. sp.

Cortical shell one and a fourth times as long as broad, with smooth surface, four times as broad as the outer spherical medullary shell. Spongy framework very compact, with very small meshes, its thickness equal to the diameter of the outer medullary shell.

Dimensions.--Length of the cortical shell 0.2, breadth 0.16; thickness of its wall 0.04; diameter of the outer medullary shell 0.04, of the inner 0.014.

Habitat.--Fossil in the rocks of Barbados.

2. Spongoliva prunulina, n. sp.

Cortical shell one and a third times as long as broad, with smooth surface, three times as large as the outer ellipsoidal medullary shell. Spongy framework very compact, with small meshes, its thickness equal to the diameter of the inner medullary shell.

Dimensions.--Length of the cortical shell 0.24, breadth 0.18; thickness of its wall 0.03; size of the outer medullary shell 0.08 to 0.06, of the inner 0.03.

Habitat.--Pacific, central area, Station 265, depth 2900 fathoms.

3. Spongoliva persicina, n. sp.

Cortical shell one and a half times as long as broad, with rough surface, five to six times as large as the ellipsoidal outer medullary shell. Spongy framework loose, with large meshes, its thickness about equal to the outer medullary shell.

Dimensions.--Length of the cortical shell 0.26, breadth 0.18; thickness of its wall 0.04; size of the outer medullary shell 0.045 to 0.035, of the inner 0.015.

Habitat.--Equatorial Atlantic, Station 348, depth (2450) fathoms.

4. Spongoliva amygdalina, n. sp.

Cortical shell twice as long as broad, with thorny surface, ten times as long as the small spherical outer medullary shell. Spongy framework loose, with large meshes, its thickness one and a half times as large as the outer medullary shell.

Dimensions.--Length of the cortical shell 0.3, breadth 0.16; thickness of its wall 0.045; size of the outer medullary shell 0.03, of the inner 0.015.

Habitat.--Fossil in the Tertiary rocks of Sicily (Caltanisetta).

Subgenus 2. Spongolivina, Haeckel.

Definition.--Surface of the shell armed with radial spines.

5. Spongoliva opuntina, n. sp.

Cortical shell one and a third times as long as broad, armed with numerous thin, bristle-shaped, radial spines, nearly as long as the shell. Spongy framework loose, with large meshes, its thickness nearly equal to the diameter of the outer spherical medullary shell.

{353}Dimensions.--Length of the cortical shell 0.18, breadth 0.14; thickness of its wall 0.035; diameter of the outer medullary shell 0.04, of the inner 0.02.

Habitat.--South Atlantic, Station 325, surface.

6. Spongoliva daturina, n. sp.

Cortical shell one and a half times as long as broad, armed with numerous, thick and short, conical radial spines, about as long as the outer medullary shell. Spongy framework compact, with small meshes, its thickness equal to half the length of the outer ellipsoidal medullary shell.

Dimensions.--Length of the cortical shell 0.24, breadth 0.16; thickness of its wall 0.025; diameter of the outer medullary shell 0.045 to 0.035, of the inner 0.025.

Habitat.--Pacific, central area, Station 272, surface.

Genus 151. Spongoxiphus,[190] n. gen.

Definition.--#Spongurida# with spongy ellipsoidal cortical shell, enclosing a double, spherical or ellipsoidal, latticed medullary shell. On the poles of the axis occur two opposite strong spines.

The genus Spongoxiphus differs from Spongoliva by the development of two strong spines in the axis of the shell, on its two opposite poles. From the similar Spongatractus it differs in the duplication of the medullary shell. It may also be regarded as a Stylatractus, in which the simple latticed cortical shell is replaced by an irregular spongy framework.

1. Spongoxiphus sphærococcus, n. sp.

Cortical shell one and a half times as long as broad, with thorny surface. Spongy framework compact, with small meshes, its thickness equal to the radius of the outer medullary shell. Both medullary shells spherical, the outer three times as broad as the inner. Polar spines very stout, conical, slightly sulcated, about half as long as the cortical shell, as broad at the base as the outer medullary shell. (Differs from Spongatractus pachystylus almost only in the double medullary shell.)

Dimensions.--Length of the cortical shell 0.18, breadth 0.12; thickness of the spongy wall 0.025; diameter of the outer medullary shell 0.05, of the inner 0.016.

Habitat.--Fossil in the rocks of Barbados (Haeckel); also living in the Pacific, central area, Station 265, depth 2900 fathoms.

{354}2. Spongoxiphus prunococcus, n. sp. (Pl. 17, figs. 12, 13).

Spongostylus prunococcus, Haeckel, 1881, Prodromus, p. 455, et Atlas, pl. xvii. figs. 12, 13.

Cortical shell one and a third times as long as broad, with smooth surface. Spongy framework very compact, with very small meshes, its thickness about equals the breadth of the outer medullary shell. Both medullary shells ellipsoidal, the outer three times as large as the inner. Polar spines very stout, three-sided pyramidal, about half as long as the cortical shell, on the base about as broad as the outer medullary shell. (Differs from the preceding in the ellipsoidal form of both medullary shells, and in the finer structure of the spongy framework.)

Dimensions.--Length of the cortical shell 0.18 to 0.2, breadth 0.14 to 0.16; thickness of the spongy wall 0.035 to 0.04; length of the outer medullary shell 0.04 to 0.06, breadth 0.03 to 0.04.

Habitat.--Pacific, central area, Stations 265 to 268, depths 2700 to 2900 fathoms.

Family XIV. #ARTISCIDA#, Haeckel (Pl. 39, figs. 9, 10; Pl. 48, fig. 5).

Artiscida, Haeckel, 1881, Prodromus, p. 462.

Definition.--#Prunoidea# with an ellipsoidal twin-shell divided by an equatorial stricture into two communicating hemiellipsoidal or hemispherical chambers, without enclosed medullary shell. Central capsule ellipsoidal, with or without equatorial stricture.

The family #Artiscida# has a simple fenestrated outer shell, like that of the Ellipsida, but differs from these in the presence of an equatorial constriction, by which it assumes a characteristic twin form, somewhat similar to a violin (Pl. 39, figs. 9, 10). From the Cyphinida, which have the same form of the cortical shell, the Artiscida differ in the absence of the medullary shell. It is possible that the Artiscida are descended from the Cyphinida (by loss of the medullary shell), but it is more probable that they arise from the Ellipsida by an annular constriction in the equatorial plane (perhaps the formation of the shell originally took place while the central capsule was undergoing division). Both halves of the twin shell are always of the same size and form. Its outer surface is either smooth or covered with radial spines (Artiscus, Pl. 39, fig. 9). Sometimes on the opposite poles of the main axis are developed solid spines (Stylartus, Pl. 48, fig. 5) or hollow fenestrated tubes (Cannartus, Pl. 39, fig. 10).

The Central Capsule is either simply ellipsoidal, or has also an equatorial constriction, which divides it into two equal halves. It is constantly smaller than the surrounding shell, and separated from its inner surface by a thicker or thinner jelly-mantle, the calymma.

Synopsis of the Genera of Artiscida.

On the poles of the main axis neither solid spines nor hollow tubes, 152. Artiscus.

On the poles of the main axis two solid spines (or bunches of spines), 153. Stylartus.

On the poles of the main axis two hollow fenestrated tubes, 154. Cannartus.

{355}Genus 152. Artiscus,[191] Haeckel, 1881, Prodromus, p. 462.

Definition.--#Artiscida# without peculiar polar appendages (without strong solid spines or hollow fenestrated tubes on the poles of the main axis).

The genus Artiscus represents the most simple and primitive form of the Artiscida, and may therefore be regarded as the ancestral form of this subfamily. It resembles an ordinary double loaf, composed of two equal, nearly ellipsoidal fenestrated shells separated by the stricture in the equatorial plane. Artiscus can be derived from Cenellipsis simply by this equatorial constriction. But it can also be derived from Cyphanta by loss of the medullary shell.

Subgenus 1. Artiscium, Haeckel.

Definition.--Surface of the shell smooth or rough, without radial rods or spines.

1. Artiscus paniscus, n. sp.

Pores of the shell regular, hexagonal, four times as broad as the bars; ten to twelve pores on the half meridian, eight to nine on the half equator. Surface smooth. (The network of this species is quite the same as that of the proximal cameræ of Panartus diploconus, Pl. 40, fig. 1.)

Dimensions.--Main axis of the shell 0.12, equatorial axis 0.07; meshes 0.013, bars 0.003.

Habitat.--Pacific, central area, Station 271, depth 2425.

2. Artiscus facetus, n. sp.

Pores of the shell regular, circular, with prominent hexagonal frame, twice as broad as the bars; twenty-two to twenty-four pores on the half meridian, fourteen to fifteen on the half equator. Surface a little thorny. (The shell of this species exhibits nearly the same formation as that of Cyphonium virgineum, Pl. 39, fig. 12, but without enclosed medullary shells.)

Dimensions.--Main axis of the shell 0.15, equatorial axis 0.09; meshes 0.01, bars 0.005.

Habitat.--Pacific, central area, Station 266, depth 2750 fathoms.

3. Artiscus paniculus, n. sp.

Pores of the shell regular, circular, without hexagonal frame, as broad as the bars; fourteen to sixteen pores on the half meridian, ten to eleven on the half equator. Surface quite smooth.

Dimensions.--Main axis of the shell 0.13, equatorial axis 0.06; meshes 0.01, bars 0.01.

Habitat.--Fossil in the Tertiary rocks of Barbados (Haeckel).

{356}4. Artiscus panarius, n. sp.

Pores of the shell irregular, roundish, twice to four times as broad as the bars; sixteen to eighteen pores on the half meridian, twelve to thirteen on the half equator. Surface smooth.

Dimensions.--Main axis of the shell 0.11, equatorial axis 0.06; meshes 0.005 to 0.02, bars 0.001 to 0.004.

Habitat.--Western Tropical Pacific, Station 224, depth 1850 fathoms.

Subgenus 2. Artidium, Haeckel, 1881, Prodromus, p. 462.

Definition.--Surface of the shell covered with radial rods or spines.

5. Artiscus elegans, n. sp.

Pores of the shell regular, circular, with hexagonal frames, twice as broad as the bars; fourteen pores on the half meridian, eight to nine on the half equator. From every corner of the hexagonal frames (between every three pores) starts a thin, three-sided pyramidal spine, twice as large as a pore.

Dimensions.--Main axis 0.13, equatorial axis 0.08; meshes 0.007, bars 0.004; spines 0.015 long.

Habitat.--South Atlantic, Station 332, depth 2200 fathoms.

6. Artiscus nodosus, n. sp. (Pl. 39, fig. 9).

Pores of the shell subregular, circular, without hexagonal frame, three times as broad as the bars; sixteen to eighteen on the half meridian, ten to twelve on the half equator. Irregularly scattered on the whole surface a variable number (twenty-five to thirty in all) of stout short radial spines or rather blunt rods; the length and thickness of these is the same, and equals the size of two to three meshes; its form resembles a truncated six-sided pyramid.

Dimensions.--Main axis 0.11, equatorial axis 0.08; meshes 0.01, bars 0.003; length and thickness of the radial sticks 0.02.

Habitat.--Pacific, central area, Station 272, depth 2600 fathoms.

7. Artiscus hystrix, n. sp.

Pores of the shell irregular, roundish, of very unequal size and dissimilar form, twice to eight times as broad as the bars; ten to fifteen on the half meridian, seven to nine on the half equator. Irregularly scattered on the whole surface a large number of thin conical spines, about as large as the meshes, partly directed radially, partly obliquely. (The shell of this species resembles very much that of Cyphonium ceratospyris (p. 366) = Didymocyrtis ceratospyris, Monogr. d. Radiol., 1862, Taf. xxii. fig. 14, but is without the enclosed inner shells.)

{357}Dimensions.--Main axis 0.12, equatorial axis 0.07; meshes 0.004 to 0.02, bars 0.002 to 0.005; spines 0.01 to 0.02.

Habitat.--Atlantic, Eastern Tropical part, Station 346, surface.

Genus 153. Stylartus,[192] Haeckel, 1881, Prodromus, p. 462.

Definition.--#Artiscida# with two strong, solid, polar spines, or two bunches of polar spines, opposite on the two poles of the main axis.

The genus Stylartus differs from Artiscus by the production of two large opposite spines in the main axis, starting from both poles of it; sometimes every spine is surrounded by a group of smaller radial spines. The genus is nearly allied to Ellipsoxiphus (p. 295), and differs from it only in the equatorial stricture of the ellipsoidal shell. But it may also be derived from the similar Cyphinus (Pl. 39, fig. 14) by loss of the medullary shell.

Subgenus 1. Stylartella, Haeckel.

Definition.--On each pole of the main axis only one single large spine.

1. Stylartus bipolaris, n. sp. (Pl. 48, fig. 5).

Shell thick walled, rough; both its chambers nearly spherical, with irregular, roundish pores, twice to four times as broad as the bars; eight to ten on the half equator of each chamber. Polar spines very strong, conical, as long as the greatest breadth.

Dimensions.--Length of the shell (without spines) 0.18, greatest breadth 0.13; length of the polar spines 0.13, basal breadth 0.03.

