Name: Report on the Radiolaria Collected by H.M.S. Challenger During the Years 1873-1876, First Part: Porulosa (Spumellaria and Acantharia) Report on the Scientific Results of the Voyage of H.M.S. Challenger During the Years 1873-76, Vol. XVIII
Author: Haeckel, Ernst

XI. LITERATURE AND HISTORY (part 1 of 5)

251. List of Publications from 1834 to 1884:--

Note.--In the text the references to the following publications are indicated by the letters L. N.

1. 1834. MEYEN, F., Palmellaria (Physematium, Sphærozoum), in Beiträge zur Zoologie, gesammelt auf einer Reise um die Erde. Nova Acta Acad. Cæs. Leop.-Carol., vol. xvi., Suppl., p. 160, Taf. xxviii. figs. 1-7.

2. 1838. EHRENBERG, G., Polycystina (Lithocampe, Cornutella, Haliomma) in Ueber die Bildung der Kreidefelsen und des Kreidemergels durch unsichtbare Organismen. Abhandl. d. k. Akad. d. Wiss. Berlin, p. 117.

3. 1839. EHRENBERG, G., Ueber noch jetzt lebende Thierarten der Kreidebildung (Haliomma radians). Abhandl. d. k. Akad. d. Wiss. Berlin, p. 154.

4. 1844-1873. EHRENBERG, G., Vorläufige Mittheilungen über Beobachtungen von Polycystinen. Monatsber. d. k. preuss. Akad. d. Wiss. Berlin. Republished with illustrations in the Mikrogeologie (L. N. 6) and in the two treatises of 1872 (L. N. 24) and 1875 (L. N. 25). Compare the Monatsberichte of 1844 (pp. 57, 182, 257), of 1846 (p. 382), of 1847 (p. 40), of 1850 (p. 476), of 1854 (pp. 54, 205, 236), of 1855 (pp. 292, 305), of 1856 (pp. 197, 425), of 1857 (pp. 142, 538), of 1858 (pp. 12, 30), of 1859 (p. 569), of 1860 (pp. 765, 819), of 1861 (p. 222), of 1869 (p. 253), of 1872 (pp. 300-321), of 1873 (pp. 214-263). Only one of these small papers is of permanent value, The First Systematic Arrangement of the Polycystina in 7 families, 44 genera, and 282 species (Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, 1847, p. 54). Compare my Monograph (1862, L. N. 16), pp. 3-12, 214-219.

5. 1851. HUXLEY, TH., Upon Thalassicolla, a new Zoophyte. Ann. and Mag. Nat. Hist., ser. 2, vol. viii. pp. 433-442, pl. xvi.

6. 1854. EHRENBERG, G., Mikrogeologie. Figures of numerous Polycystina on 8 plates; Taf. xviii. figs. 110, 111; Taf. xix. figs. 48-56, 60-62; Taf. xx. Nr. i., figs. 20-25, 42; Taf. xxi. figs. 51-56; Taf. xxii. figs. 20-40; Taf. xxxv. A., Nr. xix. A. fig. 5; Taf. xxxv. B. figs. 16-23; Taf. xxxvi. figs. 1-33.

7. 1855. BAILEY, J. W., Notice of Microscopic Forms of the Sea of Kamtschatka. Amer. Journ. Sci. and Arts, vol. xxii. p. 1, pl. i.

8. 1855. MÜLLER, JOHANNES, Ueber Sphærozoum und Thalassicolla. Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 229.

9. 1855. MÜLLER, JOHANNES, Ueber die im Hafen von Messina beobachteten Polycystinen (Haliomma, Eucyrtidium, Dictyospyris, Podocyrtis). Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 671.

10. 1856. MÜLLER, JOHANNES, Ueber die Thalassicollen, Polycystinen und Acanthometren des Mittelmeeres. Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 474.

11. 1858. MÜLLER, JOHANNES, Erläuterung einiger bei St. Tropez am Mittelmeer beobachteter Polycystinen und Acanthometren. Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 154.

12. 1858. MÜLLER, JOHANNES, Ueber die Thalassicollen, Polycystinen und Acanthometren des Mittelmeeres, Abhandl. d. k. Akad. d. Wiss. Berlin, pp. 1-62, Taf. i.-xi. (The fundamental treatise on the Radiolaria.)

{clxxvii}13. 1858. SCHNEIDER, ANTON, Ueber zwei neue Thalassicollen von Messina. Archiv f. Anat. u. Physiol., p. 38, Taf. iii. B, figs. 1-4.

14. 1858. CLAPARÈDE et LACHMANN, Echinocystida (Plagiacantha et Acanthometra). Études sur les Infusoires et les Rhizopodes, p. 458, pl. xxii. figs. 8, 9; pl. xxiii. figs. 1-6.

15. 1860. HAECKEL, ERNST, Ueber neue lebende Radiolarien des Mittelmeeres. Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, pp. 794, 835.

16. 1862. HAECKEL, ERNST, Die Radiolarien (Rhizopoda radiaria). Eine Monographie. 572 pp. fol. with an Atlas of 35 Copperplates.

17. 1862. BURY, Mrs., Polycystins, figures of remarkable forms in the Barbados Chalk Deposit. Ed. ii. By M. C. Cooke, 1868. 25 quarto plates, photographed from drawings by hand, containing many forms overlooked by Ehrenberg from Barbados.

18. 1863 HARTING, PAUL, Bijdrage tot de Kennis der mikroskopische Fauna en Flora van de Banda-Zee (Diep-Zee-Polycystinen). Verhandl. d. Kon. Akad. van. Wetensch. Amsterdam, vol. ix. p. 30, pls. i.-iii.

19. 1865. HAECKEL, ERNST, Ueber den Sarcode-Körper der Rhizopoden (Actinelius, Acanthodesmia, Cyrtidosphæra, &c.). Zeitschr. f. wiss. Zool., Bd. xv. p. 342, Taf. xxvi.

20. 1867. SCHNEIDER, ANTON, Zur Kenntniss des Baues der Radiolarien (Thalassicolla). Archiv f. Anat. u. Physiol., 1867, p. 509.

21. 1870. HAECKEL, ERNST, Beiträge zur Plastiden Theorie (Myxobrachia; Amylum in den gelben Zellen). Jenaische Zeitschr. für Naturw., Bd. v. p. 519-540, Taf. xviii.

22. 1871. CIENKOWSKI, L., Ueber Schwärmer-Bildung bei Radiolarien. Archiv f. mikrosk. Anat., Bd. vii. p. 372-381, Taf. xxix.

23. 1872. WAGNER, N., Myxobrachia Cienkowskii. Bull. d. Acad. St. Petersburg, vol. xvii. p. 140.

24. 1872. EHRENBERG, GOTTFRIED, Mikrogeologische Studien über das kleinste Leben der Meeres-Tiefgründe aller Zonen und dessen geologischen Einfluss. Abhandl. d. k. Akad. d. Wiss. Berlin, 1872. Mit 12 Tafeln. (The Latin diagnoses of 113 new species here mentioned are given in the Monatsberichte of April 25, 1872, pp. 300-321.)

25. 1875. EHRENBERG, GOTTFRIED, Polycystinen-Mergel von Barbados (Fortsetzung der Mikrogeologischen Studien). Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, 168 pag. mit 30 Tafeln. (The Latin diagnoses of 265 species here recorded are given in Namensverzeichniss der fossilen Polycystinen von Barbados. Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, Jan. 30, 1873, pp. 213-263.)

26. 1876. HERTWIG, RICHARD, Zur Histologie der Radiolarien. Untersuchungen über den Bau und die Entwickelung der Sphærozoiden und Thalassicolliden. 91 pp. with 5 plates.

27. 1876. MURRAY, JOHN, Challengerida. Preliminary Reports on Work done on board the Challenger. Proc. Roy. Soc. Lond., vol. xxiv. pp. 471-536, pl. xxiv.

28. 1876. ZITTEL, KARL, Palæozoologie, Bd. i. pp. 114-126, figs. 46-56.

29. 1876. ZITTEL, KARL, Ueber fossile Radiolarien der oberen Kreide. Zeitschr. d. deutsch. geol. Gesellsch., Bd. xxviii. pp. 75-96, Taf. ii. (with figures of six Cretaceous species).

30. 1877. MIVART, ST. GEORGE, Notes touching recent researches on the Radiolaria. Journ. Linn. Soc. Lond. (Zool.), vol. xiv. pp. 136-186. (Historical sketch of previous literature.)

31. 1877. WYVILLE THOMSON, The Voyage of the Challenger--The Atlantic, vol. i. pp. 231-237, figs. 51-54; vol. ii. pp. 340-343, figs. 58, 59, &c.

32. 1878. HAECKEL, ERNST, Das Protistenreich, eine populäre Uebersicht über das Formengebiet der niedersten Lebewesen, pp. 101-104.

33. 1879. HERTWIG, RICHARD, Der Organismus der Radiolarien. Jenaische Denkschriften, Bd. ii. Taf. vi.-xvi. pp. 129-277.

34. 1879. HAECKEL, ERNST, Ueber die Phæodarien, eine neue Gruppe kieselschaliger mariner Rhizopoden. Sitzungsb. med.-nat. Gesellsch. Jena, December 12, 1879.

35. 1880. STÖHR, EMIL, Die Radiolarien-Fauna der Tripoli von Grotte (Provinz Girgenti in Sicilien). Palæontographica, Bd. xxvi. pp. 71-124, Taf. xvii.-xxiii. A preliminary communication regarding this fauna from the tripoli is given in Tagebl. d. Naturf. Versamml. München, 1877.

{clxxviii}36. 1880. PANTANELLI, DANTE, I Diaspri della Toscana e i loro fossili. Real. Accad. dei Lincei, ser. 3, vol. vii. pp. 13-34, Tab. i. Radiolaria di Calabria. Atti. Soc. Tosc., p. 59.

37. 1881. HAECKEL, ERNST, Prodromus Systematis Radiolarium, Entwurf eines Radiolarien-Systems auf Grund von Studien der Challenger-Radiolarien. Jenaische Zeitschr. für Naturw., Bd. xv. pp. 418-472.

38. 1881. BRANDT, KARL, Untersuchungen an Radiolarien. Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, (April 21), pp. 388-404, Taf. i.

39. 1882. BRANDT, KARL, Ueber die morphologische und physiologische Bedeutung des Chlorophylls bei Thieren. I. Artikel. Archiv f. Anat. u. Physiol., pp. 125-151, Taf. i. II. Artikel. Mittheil. a. d. Zool. Station zu Neapel, Bd. iv. pp. 193-302, Taf. xix., xx.

40. 1882. BÜTSCHLI, OTTO, Beiträge zur Kenntniss der Radiolarien-Skelette, insbesondere der der Cyrtida. Zeitschr. f. wiss. Zool., Bd. xxxvi. pp. 485-540, Taf. xxxi.-xxxiii.

41. 1882. BÜTSCHLI, OTTO, Radiolaria. In Bronn's Klassen und Ordnungen des Thierreichs. Bd. i., Protozoa, pp. 332-478, Taf. xvii.-xxxii.

42. 1882. GEDDES, PATRICK, Further Researches on Animals containing Chlorophyll. Nature, pp. 303-305.

43. 1882. GEDDES, PATRICK, On the Nature and Functions of the "Yellow Cells" of Radiolarians and Coelenterates. Proc. Roy. Soc. Edin., p. 377.

44. 1882. DUNIKOWSKI, EMIL, Die Spongien, Radiolarien und Foraminiferen der Unter-Liassischen Schichten vom Schafberg bei Salzburg. Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. pp. 22-34. Taf. iv.-vi.

45. 1882. PANTANELLI, DANTE, Fauna miocenica di Radiolari del Appennino settentrional. Boll. Soc. Geol. Ital.

46. 1883. HAECKEL, ERNST, Die Ordnungen der Radiolarien (Acantharia, Spumellaria, Nassellaria, Phæodaria). _Sitzungsb. med.-nat. Gesellsch. Jena_, February 16, 1883.

47. 1883. HERTWIG, OSCAR, Die Symbiose oder das Genossenschaftsleben im Thierreich. 56. Versamml. Deutscher Naturf. u. Aerzte, Freiburg i/B.

48. 1883. RÜST, WILHELM, Ueber das Vorkommen von Radiolarien-Resten in kryptokrystallinischen Quarzen aus dem Jura und in Koprolithen aus dem Lias. 56. Versamml. Deutscher Naturf. u. Aerzte, Freiburg i/B.

49. 1884. CAR, LAZAR, Acanthometra hemicompressa (= Zygacantha semicompressa). Zool. Anzeiger, p. 94.

50. 1884. HAECKEL, ERNST, Ueber die Geometrie der Radiolarien (Promorphologie). Sitzungsb. med.-nat. Gesellsch. Jena, November 22, 1883.

251 A. Supplementary List of Works Published in 1885:--

51. 1885. D. RÜST, Beiträge zur Kenntniss der fossilen Radiolarien aus Gesteinen des Jura. 45 pp. 4to, and 20 plates. Palæontographica, Bd. xxxi. (oder iii. Folge, vii. Band).

52. 1885. KARL BRANDT, Die koloniebildenden Radiolarien (Sphærozoeen) des Golfes von Neapel und der angrenzenden Meeres-Abschnitte. 276 pp. 4to, and 8 plates.

53. 1885. JOHN MURRAY, Narrative of the Cruise of H.M.S. Challenger, with a general account of the scientific results of the Expedition. Vol i. First part, pp. 219-227, pl. A. Second part, pp. 915-926, pl. N. fig. 2.

54. 1885. ERNST HAECKEL, System der Acantharien. Sitzungsb. med.-nat. Gesellsch. Jena, November 13.

Since the printing of this Report began in 1884 and was far advanced in 1885, it was impossible to include the important works of Rüst and Brandt (L. N. 51, 52) in the descriptive portion, so that they are only referred to in the Introduction.

251 B. Phaulographic Appendix:--

A list of absolutely worthless literature, which contains either only long known facts or false statements, and may hence be entirely neglected with advantage. Compare § 252, and also L. N. 26, p. 9.