Habitat.--Western Tropical Pacific, Station 224, depth 1850 fathoms.

2. Stylartus bicuspis, n. sp.

Shell thin walled, smooth, with regular, circular pores, twice as broad as the bars; twelve to fourteen on the half equator of each chamber. Polar spines very stout, straight, three-sided pyramidal, half as long as the shell.

Dimensions.--Length of the shell 0.16, greatest breadth 0.12; length of the polar spines 0.08, basal thickness 0.025.

Habitat.--Pacific, central area. Station 266, depth 2750 fathoms.

Subgenus 2. Stylartura, Haeckel.

Definition.--On each pole of the main axis a bunch of several spines.

{358}3. Stylartus palatus, n. sp.

Shell thick walled, thorny, with irregular, roundish pores, twice to three times as broad as the bars; fifteen to eighteen on the half equator of each chamber. On each pole of the main axis a large conical spine, surrounded by a group of ten to fifteen smaller spines, one-third to two-thirds as long as the breadth of the deep equatorial stricture.

Dimensions.--Length of the shell 0.14, greatest breadth 0.09; length of the polar spines 0.03 to 0.06, basal breadth 0.005 to 0.015.

Habitat.--Indian Ocean, Madagascar, Rabbe, surface.

4. Stylartus penicillus, n. sp.

Shell thin walled, smooth, with irregular, roundish pores, three to four times as broad as the bars; ten to twelve on the half equator of each chamber. On each pole of the main axis a brush-like bunch of twenty to thirty thin conical radial spines, half as long as the shell.

Dimensions.--Length of the shell 0.15, greatest breadth 0.1; length of the polar spines 0.08, basal breadth 0.005.

Habitat.--Equatorial Atlantic, Station 347, surface.

Genus 154. Cannartus,[193] Haeckel, 1881, Prodromus, p. 462.

Definition.--#Artiscida# with two hollow polar tubes (fenestrated cylindrical or conical tubuli, opposite on the two poles of the main axis).

The genus Cannartus differs from Artiscus by the production of two opposite hollow tubes on both poles of the main axis. The cavity of the conical or cylindrical fenestrated tubes communicates freely with that of the shell; the network in both is the same. The distal end of the tubes is nearly always broken off, sometimes closed, with a conical apex. Cannartus can be derived either from Pipettella by a transverse equatorial constriction, or from Cannartiscus by the loss of the medullary shell, or from Artiscus by the production of the polar tubes.

1. Cannartus violina, n. sp. (Pl. 39, fig. 10).

Pores of the shell subregular, circular, twice to three times as broad as the bars; eighteen to twenty on the half meridian, fourteen to sixteen on the half equator. Shell-wall in the "tropical zone" of both halves thickened. Polar tubes nearly cylindrical, about as long as the main axis, distal ends broken off.

Dimensions.--Main axis 0.14, equatorial axis 0.09; meshes 0.008, bars 0.003; length of the polar tubes 0.12, breadth 0.02 to 0.03.

Habitat.--Pacific, central area, Station 268, depth 2900 fathoms.

{359}2. Cannartus bitubulus, n. sp.

Pores of the shell regular, circular, hexagonally framed, of the same breadth as the bars; fourteen to sixteen on the half meridian, ten to twelve on the half equator. Polar tubes cylindrical, longer than the main axis, sulcated, distal ends broken off. (Similar to Pipetta tuba, Pl. 39, fig. 7, but with equatorial stricture and without medullary shell.)

Dimensions.--Main axis 0.16, equatorial axis 0.12; meshes and bars 0.006; length of the polar tubes 0.2, breadth 0.025.

Habitat.--South Atlantic, Station 332, depth 2200 fathoms.

3. Cannartus biscottus, n. sp.

Pores of the shell irregular, roundish, twice to three times as broad as the bars; ten to twelve on the half meridian, six to eight on the half equator. Polar tubes conical, shorter than the main axis, with closed apex. (Similar to Cannartidium bicinctum, Pl. 39, fig. 18, but without enclosed medullary shell.)

Dimensions.--Main axis 0.11, equatorial axis 0.07; meshes 0.005 to 0.01, bars 0.003; length of the polar tubes 0.08, breadth on the base 0.03.

Habitat.--Equatorial Atlantic, Station 348, depth 2450 fathoms.

Family XV. #CYPHINIDA#, Haeckel (Pl. 39, figs. 11-19).

Cyphinida, Haeckel, 1881, Prodromus, p. 462.

Definition.--#Prunoidea# with ellipsoidal twin-shell, divided by an equatorial stricture into two communicating hemiellipsoidal or hemispherical chambers; this external twin-shell (cortical shell) is either simple or double, and encloses one or more internal concentric shells (medullary shells). Central capsule ellipsoidal, commonly with an equatorial constriction.

The family #Cyphinida# have the same characteristic twin-form of the cortical shell as the Artiscida, but differ from them in the presence of a simple or double internal medullary shell, connected with the cortical shell by radial beams. The fenestrated shell is therefore composed of two or more concentric shells as in the Druppulida, but differs from these in the ring-like equatorial constriction.

The Medullary Shell, in the middle of the central capsule, is either single or double, composed of two concentric shells. As in the Druppulida, the form of the medullary shells is either spherical (Pl. 39, fig. 12_a_) or lenticular, compressed from both poles of the main axis (Pl. 39, fig. 18_a_); sometimes the inner medullary shell is spherical, the outer lenticular.

The Radial Beams, which connect the medullary shell with the equatorial constriction of the cortical shell, lie either all in the equatorial plane (Pl. 39, fig. 11) or near it on both sides (Pl. 39, figs. 12_a_, 18_a_).

{360}The Cortical Shell is commonly simple (Pl. 39, figs. 12, 18), sometimes composed of two concentric shells (Pl. 39, fig. 13), rarely of three. As in the Artiscida, also in the Cyphinida, from both poles of the main axis solid spines or hollow fenestrated tubes are often developed (Pl. 39, figs. 14, 16-18).

The Central Capsule of the Cyphinida (Pl. 39, fig. 13) is of the same form as in the Artiscida, generally ellipsoidal, but with an equatorial ring-like stricture, which divides it into two equal halves. It encloses the simple or double medullary shell, and is perforated by the radial beams starting from this. From the inner surface of the surrounding cortical shell it is separated by a thicker or thinner jelly-layer, the calymma. (Compare also Taf. xxii. fig. 14 of my Monograph, 1862.)

Synopsis of the Genera of Cyphinida.

------------------------------------------------------------------------- Cortical shell without peculiar spines or hollow fenestrated tubes on both poles of the main axis. ------------------------------------------------------------------------- Cortical twin- {Medullary shell shell simple { simple, 155. Cyphanta. { {Medullary shell { double, 156. Cyphonium.

Cortical twin- {Cortical shell shell double { double, 157. Cypassis. or triple; { medullary {Cortical shell shell double. { triple, 158. Cyphocolpus. ------------------------------------------------------------------------- Cortical shell simple, with peculiar spines or hollow fenestrated tubes on both poles of the main axis. ------------------------------------------------------------------------- Two opposite {Medullary shell polar spines { simple, 159. Cyphinus. (or bunches { of spines). {Medullary shell { double, 160. Cyphinidium.

Two opposite {Medullary shell hollow { simple, 161. Cannartiscus. fenestrated { polar tubes. {Medullary shell { double, 162. Cannartidium.

Genus 155. Cyphanta,[194] n. gen.

Definition.--#Cyphinida# with simple cortical shell and simple medullary shell, without polar spines or tubes.

The genus Cyphanta is the most simple of all Cyphinida, and can be regarded as the common ancestral form of this family. It may be derived phylogenetically from Druppula by a ring-like constriction in the equatorial plane of the ellipsoidal cortical shell, or from Artiscus by secondary formation of a central (spherical or ellipsoidal) medullary shell.

Subgenus 1. Cyphantella, Haeckel.

Definition.--Surface of the cortical shell smooth, without spines or thorns.

{361}1. Cyphanta colpodes, n. sp.

Cortical shell thin walled, with smooth surface; its pores regular, hexagonal, three to four times as broad as the bars; ten to twelve on the half meridian, seven to eight on the half equator. Medullary shell spherical, its diameter one-third of the equatorial axis of the cortical shell. (The cortical shell of this species is nearly identical with the central half of the cortical shell of Panartus diploconus, Pl. 40, fig. 1.)

Dimensions.--Main axis of the cortical shell 0.12, equatorial axis 0.07; meshes 0.013; bars 0.003; diameter of the medullary shell 0.025.

Habitat.--South Pacific, Station 285, depth 2375 fathoms.

2. Cyphanta circopora, n. sp.

Cortical shell thick walled, with smooth surface; pores subregular, circular, twice as broad as the bars; eighteen to twenty on the half meridian, twelve to fourteen on the half equator. Medullary shell spherical, its diameter one-half of the equatorial axis of the cortical shell. (The shell of this species is very similar to that of Cannartiscus amphiconiscus, Pl. 39, fig. 19, but without the polar tubes of that species.)

Dimensions.--Main axis of the cortical shell 0.13, equatorial axis 0.08; meshes 0.007, bars 0.003; diameter of the medullary shell 0.04.

Habitat.--Pacific, central area. Station 266, depth 2750 fathoms.

3. Cyphanta lævis, Haeckel.

Ommatospyris lævis, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 318.

Cortical shell thin walled, with smooth surface; pores of it irregular, roundish, of very different size (some very large in the tropical circles of both hemispheres). Pores twice to six times as broad as the bars; ten to twelve on the half meridian, six to eight on the half equator. Medullary shell spheroidal, compressed, its main axis somewhat shorter than its equatorial axis, which attains half the length of that of the cortical shell. (This species may be perhaps identical with Ommatospyris lævis of Ehrenberg, the diagnosis of which is insufficient and figure not given.)

Dimensions.--Main axis of the cortical shell 0.1, equatorial axis 0.06; meshes 0.005 to 0.02, bars 0.002 to 0.04; diameter of the medullary shell 0.03.

Habitat.--Philippine Sea (Ehrenberg), Station 213, depths 2650 and 3300 fathoms.

4. Cyphanta arachnoides, n. sp.

Cortical shell very delicate and thin walled, cobweb-like, with smooth surface; pores irregular, polygonal (mostly pentagonal or hexagonal), eight to ten times as broad as the thread-like bars; ten to twelve on the half meridian, six to eight on the half equator. Medullary shell spheroidal, compressed, its main axis shorter than its equatorial axis, which is about one-third that of the cortical shell. (This species is very similar to the middle part of the shell of Ommatocampe profundissima, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. viii. fig. 6.)

{362}Dimensions.--Main axis of the cortical shell 0.11, equatorial axis 0.06; meshes 0.01 to 0.02, bars 0.002; diameter of the medullary shell 0.02.

Habitat.--Atlantic, Canary Islands (Lanzerote), surface.

Subgenus 2. Cyphantissa, Haeckel.

Definition.--Surface of the cortical shell spiny, everywhere scattered with numerous thorns or spines.

5. Cyphanta hispida, n. sp.

Cortical shell thick walled, with spiny surface; pores regular, circular, with hexagonal frame, twice as broad as the bars; twelve to fourteen on the half meridian, eight to ten on the half equator. From the corners of the hexagonal frames (between every three pores) arise short, straight, conical radial spines, somewhat longer than the breadth of the pores. Medullary shell subspherical, its diameter about one-third of the equatorial axis of the cortical shell. (The appearance of the cortical shell is the same as that of the middle part of Peripanartus amphiconus, Pl. 40, fig. 5.)

Dimensions.--Main axis of the cortical shell 0.12, equatorial axis 0.07; meshes 0.01, bars 0.005; length of the spines 0.012; diameter of the medullary shell 0.02.

Habitat.--Pacific, central area, Station 274, depth 2750 fathoms.

6. Cyphanta hystrix, n. sp.

Cortical shell thin walled, with thorny surface; pores irregular, roundish, of very unequal size, twice to six times as broad as the bars; twelve to eighteen on the half meridian, eight to thirteen on the half equator. Between the pores irregularly scattered, bristle-like, thin spines about the same size, partly straight, partly oblique, rising from the surface. Medullary shell lenticular, compressed, its equatorial axis one and a half times the length of the main axis, and about half that of the cortical shell.

Dimensions.--Main axis of the cortical shell 0.15, equatorial axis 0.09; meshes 0.004 to 0.02, bars 0.003 to 0.006; length of the spines 0.02; diameter of the medullary shell 0.04.

Habitat.--South Atlantic, Station 318, surface.

Genus 156. Cyphonium,[195] n. gen.

Definition.--#Cyphinida# with simple cortical shell and double medullary shell, without polar spines or tubes.

The genus Cyphonium contains a number of very common species, among which are the earliest known forms of this family, partly described by Ehrenberg as Ommatospyris {363}(which genus contains also a number of other #Prunoidea#), partly by me (1862) as Didymocyrtis. Both names are inadequate, as allusions to quite different families of Nassellaria, but may be retained as significations of subgeneric divisions. Cyphonium differs from Cyphanta by the double medullary shell, which is either spherical or lenticular.