55. 1865. WALLICH, G. C., On the structure and affinities of Polycystina. Trans. Micr. Soc. Lond., vol. xiii. pp. 57-84. (Compare L. N. 26, p. 9.)

{clxxix}56. 1879. WALLICH, G. C., Observations on the Thalassicollidæ. Ann. and Mag. Nat. Hist., ser. 4, vol. iii. p. 97.

57. 1866. STUART, ALEXANDER, Ueber Coscinosphæra ciliosa, eine neue Radiolarie (= Globigerina echinoides!!). Zeitschr. f. wiss. Zool., Bd. xvi. p. 328, Taf. xviii. (Compare L. N. 26, p. 9.)

58. 1870. STUART, ALEXANDER, Neapolitanische Studien. Göttinger Nachr., p. 99, and Zeitschr. f. wiss. Zool., Bd. xxii. p. 290 ("Blue Siliceous Crystals" in Collozoum inerme!).

59. 1871. MACDONALD, JOHN DENIS, Remarks on the Structure of Polycystina (Astromma Yelvertoni = Euchitonia Mülleri). Ann. and Mag. Nat. Hist., ser. 4, vol. viii. p. 226.

60. 1871. DOENITZ, W., Beobachtungen über Radiolarien. Archiv f. Anat. u. Physiol., 1871, p. 71, Taf. ii. (Compare L. N. 26, p. 7.)

252. Progress of our Knowledge of the Radiolaria from 1862 to 1885.--The history of our scientific knowledge of the Radiolaria extends over about half a century (from 1834 to 1885). A historical and critical discussion of the works which appeared within the first twenty-eight years of this period (from 1834 to 1862) is contained in the historical introduction to my Monograph (L. N. 16, pp. 1-24); I shall therefore give here only a brief survey of the investigations published during the last twenty-three years (from 1862 to 1885). The most important steps in our progress during this period we owe to the following naturalists:--Cienkowski (1871), Ehrenberg (1872 and 1875), Richard Hertwig (1876 and 1879), Karl Brandt (1881 and 1885), Bütschli (1882), and Rüst (1885). To the valuable works of these authors must be added a number of smaller contributions, which are recorded in the foregoing Bibliography. Some communications from dilettanti, written with insufficient knowledge of the subject, and hence of no value, are mentioned for the sake of completeness in the "Phaulographic Appendix" (compare L. N. 55-60, also L. N. 26, p. 9).

The first important advance in our knowledge of the organisation of the Radiolaria, made after the publication of my Monograph (1862), was the demonstration of the nature of the extracapsular "yellow cells." In the year 1870 I showed that these yellow cells contain starch (L. N. 21, p. 519). I regarded them, as did all authors up to that time, as integral parts of the Radiolarian organism, and hence considered this to be multicellular; for no doubt was possible regarding the true cellular nature of these remarkable, nucleated, yellow globules, which I had thoroughly studied in 1862. It was first shown by Cienkowski in 1871 that the yellow cells of the #Collodaria# remain unchanged even after the death of these organisms, "that they continue to grow uninterruptedly, and eventually multiply by division" (L. N. 22, pp. 378-380, Taf. xix. figs. 30-36). Cienkowski concluded from these important observations that the yellow cells are not integral parts of the Radiolarian body, but "parasitic structures," independent, unicellular organisms, which live only as parasites in the body of the Radiolaria (compare § 90).

This important recognition underwent ten years later a further development and complete establishment by the extensive investigations of Karl Brandt (L. N. 38, 39) {clxxx}and Patrick Geddes (L. N. 42, 43). This arrangement was compared by Brandt to the remarkable symbiosis of the Algoid gonidia and Fungoid hyphæ in the organisation of the Lichens, which had been recently discovered, and since he recognised the independent nature of the yellow cells, as unicellular Algæ, in all divisions of the Radiolaria, he founded for them the genus Zooxanthella. Geddes named them Philozoon, and showed experimentally that they give out oxygen under the influence of sunlight (compare § 90). The great physiological importance of the yellow cells in the metastasis of the Radiolaria, and, when they are developed in large quantities, in the economy of marine organisms in general, has recently been insisted upon by Brandt (see § 205 and L. N. 52, pp. 65-71, 86-94).

The proof that the yellow cells do not belong to the Radiolarian organism itself, but only live parasitically in it, was a necessary preliminary to the very important step which next took place in our knowledge of the organisation of the Radiolaria. This step consisted in the demonstration that the whole body of the Radiolaria, like that of all other Protista, is only a single cell. It was Richard Hertwig who in two remarkable works (L. N. 26, 33) firmly established this fundamental theorem of the unicellular nature of the Radiolaria. In his treatise on the histology of the Radiolaria (L. N. 26, 1876) he published complete investigations into the structure and development of the Sphærozoida and Thalassicollida. Since he made use of the modern methods of histological examination, and especially of staining fluids, which he was the first to apply to the study of the Radiolaria, he was able to show that no true cells (apart from the parasitic yellow cells) are to be found in their bodies, but rather that all their morphological components are to be regarded as differentiated parts of a single true cell, and in particular that the central capsule includes a genuine nucleus.

A wider foundation for this important discovery and its applicability to all divisions of this extensive class, was given by Hertwig in a second work on the organisation of the Radiolaria (L. N. 33, 1879). Among the numerous discoveries by which this work enriched the natural history of the Radiolaria must be specially mentioned the recognition of the fundamental differences exhibited by the main divisions of the class in the structure of their central capsule. Hertwig first observed that the capsular membrane is double in the PHÆODARIA but single in the other Radiolaria (§ 56); the former he named "TRIPYLEA" because he discovered in their capsular membrane a large, peculiarly constructed main opening and two small accessory openings. The NASSELLARIA, in which he found a single porous area at the basal pole of the main axis, with a cone of pseudopodia rising from it, he called on this account "MONOPYLEA"; whilst the other Radiolaria, whose capsular membrane is perforated on all sides with fine pores, were termed "PERIPYLEA." Besides the central capsule, Hertwig laid stress upon the significance of the gelatinous envelope as a constant and important constituent of the body. He also devoted attentive consideration to the morphology of the skeleton, and on the basis of certain {clxxxi}phylogenetic conclusions which he drew from it, he arrived at an improved systematic arrangement in which he distinguished six orders:--(1) #Thalassicollea#, (2) #Sphærozoea#, (3) #Peripylea#, (4) #Acanthometrea#, (5) #Monopylea#, (6) #Tripylea#. The numerous isolated discoveries with which Hertwig enriched the morphology of the Radiolaria, have been already alluded to in the appropriate paragraphs in the anatomical portion of this Introduction (see L. N. 42, pp. 340, 341).

The new and interesting group, which was thus erected into an order under the name TRIPYLEA, I had already a year previously separated from the other Radiolaria as "Pansolenia" in my Protistenreich (L. N. 32, p. 102). Since, however, neither the three capsular openings of the TRIPYLEA nor the skeletal tubes of the Pansolenia are present in all the families of this extensive order, I substituted in 1879 the more suitable name PHÆODARIA, which is applicable to all members of the group (L. N. 34). In the preliminary memoir then published regarding the Phæodaria, a New Group of Siliceous Marine Rhizopods, I distinguished four orders, ten families, and thirty-eight genera. The great majority of these new forms (among which were no less than 465 different species) were first discovered by the deep-sea investigations of the Challenger. John Murray was the first who called attention to the great abundance in the deep sea of these remarkable Rhizopods, and to the constant presence of their peculiar, dark, extracapsular pigment body (phæodium); even in 1876 he described a portion of them as Challengerida (L. N. 27, p. 536; L. N. 53, p. 226). The earliest observations on the PHÆODARIA were made at Messina in 1859, where I examined five genera of this remarkable group alive (compare p. 1522 and L. N. 16).

By the discovery that the PHÆODARIA, although differing in important respects from the other Radiolaria, still conform to the definition of the class, a new and extensive series of forms was added to this latter, and by their closer investigation a fresh source of interesting morphological problems was disclosed. In other groups, however, morphology was advanced by comparative anatomical studies. In addition to the smaller contributions of various authors, mentioned in the foregoing bibliography, I may specially refer to the valuable Beiträge zur Kenntniss der Radiolarien-Skelete, insbesondere der der Cyrtida by O. Bütschli (L. N. 40, 1882). On the basis of careful comparative anatomical studies, investigations into the skeletal structure of a number of fossil #Cyrtoidea# and critical application of the recently published researches of Ehrenberg into the Polycystina of Barbados (L. N. 25), Bütschli attempted to derive the complicated relations of the Monopylean skeletons phylogenetically from a simple primitive form,--the primary sagittal ring. Even if this attempt did not actually solve the very difficult morphological problem in question, still the critical and synthetic mode in which it was carried out deserves full recognition, and furnishes the proof that the comparative anatomy of the skeleton in the Radiolaria not less than in the Vertebrata, is a most interesting and fruitful field of phylogenetic investigation. A {clxxxii}further demonstration of this was furnished by Bütschli in the general account of the organisation of the Radiolaria which he published in 1882 in Bronn's Klassen und Ordnungen des Thierreichs (L. N. 41).

In our knowledge of the developmental history of these Protista the last two decades have witnessed less progress than in their comparative anatomy. The most important advance in this direction has been the proof that in all the main groups of the class the contents of the central capsule are used in the formation of swarm-spores. The movements of these zoospores in the central capsule had indeed been observed by several previous authors in the case of the SPUMELLARIA and ACANTHARIA (L. N. 10, 13, 16; compare also § 142, Note A). The origin of the flagellate spores from the contents of the central capsule and their peculiar constitution were, however, first described fully by Cienkowski in 1871 (L. N. 22, p. 372). Soon after this, R. Hertwig discovered that in the social Radiolaria (Polycyttaria or Sphærozoea) two different forms of zoospores are formed, one with, the other without crystals, and that the latter are also divided into macrospores and microspores (compare L. N. 26, and § 142). Recently this sexual differentiation has been shown by Karl Brandt to exist in all the groups of Sphærozoea, and its regular interchange with the formation of crystal-spores has been interpreted as a true "alternation of generations" (compare L. N. 52 and also § 216). The other forms of development also, especially reproduction by cell-division (§ 213) and gemmation (§ 214), have been elucidated by the recent investigations of the same author.

The palæontology of the Radiolaria has of late made important and interesting advances. Until ten years ago fossil remains of this class were known exclusively from the Tertiary period; almost the only source of our information was to be found in the researches of Ehrenberg, commenced in 1838, continued in his Mikrogeologie in 1854, and concluded in his last work (L. N. 25) published in 1875 (compare L. N. 16, pp. 3-9, 191-193). In the year 1876 a number of Mesozoic Radiolaria from the chalk were described by Zittel (L. N. 28), and afterwards others from the Jura by Dunikowski (L. N. 44). That fossil Radiolaria occur in Mesozoic formations, especially in the Jura, as well preserved and as abundantly as in the Tertiary rocks of Barbados, was shown in 1883 by Rüst (L. N. 48). By the examination of numerous thin sections he discovered that in all the main divisions of the Jurassic formation (Lias, Dogger, Malm) there are distributed jaspers, flints, cherts, and other quartzites, which consist largely of the siliceous shells of Polycystina; the same is true also of many Coprolites found in the Jura. The full account of these and the descriptions and figures of 234 Jurassic species, distributed in 76 genera, are contained in the Beiträge zur Kenntniss der fossilen Radiolarien aus Gesteinen des Jura (L. N. 51, 1885). But even in the older rocks, the Trias, the Permian, and Carboniferous systems, and even as far downwards as the Silurian and Cambrian formations, Rüst has recently shown the existence of fossil Radiolaria, {clxxxiii}and thus increased the known period of the developmental history of the class by many millions of years (§ 244).

The great significance of the Radiolaria in geology and palæontology has been brought into new light not only by these extensive discoveries, but also by the important relations which have been shown to exist between the Radiolarian rocks and the deep-sea deposits of the present day. In this direction the wonderful discoveries of the Challenger, and especially the investigation of the deep-sea deposits by Wyville Thomson (L. N. 31) and John Murray (L. N. 27), have furnished us with new and valuable information (compare §§ 236-239, and §§ 245-250). The Tertiary Polycystine formations of Barbados and the Nicobar Islands, with which we have been acquainted for the last forty years, as also the Mesozoic Radiolarian quartzes, which have only recently been made known to us from the Jura, are ascertained to be fossil representatives of the same deep-sea deposits which now occur in the form of Radiolarian ooze (§ 237), and to some extent also of Globigerina ooze and red clay (§§ 238, 239), on the bottom of the ocean, at depths of from 2000 to 4500 fathoms.

These investigations into fossil Radiolaria and their comparison with recent deep-sea forms have a further general significance, inasmuch as the identity of many living and fossil species from the Tertiary formation has been shown beyond all doubt. In this direction the numerous measurements and accurate comparisons which I have made during the last ten years of the abyssal forms in the Challenger collection, and of fossil species from Barbados and Caltanisetta, have brought to light many important facts. In this I had the able assistance of my friend, Dr. Reinhold Teuscher (compare § 250, and p. 1760). Further valuable contributions in this direction are found in the careful observations and comparative measurements recently published by Emil Stöhr (L. N. 35, 1880), regarding the Radiolarian fauna of the Tripoli of Grotte in the province of Girgenti, Sicily. From these it appears that the number of Miocene species which are still extant, is much greater than would appear from the results of Ehrenberg.

Ehrenberg himself, towards the end of his long and laborious life, collected the results of the systematic and palæontological researches, which he had begun thirty-seven years previously (L. N. 16, pp. 3-12) into the Polycystina, in two large works (L. N. 24, 25). The first treatise (L. N. 24, 1872) contains the Mikrogeologische Studien über das Kleinste Leben der Meeres-Tiefgründe aller Zonen und dessen geologischen Einfluss, with a list of 279 Polycystina observed by him from the deep-sea, as well as figures of 127 species. The second work (L. N. 25, 1875) contains the Fortsetzung der Mikrogeologischen Studien, mit specieller Rücksicht auf den Polycystinen-Mergel von Barbados; the list of fossil Polycystina observed by him includes 325 species, of which 26 are still extant; 282 of them are figured on the thirty plates accompanying the memoir. By means of these numerous figures, as well as by the appended systematic and chorological tables, Ehrenberg furnished a welcome {clxxxiv}supplement to the numerous communications regarding the Polycystina, which he had made to the Berlin Academy since 1838, and which he had published in his Mikrogeologie in 1854. It will always be the merit of this zealous and indefatigable microscopist that he first called attention to the great wealth of forms existing in this class; he separated systematically about 500 species, and published drawings of about 400; in addition to which he was the first to lay stress upon the great chorological and geological importance of the Radiolaria.