Subgenus 1. Ommatospyris, Ehrenberg (partim).

Definition.--Surface of the cortical shell smooth, without thorns or spines.

1. Cyphonium coscinoides, n. sp.

Ommatospyris coscinoides, Haeckel, 1881, Prodromus, p. 462.

Cortical shell thin walled, with smooth surface; pores regular, hexagonal, three to four times as broad as the bars; five to six on the half meridian, eight to nine on the half equator of each chamber. Medullary shells both spherical. (The cortical shell of this species is nearly the same as that of Cyphanta colpodes, and as the middle part of the cortical shell of Panartus diploconus, Pl. 40, fig. 1.)

Dimensions.--Main axis of the cortical shell 0.11, equatorial axis 0.06; greatest breadth of the chambers 0.08; pores 0.013, bars 0.003.

Habitat.--North Pacific, Station 244, surface.

2. Cyphonium virgineum, n. sp. (Pl. 39, figs. 12, 12_a_).

Ommatospyris virginea, Haeckel, 1881, Prodromus et Atlas (pl. xxxix. fig. 12_a_).

Cortical shell thick walled, with smooth surface (sometimes a little rough with very small thorns); pores subregular, circular, with hexagonal elevated frames, about as broad as the bars; ten to twelve on the half meridian, sixteen to eighteen on the half equator of each chamber. Medullary shells (fig. 12_a_) both spherical. (Sometimes, as in the figured specimen, the shell is somewhat irregular, an individual abnormality.)

Dimensions.--Main axis of the cortical shell 0.13 to 0.15; equatorial axis of the structure 0.08 to 0.09, of each chamber 0.1 to 0.12, pores and bars 0.005 to 0.007.

Habitat.--Pacific, western tropical part, Station 225, depth 4475 fathoms.

3. Cyphonium ethmarium, n. sp.

Ommatospyris ethmaria, Haeckel, 1881, Prodromus, p. 462.

Cortical shell thin walled, with quite smooth surface; pores subregular, circular (without hexagonal frame), twice as broad as the bars; nine to ten on the half meridian of each chamber, sixteen to eighteen on its half equator. Medullary shells both spherical. (This species resembles the proximal internal chambers of Peripanartus atractus, Pl. 40, fig. 7.)

Dimensions.--Main axis 0.13, equatorial axis 0.07; greatest breadth 0.09; pores 0.006, bars 0.003.

Habitat.--Equatorial Atlantic, Station 347, surface.

{364}4. Cyphonium trinacrium, n. sp.

Cortical shell thick walled, with rough surface; pores subregular, circular (without hexagonal frame), not broader than the bars; five to six on the half meridian of each chamber, nine to ten on its half equator. Medullary shells both compressed, lenticular. This species resembles Cypassis entomocora vel Ommatocampe trinacria, Stöhr, 1880, loc. cit., p. 90, Taf. ii. fig. 1, but has not its external mantle. It may be the ancestral form of it (both in an ontogenetic and phylogenetic sense).

Dimensions.--Main axis 0.11, equatorial axis 0.07; greatest breadth 0.08; pores 0.005, bars 0.005.

Habitat.--Fossil in Tertiary rocks of Sicily, Caltanisetta, Haeckel (Grotte, Stöhr?).

5. Cyphonium diattus, n. sp.

Cortical shell thin walled, with quite smooth surface; pores irregular, polygonal, mostly pentagonal or hexagonal, three to six times as broad as the bars; six to seven on the half meridian of the chamber, ten to twelve on its half equator. Medullary shells both spherical. (Resembles Cyphonium profundum, Ehrenberg, 1872, loc. cit., Taf. x. fig. 5, but does not possess the spines of the surface.)

Dimensions.--Main axis 0.13, equatorial axis 0.06; greatest breadth 0.08; pores 0.005 to 0.012, bars 0.002 to 0.004.

Habitat.--Indian Ocean, western part (Zanzibar), Pullen, depth 2200 fathoms.

6. Cyphonium mammarium, n. sp.

Cortical shell thick walled, with smooth surface (sometimes a little rough); pores irregular, roundish, twice to three times as broad as the bars; eleven to twelve on the half meridian of each chamber, sixteen to nineteen on its half equator. Internal medullary shell spherical, external lenticular compressed, sometimes both spherical or both compressed. (Resembles the internal cortical twin-shell of Cyphocolpus virginis, Pl. 40, fig. 11.)

Dimensions.--Main axis 0.14, equatorial axis 0.08, greatest breadth 0.09; pores 0.004 to 0.006, bars 0.002.

Habitat.--South Pacific, Station 285, depth 2375 fathoms.

Subgenus 2. Ommatocyrtis, Haeckel.

Definition.--Surface of the cortical shell thorny or spiny.

7. Cyphonium hexagonium, n. sp.

Didymocyrtis hexagonia, Haeckel, 1881, Prodromus.

Cortical shell thin walled, with spiny surface; pores regular or subregular, hexagonal, twice to three times as broad as the bars; five to six on the half meridian, nine to ten on the half equator {365}of each chamber. Radial spines between them conical, about as long as the pores. Medullary shells both spherical.

Dimensions.--Main axis 0.14, equatorial axis 0.08; greatest breadth of each chamber 0.1; pores 0.012, bars 0.004.

Habitat.--Pacific, central area, Station 268, depth 2900 fathoms.

8. Cyphonium facettarium, n. sp.

Didymocyrtis facettaria Haeckel, 1881, Prodromus.

Cortical shell thick walled, with spiny surface; pores subregular, circular, with elevated hexagonal frames, twice as broad as the bars; eight to nine on the half meridian, fourteen to sixteen on the half equator of each chamber. In the corners of the hexagons (between every three meshes) arise radial spines, about twice as long as the pores. Both medullary shells spheroidal compressed. (This species is nearly identical with the internal cortical twin-shell of Peripanartus amphiconiscus, Pl. 40, fig. 5.)

Dimensions.--Main axis 0.12, equatorial axis 0.07; greatest breadth of both chambers 0.09; pores 0.01, bars 0.005, spines 0.02.

Habitat.--Western Tropical Pacific, Station 225, depth 4475 fathoms.

9. Cyphonium cribellum, n. sp. (Pl. 39, fig. 11).

Cortical shell thick walled, with spiny surface; pores regular, circular, about as broad as the bars; seven to eight on the half meridian of each chamber, thirteen to fifteen on its half equator. Radial spines between them conical, twice as long as the pores. Medullary shells both lenticular.

Dimensions.--Main axis 0.11, equatorial axis 0.06; greatest breadth 0.08; pores and bars 0.004.

Habitat.--North Atlantic, Station 353, surface.

10. Cyphonium profundum, Haeckel.

Ommatospyris profunda, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. viii. fig. 5, Taf. x. fig. 5.

Cortical shell thin walled, with thorny surface; pores irregular, polygonal, three to six times as broad as the thin bars; five to six on the half meridian of each chamber, ten to twelve on its half equator. Thorns of the surface short. Medullary shells both spherical.

Dimensions.--Main axis 0.1, equatorial axis 0.06; greatest breadth 0.07; pores 0.005 to 0.012, bars 0.002, spines 0.005.

Habitat.--Pacific, tropical zone; Philippine Sea, depth 3300 fathoms, Ehrenberg; Stations 266 to 274, depth 2350 to 2925 fathoms.

{366}11. Cyphonium ceratospyris, Haeckel.

Didymocyrtis ceratospyris, Haeckel, 1862, Monogr. d. Radiol., p. 445, pl. xxii. figs. 14-16.

Haliomma didymocyrtis, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 816.

Cortical shell thin walled, with spiny surface; pores irregular, roundish, three to nine times as broad as the bars; five to six on the half meridian of each chamber, eight to nine on its half equator. Spines of the surface partly very short, partly as long as the largest pores, either radially or obliquely inserted. Medullary shells both spherical. (Compare the detailed description and figures also of the soft body in my Monograph, loc. cit.)

Dimensions.--Main axis of the cortical shell 0.12, equatorial axis (in the stricture) 0.06; greatest breadth 0.08; pores 0.03 to 0.2, bars 0.002 to 0.006, spines 0.05 to 0.015.

Habitat.--Mediterranean (Messina), Canary Islands (Lanzerote), Haeckel.

Genus 157. Cypassis,[196] n. gen.

Definition.--#Cyphinida# with double cortical shell and double medullary shell, without polar spines or tubes.

The genus Cypassis differs from Cyphonium by duplication of the cortical twin-shell; from the outer surface of the simple twin-shell arise numerous radial spines, which become connected by anastomosing transverse branches, and in this manner form an outer envelope or mantle. Cypassis may also be regarded as a Cromyodruppa, the double cortical shell of which is constricted in the equatorial plane.

Subgenus 1. Didymospyris, Haeckel (1881).

Definition.--Surface of the shell smooth, without thorns or spines.

1. Cypassis palliata, n. sp.

Inner cortical shell thin walled, with regular, circular, hexagonally-framed pores, twice as broad as the bars; seven to eight on the half meridian of each chamber, ten to twelve on its half equator. Outer cortical shell very thin, with smooth surface, and very small, irregular, roundish pores, twice to five times smaller than those of the inner shell. Distance between the two cortical shells equals the diameter of the outer medullary shell, which, like the inner, is spherical. (The network of this species resembles that of Peripanartus amphiconiscus, Pl. 40, fig. 5.)

Dimensions.--Main axis of the external cortical shell 0.18, of the internal 0.12; greatest breadth (in the equator of each chamber) of the former 0.13, of the latter 0.09; pores of the outer 0.002 to 0.005, of the inner shell 0.01, bars 0.002 to 0.005.

Habitat.--South Pacific, Station 288, surface.

{367}2. Cypassis eucolpos, n. sp.

Inner cortical shell thick walled, with regular, circular pores, twice as broad as the bars (without hexagonal frames); nine to ten on the half meridian of each chamber, fifteen to seventeen on its half equator. Outer cortical shell very thin, with smooth surface, and very small, irregular, roundish pores, twice to three times smaller than those of the inner shell. Distance between the two cortical shells about one and a half times the diameter of the inner medullary shell, which, like the outer, is spherical. (The inner cortical shell resembles that of Cannartiscus amphiconiscus, Pl. 39, fig. 19, but without polar tubes.)

Dimensions.--Main axis of the external cortical shell 0.2, of the internal 0.15; greatest breadth of the former 0.16, of the latter 0.12; pores of the outer 0.002, of the inner 0.006, bars 0.003.

Habitat.--South Atlantic, Station 319, surface.

Subgenus 2. Didymocyrtis, Haeckel (1862).

Definition.--Surface of the cortical shell thorny or spiny.

3. Cypassis entomocora, Haeckel.

Astromma entomocora, Ehrenberg, 1847, Mikrogeol., Taf. xxii. fig. 32.

Haliomma didymum, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 83.

? Haliomma amphisiphon, Ehrenberg, 1844, Monatsber. d. k. Akad. d. Wiss. Berlin, p. 267.

Ommatospyris entomocora, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, pp. 66, 74.

? Ommatocampe trinacria, Stöhr, 1880, Palæontogr., vol. xxvi. p. 90, Taf. ii. fig. 1.

Didymospyris entomocora, Haeckel, 1881, Prodromus.

Didymocyrtis entomocora, Haeckel, 1862, Monogr. d. Radiol., p. 445.

Inner cortical shell thick walled, with regular, circular pores, twice as broad as the bars (without hexagonal frames); eight to nine on the half meridian of each chamber, ten to eleven on its half equator. Outer cortical shell thin walled, with regular, circular pores like those of the inner. Distance between the two cortical shells equals about twice the diameter of one pore (or the short axis of the lenticular double medullary shell). Surface covered with short conical spines (in the figure of Ehrenberg broken off).

Dimensions.--Main axis of the external cortical shell 0.2, of the internal 0.15; greatest breadth of the former 0.13, of the latter 0.1; pores of the outer 0.005 to 0.01, of the inner 0.01, bars 0.004; length of the surface spines 0.005 to 0.01.

Habitat.--Fossil in the Tertiary rocks of Barbados, Bermuda, and Sicily (Caltanisetta); also living in the greatest depth of the Pacific, Stations 268, 225, depth 2900 to 4475.

4. Cypassis puella, n. sp. (Pl. 39, fig. 13).

Didymospyris colpodes, Haeckel, 1881, Prodromus et Atlas (pl. xxxix., fig. 13).

Internal cortical shell thin walled, with irregular, circular pores of very different size, once to four times as broad as the bars; fourteen to fifteen on the half meridian of each chamber, eighteen {368}to twenty on its half equator. Outer cortical shell thin walled, with irregular, circular pores, only one-third to one-half as large as those of the inner. Distance between the two shells equals the largest diameter of the double lenticular medullary shell. Surface of both cortical shells covered with short conical spines (not longer than the largest pores).

Dimensions.--Main axis of the external cortical shell 0.2, of the internal 0.15, of the central capsule 0.1; greatest breadth of the first 0.14, of the second 0.1, of the third 0.07; pores of the outer shell 0.001 to 0.005, of the inner 0.002 to 0.01, bars 0.002 to 0.003; length of the surface spines 0.005 to 0.01.