With these systematic and descriptive, chorological and palæontological works, however, which relate exclusively to the Polycystina, the merits of the famous naturalist of Berlin are exhausted as regards this class of animals. Of the organisation of the Radiolaria, Gottfried Ehrenberg remained entirely ignorant up till his death in 1876. All that a number of famous naturalists had observed during a quarter of a century as to the structure and life-history of the Radiolaria, all the important discoveries of Huxley (1851), Johannes Müller (1858), Claparède (1858), Cienkowski (1871), and many others (L. N. 1-22), and all that I had published in my Monograph (1862) on the basis of three years' study of their anatomy and physiology--all this Ehrenberg ignored, or rather, he regarded it all as worthless rubbish of science, as a chaos of devious errors, resting upon incomplete observations and false conclusions. His strange "special considerations regarding the Polycystina" (L. N. 24, pp. 339-346) and the general "concluding remarks" (L. N. 25, pp. 146-147) leave no room for doubt on this point. Ehrenberg indeed doubted to the last whether any observer had seen living Radiolaria at all (L. N. 25, p. 108).

The invincible obstinacy with which Ehrenberg maintained his preconceived opinion of the high organisation of the Radiolaria, and entirely ignored the contrary observations of other naturalists, is explained by the consistency with which he held to the end the "principle peculiar to himself of the universally equal development of the animal kingdom" (L. N. 16, p. 7). From the complicated arrangement of their siliceous shells he concluded that the animals inhabiting them must possess a structure correspondingly complex, and nearly related to that of the Echinodermata (Holothuria). Like all other animals the Radiolaria must possess systems of organs for locomotion, sensation, nutrition, circulation, and reproduction. Whilst Ehrenberg originally interpreted the Polycystina as siliceous Infusoria polygastrica, and regarded them as compound Arcellina, he afterwards classed them sometimes with the Echinodermata (Holothuria), sometimes with the Bryozoa, sometimes with the Oscillaria (see L. N. 41, p. 336). Although a decided opponent of the cell-theory he called them "multicellular animalcules" (Polycystina), interpreting the pores of the siliceous shell as cells. To-day the opposite term (Monocystina) might be adopted to express their unicellular organisation. It was a remarkable irony of fate that in the self-same year (1838) in which Schwann of Berlin made by his foundation of the cell theory the greatest advance in the whole {clxxxv}of Biological Science, that Ehrenberg, all his life the most zealous opponent of that theory, published his great work on the Infusoria, and at the same time established the "family of multicellular animalcules or Polycystina" (L. N. 16, p. 4).

The "short systematic survey of the genera of cellular animalcules" given by Ehrenberg in 1875 (L. N. 25, p. 157), is only a new edition, increased by sixteen genera, of his first systematic arrangement of the Polycystina of 1847 (L. N. 4, p. 53). Since I have already given a full discussion of this in my Monograph (L. N. 16, pp. 214-219), I need only here remark that a correct understanding of his very inadequate generic diagnoses is only possible by the aid of his figures. Relying upon these I have retained almost all Ehrenberg's genera, although entirely new definitions of most of them have been necessary.

The same is true also of the two orders which Ehrenberg distinguished in his class of "Zellenthierchen." The first order is constituted by his "Netzkörbchen" (Monodictya or NASSELLARIA) formerly known as "Polycystina solitaria"; they include our #Cyrtoidea#, the greater part of Hertwig's Monopylea. Ehrenberg's second order is the "Schaumsternchen" (Polydictya or SPUMELLARIA), previously called "Polycystina composita"; they include the Peripylea of Hertwig, as well as the Spyridina (our #Spyroidea#), which belong properly to the NASSELLARIA. Although Ehrenberg's statements regarding the organisation of both these orders were quite erroneous, and his knowledge even of the structure of their shells very defective, I still thought it advisable to retain his names for the groups, since they constituted his one successful effort in the systematic treatment of the Radiolaria (compare L. N. 41, p. 336).

The sketch of a systematic arrangement of the Radiolaria (L. N. 37), which I published in 1881 on the basis of the study of the Challenger Radiolaria, resembles, in respect of seven orders being distinguished, the new system which R. Hertwig founded in 1879, in consequence of the variations which he discovered in the structural relations of the central capsule (L. N. 33, p. 133). It differs, however, inasmuch as his Sphærozoea (my Polycyttaria) are here divided into two orders, Symbelaria (#Collosphærida#) and Syncollaria (#Sphærozoida#). In that sketch too I separated for the first time the two subclasses Holotrypasta (Porulosa) and Merotrypasta (Osculosa). The fifteen families established by Hertwig were then raised to twenty-four. The six hundred and thirty genera, which I then distinguished, are still for the most part retained, some, however, in a restricted sense, or with amended definitions.

The differential characters of the orders and families of the Radiolaria, given in the Prodromus in 1881, were amended in a further communication which I gave in 1883 regarding the orders of the Radiolaria (L. N. 46, p. 17). There I reduced the seven orders to four, the structural relations of the central capsule being precisely the same in the Polycyttaria and #Collodaria# as in the #Peripylea#. The survey of the affinities of the class was thus rendered much simpler and clearer, and the {clxxxvi}hypothetical genealogical tree, which I then published, has been still further carried out in Chapter VI. of the present Introduction (see §§ 153-200).

253. General Survey of the Growth of our Systematic Acquaintance with the Radiolaria from 1834 to 1885.

1834. MEYEN (L. N. 1) describes 2 genera and species of #Collodaria#:--Sphærozoum fuscum and Physematium atlanticum.

1838. EHRENBERG (L. N. 2) founds the family Polycystina upon 3 fossil genera (with 6 species):--Lithocampe, Cornutella, Haliomma.

1847. EHRENBERG (L. N. 4) publishes his preliminary communications regarding the fossil Polycystina of Barbados and distinguishes 282 species, distributed in 44 genera and 7 families. In the tabular view of the genera he distinguishes two orders:--I. #Solitaria#--(1) Halicalyptrina, (2) Lithochytrina, (3) Eucyrtidina; and II. #Composita#--(4) Spyridina, (5) Calodictya, (6) Haliommatina, (7) Lithocyclidina (compare L. N. 16, pp. 214-219).

1851. HUXLEY (L. N. 5) gives the first accurate account of living Radiolaria, and describes 2 species of the genus Thalassicolla (nucleata and punctata); under the latter are included 4 genera of #Sphærozoea#:--Collozoum, Sphærozoum, Collosphæra, Siphonosphæra (compare L. N. 16, pp. 12-14).

1854. EHRENBERG (L. N. 6) publishes in his Mikrogeologie, figures of seventy-two species of fossil Polycystina (without descriptions).

1855. JOHANNES MÜLLER (L. N. 8, p. 248) describes the first Acanthometra, and elucidates its affinity to Huxley's Thalassicolla and Ehrenberg's Polycystina.

1858. JOHANNES MÜLLER (L. N. 12) establishes the new group Radiolaria as a special order of the Rhizopoda, and includes in it the Thalassicolla, Polycystina, and Acanthometra as closely related families. He opposes these radiate Rhizopoda to the Polythalamia, and describes 50 species observed by him living in the Mediterranean, these he arranges in 20 genera, of which 10 are new. The figures are contained in eleven plates (see L. N. 16, pp. 22-24).

1858. CLAPARÈDE (L. N. 14) describes the first #Plectoidean# (Plagiacantha arachnoides) and two species of Acanthometra, which he had observed living in Norway (see L. N. 16, p. 18).

1860. EHRENBERG (L. N. 4) gives a short diagnosis of 22 new genera of Polycystina, based on the investigation of numerous deep-sea species brought up by Brooke from the depths of the Pacific Ocean. The number of his genera is thus increased to 66 (compare L. N. 16, pp. 10, 11).

1862. ERNST HAECKEL (L. N. 16) embraces in his Monograph of the Radiolaria all the species hitherto known either by figures or descriptions, and arranges them in 15 families and 113 genera; of which latter 46 are new. The number of new species observed living amounts to 144. In a "survey of the Radiolarian fauna of Messina" (p. 565) he records 72 genera and 169 species. Most of these are figured in the accompanying atlas of thirty-five plates.

{clxxxvii}1862. BURY (L. N. 17) gives in an atlas of twenty-five plates, photographed from drawings, the figures of numerous fossil Polycystina of Barbados (without descriptions), of which many are new species overlooked by Ehrenberg (compare § 242, above).

1872. EHRENBERG (L. N. 24) gives a list of names (without description) of all the Polycystina observed by him from the bottom of the sea, 279 species, of which 127 are figured on twelve plates.

1875. EHRENBERG (L. N. 25) gives a list of names of all the fossil Polycystina observed by him (from Barbados, the Nicobar Islands and Sicily), 326 species, of which 282 are figured (compare § 242 above). In a new "Systematic Survey of the Genera" the number of these is given as 63. The 7 families are the same as given in 1847 (see above), as also the two orders (NASSELLARIA = Solitaria, SPUMELLARIA = Composita).

1876. ZITTEL (L. N. 29) describes the first fossil Radiolaria from the chalk (6 species) and establishes the new Cyrtoid genus Dictyomitra.

1876. JOHN MURRAY (L. N. 27) establishes the new family Challengerida, and figures 6 new generic types of PHÆODARIA.

1879. RICHARD HERTWIG (L. N. 33) first describes the fundamental differences in the structure of the central capsule, and in accordance with them divides the Radiolaria into six orders:--(1) Thalassicollea, (2) Sphærozoea, (3) Peripylea, (4) Acanthometrea, (5) Monopylea, (6) Tripylea (p. 133). These are subdivided into 18 families, and their phylogenetic affinities discussed (p. 137). On the ten plates, several new species from Messina are figured, among them the types of several new genera (Cystidium, Coelacantha, Echinosphæra) (compare § 252).

1879. ERNST HAECKEL (L. N. 34) founds the order PHÆODARIA as a "new group of marine siliceous Rhizopods," and distinguishes in it 4 suborders, 10 families and 38 genera.

1880. EMIL STÖHR (L. N. 35) describes the Miocene "Radiolarian fauna of the tripoli from Grotte in Sicily," 118 species, of which 78 are new; among them is the new genus Ommatodiscus, the type of a new family, Ommatodiscida. The new species are figured on seven plates.

1880. DANTE PANTANELLI (L. N. 36) describes 30 species of fossil Polycystina from the jaspers of Tuscany, which he regarded as Eocene, but which were probably of Jurassic origin (compare § 243, note B, above).

1881. ERNST HAECKEL (L. N. 37) publishes a "Sketch of a classification of the Radiolaria on the basis of the study of the Challenger Collection," and distinguishes in his "conspectus ordinum" (p. 421) 2 subclasses and 7 orders, and in the "prodromus systematis Radiolarium" (pp. 423-472) 24 families with 630 genera, among which are more than 2000 new species.

1882. BÜTSCHLI (L. N. 40) on the basis of studies of the fossil Monopylea of Barbados, investigates the "mutual relations of the Acanthodesmida, Zygocyrtida and Cyrtida," and gives a critical revision of the genera of these "Cricoidea;" a number of new species are described and figured (Tafs. xxxii., xxxiii.), and some new genera of Stichocyrtida established (Lithostrobus, Lithomitra, &c.).

1882. DUNIKOWSKI (L. N. 44) describes 18 new fossil Polycystina from the lower lias of the Salzburg Alps, among them the types of 3 new genera (Ellipsoxiphus, Triactinosphæra, and Spongocyrtis).

{clxxxviii}1883. ERNST HAECKEL (L. N. 46) revises the 4 orders and 32 families of Radiolaria, and gives more accurate definitions of them, as well as of the 2 subclasses (I. Holotrypasta = ACANTHARIA and SPUMELLARIA; II. Merotrypasta = NASSELLARIA and PHÆODARIA).

1885. D. RÜST (L. N. 51) describes 234 new species of fossil Radiolaria from the Jura, and illustrates them by twenty plates. Among them are 103 SPUMELLARIA, 130 NASSELLARIA, and 1 PHÆODARIA; these are contained in 35 genera, of which 20 belong to the Porulosa, and 15 to the Osculosa.