Habitat.--Pacific, central area; Stations 266 to 274, surface; Atlantic, Canary Islands (Haeckel), Station 354, surface.

5. Cypassis halicora, n. sp.

Internal cortical shell thin walled, with irregular, roundish pores, once to three times as broad as the bars; ten to eleven on half meridian of each chamber, fourteen to sixteen on its half equator. Outer cortical shell thin walled, with very delicate network, spindle-like, with conical prolongations at both poles. Distance between the two shells larger than the greatest diameter of the double lenticular medullary shell. Surface of both cortical shells covered with innumerable small thorns. (Resembles closely Cyphocolpus virginis, Pl. 40, fig. 11, but without the third shell.)

Dimensions.--Main axis of the external cortical shell 0.21, of the internal 0.14, greatest breadth of the former 0.13, of the later 0.09; pores 0.003 to 0.009; bars of the outer shell 0.001, of the inner 0.004.

Habitat.--Indian Ocean, Ceylon (Haeckel), surface.

Genus 158. Cyphocolpus,[197] n. gen.

Definition.--#Cyphinida# with triple cortical shell and double medullary shell, without polar spines or tubes.

The genus Cyphocolpus differs from both foregoing genera by the increased number of the cortical twin-shells. Whilst these are simple in Cyphonium, double in Cypassis, they are triple in Cyphocolpus, composed of three concentric envelopes. The three genera named represent a phylogenetic series, which is repeated in the ontogenetic development of Cyphocolpus.

1. Cyphocolpus didymus, n. sp.

Inner cortical shell with circular, subregular pores, twice as broad as the bars; five to six on the half meridian of each chamber, eight to ten on its half equator. Middle cortical shell also with subregular, circular pores of the same size. Outer cortical shell with smooth surface, with more irregular, roundish pores of very different size. The distance between every two shells equals the diameter of the inner medullary shell, which, like the outer, is spheroidal.

{369}Dimensions.--Main axis of the outer cortical shell 0.3, of the middle 0.22, of the inner 0.15; greatest breadth of the inner cortical shell 0.1, its pores 0.01, bars 0.005.

Habitat.--Indian Ocean, Madagascar, Rabbe, surface.

2. Cyphocolpus virginis, n. sp. (Pl. 40, fig. 11).

Zygartus virginis, Haeckel, 1881, Prodromus et Atlas (pl. xl. fig. 11).

Inner cortical shell with irregular, roundish pores, twice to three times as broad as the bars; eleven to twelve on the half meridian of each chamber, sixteen to eighteen on its half equator. Middle cortical shell with very delicate network, its irregular, polygonal pores of the same size as those of the inner, but separated by extremely thin bars. Outer cortical shell with spiny surface, and with more irregular, roundish pores of different size. The distance between each two shells is variable, and attains more than the diameter of the outer medullary shell, which, like the inner, is spheroidal, slightly compressed.

Dimensions.--Main axis of the outer cortical shell 0.26, of the middle 0.22, of the inner 0.14; greatest breadth of the inner cortical shell 0.09, its pores 0.004 to 0.006, bars 0.002.

Habitat.--Pacific, central area, Station 271, surface.

Genus 159. Cyphinus,[198] Haeckel, 1881, Prodromus, p. 463.

Definition.--#Cyphinida# with simple cortical shell and simple medullary shell, with two opposite polar spines (or bunches of polar spines) on the poles of the main axis.

The genus Cyphinus differs from Cyphanta by the development of two opposite spines (or bunches of spines) on both poles of the main axis. It simulates therefore the bipolar formation of Stylartus, and differs from this in the possession of a medullary shell.

Subgenus 1. Cyphinoma, Haeckel.

Definition.--On both poles of the main axis only one single large spine.

1. Cyphinus amphacanthus, n. sp.

Cortical shell with smooth surface, and circular, regular pores, twice as broad as the bars; five to six pores on the half meridian of each chamber, ten to twelve on its half equator. On both poles of the main axis, one single, very strong, conical spine, about half as long as this axis, and half as broad at the base as the spherical medullary shell.

Dimensions.--Main axis of the cortical shell (without spines) 0.2, greatest breadth (in the equator of each chamber) 0.1; pores 0.006, bars 0.003; length of the polar spines 0.1, basal thickness of them 0.02.

Habitat.--North Pacific, Station 244, depth 2900 fathoms.

{370}2. Cyphinus dixiphus, n. sp.

Cortical shell with rough surface, and irregular, roundish pores, twice to four times as broad as the bars; eight to nine pores on the half meridian of each chamber, twelve to fourteen on its half equator. On both poles of the main axis, one single, strong, conical spine, with prominent edges at the base, and nearly as broad as the spherical medullary shell, nearly as long as the main axis.

Dimensions.--Main axis (without spines) 0.18, greatest breadth 0.13; pores 0.003 to 0.008, bars 0.002; length of the polar spines 0.16, basal thickness 0.03.

Habitat.--South Pacific, Station 295, depth 1500 fathoms.

Subgenus 2. Cyphinura, Haeckel.

Definition.--On both poles of the main axis a bunch or circle of several spines.

3. Cyphinus amphilophus, n. sp. (Pl. 39, fig. 14).

Cyphinidium amphilophus, Haeckel, 1882, Atlas (pl. xxxix. fig. 14).

Cortical shell thick walled, with rough surface, and subregular, circular pores of different size, twice to five times as broad as the bars; nine to ten pores on the half meridian of each chamber, twelve to fourteen on its half equator. On both poles of the main axis a bunch of six to eight strong conical spines, the largest of which are about as long as the greatest breadth of the shell; their basal part is furrowed, and nearly half as thick as the spherical medullary shell.

Dimensions.--Main axis of the cortical shell (without spines) 0.18 to 0.2, greatest breadth 0.1 to 0.12; pores 0.004 to 0.01, bars 0.002; length of the polar spines 0.04 to 0.12, basal thickness 0.02 to 0.04.

Habitat.--Pacific, central area, Station 271, depth 2425 fathoms.

4. Cyphinus penicillatus, Haeckel.

Ommatospyris penicillata, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 318; Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. viii. fig. 4.

Cortical shell thin walled, with rough surface, and irregular, polygonal pores, six to eight times as broad as the bars; five to six pores on the half meridian of each chamber, nine to ten on its half equator. Around both poles of the main axis a polar circle of eight to ten divergent radial spines, scarcely thicker than the bars, and about as long as the diameter of the spherical medullary shell. (In the figure of Ehrenberg the network is too thin and the spines too short.)

Dimensions.--Main axis (without spines) 0.1, greatest breadth 0.09; pores 0.008 to 0.014, bars 0.001 to 0.002; length of the spines 0.02 to 0.04.

Habitat.--Pacific, Philippine Sea, 3300 fathoms, Ehrenberg; Station 206, depth 2100 fathoms.

{371}Genus 160. Cyphinidium,[199] n. gen.

Definition.--#Cyphinida# with simple cortical shell and double medullary shell, with two opposite polar spines (or bunches of polar spines) on the poles of the main axis.

The genus Cyphinidium differs from Cyphinus only in the duplication of the medullary shell, which is composed of two concentric spheres or somewhat compressed lenticular spheroids. It exhibits therefore the same relation to Cyphinus that Stylatractus in the Druppulida bears to Lithatractus. Possibly the two former genera are derived from the two latter by an annular constriction in the equatorial plane.

Subgenus 1. Cyphinidoma, Haeckel.

Definition.--On both poles of the cortical shell one single polar spine or a bunch of polar spines.

1. Cyphinidium amphistylium, n. sp.

Cortical shell thick walled, with smooth surface, and subregular, circular pores, twice to three times as broad as the bars; eight to ten on the half meridian, sixteen to eighteen on the half equator of each chamber. Both medullary shells spherical. The cortical shell resembles very much that of Cannartiscus amphiconiscus (Pl. 39, fig. 19), but exhibits instead of the hollow polar tubes two strong solid polar spines of conical form, half as long as the main axis, and as broad at the base as the inner medullary shell.

Dimensions.--Main axis of the cortical shell (without polar spines) 0.14, greatest breadth 0.1; pores 0.008, bars 0.004; length of the polar spines 0.08, basal thickness 0.02.

Habitat.--North Pacific, off Japan, Station 241, depth 2300 fathoms.

2. Cyphinidium apicatum, Haeckel.

Ommatospyris apicata, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 317.

Cortical shell thin walled, with thorny surface, and irregular, polygonal pores, three to five times as broad as the thin bars; eight to nine on the half meridian, thirteen to fifteen on the half equator of each chamber. On both poles a bunch of four to eight strong conical spines, the central of which (in the main axis) is much larger than the others, and twice as long as the diameter of the outer spheroidal medullary shell; size and number of the polar spines is very variable (commonly five to six).

{372}Dimensions.--Main axis (without spines) 0.12, greatest breadth 0.08; pores 0.005 to 0.01, bars 0.002; length of the polar spines 0.02 to 0.06, basal thickness 0.01.

Habitat.--Northern Pacific, Californian Sea, depth 2500 fathoms, Ehrenberg; Station 253, depth 3125 fathoms.

Subgenus 2. Cyphinidura, Haeckel.

Definition.--On both poles of the cortical shell, a circle of divergent polar spines.

3. Cyphinidium coronatum, n. sp.

Cortical shell with thorny surface, and irregular, roundish pores, twice to four times as broad as the bars; seven to eight on the half meridian, eleven to thirteen on the half equator of each chamber. Around both poles of the main axis occurs a circle of ten to twelve strong, radially divergent spines, about as long as the diameter of the outer medullary shell, which, like the inner, is spheroidal. (This species is identical with the younger developmental stage of Panicium coronatum, Pl. 40, fig. 4, before the formation of two distal chambers.)

Dimensions.--Main axis 0.12, greatest breadth 0.1; pores 0.008 to 0.016, bars 0.004; length of the polar spines 0.02, thickness 0.005.

Habitat.--Pacific, central area, Stations 270 to 274, depth 2350 to 2925 fathoms.

Genus 161. Cannartiscus,[200] n. gen.

Definition.--#Cyphinida# with simple cortical shell and simple medullary shell, with two hollow fenestrated polar tubes, opposite on both poles of the main axis.

The genus Cannartiscus differs from Cyphanta in the development of two hollow fenestrated tubes, opposite on both poles of the main axis. It simulates therefore the characteristic formation of Cannartus, and differs from this Artiscid in the possession of a medullary shell.

1. Cannartiscus amphiconiscus, n. sp. (Pl. 39, fig. 19).

Cannartidium amphiconiscus, Haeckel, 1882, Atlas (pl. xxxix. fig. 19).

Cortical shell thick walled, smooth, with regular, circular pores, twice as broad as the bars; nine to ten on the half meridian, sixteen to eighteen on the half equator of each chamber. Polar tubes conical, about as long as one single chamber, on the base somewhat broader than the simple spherical medullary shell. Pores of the tubes only one-third as great as those of the chambers.

Dimensions.--Main axis of the cortical shell (without tubes) 0.14, greatest breadth 0.1; {373}pores 0.008, bars 0.004. Length of the polar tubes 0.07, basal breadth 0.04; pores 0.003, bars 0.002.

Habitat.--North Pacific, Station 253, depth 3125 fathoms.

2. Cannartiscus amphicylindrus, n. sp.

Cortical shell thick walled, rough, with subregular, circular pores, twice to four times as broad as the bars; six to seven on the half meridian, ten to twelve on the half equator of each chamber. Polar tubes cylindrical, on the distal end open (broken off?) nearly as long as the main axis, somewhat narrower than the spherical medullary shell. Pores of the tubes much smaller than those of the chambers.

Dimensions.--Main axis (without tubes) 0.17, greatest breadth 0.12; pores 0.006 to 0.012, bars 0.003. Length of the polar tubes 0.15, breadth of them 0.03; pores 0.003, bars 0.002.

Habitat.--Pacific, central area, Station 268, 2900 fathoms; the same form occurs fossil in the rocks of Barbados.

Genus 162. Cannartidium,[201] n. gen.

Definition.--#Cyphinida# with simple cortical shell and double medullary shell, with two hollow fenestrated polar tubes, opposite on both poles of the main axis.

The genus Cannartidium differs from Cannartiscus and Cannartus in the duplication of the medullary shell, which is composed of two concentric spheres or compressed lenticular spheroids. The three genera named form therefore one morphological series, with identical cortical shell, and only differing in the absence or presence of a simple or double medullary shell.

Subgenus 1. Cannartidella, Haeckel.

Definition.--Surface of the cortical shell smooth or a little rough, but without spines or fenestrated protuberances.

1. Cannartidium amphiconicum, n. sp.

Cortical shell thick walled, smooth with regular circular pores twice as broad as the bars; eight to nine on the half meridian, fifteen to sixteen on the half equator of each chamber. Polar tubes conical, with smaller pores, tapering towards the closed apex, about as long as one single chamber, at the base one-third as broad as the equatorial constriction. Both concentric medullary shells spherical. (Nearly identical with Cannartiscus amphiconiscus, Pl. 39, fig. 19, but differs in the possession of the double medullary shell.)