254. Statistical Synopsis of the Twenty Orders:--

(a) Number of Families. (b) Number of Genera. (c) Number of Species. (d) Previously known Species. (e) New Species. (f) Fossil Species. (g) Pelagic Abundance. (h) Abyssal Abundance. (i) Figured on Plates

+-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | | | | | | | | Figured on | | (a) | (b) | (c) | (d) | (e) | (f) | (g) | (h) | Plates. | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | I. Legion SPUMELLARIA (Porulosa peripylea) | +-----+---------------------------------------------------------------+ | | I. COLLODARIA (Spumellaria palliata) | +-----+-----+---------------------------------------------------------+ | | 1. Colloidea | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 2 | 6 | 36 | 9 | 27 | 0 | A | E | 1, 3 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | 2. Beloidea | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 2 | 8 | 56 | 9 | 47 | 0 | A | D | 2, 4 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | II. SPHÆRELLARIA (Spumellaria loricata) | +-----+-----+---------------------------------------------------------+ | | 3. Sphæroidea | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 6 | 107 | 660 | 105 | 555 | 66 | A | B | { 5-8 | | | | | | | | | | { 11-30 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | 4. Prunoidea | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 7 | 53 | 280 | 35 | 245 | 36 | B | B | { 16, 17 | | | | | | | | | | { 39, 40 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | 5. Discoidea | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 6 | 91 | 503 | 126 | 376 | 102 | B | A | { 31-38 | | | | | | | | | | { 41-48 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | 6. Larcoidea | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 9 | 51 | 260 | 8 | 252 | 0 | E | B | { 9, 10 | | | | | | | | | | { 49, 50 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | II. Legion ACANTHARIA (Porulosa actipylea) | +-----+---------------------------------------------------------------+ | | III. ACANTHOMETRA (Acantharia palliata) | +-----+-----+---------------------------------------------------------+ | | 7. Actinelida | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 3 | 6 | 22 | 6 | 16 | 0 | E | E | 129 (figs. 1-3) | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | 8. Acanthonida | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 3 | 21 | 138 | 50 | 88 | 0 | A | C | 130-132 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | IV. ACANTHOPHRACTA (Acantharia loricata) | +-----+-----+---------------------------------------------------------+ | | 9. Sphærophracta | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 3 | 27 | 149 | 9 | 140 | 0 | B | B | 133-138 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | 10. Prunophracta | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 3 | 11 | 63 | 5 | 58 | 0 | D | B | 139, 140 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | III. Legion NASSELLARIA (Osculosa monopylea) | +-----+---------------------------------------------------------------+ | | V. PLECTELLARIA (Nassellaria palliata) | +-----+-----+---------------------------------------------------------+ | | 11. Nassoidea | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 1 | 2 | 5 | 1 | 4 | 0 | E | E | 91 (fig. 1) | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | 12. Plectoidea | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 2 | 17 | 61 | 5 | 56 | 0 | D | C | 91 (figs. 2-12) | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | 13. Stephoidea | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 4 | 40 | 205 | 14 | 191 | 17 | C | B | { 81, 82 | | | | | | | | | | { 92-94 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | VI. CYRTELLARIA (Nassellaria loricata) | +-----+-----+---------------------------------------------------------+ | | 14. Spyroidea | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 4 | 45 | 239 | 51 | 188 | 53 | C | A | 83-90 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | 15. Botryodea | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 3 | 10 | 55 | 15 | 40 | 10 | E | C | 96 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | 16. Cyrtoidea | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 12 | 160 | 1122 | 328 | 794 |250 | C | A | 51-80 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | IV. Legion PHÆODARIA (Osculosa cannopylea) | +-----+---------------------------------------------------------------+ | | VII. PHÆOCYSTINA (Phæodaria palliata) | +-----+-----+---------------------------------------------------------+ | | 17. Phæocystina | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 3 | 15 | 112 | 30 | 82 | 24 | C | B | 101-105 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | VIII. PHÆOCOSCINA (Phæodaria loricata) | +-----+-----+---------------------------------------------------------+ | | 18. Phæosphæria | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 4 | 22 | 121 | 5 | 116 | 0 | C | A | 106-112 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | 19. Phæogromia | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 5 | 27 | 159 | 5 | 154 | 0 | C | A | { 99, 100 | | | | | | | | | | { 113-120 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | 20. Phæoconchia | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 3 | 20 | 73 | 4 | 69 | 0 | D | B | 121-128 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | Total, | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 85 | 739 | 4318 | 810 | 3508 | 558 | ... | ... | 140 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+

Note.--In the tenth and eleventh columns the relative abundance of each order at or near the surface and near the bottom is approximately indicated by the letters A-E, which have the following significance:--A, abundant; B, very numerous; C, many (medium quantity); D, few; E, very few.

{1}SYSTEMATIC PART.

----

CLASS RADIOLARIA.

RADIOLARIA, Johannes Müller, 1858. RHIZOPODA RADIARIA, Johannes Müller, 1858. POLYCYSTINA (pro parte), Ehrenberg, 1838. ECHINOCYSTIDA, Claparède, 1858. RHIZOPODA CAPSULARIA, Haeckel, 1861. CYTOPHORA, Haeckel, 1862.

Definition of the Class:--#Rhizopoda with unicellular body, divided by a porous membrane into an internal or intracapsular part (with nucleus), and an external or extracapsular part (with calymma); propagating by flagellated spores.#

The RADIOLARIA or CAPSULATE RHIZOPODA, first constituted by Johannes Müller in the year 1858 as a separate group of the Rhizopoda, form a peculiar class of the PROTISTA, or unicellular organisms. This class is exclusively marine, and has in general the characteristic organisation of the Rhizopoda, with the development of numerous pseudopodia from the surface of the cell; but it differs from all other Rhizopoda in the possession of a peculiar membrane, dividing the cell-body into two different parts; the central capsule or the internal part with the nucleus, and the external part or extracapsulum with the calymma; propagation by flagellated spores produced in the central capsule; the sarcode or the protoplasm of both parts communicates by fine pores, piercing the separating membrane, which is called the capsule-membrane.

The Central Capsule or the inner part of the Radiolarian body is constantly composed of three essential parts, viz.:--

1. The Central Nucleus (a true cell-nucleus).

2. The Intracapsular Sarcode (endosarc) or surrounding internal protoplasm.

3. The Capsule Membrane or enveloping porous membrane.

{2}Besides these constant and essential elements, the central capsule contains very commonly (but not constantly) some other enclosed structures, viz.:--

4. An internal or intracapsular skeleton.

5. Intracapsular vacuoles or alveoli.

6. Fat-granules or oil-globules.

7. Crystals of different composition.

8. Pigment-granules.

The Extracapsulum, or the outer part of the Radiolarian body is also constantly composed of three essential elements,--

1. The Calymma, or the thick extracapsular jelly-veil, completely enveloping the whole central capsule.

2. The Matrix, or the maternal tissue of the external protoplasm, enveloping immediately the capsule-membrane as a thin continuous layer of extracapsular sarcode (ectosarc).

3. The Pseudopodia, or the very numerous thread-like filaments of protoplasm, which radiate from the matrix; whilst their inner part is enclosed in the calymma, their outer part floats freely in the sea-water.

Besides these three constant and essential elements, the extracapsulum contains very commonly (but not constantly) some other enclosed structures, viz.:--

4. An external or extracapsular skeleton.

5. Extracapsular vacuoles or alveoli.

6. Fat-granules or oil-globules.

7. Pigment-granules or a peculiar large body of dark extracapsular pigment, the "phæodium."

8. "Xanthellæ" or "zooxanthellæ," peculiar yellow cells, which contain starch and are unicellular yellow Algæ, living as "Symbiontes" in true Symbiosis with a great many Radiolaria.

The Nucleus of the Radiolaria is a large true simple cell-nucleus, originally a solid spherical, roundish or longish body of nuclein. It is placed either in the centre of the capsule (in most Peripylea) or excentrically (in most other Radiolaria). Originally solid, the nucleus is commonly differentiated later into an outer dense nuclear-membrane and an inner softer or fluid content; either with one single nucleolus or with a variable number of nucleoli. Originally always simple, the nucleus becomes afterwards constantly divided into numerous small nuclei, each of which, together with a part of the surrounding {3}protoplasm, forms a vibratile-spore or "flagellate-spore." This division in the Acantharia and in the social (or colonial) Peripylea begins very early, in all other Radiolaria much later, immediately before propagation.

The Endoplasm or "endosarc," or "intracapsular protoplasm" or "inner sarcode," in all Radiolaria originally fills that space within the capsule, which is not taken up by the nucleus. It seems to be employed mainly for the purpose of propagation, becoming divided earlier or later into numerous small particles, each of which surrounds a small particle of the nucleus and forms together with it a flagellate-spore. Besides this the endoplasm of the Radiolaria seems to have a great significance for the nutrition, mainly for the interchange of materials. It becomes very often vacuolate or alveolate, filled with smaller or larger spherical drops of fluid; it produces very commonly smaller fat-granules or larger oil-globules, and further pigment-granules of different colours, more rarely crystals and other peculiar enclosed parts.

The Membrane or "capsule-membrane" is the most typical and characteristic part of the body of a Radiolarian, sufficient of itself to separate this class from all other Rhizopoda. At the same time, by its different shape it presents the best means for the systematic distinction of the four subclasses or "legions" of the class. The membrane is composed of a special organic matter (probably nearly related to chitin) and combines density with elasticity to a high degree. Observed with a high power of the microscope its margin (or section) appears commonly simple-edged, but often in larger forms distinctly double-edged.

The legion PHÆODARIA is distinguished by a double membrane (the thinner inner and thicker outer membranes being separated by an interval); in the three other legions it is simple. The membrane completely separates the intracapsular from the extracapsular body, both communicating only by certain pores or openings in the membrane. With reference to this important communication, the whole class can be divided into two subclasses, Holotrypasta and Merotrypasta: the HOLOTRYPASTA contain the Peripylea and Actipylea, in which the membrane is pierced by innumerable very small pores; the MEROTRYPASTA consist of the Monopylea and the Cannopylea, in which the membrane exhibits only one large main opening, distinguished in the former by a peculiar "porous area," in the latter by an "osculum" or a prolonged tubule.

The Calymma or "jelly-veil" is the most characteristic part of the extracapsular body in all Radiolaria; in the majority of the class it is the most voluminous part of the whole body, being much more voluminous than all the other parts taken together. The calymma is a structureless, clear, and transparent jelly-envelope which always includes the whole central capsule and often also the whole extracapsular skeleton. Owing to the high degree of its consistence, this jelly-veil takes a very important part in the formation of the extracapsular skeleton, furnishing the matrix for the deposition of its tangential parts.

{4}The Matrix or the "maternal tissue of the pseudopodia" is formed in all Radiolaria by the thin layer of exoplasm or of extracapsular sarcode, which immediately envelops the central capsule and is itself enclosed by the calymma. This continuous sarcode-cover of the capsule communicates by its pores or openings with the endoplasm or the intracapsular sarcode; whilst from its outer surface arise the pseudopodia. The morphological signification of the matrix is very small, but the physiological importance is very great, for it seems to be the chief organ of many vital functions.

The Pseudopodia or the very fine, long, thread-like filaments of exoplasm arise in all Radiolaria in very great numbers from the surface of the matrix, and exhibit in general the same characteristic shape as in the other Rhizopoda. Their inner or proximal part is enclosed within the jelly-veil or calymma, whilst their outer or distal part floats freely in the sea-water. Their special motions and modifications exhibit considerable variations in different groups, their tendency to ramify, anastomose, and form networks being in some cases very small, in others very great. Also the characteristic motion of granules in the pseudopodia is very different. In general those most important exoplasmatic filaments serve as organs both for the vegetative functions of nutrition, and for the animal functions of motion and sensation.

The class Radiolaria can be divided according to its varying structure into four different legions or subclasses, the characters of which are the following:--

I. PERIPYLEA OR SPUMELLARIA.

Membrane of the central capsule simple, perforated by innumerable very fine pores. Fundamental form originally homaxon or spherical. Skeleton wanting or siliceous. No phæodium in the extracapsular calymma. The Peripylea comprise two orders:--

A. COLLODARIA (without lattice-shell). B. SPHÆRELLARIA (with lattice-shell).

II. ACTIPYLEA OR ACANTHARIA.

Membrane of the central capsule simple, perforated by innumerable fine pores. Fundamental form originally homaxon or spherical. Skeleton acanthinic (not siliceous). No phæodium in the extracapsular calymma. The Actipylea consist of two orders:--

A. ACANTHOMETRA (without complete lattice-shell). B. ACANTHOPHRACTA (with complete lattice-shell).

{5}III. MONOPYLEA OR NASSELLARIA.

Membrane of the central capsule simple, perforated by a porous-area, or by one single large opening, divided into numerous very fine pores. Fundamental form originally monaxon or egg-shaped. Skeleton siliceous. No phæodium in the extracapsular calymma. The Monopylea comprise two orders:--

A. PLECTELLARIA (without complete lattice-shell). B. CYRTELLARIA (with complete lattice-shell).

IV. CANNOPYLEA OR PHÆODARIA.

Membrane of the central capsule double, perforated by one simple main-opening, prolonged into a tubulus, and besides this commonly by one or two (rarely more) small accessory openings. Fundamental form originally monaxon or egg-shaped. Skeleton siliceous. Constantly a peculiar dark pigment-body or "phæodium" in the extracapsular calymma. The Cannopylea comprise two orders:--

A. PHÆOCYSTINA (without lattice-shell). B. PHÆOCOSCINA (with lattice-shell).

Synopsis of the four Subclasses or Legions of Radiolaria.

{6}LEGION I. #SPUMELLARIA#,

VEL PERIPYLEA, VEL PERIPYLARIA (PLS. 1-50).

Spumellaria (exclusis Spyridinis), Ehrenberg, 1875. Peripylea (inclusis Thalassicollis et Sphærozois), Hertwig, 1879. Peripylaria (inclusis Collodariis et Polycyttariis), Haeckel, 1881.

Definition.--Radiolaria with simple membrane of the central capsule, which is everywhere perforated by innumerable very fine pores. Extracapsulum without phæodium. Skeleton wanting or siliceous. Fundamental form originally spherical.

The legion SPUMELLARIA vel PERIPYLEA, in the extent here defined, was constituted by me in 1883 in my paper on Die Ordnungen der Radiolarien.[2] I propose to retain for this legion either the name SPUMELLARIA of Ehrenberg (1875) or PERIPYLEA of Hertwig (1879), although both groups have not quite the same extension. We exclude from the SPUMELLARIA the Spyridina (united with them by Ehrenberg) and include the Collodaria. With the Peripylea of Hertwig we unite his Thalassicollea and Sphærozoea. To avoid any confusion it would perhaps be better to name this legion "Peripylaria."

The SPUMELLARIA agree with the ACANTHARIA in the structure of the simple capsule-membrane, which is perforated by numerous small pores (but devoid of the large main opening, which the NASSELLARIA and PHÆODARIA possess), whence we unite both the former as Holotrypasta, both the latter as Merotrypasta.

The difference between the two legions of Holotrypasta is determined by the skeleton, which in the SPUMELLARIA is either siliceous or wanting, whilst in the Acantharia it consists of the peculiar organic substance, acanthin.

The legion SPUMELLARIA is by far the largest and most important of the four legions of Radiolaria, as well with respect to the number of different forms, as to the enormous masses of individuals, which we encounter living and fossil. We distinguish in this legion not less than thirty-two different families, three hundred and sixteen genera, and more than seventeen hundred species.

The classification of this large group requires for its better comprehension a careful division into larger and smaller groups. We divide it therefore first of all into two orders, #Collodaria# and #Sphærellaria#, as proposed in the paper mentioned above.[3]

The #Collodaria# have no perfect latticed skeleton, and comprise two suborders or sections: in the #Colloidea# the skeleton is entirely wanting, in the #Beloidea# it is represented by a variable number of siliceous needles or spicules, scattered in the calymma around the central capsule.

{7}The #Sphærellaria# differ from the #Collodaria# in the possession of a perfect siliceous skeleton, which is originally a latticed spherical shell, enveloping the central capsule. By modification of this fenestrated sphere arises an enormous mass of different forms, which we dispose in twenty-eight families, and these in four larger groups, suborders or sections,--#Sphæroidea#, #Prunoidea#, #Discoidea#, and #Larcoidea#.

The #Sphæroidea#, the common ancestral group of the #Sphærellaria#, possess a skeleton which is either a simple fenestrated sphere, or composed of two or more concentric latticed spheres, which are united by radial beams; more rarely it becomes more or less spongy.

The #Prunoidea# are derived from the #Sphæroidea# by prolongation of the latticed sphere in one axis; the skeleton therefore becomes here ellipsoidal or cylindrical (often with annular transversal constrictions).

The #Discoidea# on the contrary must be derived from the #Sphæroidea# by shortening in one axis; here therefore the fenestrated shell becomes more or less lenticular or iscoidal (often with radial spines or arms in the equatorial plane, on the circular margin).

The #Larcoidea#, the fourth section, differ from the three foregoing sections by the different growth of the shell in three different dimensions of space; therefore here the fenestrated shell becomes "lentelliptical," or a "triaxial ellipsoid," its length, breadth, and height being different.

The Skeleton consists in all SPUMELLARIA either of pure silica or of a peculiar silicate. The siliceous bars and beams constituting it are invariably solid, as also in the NASSELLARIA, never hollow, as in the PHÆODARIA. Never is the skeleton composed of acanthin, as in all ACANTHARIA. Whilst in the first order of SPUMELLARIA, #Collodaria#, the form of the spicula, or the scattered needles, composing the skeleton, is very simple, never latticed, in the second order, the #Sphærellaria#, it is constantly latticed or fenestrated, often also spongy.

The geometrical fundamental form of the lattice-shell in the #Sphærellaria# is originally spherical (homaxon), as preserved in all #Sphæroidea#; in the #Prunoidea# and #Discoidea# it becomes monaxon, with one single axis (prolonged in the former, shortened in the latter); in the #Larcoidea# it becomes triaxon, by different growth in three principal axes, perpendicular one to another. The further development of radial parts of the skeleton in these three axes is very important for the "promorphology" of the Radiolaria.

The Malacoma, or the whole soft body of the SPUMELLARIA as opposed to the skeleton, exhibits some differences of structure in two different groups, which were separated formerly (1862) as Monocyttaria and Polycyttaria, corresponding to the "Radiolaria monozoa and polyzoa" of Johannes Müller (1858).

The #Monocyttaria# (or the Spumellaria solitaria) live isolated as single cells--like {8}all other Radiolaria--and are never aggregated in colonies; the calymma includes one single central capsule, and this again one central nucleus, which does not become divided until full maturity.

The #Polycyttaria# on the contrary (or the Spumellaria socialia) live aggregated in large colonies; the calymma includes a variable number of associated central capsules and each of these commonly one central oil-globule, whilst the original simple nucleus commonly becomes very early divided into numerous small nuclei.

The Nucleus of the SPUMELLARIA is originally constantly central, placed quite in the centre of the concentric capsule, and it retains this central position in all Monocyttaria or solitary Peripylea; whereas in the Polycyttaria--in consequence of its early division--its place is commonly taken by a central oil-globule. Whilst the numerous nuclei of the latter are very small, the single nucleus of the former is comparatively large, extremely large (more than a millimeter in diameter) in some gigantic #Collodaria#.

The Endoplasm or the intracapsular sarcode exhibits in the greater number of SPUMELLARIA a more or less distinct radial striation. It encloses a great variety of different parts; vacuoles, oil-globules, pigment-granules, crystals, &c.

The Membrane of the capsule in all SPUMELLARIA is simple (never double as in the Phæodaria) and everywhere equally perforated by innumerable small pores; in the thick, double-edged membrane of many large #Collodaria# these pores appear (in the optical section of the capsule-wall) as distinct fine radial canals, very densely and regularly disposed.

The Central Capsule in the SPUMELLARIA is originally a geometrical sphere, and this simple globular form is preserved in all #Sphæroidea#, and in the greatest part of #Colloidea# and #Beloidea#. By prolongation of one axis the form becomes ellipsoidal (or even cylindrical) in the #Prunoidea#, and in some few forms of #Colloidea#. By shortening of one axis it becomes lenticular (or even discoidal) in the Discoidea, and in some few forms of #Colloidea#. By unequal growth in three different axes, perpendicular one to another, the capsule becomes lentelliptical in all #Larcoidea#. Very rarely the capsule assumes in the SPUMELLARIA a polyhedral or irregular (sometimes even amoeboid) form, only in a few #Colloidea#.

The Calymma, or the jelly-veil including the central capsule, is very voluminous in many SPUMELLARIA of gigantic size, mainly in the large #Colloidea#, and in all Polycyttaria or social Radiolaria. It includes here a considerable number of large vacuoles or "alveoli." The calymma never exhibits in this legion the dark voluminous phæodium, possessed by all PHÆODARIA.

Xanthellæ or "zooxanthellæ" are numerous in the calymma of most SPUMELLARIA, but by no means constant; they are very variable in number and size.

The Matrix, placed between the calymma and central capsule, is, in the majority of the SPUMELLARIA, a rather thick layer of granular exoplasm.

The Pseudopodia arising from it are very numerous, equally disposed over the whole {9}surface, and are in general rather fluid, exhibiting a considerable tendency to ramify, anastomose, and form networks. The movement of granules is commonly lively. In the Polycyttaria all capsules of one colony or "coenobium" are connected by the dense variable network of anastomosing pseudopodia.

Synopsis of the Orders and Suborders of SPUMELLARIA.

I. COLLODARIA. { Skeleton entirely wanting, 1. #Colloidea.# Skeleton wanting or { quite imperfect, { Skeleton represented by not latticed. { numerous scattered spicules, 2. #Beloidea.#

II. SPHÆRELLARIA. { Lattice-shell spherical or { composed of concentric spheres, 3. #Sphæroidea.# Skeleton a perfect { shell of lattice { Lattice-shell ellipsoidal or work, or spongy and { prolonged in one axis, 4. #Prunoidea.# resembling { wicker-work. { Lattice-shell discoidal or { shortened in one axis, 5. #Discoidea.# { { Lattice-shell lentelliptical, { with different extent of growth { in three axes, 6. #Larcoidea.#

----

Order I. COLLODARIA, Haeckel, 1881.

Collodaria, Haeckel, Prodromus, 1881, p. 469. Collida et Sphærozoida, Haeckel, 1862, Monogr. d. Radiol., pp. 246, 522.

Definition.--SPUMELLARIA without latticed shell.

The order #Collodaria#, the first order of Radiolaria, comprises all those SPUMELLARIA in which the skeleton is either entirely wanting, or represented by numerous single, solid, siliceous needles or spicules, loosely scattered in the calymma around the central capsule. Never in this order is there any trace of the latticed or fenestrated shell, which characterises the second order, #Sphærellaria#. The skeleton exhibits no trace of phylogenetic connection in the two orders.

In my monograph (1862) two families appertaining to this order are described, the Collida (p. 244) and the Sphærozoida (p. 521). Both families contain forms with and without a skeleton. Of the solitary or monozous Collida the Thalassicollida are devoid of a skeleton, whilst the Thalassosphærida are provided with a skeleton. Of the social or polyzous Sphærozoida the Collozoida are without a skeleton, the Rhaphidozoida provided with one. As the special form in both skeletophorous subfamilies is exactly the same, I prefer now to associate them in the suborder #Beloidea#, and to oppose them to the other two skeletonless subfamilies, which are united under the name of #Colloidea#.

{10}Synopsis of the four Families of Collodaria.

Suborder I. { Solitary cells, living COLLOIDEA. { as isolated individuals { (Colloidea monozoa), 1. THALASSICOLLIDA. Skeleton entirely { wanting. { Associated cells, living { in colonies or coenobia { (Colloidea polyzoa), 2. COLLOZOIDA.

Suborder II. { Solitary cells, living as BELOIDEA. { isolated individuals { (Beloidea monozoa), 3. THALASSOSPHÆRIDA. Skeleton composed { of numerous { Associated cells, living in needles or { colonies or coenobia spicula, scattered { (Beloidea polyzoa), 4. SPHÆROZOIDA. in the calymma. {

----

Suborder I. COLLOIDEA, Haeckel.

Definition.--SPUMELLARIA without skeleton.

The suborder #Colloidea# comprises all those SPUMELLARIA in which no skeleton is developed. The whole body is therefore soft--a true malacoma--and is composed only of two essential parts, the central capsule and the enveloping extracapsulum. The suborder contains only two different families, the solitary #Thalassicollida# (or Colloidea monozoa) and the associated #Collozoida# (or Colloidea polyzoa). Both families are very nearly allied, and differ only in one single essential character: the solitary life of the former, the social union of the latter. It seems to be merely in consequence of this difference that the cleavage of the nucleus commonly takes place very late in the former, very early in the latter.

Therefore the full-grown Thalassicollida (till immediately before propagation) commonly exhibit one single nucleus in the centre of the capsule, whilst in the Collozoida the capsule is distended by numerous small nuclei. In these latter the centre of the capsule usually contains one large oil-globule, whilst in the former oil-globules are either wanting, or scattered in large numbers in the endoplasm, or disposed in one layer on the inside of the capsule membrane.

In the solitary Thalassicollida each capsule is enclosed in its own peculiar spherical calymma, whilst in the associated Collozoida all capsules of the colony are united in one common, very voluminous calymma.

Family I. #THALASSICOLLIDA#, Haeckel, 1862.

Thalassicollida, Haeckel, 1862, Monogr. d. Radiol., p. 246. Thalassicollida, Haeckel, 1881, Prodromus, p. 469.

Definition.--#Colloidea# solitaria.

The family Thalassicollida comprises all solitary SPUMELLARIA without a skeleton. The oldest and best known form of this family is the genus Thalassicolla, as restricted by {11}Johannes Müller.[4] The most common representative of it, the cosmopolitan Thalassicolla nucleata, was first described by Huxley in 1851. But as early as 1834 another large Radiolarian, appertaining either to this or to a nearly allied family, had been described by Meyen as Physematium atlanticum. A third genus was detected by me in 1859 at Messina and figured under the name Thalassolampe margarodes.[5] A very accurate histological description of these forms was given in 1876 by Richard Hertwig.[6] The same author figured in his Organismus in 1879 a very interesting simpler form under the name Thalassolampe primordialis (Taf. iii. fig. 5). Some similar forms had already been observed by me, and are here united with it to form the first genus Actissa.[7]

Actissa is of the highest general interest as the most simple and typical form of all Radiolaria, and as the common ancestral form, from which all other forms of this large class may be derived. Its unicellular body exhibits neither the extracapsular alveoli of Thalassicolla, nor the intracapsular alveoli of Thalassolampe, and shows all essential characters of the Radiolarian type in its most simple form (Pl. 1, figs. 1 to 1_c_). The simple cell-body is composed of a spherical central capsule and a concentric, spherical, enveloping calymma, both separated by a thin membrane which is perforated by innumerable pores. The capsule includes the endoplasm and in the centre a simple spherical nucleus with nucleolus; at the time of propagation this latter becomes cleft into numerous small nuclei, each of which, together with a small piece of the surrounding endoplasm, forms a flagellated zoospore (fig. 1_c_). The extracapsulum is formed by the large, structureless, spherical calymma or concentric jelly-veil enveloping the capsule, and by the thin granular matrix or the layer of exoplasm which separates the calymma from the membrane. From this matrix or maternal tissue arise innumerable very long and thin pseudopodia, as simple radiating filaments, the proximal part of which is included in the calymma, whilst the distal part floats freely in the sea-water (Pl. 1, fig. 1).

The other Thalassicollida differ from their common ancestral form, Actissa, mainly by the higher histological differentiation of the unicellular body. Whilst in Thalassicolla and Thalassolampe the nucleus remains a single sphere as in Actissa, it becomes branched or covered with radial blind saccules in Thalassopila and Thalassophysa; also the intracapsular protoplasm develops here a great variety of peculiar different corpuscles, as oil-globules, pigment-granules, concentric concretions, crystals, &c. But the most striking peculiarity by which the other Thalassicollida differ from Actissa is the development of large vesicular alveoli, either within or without the capsule; the unicellular body reaches by this inflation the extraordinary size of 5 to 10 mm. or more.

{12}Synopsis of the Genera of Thalassicollida.

A. Alveoli neither { Nucleus spherical within nor without { (sometimes ellipsoidal), the central capsule. { not branched, 1. Actissa.

B. Numerous large { Nucleus spherical, 2. Thalassolampe. alveoli within the { central capsule (not { Nucleus branched or in the calymma). { covered with radial { sacs, 3. Thalassopila.

C. Numerous large { Nucleus spherical, 4. Thalassicolla. alveoli without the { central capsule, { Nucleus branched, or within the jelly-veil { covered with radial or calymma. { sacs, 5. Thalassophysa.

Genus 1. Actissa,[8] n. gen.

Definition.--#Thalassicollida# with simple spherical nucleus, without any alveoli (either within or outside the central capsule).