{374}Dimensions.--Main axis of the cortical shell (without tubes) 0.15, greatest breadth 0.11; pores 0.009, bars 0.004; length of the polar tubes 0.08, basal breadth 0.04.

Habitat.--Pacific, western tropical part, Station 225, depth 4475 fathoms.

2. Cannartidium amphicanna, Haeckel.

"Curious twin Polycystin," Bury, 1862, Polycystins of Barbados, pl. xx. fig. 4.

Cortical shell thick walled, rough, with regular, circular pores, not broader than the bars; six to seven on the half meridian, ten to twelve on the half equator of each chamber. Polar tubes cylindrical, at the distal end open (broken off?), nearly as long as the main axis, about one-third as broad as the equatorial constriction. Both concentric medullary shells spherical.

Dimensions.--Main axis 0.14, greatest breadth 0.11; pores and bars 0.005; length of the polar tubes 0.13, breadth of them 0.03.

Habitat.--Fossil in the Barbados deposits.

3. Cannartidium amphisiphon, Haeckel.

? Haliomma amphisiphon, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 267.

Cortical shell thick walled, rough, with irregular, roundish pores, twice to five times as broad as the bars; five to six on the half meridian, nine to ten on the half equator of each chamber. Polar tubes conical, with smaller pores, about as long as one single chamber, half as broad at the base as the equatorial constriction. (This deep-sea form is probably identical with that fossil species which Ehrenberg, in 1844, described as Haliomma amphisiphon, and which he afterwards, in 1875, erroneously identified with his Astromma entomocora (= Cypassis entomocora). But the figure given of the latter is quite different from the given diagnosis of the former.)

Dimensions.--Main axis of the cortical shell (without tubes) 0.13, greatest breadth 0.1; pores 0.006 to 0.12, bars 0.003; length of the polar tubes 0.07, basal breadth of them 0.04.

Habitat.--Tropical Atlantic, Antilles, Station 24, depth 390 fathoms; fossil in the Tertiary rocks of Bermuda.

4. Cannartidium bicinctum, n. sp. (Pl. 39, fig. 18).

Cortical shell thick walled, with a thickened ring-shaped protuberance in the greatest breadth of both chambers. Pores subregular, circular, twice to three times as broad as the bars; seven to eight on the half meridian, thirteen to fifteen on the half equator of each chamber. Polar tubes conical, with smaller pores, somewhat shorter than the greatest breath, nearly as thick at the base as the outer spheroidal medullary shell (fig. 18_a_).

Dimensions.--Main axis (without tubes) 0.12, greatest breadth 0.08; pores 0.003 to 0.006, bars 0.002; length of the polar tubes 0.08, basal thickness 0.03.

Habitat.--South Atlantic, Station 332, depth 2200 fathoms.

{375}Subgenus 2. Cannartidissa, Haeckel.

Definition.--Surface of the cortical shell with conical fenestrated protuberances in the greatest breadth of both chambers.

5. Cannartidium mammiferum, n. sp. (Pl. 39, fig. 16).

Cortical shell-thin walled, having a circle of six to eight conical protuberances in the greatest breadth of both chambers, each of which exhibits a central apical pore, surrounded by a circle of six to eight oblique larger pores. Between the protuberances occur nine to ten pores on the half meridian of each chamber, circular, subregular, twice to three times as broad as the bars. Polar tubes cylindrical, conical at the closed end, with smaller pores, about as long as the greatest breadth of the chambers, as broad as the spherical outer medullary shell.

Dimensions.--Main axis (without tubes) 0.13, greatest breadth (including the protuberances) 0.1; pores 0.005 to 0.008, bars 0.003; length of the polar tubes 0.09, basal thickness 0.02.

Habitat.--Pacific, central area, Station 268, depth 2900 fathoms.

6. Cannartidium mastophorum, n. sp. (Pl. 39, fig. 17).

Cortical shell thin walled, of the same form and structure as in the foregoing species, differs from this mainly in the form of the polar tubes, which are not cylindrical but conical, tapering gradually from the base towards the closed apex. Besides this, the conical protuberances (six in the greatest periphery of each chamber) are more regular and acute, with smaller and more numerous pores. Both medullary shells are here also spherical.

Dimensions.--Main axis (without tubes) 0.14, greatest breadth (including the protuberances) 0.13; pores 0.006 to 0.009, bars 0.004; length of the polar tubes 0.07, basal thickness 0.03.

Habitat.--Pacific, central area, Station 266, depth 2750 fathoms.

Family XVI. #PANARTIDA#, Haeckel (Pl. 40, figs. 1-9).

Definition.--#Prunoidea# with a four-jointed cortical shell, the external shell being divided by three parallel transverse constrictions into four chambers, in the centre enclosing two internal concentric shells (medullary shells). Central capsule cylindrical, commonly four-jointed (with three transverse annular constrictions).

The family #Panartida# (Pl. 40, figs. 1-9) is characterised by its four-jointed cortical shell, constantly composed of four chambers, lying one behind another in the elongated main axis. They are separated by three ring-like constrictions lying in three parallel transverse planes; the middle of these is the equatorial plane. In the centre of this latter lies constantly a double medullary shell.

The Panartida must be derived from the Cyphinida by further increase in the longitudinal or main axis, and by repetition of the equatorial constriction in two transverse planes parallel to it and at an equal distance from it.

{376}The Medullary Shell is always double in this family, composed of two small concentric shells lying in the middle of the central capsule. They are either spherical or lenticular, compressed towards both poles of the main axis; sometimes the inner is spherical, the outer lenticular. From the equatorial circumference of the latter starts a number of radial beams, which perforate the central capsule, and are inserted into the equatorial constriction of the cortical shell. Commonly all radial beams lie in the equatorial plane, sometimes also a part of them on both sides of it.

The Cortical Shell is constantly composed of four completely latticed chambers, which are only separated by the three annular constrictions. In many species all four chambers have the same form and size (Pl. 40, fig. 3), but in the greater number of species both proximal (or central) chambers are different in size, shape, or structure from both distal (or polar) chambers. The cortical shell is either simple or double, composed of two concentric four-jointed shells; rarely it is triple or multiple, composed of three or more shells fitting one inside the other. Very often the outer cortical shell is incomplete, and only developed around the two proximal chambers of the complete inner cortical shell, both distal chambers of the latter remaining simple.

On both poles of the main axis often are developed solid spines (Panicium, Pl. 40, fig. 4) or hollow fenestrated tubes (Panarium, Pl. 40, fig. 9), as in the foregoing families. Besides this, the surface of the cortical shell may be armed with spines.

The Central Capsule of the Panartida is always cylindrical, on both poles hemispherical; commonly it is more or less distinctly four-jointed, with three ring-like constrictions corresponding to those of the enclosing cortical shell. From the inner surface of the latter it is separated by a thinner or thicker jelly-mantle.

Synopsis of the Genera of Panartida.

On both poles of the main { Cortical shell simple, 163. Panartus. axis neither peculiar { polar spines nor { Cortical shell double or fenestrated tubes. { triple, 164. Peripanartus.

On both poles of the main { Cortical shell simple, 165. Panicium. axis a large apical { spine or a group of { Cortical shell double or polar spines. { triple, 166. Peripanicium.

On both poles of the main { Cortical shell simple, 167. Panarium. axis a conical or { cylindrical fenestrated { Cortical shell double or tube. { triple, 168. Peripanarium.

Genus 163. Panartus,[202] n. gen.

Definition.--#Panartida# with simple cortical shell and double medullary shell, without polar spines or tubes on both poles of the main axis.

{377}The genus Panartus represents the common ancestral form of all Panartida, as all other genera of this subfamily must be derived from it and are only further developmental stages, from an ontogenetic as well as from a phylogenetic point of view. The cortical shell of Panartus is constantly composed of four fenestrated chambers jointed to one another in the main axis; both proximal chambers are separated from one another by the equatorial ring-like constriction, in the centre of which lies the double medullary shell; both distal chambers are separated from the former by two other annular constrictions (in planes parallel to the equatorial plane). All four chambers may exhibit the same (kidney-shaped) form and structure (in the subgenera Panartella and Panartoma); or the proximal chamber may differ more or less in shape and size from the distal (in the subgenera Panartissa and Panartura). The outer surface of the cortical shell is sometimes smooth (as in Panartella and Panartissa), at other times spiny or thorny (as in Panartoma and Panartura). The double medullary shell is sometimes spherical, or commonly compressed at both poles and spheroidal or lenticular.

Subgenus 1. Panartella, Haeckel.

Definition.--Surface of the cortical shell smooth, without spines or thorns. All its four chambers exhibit nearly the same form and structure.

1. Panartus tetraplus, n. sp.

All four chambers of the cortical shell of the same form, size, and structure, kidney-shaped, twice as broad as long. Pores rather regular, hexagonal, all nearly of the same size and form, four times as broad as the thin bars; five to six pores on the half meridian, nine to ten on the half equator of each chamber. Surface of the cortical shell smooth, its main axis three times as long as its equatorial axis (in the median constriction). Both concentric medullary shells spherical; the equatorial axis of the outer half as long as that of the cortical shell. (All four chambers of this species have the same appearance as the two proximal chambers of Panartus diploconus, Pl. 40, fig. 1.)

Dimensions.--Main axis of the cortical shell 0.21, equatorial axis 0.07; breadth of every chamber 0.09; meshes 0.013, bars 0.03.

Habitat.--Central area of the Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

2. Panartus tetracolus, n. sp.

All four chambers of the cortical shell of the same form, size, and structure, kidney-shaped, twice as broad as long. Pores regular, circular, with hexagonal frame, twice as broad as the bars; six to seven pores on the half meridian, ten to twelve on the half equator of each chamber. Surface of the cortical shell smooth; its main axis three times as long as the equatorial axis. Both concentric medullary shells spheroidal, somewhat compressed at both poles; the equatorial axis {378}of the outer almost equals half that of the cortical shell. (All four chambers of this species exhibit the structure of the two proximal chambers of Peripanartus amphiconus, Pl. 40, fig. 5.)

Dimensions.--Main axis of the cortical shell 0.24, equatorial axis 0.08; breadth of every chamber 0.01; meshes 0.01, bars 0.005.

Habitat.--Equatorial Atlantic, Station 348, depth 2450 fathoms.

3. Panartus tetrameres, n. sp.

All four chambers of the cortical shell of the same form, size, and structure, kidney-shaped, twice as broad as long. Pores rather regular, circular, without hexagonal frame, about as broad as the bars; five to six pores on the half meridian, ten to twelve on the half equator of each chamber. Surface of the cortical shell smooth, its main axis three times as long as the equatorial axis. Both concentric medullary shells spheroidal, compressed; the outer half as broad as the constriction. (This species is very much like Ommatocampe increscens, Stöhr, 1880, loc. cit., Taf. ii. fig. 2, and may be considered as the ancestral form of it.)

Dimensions.--Main axis of the cortical shell 0.2, equatorial axis 0.065; breadth of every chamber 0.08; meshes and bars 0.005.

Habitat.--Fossil in the Tertiary rocks of Sicily, Caltanisetta, Haeckel.

4. Panartus tetraphalangus, n. sp.

All four chambers of the cortical shell of the same form, size, and structure, kidney-shaped, twice as broad as long. Pores irregular, polygonal (mostly pentagonal or hexagonal), four to eight times as broad as the thin bars; four to seven on the half meridian, eight to fifteen on the half equator of each chamber. Surface of the cortical shell smooth, its main axis three times as long as its equatorial axis. Both concentric medullary shells compressed, the outer, half as broad as the constriction.

Dimensions.--Main axis of the cortical shell 0.26, equatorial axis 0.09; breadth of every chamber 0.12; meshes 0.003 to 0.02, bars 0.001 to 0.003.

Habitat.--Fossil in the rocks of Barbados, Haeckel.

5. Panartus tetrathalamus, n. sp. (Pl. 40, fig. 3).

All four chambers of the cortical shell of the same form, size, and structure, kidney-shaped, twice as broad as long. Pores irregular, roundish, twice to three times as broad as the bars; a circle of larger pores at the base of both distal chambers; five to six pores on the half meridian, ten to twelve on the half equator of each chamber. Surface of the cortical shell smooth; its main axis two and a half times as long as the equatorial axis. Both medullary shells spheroidal, compressed, the outer one-third as broad as the constriction. (In the specimen figured spines begin to arise from both distal chambers; this forms a transition to Panartus quadrijugus.)

Dimensions.--Main axis of the cortical shell 0.18, equatorial axis 0.07; breadth of every chamber 0.09; meshes 0.003 to 0.01, bars 0.002 to 0.004.

Habitat.--Cosmopolitan; Mediterranean, Atlantic, Pacific, in various depths.

{379}Subgenus 2. Panartissa.

Definition.--Surface of the cortical shell smooth, without spines or thorns. Both its proximal chambers differ in form and structure from the two distal chambers.

6. Panartus diploconus, n. sp. (Pl. 40, fig. 1).

Both proximal chambers nearly ellipsoidal, one and a half times as broad as long, with regular hexagonal pores, four times as broad as the bars; five to six pores on the half meridian, nine to ten on the half equator of each chamber. Both distal chambers conical, with a circle of ten to twelve large square pores at the base; the other pores very small and numerous, roundish, sixteen to twenty in the height of each cone, and the same number on the half periphery of its base. Both concentric medullary shells compressed, the outer, half as broad as the constriction of the cortical shell, the surface of which is quite smooth.