The genus Actissa is the most simple and typical form of all Radiolaria, and may be regarded as the common ancestral form of the whole class. The spherical body is composed of a simple spherical capsule and a concentric spherical calymma or jelly-envelope. Neither the former nor the latter contains alveoli. The central capsule possesses a strong membrane perforated by small pores, and contains in the intracapsular sarcode numerous small pellucid vacuoles, and in its middle a simple, concentric, spherical nucleus (often with some nucleoli); sometimes also one or more oil-globules. The extracapsularium forms a soft, voluminous, structureless calymma or enveloping jelly-sphere, perforated by the numberless, fine pseudopodia, which radiate outwards from the matrix or the thin granulated sarcode-layer, surrounding the capsule. Often (but not constantly) xanthellæ or yellow cells are scattered in it. Actissa differs from the following skeletonless genera in the absence of all alveoli; it has neither intracapsular alveoli (like Thalassolampe) nor extracapsular alveoli (like Thalassicolla). The first observed species of this genus is that which I found in 1866 at the Canary Islands, Actissa prototypus; the second is that which Hertwig accurately described in 1879, from the Mediterranean (Messina), Actissa primordialis; the third I observed in 1881 at Ceylon, frequent and sporiparous, Actissa princeps. A fourth species (Actissa radiata) exhibited a distinct radial segmentation of the capsule-contents. These four species are quite spherical. Six other species, occurring in different preparations from the Challenger, are distinguished by modifications of the spherical capsule-form and may represent three different subgenera (or, perhaps better, genera?)--Actiprunum ellipsoidal, Actidiscus lenticular, Actilarcus lentelliptical; perhaps these are the ancestral forms of the three sections: #Prunoidea#, #Discoidea#, #Larcoidea#.

{13}Subgenus 1. Procyttarium, Haeckel, 1879.

Procyttarium, Haeckel, Natürl. Schöpfungsgeschichte, ed. vii. p. 705.

Definition.--Central capsule spherical.

1. Actissa princeps, n. sp. (Pl. 1, fig. 1).

Central capsule spherical, colourless or a little reddish, transparent, with a thick double-edged membrane. Nucleus central, spherical, one-third as broad as the central capsule, containing a single, central, glossy nucleolus. Protoplasm finely granulated, without oil-globules, with numerous clear spherical vacuoles of equal size and at equal distances; the superficial layer of protoplasm (immediately below the membrane) radially striated (fig. 1). In some older specimens the nucleus was divided into numerous small nuclei (fig. 1_a_), which by further division gave the nuclei of the flagellated spores (fig. 1_b_); each spore with a very thin lateral flagellum (fig. 1_c_). Jelly-like calymma twice as broad as the enclosed capsule, without xanthellæ or yellow cells, pierced by innumerable, very thin and long, undivided pseudopodia, which arise from the sarcode-matrix on the outside of the membrane (six to eight times longer than shown in fig. 1).

Dimensions.--Diameter of the central capsule 0.1 to 0.12, of the nucleus 0.03 to 0.04, of the jelly calymma 0.2 to 0.3.

Habitat.--Indian Ocean, Ceylon, Belligemma, Haeckel, 1881; also in a preparation from Station 271, Central Pacific, surface.

2. Actissa primordialis, Haeckel.

Thalassolampe primordialis, R. Hertwig, 1879, Organismus der Radiolarien, p. 32, Taf. iii. fig. 5.

Procyttarium primordiale, Haeckel, 1879, Natürl. Schöpf., ed. vii. p. 705, Taf. xvi. fig. 1.

Central capsule spherical, dim-yellowish, with a thin, simple-edged but compact membrane. Nucleus large, central (about half as broad), with one or two dark nucleoli; on its side an excentric oil-globule, nearly of the same size. Protoplasm between nucleus and membrane, in the younger specimens finely granulated and radially striped; in the older specimens with numerous hyaline globules (vacuoles). Jelly-envelope or calymma very voluminous, ten to twelve times as broad as the central capsule, structureless, containing numerous yellow bodies (xanthellæ?), pierced by very numerous simple pseudopodia.

Dimensions.--Diameter of the central capsule 0.11 to 0.18, of the nucleus 0.04 to 0.09, of the jelly-like calymma 1.2 to 1.5.

Habitat.--Mediterranean, Messina, Hertwig, 1878, surface.

3. Actissa prototypus, n. sp.

Central capsule spherical, red-coloured, with a thick, double-edged membrane. Nucleus central, spherical, half as large as the radius of the capsule, containing a large number (forty to sixty) of small {14}dark nucleoli. Protoplasm filled up with numerous small clear vacuoles, and between them fine red pigment granules; on the inside of the membrane one layer of dark oil-globules. Jelly-like calymma four times as broad as the enclosed capsule, with very numerous small xanthellæ.

Dimensions.--Diameter of the capsule 0.2, of the nucleus 0.05, of the calymma 0.8.

Habitat.--Atlantic, Canary Islands (Lanzerote, Haeckel), 1866; also at Station 348, surface.

4. Actissa radiata, n. sp.

Central capsule spherical, dark, with a thick, double-edged membrane. Nucleus central, spherical, half as large as the capsule, transparent. Protoplasm divided into numerous cuneiform radial pieces which are separated by clear intervals, and filled with very fine dark granules (darker in the distal half). The equatorial optical section exhibits around the circular clear nucleus a coronal of twenty-five such wedge-shaped pieces (mother-cells of spores?) No oil-globules in the central capsule. Jelly-like calymma one and a half times as broad as the enclosed capsule, with numerous small xanthellæ.

Dimensions.--Diameter of the capsule 0.15, of the nucleus 0.07, of the calymma 0.24.

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

Subgenus 2. Actiprunum, Haeckel, 1882.

Definition.--Central capsule ellipsoidal, with one prolonged axis.

5. Actissa prunoides, n. sp.

Actiprunum prunoideum, Haeckel, 1882, Manuscript.

Central capsule ellipsoidal, colourless, with a thin, simple-edged membrane. Proportion of its major axis to the minor 4 : 3. Nucleus spherical, its diameter equal to one-third of the minor axis, in its centre a large, dark, spherical nucleolus. Protoplasm clear, containing numerous small vacuoles, separated by regular distances, and on the inside of the capsule-membrane, numerous (forty to fifty) small oil-globules. Calymma (or jelly-veil) ellipsoidal, with a thin sarcode-stratum on the outside of the capsule; its diameter twice as large as that of the central capsule.

Dimensions.--Major axis of the capsule 0.16, minor 0.12; diameter of the nucleus 0.04; major axis of the calymma 0.32, minor 0.24.

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

6. Actissa ellipsoides, n. sp.

Actiprunum ellipsoides, Haeckel, 1882, Manuscript.

Central capsule ellipsoidal, red-coloured, with a thick, double-edged membrane. Proportion of its major axis to the minor 5 : 3. Nucleus ellipsoidal, one-third as large as the capsule, containing eight small dark nucleoli. Protoplasm dusky, filled with dark pink pigment-granules; in the {15}major axis, on both poles of the nucleus-axis, two large oil-globules, half as large as the nucleus. Calymma ellipsoidal, with numerous xanthellæ; its diameter four times as large as that of the capsule.

Dimensions.--Major axis of the capsule 0.2, minor 0.12; major axis of the nucleus 0.07, minor 0.04; major axis of the calymma 0.8, minor 0.5.

Habitat.--Mediterranean, Corfu, 1877, Haeckel, surface.

Subgenus 3. Actidiscus, Haeckel, 1882.

Definition.--Central capsule lenticular, with one shortened axis.

7. Actissa discoides, n. sp.

Actidiscus discoides, Haeckel, 1882, Manuscript.

Central capsule lenticular, red-coloured, about twice as broad as high, with a thick, double-edged membrane. Nucleus spherical, one-third as broad as the capsule, with one single, large central nucleolus. Protoplasm dusky, filled with scarlet pigment; granules and small oil-globules between them. Calymma lenticular, three times as broad as the capsule.

Dimensions.--Major axis of the capsule 0.16, minor 0.08; diameter of the nucleus 0.05; breadth of the calymma 0.5.

Habitat.--North Pacific, Station 236, surface.

8. Actissa lenticularis, n. sp.

Central capsule lenticular, flattened, about three times as broad as high, with a thin, simple-edged membrane. Nucleus lenticular, one-third as large as the capsule, with ten small dark nucleoli. Protoplasm transparent, colourless, filled with small vacuoles at regular distances; on the inside of the membrane in the circular periphery of the lens twenty dark oil-globules. Calymma lenticular, twice as broad as the capsule.

Dimensions.--Major axis of the capsule 0.15, minor 0.05; breadth of the nucleus 0.05, height 0.02; breadth of the calymma 0.03.

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

9. Actissa phacoides, n. sp.

Actidiscus phacoides, Haeckel, 1882, Manuscript.

Central capsule lenticular, strongly flattened, about four times as broad as high, with a thin, simple-edged membrane. Nucleus lenticular, one-fourth as broad as the capsule, with numerous (twenty or more) small nucleoli. Protoplasm filled with dark pigment-granules; on the inside of the membrane in the circular periphery of the lens thirty-two dark oil-globules. Calymma lenticular, three times as broad as the capsule.

{16}Dimensions.--Major axis of the capsule 0.2, minor 0.05; breadth of the nucleus 0.05, height 0.015; breadth of the calymma 0.6.

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

Subgenus 4. Actilarcus, Haeckel.

Definition.--Central capsule lentelliptical, with three different axes.

10. Actissa larcoides, n. sp.

Central capsule lentelliptical; with three different axes, bearing the proportion 4 : 3 : 2. Nucleus spherical; its diameter equal to the shortest radius of the capsule. No nucleoli visible. Protoplasm transparent, with small vacuoles; on the inside of the thin capsule-membrane numerous (fifty to sixty) small oil-globules, regularly disposed. Calymma lentelliptical, twice as large as the central capsule.

Dimensions.--Major axis or length of the capsule 0.2, middle axis or breadth 0.15, minor axis or height 0.1; diameter of the nucleus 0.05, of the calymma 0.3-0.4.

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

Genus 2. Thalassolampe,[9] Haeckel, 1862, Monogr. d. Radiol., p. 253.

Definition.--#Thalassicollida# without extracapsular alveoles, but with large roundish or globular alveoles within the central capsule, with a simple spherical, not branched nucleus in the centre.

The genus Thalassolampe is, next to Actissa, the most simple of all Radiolaria, but differs from it by the large intracapsular alveoles. By these the central capsule is inflated to an extraordinary size, which in Thalassolampe maxima exceeds that of most other Radiolaria. From the nearly allied Thalassopila it differs by the simple spherical nucleus, from Physematium by the absence of spicula. Of the two species of the genus the first observed Thalassolampe margarodes, 1862, is Mediterranean, the second, Thalassolampe maxima, 1882, is Indian.

1. Thalassolampe margarodes, Haeckel.

Thalassolampe margarodes, Haeckel, 1862, Monogr. d. Radiol., p. 253, Taf. ii. figs. 4, 5.

Thalassolampe margarodes, R. Hertwig, 1876, Histologie d. Radiol., p. 68, Taf. iii. figs. 1-5.

Spherical body very soft and limpid, somewhat pearl-like opalescent, yellowish or bluish. Central capsule with a very thin structureless membrane, its diameter six to eight times as large as that of the central spherical nucleus. Wall of the vesicular nucleus thick, perforated by fine {17}pore-canals; on its inside often numerous oval nucleoli. In the movable protoplasmic network between the large alveoles a considerable number of large yellowish or orange oil-globules. Extracapsular jelly-envelope very thin, contains small yellow bodies (zooxanthellæ). (Compare the accurate description of this Mediterranean species in my monograph and in Hertwig's work.) In the Canary Islands I found very often a large variety of it, of double and triple the size, distinguished by the delicate orange colour of the intracapsular oil-globules. This may be distinguished as Thalassolampe aurantiaca.

Dimensions.--Diameter of the whole jelly-sphere 2 to 4 mm., of the central capsule 2 to 3 mm., of its nucleus 0.2 to 0.4 mm.

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

2. Thalassolampe maxima, n. sp. (Pl. 1, fig. 2).

Spherical body quite pellucid, like a glass globule, colourless. Central capsule with a moderately thick, but quite transparent, structureless membrane, its diameter ten to twelve times as large as that of the central spherical nucleus. Wall of the vesicular nucleus thick, perforated by fine pore-canals; on its inside numerous small spherical nucleoli. No large oil-globules in the movable protoplasmic network between the large alveoles. Extracapsular jelly-envelope very thin, containing no yellow bodies. This differs from the preceding nearly allied species in the want of the intracapsular oil-globules and of the extracapsular yellow bodies. It possesses the largest central capsule of all known Radiolaria. I found them living and floating in water taken from the surface of the Indian Ocean by a bucket.

Dimensions.--Diameter of the whole jelly-body 12 to 15 mm., of the central capsule 10 to 12 mm., of the nucleus 0.8 to 1.2 mm.

Habitat.--Indian Ocean, near the Maldive Islands, Haeckel, 1882, surface.

Genus 3. Thalassopila,[10] Haeckel, 1881, Prodromus, p. 469.

Definition.--Thalassicollida without extracapsular alveoles, but with large roundish or globular alveoles within the central capsule, with a papillate or branched nucleus in its centre.

The genus Thalassopila has, like Thalassolampe, a voluminous foamy central capsule, inflated by numerous large alveoles; but it differs in the complicated form of the nucleus, which is like that of Thalassophysa, and is either branched or occupied by conical or roundish papillæ.

1. Thalassopila cladococcus, n. sp. (Pl. 1, fig. 3).

Spherical body dark-spotted, with a thin yellowish jelly-envelope. Central capsule with a thick and firm membrane, perforated by pores; its diameter three times that of the central nucleus, {18}three-fourths that of the whole jelly-sphere. Nucleus profusely branched or papillated, its spherical surface covered with numerous (more than a hundred) finger-shaped obtuse blind sacs, about as long as its radius. Protoplasm of the central capsule forming a loose network between the large roundish alveoles, in the cortical zone radially striped and containing one layer of large dark oil-globules. These are regularly distributed on the inside of the capsule-membrane and separated by intervals, twice as broad as its diameter, giving to the capsule-surface a spotted appearance. Extracapsular jelly-envelope thin, yellowish, with very numerous and small xanthellæ.

Dimensions.--Diameter of the whole jelly-sphere 5 mm., of the central capsule 4 mm., of the nucleus 1.3 mm.

Habitat.--Antarctic Ocean, Station 154 (south of Kerguelen), surface.

Genus 4. Thalassicolla,[11] Huxley, 1851, Ann. and Mag. Nat. Hist., ser. 2, vol. viii. p. 433.

Definition.--Thalassicollida without intracapsular alveoles, but with large roundish or globular alveoles within the extracapsular calymma. Nucleus in the centre of the capsule simple spherical, not branched.

The genus Thalassicolla was proposed by Huxley in 1851, for a certain number of different voluminous jelly-like Radiolaria, which he had observed living during his voyage in the "Rattlesnake" through the tropical seas, and of which he gives an excellent description--the first accurate observations on living Radiolaria. Johannes Müller afterwards removed from this genus the social genera Sphærozoum and Collosphæra (formerly Thalassicolla punctata), and retained as type of the genus Thalassicolla nucleata. In 1862 in my Monograph I added two other species, Thalassicolla pelagica and Thalassicolla zanclea, and later (1870) Thalassicolla sanguinolenta. Now I think it better to separate the last two species as a new genus, Thalassophysa, characterised by the papillate or branched nucleus, and to retain in Thalassicolla only those forms with simple spherical nucleus. For both genera the extracapsular, voluminous, spherical calymma or jelly-envelope, with numerous large alveoles, is characteristic. The membrane of the central capsule in Thalassicolla is now structureless (subgenus Thalassicollarium, with three species), now characterised by a peculiar structure, prominent ridges on the inside of the membrane, which form a network with polygonal plates, resembling an epithelium (Pl. 1, fig. 5_b_; subgenus Thalassicollidium, with four species). Of the seven species here described, two are cosmopolitan, widely distributed, and common; one is Mediterranean, one Atlantic, and three Pacific.

Subgenus 1. Thalassicollarium, Haeckel.

Definition.--Membrane of the central capsule structureless, only perforated by innumerable very small radial pores.

{19}1. Thalassicolla pellucida, n. sp.

Spherical body very soft, transparent, clear and colourless, without any pigment. Central capsule soft, hyaline, with a thin, structureless, not areolated membrane. Diameter of the central capsule about three times that of the nucleus, one-fourth to one-sixth that of the jelly-envelope. Nucleus delicate, transparent, with one single central nucleolus, about one-third its diameter. Protoplasm of the central capsule contains only small, pellucid, densely packed globules (vacuoles?), no oil-globules. Extracapsular body quite transparent, without pigment or oil-globules, only composed of the large alveoles imbedded in the jelly-cover, and of the fine protoplasmic network between them. No xanthellæ.

Dimensions.--Diameter of the central capsule 0.8 to 1.2, of the nucleus 0.3 to 0.4, of the calymma 3 to 6 mm.

Habitat.--Cosmopolitan, Canary Islands, Haeckel; Cape, Australia, Pacific, Challenger; surface.

2. Thalassicolla spumida, n. sp.

Spherical body nearly transparent, yellowish, without dark pigment. Central capsule pellucid, with a thick, structureless, not areolated membrane. Diameter of the central capsule about twice that of the nucleus, one-sixth to one-eighth that of the jelly-cover. Nucleus delicate, somewhat opaque, with numerous small nucleoli. Protoplasm of the central capsule contains small pellucid globules (vacuoles?), and immediately under its membrane (on its inside) one single layer of large, dark, refractive oil-globules. Extracapsular body very voluminous, foamy, with innumerable alveoles in the jelly, and many xanthellæ between them.

Dimensions.--Diameter of the central capsule 0.6 to 0.8, of the nucleus 0.3 to 0.4, of the calymma 3 to 5 mm.

Habitat.--Atlantic, Canary Islands, Haeckel; Cape Verde Islands, Challenger Station 350; Brazil, Rabbe; surface.

3. Thalassicolla zanclea, Haeckel.

Thalassicolla zanclea, Haeckel, 1862, Monogr. d. Radiol., p. 252, Taf. ii. fig. 3.

Spherical body opaque, transparent only in the periphery, with colourless central capsule, but with brown or black pigment-powder scattered everywhere through the extracapsular alveolated jelly-cover. Central capsule soft, transparent, colourless, with a thin structureless, not areolated membrane. Diameter of the central capsule about one and a half times that of the nucleus, one-half or one-third that of the jelly-cover. Nucleus delicate, transparent, with a thin, finely punctated membrane, with one or more nucleoli. Protoplasm of the central capsule contains only small, pellucid, densely packed globules (vacuoles?), no oil-globules. Extracapsular body very dark and opaque, with a great mass of brown or blackish-brown pigment between the alveoles of the jelly-cover. Numerous xanthellæ.

Dimensions.--Diameter of the central capsule 0.1 to 0.12, of the nucleus 0.07 to 0.08, of the calymma 0.2 to 0.4.

Habitat.--Mediterranean, Messina, Haeckel.

{20}Subgenus 2. Thalassicollidium, Haeckel.

Definition.--Membrane of the central capsule areolated, with small polygonal plates, resembling an epithelial cell-tissue, spotted by innumerable fine radial pores.

4. Thalassicolla australis, n. sp.

Spherical body nearly transparent, without dark pigment. Central capsule colourless, somewhat opaque, with a thick and firm, very elastic membrane, areolated by polygonal, punctated figures resembling cells. Diameter of the central capsule about three times that of the nucleus, one-third that of the jelly-cover. Nucleus thin-walled, with many small nucleoli. Protoplasm of the central capsule finely granulated, containing numerous hyaline globules (vacuoles?) of different size, and in each of these one single roundish, dark refringing corpuscle, concentrically lamellated like an amylum grain. Extracapsular body without pigment or oil-globules, only composed of the large alveoles imbedded in the jelly-cover, and of the fine protoplasmic network between them. No xanthellæ.

Dimensions.--Diameter of the central capsule 1 to 2, of its nucleus 0.3 to 0.4, of the nucleoli 0.12 to 0.16, of the hyaline globules in the protoplasm of the capsule 0.02 to 0.05; calymma, 4 to 6 mm.

Habitat.--South-west Pacific, east coast of Australia, New Zealand, &c.; Challenger Stations 163, 171; surface.

5. Thalassicolla nucleata, Huxley.

Thalassicolla nucleata, Huxley, 1851, Ann. and Mag. Nat. Hist., ser. 2, vol. viii. p. 435, pl. xvi. fig. 4.

Thalassicolla nucleata, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 28.

Thalassicolla coerulea, Schneider, 1858, Archiv f. Anat. u. Physiol., p. 40, Taf. iii. Bd. i. figs. 5-7.

Thalassicolla nucleata, Haeckel, 1862, Monogr. d. Radiol., p. 249, Taf. iii. figs. 1-5.

Thalassicolla nucleata, R. Hertwig, 1876, Histologie d. Radiol., p. 43, Taf. iii. figs. 61-5, Taf. iv., v.

Thalassicolla nucleata, R. Hertwig, 1879, Organismus d. Radiol., p. 34.

Spherical body in the central part opaque, black or dark coloured, in the periphery transparent, whitish, or yellowish. Central capsule rather compact, yellowish, opaque, with a thick and firm, very elastic membrane, areolated by polygonal, punctated figures resembling cells. Diameter of the central capsule about twice as large as that of the nucleus, one-half to one-fourth that of the jelly-cover. Nucleus with a very thick, finely punctated membrane, containing a viscous fluid (when coagulated finely granular), and sometimes one large, central, spherical, or ramified nucleolus, sometimes a variable number of smaller roundish nucleoli. Protoplasm of the central capsule containing many very variable corpuscles, mostly pellucid (albuminous?) spherules, containing oil-globules, or concentric amyloid concretions, or crystals, &c. Extracapsular body with dark pigment-powder of variable colour (black, brown, violet, blue, &c.), densely aggregated around the central capsule, more loosely dissipated between the alveoles of the outer jelly-cover. Xanthellæ very numerous.

{21}Dimensions.--Diameter of the central capsule 0.4 to 0.8, of the nucleus 0.02 to 0.05, of the calymma 1 to 5 mm.

Habitat.--Cosmopolitan; common in all warmer seas; Mediterranean, Atlantic, Indian Ocean, Pacific, mainly between lat. 40° N. and lat. 40° S.; surface.

6. Thalassicolla maculata, n. sp. (Pl. 1, fig. 4).

Spherical body in the central part opaque, black or dark coloured, in the periphery semi-transparent, spotted. Central capsule compact, yellowish, opaque, with a thick and firm, very elastic membrane, areolated by polygonal, punctated figures resembling cells. Diameter of the central capsule about twice that of the nucleus, one-third to one-fifth that of the jelly-cover. Nucleus thin-walled, with one large spherical nucleolus. Protoplasm of the central capsule contains innumerable very small, hyaline, spherical vesicles of equal size (or vacuoles?), two to four times as broad as the separating bridges of protoplasm. Extracapsular body with dark pigment-powder of black or brown colour, densely accumulated around the central capsule (in the matrix), loosely scattered between the alveoles of the outer jelly-cover. The latter appears spotted by numerous large, roundish lumps of protoplasm, scattered between the alveoles. No xanthellæ.

Dimensions.--Diameter of the central capsule 0.3 to 0.6, of the nucleus 0.2 to 0.3, of the hyaline globules in the protoplasm of the capsule 0.02 to 0.03; calymma, 2 to 3 mm.

Habitat.--South Pacific, Challenger Station 289.

7. Thalassicolla melacapsa, n. sp. (Pl. 1, fig. 5).

Spherical body in the central part opaque, black or dark coloured, in the periphery semi-transparent, spotted. Central capsule compact, black, with a thick and firm, very elastic membrane, areolated by polygonal, punctated figures resembling cells. Diameter of the central capsule about twice that of the nucleus, one-third or half that of the jelly-cover. Nucleus thin-walled, transparent, containing very numerous and small nucleoli. Protoplasm of the central capsule filled with small black pigment-granules, quite intransparent, contains densely packed hyaline (albuminous?) globules of equal size; every pellucid globule includes a smaller globule (one-third or one-fourth its diameter), which appears to be composed of aggregated oil-bubbles. Extracapsular body without pigment, contains between its alveoles in the inner half numerous, dark refractive oil-globules, in the outer half numerous amoeboid lumps of protoplasm, irregularly scattered. No xanthellæ.

Dimensions.--Diameter of the central capsule 2 to 2.5, of the nucleus 1 to 1.5, of the hyaline globules in the protoplasm of the capsule 0.03 to 0.04; calymma, 3 to 5 mm.

Habitat.--South-east Pacific (near Valparaiso), Challenger Station 300, surface.

Genus 5. Thalassophysa,[12] Haeckel, 1881, Prodromus, p. 470.

{22}The genus Thalassophysa contains those species of Thalassicollida formerly associated with Thalassicolla, which are distinguished by the complicated, ramose, or papillate form of the large nucleus. All three species here described are found in the Mediterranean and the Atlantic. To this genus appertains also that strange form of Radiolaria which I described in 1870 as Myxobrachia (compare Thalassophysa sanguinolenta).

1. Thalassophysa papillosa, n. sp.

Thalassicolla papillosa, Haeckel, 1867, Manuscript.

Spherical body transparent, colourless, or somewhat yellowish. Central capsule soft, colourless, with a very thin but firm, elastic, structureless membrane. Diameter of the central capsule about twice that of the nucleus, one-fourth to one-sixth that of the jelly-envelope. Nucleus papillated, its spherical surface covered with a great number (50 to 80) of conical or finger-like protuberances or blind sacs, not longer than half its radius. Protoplasm of the central capsule filled with very small and numerous spherical vacuoles, without oil-globules. Extracapsular jelly-body, without dark pigment, oil-globules, and large protoplasmic lumps, contains between its alveoles very numerous xanthellæ.

Dimensions.--Diameter of the whole jelly sphere 4 to 5 mm., of the central capsule 0.8 to 1 mm., of its nucleus 0.4 to 0.5.

Habitat.--Canary Islands, Lanzerote, common, Haeckel; Cape Verde Islands, Challenger; surface.

2. Thalassophysa sanguinolenta, Haeckel.

Thalassicolla sanguinolenta, Haeckel, 1870, Jenaische Zeitschr., Bd. v. p. 526, Taf. 18.

Thalassicolla sanguinolenta, Haeckel, 1870, Biolog. Studien, i. p. 113, Taf. iv.

Thalassicolla sanguinolenta, R. Hertwig, 1879, Organismus d. Radiol., p. 37, Taf. iii. fig. 1.

Myxobrachia rhopalum, Haeckel, 1870, Jenaische Zeitschr., Bd. v. p. 519, Taf. 18 (et in Biol. Stud., loc. cit.).

Myxobrachia pluteus, Haeckel, 1870, Jenaische Zeitschr., Bd. v. p. 520, Taf. 18 (et in Biol. Stud., loc. cit.).

Spherical body in the central part opaque, reddish, in the periphery transparent, yellowish. Central capsule compact, white, red spotted, with a thick elastic membrane, perforated by pores, but not areolated. Diameter of the central capsule three times that of the nucleus, one-fifth to one-eighth that of the jelly-envelope. Nucleus papillated, its spherical surface covered with numerous (80 to 120) conical or finger-like protuberances not longer than one-fourth or one-third of its radius. On the inside of these blind sacs lie numerous small roundish nucleoli. Protoplasm of the central capsule in the outer (cortical) zone (on the inside of the membrane) radially striped, with one layer of very numerous red oil-globules of equal size, producing its blood-spotted appearance; in the inner (medullary) zone foamy, with numerous small spherical vacuoles. Extracapsular jelly-body without dark pigment, contains between its alveoles no large protoplasmic lumps (as in Thalassophysa pelagica), but numerous small oil-globules and xanthellæ. This species sometimes amasses in its jelly-envelope large accumulations of Coccoliths and Coccospheres, {23}which are much heavier than the jelly-body, and produce arm-like protuberances of it; this modified form, often of very regular and peculiar appearance, I formerly described as Myxobrachia (compare my Biolog. Studien, loc. cit., and Hertwig, loc. cit., p. 37). Compare also Myxobrachia cienkowski, Wagner, 1872, L. N. 23.