Dimensions.--Total length of the shell (or main axis) 0.34; greatest breadth of each chamber 0.09; pores of the proximal chambers 0.013, bars 0.003; pores and bars of the distal chambers 0.003; large basal square pores 0.02.

Habitat.--Pacific, central area, Station 272, depth 2600 fathoms.

7. Panartus amphiconus, n. sp.

Both proximal chambers nearly kidney-shaped, one and a half times as broad as long, with regular, circular pores, with hexagonal frames, twice as broad as the bars; six to seven pores on the half meridian, ten to twelve on the half equator of each chamber. Both distal chambers conical, with a circle of ten to twelve very large pores at the base; the other pores very small, roundish, ten to fifteen in the height of each cone, twenty to thirty on the half basal periphery. Both concentric medullary shells compressed, the outer one-third as broad as the constriction of the cortical shell, whose surface is smooth. (This species resembles Peripanartus amphiconus, Pl. 40, fig. 5, but is without the surface spines and the outer envelope.)

Dimensions.--Total length of the shell 0.28; greatest breadth of the proximal chambers 0.1, of the distal chambers 0.14; pores of the former 0.008, of the latter 0.004; bars of both 0.003 to 0.005.

Habitat.--North Pacific, Station 244, depth 2900 fathoms.

8. Panartus fusiformis, n. sp.

Both proximal chambers nearly ellipsoidal, one and a half times as long as broad, with irregular, roundish pores, twice to three times as broad as the bars; eight to ten pores on the half meridian, twelve to fifteen on the half equator of each chamber. Both distal chambers hemiellipsoidal or egg-shaped, somewhat higher and narrower than the proximal chambers, with a circle of larger square pores at their base; the other pores roundish and very irregular. Both medullary shells spheroidal, one-third as broad as the constriction of the cortical shell, whose surface is quite smooth. (This {380}species is similar to Peripanartus atractus, Pl. 40, fig. 7, but is without the superficial spines and the equatorial girdle-like envelope of the latter.)

Dimensions.--Total length of the shell 0.25 to 0.3; greatest breadth (in the equator of the proximal chambers) 0.08 to 0.1; pores of the proximal chambers 0.008 to 0.012, pores of the distal chambers half their size, bars 0.002 to 0.006.

Habitat.--North Pacific, Station 237, surface.

9. Panartus profundissimus, Haeckel.

Ommatocampe profundissima, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. viii. fig. 6.

Both proximal chambers nearly ellipsoidal, with irregular, polygonal pores, six to eight times as broad as the bars; four to five pores on the half meridian, eight to nine on the half equator of each chamber. Both distal chambers hemispherical, with a very delicate irregular network. Medullary shells spherical; surface of the shell smooth.

Dimensions.--Total length of the shell 0.15; greatest breadth in the equator of the proximal chambers 0.08; pores of the proximal chambers 0.015, bars 0.002.

Habitat.--Philippine Sea, depth 3300 fathoms, Ehrenberg; Station 213, depth 2050 fathoms.

Subgenus 3. Panartoma, Haeckel.

Definition.--Surface of the cortical shell thorny, covered with scattered spines. All its four chambers exhibit the same form and structure.

10. Panartus quadriceps, n. sp.

All four chambers of the cortical shell of the same form, size, and structure, kidney-shaped, twice as broad as long. Pores rather regular, circular, with hexagonal frames, twice to three times as broad as the bars; six to seven pores on the half meridian, ten to twelve on the half equator of each chamber. Surface spiny; from the corners of the hexagonal frames (between every three pores) arise short radial spines. Both medullary shells spherical, the outer one-third as broad as the constriction of the cortical shell. (All the four chambers of this species have the same form as the two proximal chambers of Peripanartus amphiconus, Pl. 40, fig. 5.)

Dimensions.--Main axis of the cortical shell 0.24, equatorial axis 0.08; meshes 0.01, bars 0.003 to 0.005; length of the spines 0.01 to 0.02.

Habitat.--Pacific, central area, Station 274, depth 2750 fathoms.

11. Panartus quadrijugus, n. sp.

All four chambers of the cortical shell of the same form and size, kidney-shaped, twice as broad as long. Pores irregular, roundish, twice to three times as broad as the bars; a circle of larger pores at the base of both distal chambers; six to eight pores on the half meridian, twelve to {381}fourteen on the half equator of each chamber. Surface spiny, everywhere covered with small irregular thorns. (This species differs from the smooth Panartus tetrathalamus, Pl. 40, fig. 3, almost entirely by the thorny surface.)

Dimensions.--Main axis 0.2, equatorial axis 0.08; breadth of every chamber 0.1; meshes 0.005 to 0.01, bars 0.003, spines 0.01 to 0.02.

Habitat.--Cosmopolitan; on the surface of the Atlantic, Indian, and Pacific Oceans.

12. Panartus quadrigeminus, n. sp.

All four chambers of the cortical shell nearly of the same size and form, kidney-shaped, twice as broad as long. Pores irregular, polygonal (mostly pentagonal or hexagonal), six to eight times as broad as the thin bars; five to seven on the half meridian, twelve to sixteen on the half equator of each chamber. Surface of the cortical shell spiny, covered with numerous irregularly scattered, often oblique, bristle-like thorns.

Dimensions.--Main axis 0.27, equatorial axis 0.1; breadth of each chamber 0.13; meshes 0.01 to 0.02, bars 0.001 to 0.005.

Habitat.--Cosmopolitan; surface of the Atlantic and Pacific, many Stations.

Subgenus 4. Panartura, Haeckel.

Definition.--Surface of the cortical shell thorny, covered with scattered spines. Both its proximal chambers differ in form or structure from the two distal chambers.

13. Panartus spinosus, n. sp.

Both proximal chambers nearly ellipsoidal, with regular, circular pores enclosed by hexagonal frames. Both distal chambers conical, with a circle of ten to twelve large square pores at the base; the other pores small, roundish. The cortical shell of this species is quite the same as that of Panartus amphiconus (Pl. 40, fig. 5), but differs in the absence of the external envelope (or the second cortical shell), and is covered with short, conical spines on the whole surface.

Dimensions.--Total length of the cortical shell 0.25, greatest breadth (on the base of the distal chambers) 0.12; meshes of the proximal chambers 0.008, of the distal chambers 0.004; bars 0.002 to 0.04, spines 0.01 to 0.02.

Habitat.--North Pacific, Station 240, surface.

14. Panartus setosus, Haeckel.

Ommatocampe setosa, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. viii. fig. 7.

Both proximal chambers kidney-shaped, broader than the two hemispherical distal chambers. Meshes of the cortical shell irregular, polygonal, or subregular hexagonal; at the base of each {382}distal chamber a circle of large square meshes. The breadth of the pores is eight to twelve times that of the bars between them. The whole surface is covered with small bristle-like spines.

Dimensions.--Total length of the cortical shell 0.14, greatest breadth (in the equator of each proximal chamber) 0.07; meshes 0.008 to 0.015, bars 0.002, spines 0.01.

Habitat.--Pacific (Philippine and Californian Sea) 3300 and 2300 fathoms, Ehrenberg; Station 200, depth 250 fathoms; Station 253, depth 3125 fathoms.

15. Panartus pluteus, n. sp. (Pl. 40, fig. 2).

Both proximal chambers kidney-shaped, with irregular, roundish pores, twice to four times as broad as the bars; their surface everywhere covered with short conical thorns. From both polar circles arise ten to twelve radial rods, which bear a fenestrated cap, and form thus either the beginning of a second, external, cortical shell, or (if remaining thus) two imperfect distal chambers. The spherical segment, which forms their surface, is concentric with the proximal chambers, is perforated by the same irregular, roundish pores, and covered with numerous bristle-like spines.

Dimensions.--Main axis of the cortical shell 0.17, equatorial axis (in the constriction) 0.06; distance between the proximal and distal chambers 0.03; pores 0.003 to 0.01, bars 0.003 to 0.005.

Habitat.--Pacific, central area, Station 272, depth 2600 fathoms.

Genus 164. Peripanartus,[203] n. gen.

Definition.--#Panartida# with double cortical shell and double medullary shell, without polar spines or tubes on both poles of the main axis.

The genus Peripanartus differs from Panartus only in the development of an outer reticulated envelop, which mantle-like surrounds the shell and represents a second or external cortical shell. This mantle or veil envelops either the whole internal cortical shell or only both proximal chambers. Peripanartus exhibits the same relation to Panartus as in the foregoing ancestral family Cypassis bears to Cyphonium.

Subgenus 1. Peripanartula, Haeckel.

Definition.--Surface of the outer cortical shell smooth, without spines or thorns.

1. Peripanartus palliatus, n. sp.

Internal cortical shell with four kidney-shaped chambers of equal size and similar form, identical with the cortical shell of Panartus tetrathalamus and Panartus quadrijugus (Pl. 40, fig. 3), with irregular, roundish pores, twice to three times as broad as the bars. It differs from these two species {383}only by the external cortical shell enveloping the whole internal one, in the same manner as in Peripanartus cylindrus (Pl. 40, fig. 6). The two shells are connected by numerous radial rods. The surface of the outer cortical shell is quite smooth, its irregular, roundish pores about half as large as those of the inner cortical shell.

Dimensions.--Main axis of the external cortical shell 0.27, of the internal 0.2; greatest breadth of the former (in the equator of each chamber) 0.13, of the latter 0.09; pores of the external cortical shell 0.002 to 0.004, of the internal 0.004 to 0.008; bars of the former 0.002, of the latter 0.003.

Habitat.--Pacific, central area, Stations 271, 272, depth 2425 to 2600 fathoms.

2. Peripanartus lævigatus, n. sp.

Internal cortical shell with four unequal chambers, both proximal kidney-shaped (with subregular polygonal pores, twice to three times as broad as the bars), both distal nearly hemispherical, with subregular, roundish pores of half that size. External cortical shell envelops only the proximal chambers, and appears as the direct continuation of the internal shell of the distal chambers, with the same small roundish pores. The outer surface is quite smooth. This species has nearly the same structure as Peripanicium amphicorona (Pl. 40, fig. 8), but differs from it by the absence of the polar spine-circles, and by the perfect smoothness of the surface.

Dimensions.--Main axis of the shell 0.25, greatest breadth (in the equator of the proximal chambers) 0.15; equatorial stricture of the external shell 0.10, of the internal 0.07; pores of the internal shell of the proximal chambers 0.013, of the external 0.006; bars 0.003.

Habitat.--Pacific, central area, Station 274, depth 2750 fathoms.

3. Peripanartus amphiconus, n. sp. (Pl. 40, fig. 5).

Inner cortical shell with four very unequal chambers; both proximal chambers kidney-shaped (with regular, circular, hexagonally framed pores, twice as broad as the bars); both distal chambers conical, with a circle of large square pores at the base, the other pores very small, roundish. Outer cortical shell very thin, quite smooth, with irregular, roundish pores, envelops in younger specimens only the distal chambers. But the radial spines on the surface of the internal cortical shell of the proximal chambers indicate that these will also be afterwards enclosed by the growing of the external shell. This species exhibits the progressive (ontogenetic as well as phylogenetic) development of Panartus amphiconus.

Dimensions.--Main axis of the outer cortical shell 0.3, its greatest breadth (at the prominent distal ends of the radial rods between the large square pores) 0.15; pores 0.003 to 0.001, bars 0.005; main axis of the inner cortical shell 0.26, its greatest breadth 0.13; pores of its distal chambers 0.003, of its proximal chambers 0.01; large square pores 0.03; bars 0.004.

Habitat.--Pacific, central area, Station 270, depth 2925 fathoms.

{384}Subgenus 2. Peripanartium, Haeckel.

Definition.--Surface of the outer cortical shell covered with spines or thorns.

4. Peripanartus atractus, n. sp. (Pl. 40, fig. 7).

Inner cortical shell with four very unequal chambers; both proximal chambers spheroidal (with subregular, roundish pores, twice to three times as broad as the bars), both distal chambers nearly conical, with a circle of eight to ten very large square pores at the base; the other pores very small, roundish. Outer cortical shell envelops only the proximal chambers and the basal half of the distal chambers, appearing as the direct continuation of the microporous covering of their apical half. The whole external cortical shell is inflated in the equatorial zone, and hence assumes an irregular, spindle-like appearance. Its whole surface is rough with innumerable very short thorns.

Dimensions.--Main axis 0.28, equatorial axis 0.17; pores of the external cortical shell 0.002 to 0.004, bars 0.002; main axis of the proximal chambers of the internal cortical shell 0.07, equatorial axis 0.09; pores 0.007, bars 0.004.

Habitat.--North Pacific, Station 244, depth 2900 fathoms.

5. Peripanartus cylindrus, n. sp. (Pl. 40, fig. 6).

Internal cortical shell with four unequal chambers; both proximal chambers kidney-shaped (with regular, circular, hexagonally framed pores of the same breadth as the bars), both distal chambers nearly hemispherical, with a circle of eight to ten very large square pores at their base; the other pores very small, roundish. External cortical shell envelops the whole internal like a perfect hollow cylinder, which is closed at both poles by a hemispherical cap. The whole surface of this cylindrical mantle is perforated by innumerable very small roundish pores, and covered with small bristle-like spines.

Dimensions.--Main axis of the cylinder 0.3, equatorial axis 0.12; pores and bars 0.006; spines of its surface 0.012 to 0.15; main axis of the internal cortical shell 0.2; equatorial axis (in the constriction) 0.06; pores and bars of its proximal chambers 0.007, of its distal chambers 0.003; large square pores at their base 0.02.

Habitat.--Pacific, central area, Stations 270 to 274, depth 2350 to 2925 fathoms.

Genus 165. Panicium,[204] n. gen.

Definition.--#Panartida# with simple cortical shell and double medullary shell, with two opposite apical spines on both poles of the main axis, or with a group of polar spines.

The genus Panicium comprises those forms of Panartus which develop a peculiar armature on both poles of the cortical shell. This may be only a single strong spine {385}on each pole, lying in the main axis (subgenus Panicidium); or a bunch or a circle of polar spines diverging radially (subgenus Panartidium); in the latter case the polar spines can either form a bunch on the pole itself, or a crown of thorns around it.

Subgenus 1. Panicidium, Haeckel.

Definition.--On both poles of the main axis only a single large spine.

1. Panicium amphacanthum, n. sp.

All four chambers of the cortical shell nearly of the same size and form, kidney-shaped, with subregular, circular pores, twice as broad as the bars; five to six pores on the half meridian, ten to eleven on the half equator of each chamber. Surface covered with small spines. On both poles of the main axis is a very strong, conical, apical spine, half as long as the main axis, on the base one-fourth as broad as the equatorial axis.

Dimensions.--Main axis (without polar spines) 0.22, equatorial axis 0.06; pores 0.01, bars 0.005; length of the polar spines 0.12, basal thickness 0.015.

Habitat.--Antarctic, Station 152, depth 1260 fathoms.

2. Panicium amphistylus, n. sp.

Both proximal chambers kidney-shaped, both distal chambers nearly hemispherical, somewhat smaller. Pores irregular, roundish, twice to three times as broad as the bars; four to six on the half meridian, eight to ten on the half equator of each chamber; a circle of larger square pores on the base of each distal chamber. Surface thorny. On both poles of the main axis one strong, pyramidal, apical spine, one-third as long as the main axis, on the base one-fourth as broad as the equatorial constriction. (Similar to Panarium tubularium, Pl. 40, fig. 9, but without tubes.)

Dimensions.--Main axis (without polar spines) 0.2, equatorial axis 0.05; pores 0.005 to 0.01, bars 0.003; length of the polar spines 0.07, basal thickness 0.012.

Habitat.--Antarctic, Station 156, depth 1975 fathoms.

Subgenus 2. Panartidium, Haeckel.

Definition.--On both poles of the main axis a bunch or a circle of aggregated spines.

3. Panicium scoparium, n. sp.

Both proximal chambers kidney-shaped, both distal chambers nearly hemispherical, somewhat smaller. Pores irregular, polygonal, twice to five times as broad as the bars; six to eight on the half meridian, twelve to fourteen on the half equator of each chamber. Surface spiny, covered with thin, {386}bristle-like spines. On both poles of the main axis a bunch of six to eight aggregated larger conical spines, about as high as a single chamber.

Dimensions.--Main axis (without polar spines) 0.2, equatorial axis 0.06; pores 0.005 to 0.015, bars 0.003; length of the polar spines 0.05, basal thickness 0.005.

Habitat.--Pacific, central area, Stations 270 to 274, depth 2350 to 2925 fathoms.

4. Panicium coronatum, n. sp. (Pl. 40, fig. 4).

Both proximal chambers kidney-shaped, covered with short stout spines. Pores irregular, roundish, twice to four times as broad as the bars; seven to eight on the half meridian, eleven to thirteen on the half equator of each chamber. Both distal chambers cap-like, separated from the former by a circle of ten to twelve very large square pores; the other pores very small, roundish. The circumpolar area is smooth, surrounded by a circle of ten to twelve very stout, conical, radial spines, which arise from the distal ends of the bars separating the large square meshes.

Dimensions.--Main axis (without spines) 0.22, equatorial axis 0.08; greatest breadth in the equator of the chambers 0.1; pores of the proximal chambers 0.007 to 0.015, bars 0.004; square pores of the distal chambers 0.02 to 0.03, small pores 0.005, bars 0.004; length of the radial spines of the polar circles 0.07, basal thickness 0.007.

Habitat.--Pacific, central area, Station 271, depth 2425 fathoms.

Genus 166. Peripanicium,[205] n. gen.

Definition.--#Panartida# with double cortical shell and double medullary shell, on both poles of the main axis with two opposite apical spines, or with a bunch or circle of polar spines.

The genus Peripanicium differs from Panicium only in the development of an outer reticulated envelope, which mantle-like surrounds the shell, and represents a second or external cortical shell. As in Panicium, its ancestral form, so also in Peripanicium, there can be distinguished two subgenera:--Peripanicea, where only a single large spine arises from each pole (lying in the main axis), and Peripanicula, where a variable number of spines is to be found, either diverging bunch-like from the pole itself, or surrounding it as a crown-like polar circle.

Subgenus 1. Peripanicea, Haeckel.

Definition.--On both poles of the main axis only a single large spine.

1. Peripanicium amphixiphus, n. sp.

Internal cortical shell with four unequal chambers, with thorny surface. Both proximal chambers kidney-shaped (with subregular hexagonal pores, three times as broad as the bars). {387}Both distal chambers nearly hemispherical (with a circle of ten to twelve very large square pores at their base, the other pores very small). From both poles arises a single, strong, conical spine, half as long as the main axis. The internal cortical shell is very much like that of Panarium tubularium (Pl. 40, fig. 9), but differs by the solid polar spines (instead of the hollow tubules) and by the formation of an external, cylindrical, very thin, cortical shell, which envelops the whole internal, and is connected with it by numerous beams. The surface of the external shell is quite smooth, and perforated by innumerable very small roundish pores.

Dimensions.--Main axis of the external cortical shell 0.25, of the internal 0.19; transverse axis of the former 0.13, of the latter 0.08; pores of the proximal chambers of the internal shell 0.01, bars 0.003; pores of external cortical shell 0.002, bars 0.001; length of both polar spines 0.12, basal thickness of them 0.02.

Habitat.--South Atlantic, near Tristan da Cunha, Station 333, depth 2025 fathoms.

Subgenus 2. Peripanicula, Haeckel.

Definition.--On both poles of the main axis a bunch or a circle of aggregated polar spines.

2. Peripanicium amphicorona, n. sp. (Pl. 40, fig. 8).

Peripanartus amphicorona, Haeckel, 1881, Prodromus et Atlas (pl. xl. fig. 8).

Internal cortical shell with four very unequal chambers. Both proximal chambers kidney-shaped, with subregular, polygonal pores, three times as broad as the bars. Both distal chambers double cone-shaped; the proximal cone of these formed by a circle of ten to twelve radial beams, which separate the same number of large square meshes; the distal cone with five to six circles of very small roundish, irregular pores. The continuation of the thin porous lamella of this distal cone forms the external cortical shell, whose surface is a little rough with innumerable very small thorns. On both poles is a large circular opening (nearly as broad as the equatorial constriction of the inner shell), surrounded by a delicate crown of thorns. The spines of this crown equal the diameter of the polar opening; they are very thin and bristle-like, connected by a few bridges and diverge outwards.

Dimensions.--Main axis (without the crowns of polar thorns) 0.26, greatest breadth (in the equator of the proximal chambers) 0.15; equatorial constriction of the external shell 0.12, of the internal 0.07; pores of the proximal chambers of the internal cortical shell 0.01, of the external 0.005, bars 0.003; diameter of the circular polar opening 0.05; length of the polar spines 0.05.

Habitat.--Pacific, central area, Station 271, depth 2425 fathoms.

3. Peripanicium coronarium, n. sp.

Internal cortical shell with four unequal chambers. Both proximal chambers kidney-shaped, with irregular, roundish pores, twice to four times as broad as the bars. Both distal chambers cap-like, with a basal circle of ten to twelve large square meshes, the other pores very small. External {388}cortical shell very thin, with smooth surface, and very small, irregular, roundish pores; it envelops the whole internal shell at a constant distance, which equals the breadth of the square meshes. From the distal ends of the radial beams between the square meshes arise on every polar circle ten to twelve strong spines, as direct prolongations of those beams. These form two regular, polar crowns of thorns. The inner part of the thorns (between both shells) has only one-third to one-fourth the length of the outer free part. (This species represents a further development of Panicium coronatum, Pl. 40, fig. 4, by secondary formation of an external mantle, like that of Peripanartus atractus, Pl. 40, fig. 7.)

Dimensions.--Main axis 0.27, greatest breadth 0.15; pores of the internal proximal chambers 0.008 to 0.016, bars 0.004; square meshes of the distal chambers 0.03; pores of the outer cortical shell 0.003; length of the spines of the polar circles 0.1 to 0.15.

Habitat.--Pacific, central area, Station 274, depth 2750 fathoms.

Genus 167. Panarium,[206] Haeckel, 1881, Prodromus, p. 463.

Definition.--#Panartida# with simple cortical shell and double medullary shell, with two hollow fenestrated tubes, opposite on the poles of the main axis.

The genus Panarium differs from Panartus by two hollow latticed tubes, which start from both poles of the main axis and lie in it. It repeats therefore in this family the same peculiar and remarkable formation, which we find in Pipettella among the Ellipsida, in Pipetta among the Druppulida, in Cannartidium among the Cyphinida, in Cannartus among the Artiscida, &c.

Subgenus 1. Panarelium, Haeckel.

Definition.--Surface of the shell smooth, without spines or thorns.

1. Panarium facettarium, n. sp.

Surface of the cortical shell smooth. All the four chambers nearly of the same size and form, kidney-shaped, about twice as broad as long. Pores of these subregular, circular, with hexagonal frames, about as broad as the bars; nine to ten on the half meridian, twelve to fourteen on the half equator of each chamber. Polar tubuli nearly cylindrical, longer than half the main axis of the cortical shell, about one-fourth as broad as the equatorial constriction. Pores of the tubuli of the same shape as those of the chambers, but only half as large. (This species is like Pipetta tuba, Pl. 39, fig. 7, but distinguished by three parallel transverse constrictions.)

Dimensions.--Total length of the shell (without tubuli) 0.26; breadth of each chamber 0.12; pores 0.01, bars 0.01; length of the tubuli 0.15, breadth of them 0.03.

Habitat.--Pacific central area, Station 268, depth 2900 fathoms.

{389}2. Panarium pipettarium, n. sp.

Surface of the cortical shell smooth. Both proximal chambers nearly kidney-shaped; both distal chambers somewhat smaller, hemispherical. Pores of all four chambers subregular, circular, without hexagonal frames, twice as broad as the bars; six to seven pores on the half meridian, ten to eleven on the half equator of each chamber. Polar tubuli slender, conical, nearly half as long as the main axis of the shell, one-third as broad at the base as the equatorial constriction. Pores of the tubuli of the same shape as those of the chambers, but only half as large. (This species resembles somewhat Cannartiscus amphiconiscus, Pl. 39, fig. 19, but with double the number of chambers.)

Dimensions.--Total length of the shell (without tubuli) 0.25, greatest breadth 0.1; pores 0.008, bars 0.004; length of the polar tubuli 0.11, basal breadth 0.03.

Habitat.--Pacific, western tropical part, Station 225, depth 4475 fathoms.

Subgenus 2. Panaromium, Haeckel.

Definition.--Surface of the shell spiny, covered with short thorns.

3. Panarium annularium, n. sp.

Surface of the cortical shell thorny, everywhere covered with small bristle-like spines. All four chambers nearly of the same size and form, kidney-shaped. Their pores subregular, circular, three to four times as broad as the bars; seven to eight on the half meridian, ten to eleven on the half equator of each chamber. Polar tubuli conical, nearly half as long as the main axis, half as broad at the base as the equatorial constriction. Pores of the tubuli like those of the chambers, but only half as broad.

Dimensions.--Total length of the shell (without tubuli) 0.16; breadth of each chamber 0.07; pores 0.006 to 0.008, bars 0.002; length of the polar tubuli 0.07, basal breadth 0.03.

Habitat.--Northern Pacific, Station 253, depth 3125 fathoms.

4. Panarium artophorum, n. sp.

Surface of the shell thorny, with scattered small spines. Both proximal chambers nearly kidney-shaped; both distal hemispherical, somewhat smaller. Pores of all chambers irregular, roundish, little broader than the bars; four to five on the half meridian, six to eight on the half equator of each chamber. Polar tubuli cylindrical, longer than the half main axis, only one-fourth as broad the equatorial constriction. Pores of the tubuli only one-third to one-fourth as broad as those of the chambers.

Dimensions.--Total length of the shell (without tubuli) 0.22, greatest breadth (in the equator of the proximal chambers) 0.09; pores and bars 0.008 to 0.012; length of the polar tubuli 0.14, breadth of them 0.02.

Habitat.--Southern Pacific, Station 289, depth 2550 fathoms.

{390}5. Panarium tubularium, n. sp. (Pl. 40, fig. 9).

Surface of the cortical shell thorny, covered with small spines. Both proximal chambers nearly kidney-shaped, with irregular, polygonal pores, three to four times as broad as the bars; five to six pores on the half meridian, nine to ten on the half equator of each chamber. Both distal chambers nearly hemispherical, with a circle of ten to twelve large square pores at their base; the other pores much smaller, irregular, roundish. Polar tubuli prismatic, with prominent edges, nearly half as long as the main axis, only one-fourth as broad as the equatorial constriction. Pores of the tubuli very small, in longitudinal series between the edges.

Dimensions.--Total length of the shell (without tubuli) 0.18 to 0.2, greatest breadth (in the equator of the proximal chambers) 0.07 to 0.09; pores 0.003 to 0.01, bars 0.002 to 0.004; length of the polar tubuli 0.06 to 0.09, breadth of them 0.015 to 0.02.

Habitat.--Pacific, central area, Stations 270 to 272, depth 2425 to 2925 fathoms.

Genus 168. Peripanarium,[207] n. gen.

Definition.--#Panartida# with double cortical shell and double medullary shell, with two hollow fenestrated tubes, opposite on the poles of the main axis.

The genus Peripanarium differs from Panarium only in the development of an outer reticulated envelop, which mantle-like surrounds the shell and represents a second or external cortical shell. It bears therefore to Panarium the same relation as Peripanartus to Panartus, &c.

1. Peripanarium cenoconicum, n. sp.

Internal cortical shell with four kidney-shaped chambers of nearly the same form and size; their pores irregular, roundish, twice to four times as broad as the bars. External cortical shell cylindrical, hemispherical at both poles, with irregular, very small, roundish pores, only one-third to one-half as large as those of the internal. From both poles of the internal cortical shell arises a hollow conical fenestrated tube, which perforates the external. The outer free part of this slender cone equals in length the inner part or the distance between the two cortical shells, which is about equal to the length of one chamber. External surface covered with small thorns. (This species has the same appearance as Desmartus larvalis, Pl. 40, fig. 12, but has only four chambers instead of six.)

Dimensions.--Main axis (without cones) 0.23, greatest breadth 0.11; pores of the inner cortical shell 0.004 to 0.009, of the outer 0.002 to 0.003; bars of the former 0.002, of the latter 0.001; total length of the polar cones 0.05, basal thickness of them 0.03.

Habitat.--West Tropical Pacific, Station 225, depth 4475 fathoms.

{391}2. Peripanarium cenocylindricum, n. sp.

Internal cortical shell with four unequal chambers, the two proximal kidney-shaped, the two distal conical, and somewhat smaller; pores irregular, polygonal-roundish, twice to five times as broad as the bars. External cortical shell nearly spindle-shaped, in the equatorial zone inflated, conical, tapering towards both poles, its pores very small, roundish, its surface covered with small thorns. The shell of this species resembles very much Peripanartus atractus (Pl. 40, fig. 7), but differs by the hollow cylindrical polar tubes, which arise from both poles of the inner cortical shell and attain more than half the length of the main axis. They are open at their ends (broken away), about as broad as the outer medullary shell, and perforated by irregular, roundish pores.

Dimensions.--Main axis (without polar tubes) 0.28, greatest breadth (in the equator) 0.16; pores of the inner cortical shell 0.004 to 0.01, of the outer 0.002 to 0.005; bars of the former 0.004, of the latter 0.002; total length of the polar tubes 0.16, breadth of them 0.03.

Habitat.--Pacific, central area, Station 268, depth 2900 fathoms.

Family XVII. #ZYGARTIDA#, Haeckel (Pl. 40, figs. 10-13).

Zygartida, Haeckel, 1881, Prodromus, p.462 (sensu restricto).

Definition.--#Prunoidea# with annulated cortical shell, the external shell being divided by five or more parallel transverse constrictions into six or more chambers, enclosing in the centre two internal concentric shells (medullary shells). Central capsule cylindrical, commonly annulated (corresponding to the transverse annular constrictions of the cortical shell).

The family #Zygartida#, the seventh and last of the #Prunoidea#, comprises, in the sense here restricted, all those #Prunoidea# in which the cortical shell is annulated and composed of six to twenty or more (at least six) cameræ, lying one behind another in the elongated main axis, and separated by five or more annular constrictions. When I constituted this family in 1881 (loc. cit.), I had given to it a much wider extent, embracing all those #Prunoidea# which exhibit annular constrictions of the cortical shell; as the number of these, in consequence of further researches, is much increased, it seems now more convenient to restrict the family to the extent here given.

No doubt the Zygartida must be derived from the Panartida by progressive growth of the cortical shell in the main axis and accompanying increase of the number of its chambers. Whilst this number in the Panartida is constantly restricted to four, in the Zygartida it amounts to ten, twenty, or more, and is in the lowest case six (Pl. 40, fig. 10). The maximum number is variable in the different species, but of course also different in the various degrees of individual development. Each Zygartid is at the beginning of its growth a Cyphinid, later a Panartid. The number of the annular constrictions separating the chambers and lying in parallel transverse planes is at least {392}five, but may amount to nineteen, to twenty-one or more; they lie constantly in pairs on both sides of the equatorial constriction (Pl. 40, figs. 12, 13).

The cortical shell may either remain simple (Ommatocampe, Pl. 40, fig. 10), or become double (Desmocampe, Pl. 40, fig. 12), or sometimes triple (Zygocampe, Pl. 40, fig. 13). In the latter cases the outer (secondary and tertiary) cortical shells are commonly incomplete, and only developed around the proximal chambers of the complete first (primary) cortical shell, its distal chambers remaining simple.

The Medullary Shell is constantly double, as in the Panartida; its form is either spherical or lenticular, compressed in the direction of the main axis. It is always connected with the equatorial constriction of the cortical shell by a number of radial beams, lying either in the equatorial plane or on each side of it (Pl. 40, figs. 10-13).

The Central Capsule of the Zygartida is constantly cylindrical; its increasing growth on both poles of the axis corresponds to that of the including cortical shell. Commonly (but not always) its cylindrical surface is annulated, with five or more transverse strictures, corresponding to those of the cortical shell. From the inner surface of the latter it is separated by a jelly-mantle, the calymma.

Synopsis of the Genera of Zygartida.

I. Ommacampida. { Without polar tubes, 169. Ommatocampe. 1. Cortical shell { simple. { With two hollow fenestrated (Medullary shell { tubes, on the poles of double.) { the axis, 170. Ommatartus.

II. Desmocampida. { Without polar tubes, 171. Desmocampe. 2. Cortical shell { double. { With two hollow fenestrated (Medullary shell { tubes, on the poles of double.) { the axis, 172. Desmartus.

III. Zygocampida. { Without polar tubes, 173. Zygocampe. 3. Cortical shell { triple. { With two hollow fenestrated (Medullary shell { tubes, on the poles of double.) { the axis, 174. Zygartus.

Genus 169. Ommatocampe,[208] Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 832.

Definition.--#Zygartida# with simple cortical shell and double medullary shell, without polar tubes.

The genus Ommatocampe was founded by Ehrenberg in 1860 for one of his "Haliommatina," with the following diagnosis:--"Shell rod-like, long, articulate, with nucleus, without spines, with four or more joints." The species figured by him, Ommatocampe {393}polyarthra, exhibits five pairs of chambers on both sides of the meridian plane of the cortical shell, the centre of which includes a double medullary shell. It represents the most simple form of all Zygartida, and may be derived phylogenetically from Cyphonium simply by multiplication of the chambers of the cortical shell, growing on both poles of the main axis.

Subgenus 1. Ommatocampium.

Definition.--Surface of the cortical shell smooth or rough, without thorns or spines, also without polar spines.

1. Ommatocampe polyarthra, Ehrenberg.

Ommatocampe polyarthra, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 279, Taf. vi. fig. 9.

Cortical shell with smooth surface, composed of six to ten chambers of the same size and form. Every chamber kidney-shaped, about twice as broad as long, with three transverse rows of circular, subregular pores, twice to three times as broad as the bars. Both medullary shells spherical.

Dimensions.--Length of the six-chambered cortical shell 0.15; greatest breadth of each chamber 0.04; pores 0.005 to 0.007, bars 0.002 to 0.003.

Habitat.--Californian Sea, depth 2600 fathoms, Ehrenberg; Pacific, central area, Station 268, depth 2900 fathoms; fossil in the Tertiary rocks of Barbados, Haeckel.

2. Ommatocampe increscens, Stöhr.

Ommatocampe increscens, Stöhr, 1880, Palæontogr., vol. xxvi. p. 90, Taf. ii. fig. 2, a, b.

Cortical shell with rough surface, composed of six to ten chambers of nearly the same size and form; the breadth of the chambers a little increasing towards both poles. Every chamber kidney-shaped, the proximal chambers twice as broad as long, with four or five transverse rows of pores; the distal chambers three to four times as broad as long, with two or three transverse rows of pores. Form of the pores irregular, roundish, bars between them in the distal part smaller, in the proximal part larger than the pores. Both medullary shells compressed lenticular.

Dimensions.--Length of the six-chambered cortical shell 0.22; greatest breadth of the chambers 0.09 to 0.1; pores and bars 0.003 to 0.006.

Habitat.--Fossil in the Tertiary rocks of Sicily, Grotte, Stöhr.

3. Ommatocampe annulata, n. sp.

Cortical shell with smooth surface, composed of six to twelve chambers of nearly the same size and form. Each chamber kidney-shaped, twice as broad as long, with four to five transverse rows of {394}irregular, roundish pores, once to five times as broad as the bars. On the base of each distal chamber (beginning in the second or third pair) a circle of twelve to sixteen larger square pores. Both medullary shells compressed lenticular. (Resembles the inner cortical shell of Desmartus larvalis, Pl. 40, fig. 12, but is without the polar tubes and the outer envelope of this species.)

Dimensions.--Length of the six-chambered cortical shell 0.23; greatest breadth of each chamber 0.07; pores 0.002 to 0.01, bars 0.002.

Habitat.--Cosmopolitan; Mediterranean, Atlantic, Pacific, in various depths.

Subgenus 2. Ommatocampula, Haeckel.

Definition.--Surface of the cortical shell thorny or spiny, but without peculiar polar spines and without regular coronals of spines.

4. Ommatocampe erucæformis, n. sp.

Cortical shell with spiny surface, composed of six to twelve chambers of nearly the same size and form, the distal chambers a little smaller. The form and structure of the cortical shell is nearly the same as in the foregoing species, only the pores are somewhat larger, and the whole surface is covered with bristle-like radial spines, about half as long as the breadth of one chamber. Both medullary shells compressed and lenticular.

Dimensions.--Length of the six-chambered cortical shell 0.24; greatest breadth of each chamber 0.08; pores 0.005 to 0.012, bars 0.002.

Habitat.--North Atlantic, Canary Islands, Station 353, depth 2965 fathoms.

5. Ommatocampe nereis, n. sp. (Pl. 40, fig. 10).

Cortical shell with spiny surface, composed of six (or more) chambers of different size and structure. Both proximal chambers kidney-shaped, with subregular, circular, hexagonally framed pores, twice as broad as the bars. All following chambers cap-like, with much smaller, irregular, roundish pores, at the base of every chamber a circle of ten to twelve large square pores. Spines of the surface short, irregularly scattered. Both medullary shells spherical. (All the observed specimens possessed only six chambers.)

Dimensions.--Length of the six-chambered cortical shell 0.25; greatest breadth of each chamber 0.08; pores of both proximal chambers 0.01, bars 0.005; basal pores of the other chambers 0.02; pores of their distal caps 0.003 to 0.006, bars 0.003.

Habitat.--Pacific, central area, Stations 271 to 274, depth 2350 to 2750 fathoms.

Subgenus 3. Ommatocorona, Haeckel.

Definition.--Surface of the cortical shell spiny, on every chamber a regular circle or coronal of radial spines.

{395}6. Ommatocampe chætopodum, n. sp.

Cortical shell with spiny surface, composed of six (or more) kidney-shaped chambers of different size and form. Both proximal chambers kidney-shaped, with subregular, circular, hexagonally framed pores, about as broad as the bars. All the following chambers hemispherical, with irregular, roundish pores; at the base of every chamber a circle of ten to twelve larger square pores. The beams between these latter are prolonged into free radial spines, twice as thick as the bars. Therefore every chamber is surrounded by a circle of radial spines, like those of Panicium coronatum (Pl. 40, fig. 4). Both medullary shells lenticular.

Dimensions.--Length of the six-chambered cortical shell 0.3, greatest breadth 0.08, pores and bars of both proximal chambers 0.01; pores of the other chambers 0.002 to 0.008; square pores 0.02, bars 0.005; length of the coronal spines 0.03, thickness 0.01.

Habitat.--Indian Ocean, Madagascar, Rabbe.

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