Dimensions.--Diameter of the whole jelly-sphere 5 to 8 mm., of the central capsule 1 to 1.2 mm., of its nucleus 0.3 to 0.4.

Habitat.--Canary Islands, Lanzerote; common, Haeckel; Mediterranean, Messina, Hertwig; surface.

3. Thalassophysa pelagica, Haeckel.

Thalassicolla pelagica, Haeckel, 1862, Monogr. d. Radiol., p. 247, Taf. i.

Thalassicolla pelagica, R. Hertwig, 1879, Organismus d. Radiol., p. 35, Taf. iii. fig. 4.

Spherical body in the central part opaque, yellowish, in the periphery semi-transparent, spotted. Central capsule compact, yellowish-white, with a thick and compact membrane, perforated by pores, but not areolated. Diameter of the central capsule about twice that of the nucleus, one-half to one-sixth that of the jelly-envelope. Nucleus papillated, its spherical surface covered with numerous (20 to 60) conical, roundish, or finger-like protuberances, not longer than its radius (commonly only one-half or one-third as long). Enclosed in the semi-fluid substance of the nucleus are very long and thin cylindrical nucleoli snake-like, contorted, and penetrating into the protuberances of the nucleus. Protoplasm of the central capsule in the outer (cortical) zone (on the inside of the membrane) radially striped, with one layer of large oil-globules of different sizes; in the inner (medullary) zone foamy, with numerous small spherical vacuoles, mostly of equal size. Extracapsular jelly-body without dark pigment, contains between its alveoles a large number of large roundish or amoeboid lumps of protoplasm, and very numerous yellow cells or xanthellæ (compare the detailed description in my Monograph, and in R. Hertwig's work).

Dimensions.--Diameter of the whole jelly-sphere 1 to 4 mm., of the central capsule 0.5 to 0.6, of the nucleus 0.2 to 0.3.

Habitat.--Mediterranean--Messina, Corfu, Nizza, Genoa, Haeckel; Messina, R. Hertwig; surface.

Family II. #COLLOZOIDA#, Haeckel, 1862 (Pl. 3).

Collozoida, Haeckel, 1862, Monogr. d. Radiol., p. 522.

Definition.--#Colloidea# socialia.

The family Collozoida comprises all associated or colony-building Radiolaria without skeleton. We unite here all these skeletonless Radiolarian colonies into one single genus Collozoum, constituted (1862) in my Monograph (p. 522). The oldest known form of it was the Collozoum inerme, described firstly by Johannes Müller (1856) as Sphærozoum inerme. Two other species of the genus were figured (1862) in my Monograph (p. 522, Tafn. xxxii., xxxv.). A most accurate description of its histological structure and {24}development was given in 1876 by Richard Hertwig in his Histologie der Radiolarien (pp. 12-42, Tafn. i., ii.). A number of other very remarkable forms of Collozoum have been observed by me during the last few years, and partly figured in Pl. 3.

Collozoum, as the only representative of this family, is sufficiently distinguished from all other Radiolaria by the definition "Skeletonless Radiolarian Colonies." These occur floating on the surface of all warmer seas, often in astonishing masses, and may be easily confounded, owing to their external resemblance, with the jelly-like egg-masses of certain Mollusca. Collozoum is derived either from Actissa or from Thalassicolla, simply by multiplication of the unicellular body and by reunion of the associated capsules in one common calymma or jelly-veil; this is constantly alveolated, as in Thalassicolla. As in Actissa, the form of the central capsule remains either spherical, or it becomes ellipsoidal or discoidal, rarely polyhedral or amoeboid. In Collozoum as in all colonial Radiolaria, the original central nucleus commonly undergoes cleavage very early into numerous small nuclei, whilst its place is usually taken by a central oil-globule. This peculiarity may serve often (but not constantly) for the distinction of isolated capsules of Collozoum from Actissa.

Genus 6. Collozoum,[13] Haeckel, 1862, Monogr. d. Radiol., p. 522.

Definition.--Skeletonless colonies of Radiolaria.

The genus Collozoum, as already mentioned, is the only representative of its family, and comprises all Radiolaria living associated in colonies, and having no skeleton. Therefore Collozoum possesses all the peculiarities described above. Although the floating colonies of this genus occur in enormous masses on the surface of all warmer seas, nevertheless the number of different species in this genus is not great, and amounts only to thirteen. If this number increase by further investigations, the subgenera distinguished in the following description can be advanced to the range of genera; in which case Collodinium (or Collozoum sensu restricto) will be characterised by the spherical form of its central capsules, Colloprunum by the ellipsoidal form (Pl. 3, fig. 9), Collophidium by the cylindrical, very prolonged form (figs. 2, 3), Collodiscus by the lenticular or discoidal form, and Collodastrum by the indefinite, polyhedral, or amoeboid form (figs. 4, 5).

Subgenus 1. Collodinium, Haeckel.

Definition.--Form of the central capsules spherical or subspherical, never polyhedral, ellipsoidal, or cylindrical.

{25}1. Collozoum inerme, Haeckel (Pl. 3, figs. 10-12).

Collozoum inerme, Haeckel, 1862, Monogr. d. Radiol., p. 522, Taf. xxxv.

Collozoum inerme, Cienkowski, 1871, Archiv. f. mikrosk. Anat., vol. vii. p. 376, Taf. xxix. figs. 18-36.

Collozoum inerme, R. Hertwig, 1876, Histologie der Radiol., p. 12, Taf. i., ii.

Collozoum inerme, R. Hertwig, 1879, Organismus d. Radiol., p. 31, Taf. iii. fig. 12.

Sphærozoum inerme, J. Müller, 1856, Monatsber. d. k. Akad. d. Wiss. Berlin, p. 478; Abhandl., p. 54.

Sphærozoum bicellulare, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 54, Taf. viii. fig. 5.

Thalassicolla punctata, Huxley (pro parte), 1851, Ann. and Mag. Nat. Hist., ser. 2, vol. viii. p. 433.

Central capsules spherical, with thin, simple-edged membrane, with one single oil-globule in the centre. (If the capsules multiply by division, the spherical form becomes violin-shaped, constricted in the middle; and in this condition the number of oil-globules increases; but in the ordinary mature state the capsule of this species remains spherical, and its oil-globule solitary. In quite young capsules the oil-globules are wanting; Pl. 3, fig. 12.)

Dimensions.--Diameter of the central capsules 0.04 to 0.16.

Habitat.--Cosmopolitan, common in all warmer seas (Mediterranean, Atlantic, Indian, and Pacific), surface.

2. Collozoum nostochinum, n. sp.

Central capsules spherical, very large, opaque, distended with red pigment-granules and with very numerous (two hundred to three hundred) small oil-globules. Membrane thick, double-edged.

Dimensions.--Diameter of the central capsules 0.3 to 0.5.

Habitat.--Indian Ocean, off Socotra, surface, Haeckel.

3. Collozoum volvocinum, n. sp.

Central capsules spherical, very large, opaque, containing a great number (ten to thirty) of large oil-globules, and between them densely packed masses of dark pigment. Membrane thick, double-edged. This species differs from Collozoum inerme, mainly by the great size of the central capsules (three to five times as big as in the former) and the great number of oil-globules in them.

Dimensions.--Diameter of the central capsules 0.2 to 0.3.

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

Subgenus 2. Colloprunum, Haeckel.

Definition.--Form of the central capsules ellipsoidal, with one prolonged axis.

4. Collozoum ovatum, n. sp.

Colloprunum ovatum, Haeckel, 1882, Manuscript.

Central capsules ovate or ellipsoidal, its longer diameter twice to three times as large as the shorter. In the centre of every capsule one single oil-globule.

{26}Dimensions.--Length of the central capsules 0.2 to 0.3, breadth of them 0.1 to 15.

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

5. Collozoum ellipsoides, n. sp. (Pl. 3, figs. 8, 9).

Colloprunum ellipsoides, Haeckel, 1882, Manuscript.

Central capsules regularly ellipsoidal, very large; their longer diameter once and a half to twice as large as the shorter. In every capsule fifty to eighty oil-globules.

Dimensions.--Length of the central capsules 0.3 to 4, breadth of them 0.2.

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

Subgenus 3. Collophidium, Haeckel.

Definition.--Form of the central capsules cylindrical, often snake-like, contorted, with one axis much prolonged, several times longer than the transverse axis.

6. Collozoum contortum, n. sp.

Collophidium contortum, Haeckel, 1882, Manuscript.

Central capsules cylindrical, three to four times as long as broad, C- or S-like curved, transparent, without oil-globules.

Dimensions.--Length of the central capsules 0.2 to 0.3, breadth 0.06 to 0.08.

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

7. Collozoum serpentinum, n. sp. (Pl. 3, figs. 1-3).

Collophidium serpentinum, Haeckel, 1882, Manuscript.

Central capsules cylindrical, filiform, much elongated, ten to one hundred times, sometimes two hundred to four hundred times as long as broad, snake-shaped or worm-shaped, curved and contorted in the most irregular manner, often spiral or twisted into a large nodule. Numerous oil-vesicles constantly present, forming one series of globules in the axis of every capsule; distance of the globules, one from another, and also from the capsule-membrane, about equal to their diameter. (This interesting and very curious form was very frequently observed living by me in the Canary Islands, in January 1867; the jelly-colonies were commonly spherical, and contained fifty to two hundred or more capsules of very different size and form.)

Dimensions.--Length of the central capsules 1 to 10, sometimes 20 to 40 mm.; average breadth 0.1 mm.

Habitat.--Canary Islands, Lanzerote, Haeckel, surface.

{27}8. Collozoum vermiforme, n. sp. (Pl. 3, figs. 6, 7).

Collophidium vermiforme, Haeckel, 1882, Manuscript.

Central capsules cylindrical, much elongated, five to ten times (sometimes twenty to fifty times) as long as broad, snake-shaped or worm-shaped, very irregularly curved and contorted. Numerous oil-globules constantly present, forming in the axis of every capsule a double series of alternating rose-coloured globules. (This species is nearly allied to the preceding; but its capsules are thicker and shorter, and the oil-vesicles in them are arranged not in a single, but in a double row.)

Dimensions.--Length of the central capsules 0.6 to 1.2 mm., sometimes 3 to 6 mm.; breadth 0.12.

Habitat.--Tropical Atlantic, near the west coast of Africa, Station 349, Canary Islands, surface.

Subgenus 4. Collodiscus, Haeckel.

Definition.--Form of the central capsules discoidal or lenticular, with one shortened axis.

9. Collozoum coeruleum, Haeckel.

Collozoum coeruleum, Haeckel, 1862, Monogr. d. Radiol., p. 523, Taf. xxxii. figs. 6-8.

Collodiscus coeruleus, Haeckel, 1882, Manuscript.

Central capsule lenticular or discoidal, flattened, blue coloured, with one single oil-globule in the centre. Protoplasm containing numerous crystals and dark blue pigment-granules. Membrane very thick, double-edged. (Whilst at Messina in 1859 I found this form not constantly discoidal, in 1867 in the Canary Islands I observed it constantly lenticular.)

Dimensions.--Breadth of the central capsules 0.1 to 0.15, height 0.04 to 0.08.

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

10. Collozoum discoideum, n. sp.

Collodiscus discoideus, Haeckel, 1882, Manuscript.

Central capsule discoidal, flattened, transparent, with a ring of twenty to twenty-five oil-globules in its circular periphery (on the inside of the thin membrane).

Dimensions.--Breadth of the central capsules 0.2, height 0.05.

Habitat.--South Pacific (Juan Fernandez), Station 300, surface.

Subgenus 5. Collodastrum, Haeckel.

Definition.--Form of the central capsules irregular and indefinite, variable, commonly polyhedral or polygonal, or amoeboid, often with irregular, finger-like processes.

{28}11. Collozoum pelagicum, Haeckel.

Collozoum pelagicum, Haeckel, 1862, Monogr. d. Radiol., p. 525, Taf. xxxii. figs. 4, 5.

Sphærozoum pelagicum, Haeckel, 1860, Monatsber. d. k. Akad. d. Wiss. Berlin, 1860, p. 845.

Central capsules small, quite irregularly formed, roundish-polyhedral or depressed-polygonal, transparent, without oil-globules. Often many extracapsular oil-vesicles in the common jelly-body between the central capsules. Membrane very thin and delicate.

Dimensions.--Diameter of the central capsules 0.02 to 0.08.

Habitat.--Mediterranean, Messina, Haeckel; Naples, Brandt; surface.

12. Collozoum stellatum, n. sp.

Collodastrum stellatum, Haeckel, 1882, Manuscript.

Central capsules star-shaped, irregularly radiating, with a great number (eight to twenty or more) of radial, short, conical, acute processes, very variable in size and number. Membrane thin. In every capsule several (four to eight) oil-globules.

Dimensions.--Diameter of the central capsules 0.12 to 0.2.

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

13. Collozoum amoeboides, n. sp. (Pl. 3, figs. 4, 5).

Collodastrum amoeboides, Haeckel, 1882, Manuscript.

Central capsules amoebiform, of moderate size, quite irregularly formed, with a variable number of finger-like, obtuse, irregular prolongations (commonly three to six), very variable in size and form. Membrane thin. In the centre of every capsule one single oil-globule.

Dimensions.--Diameter of the central capsules 0.04 to 0.08.

Habitat.--Indian Ocean, Ceylon, Haeckel; Madagascar, Rabbe; surface.

----

Suborder II. BELOIDEA, Haeckel.

Definition.--SPUMELLARIA with an imperfect skeleton, composed of numerous solid needles or spicula, scattered irregularly in the calymma.

The suborder #Beloidea# comprises all those SPUMELLARIA which possess an imperfect or rudimentary skeleton, composed of a variable number of isolated spicula scattered in the extracapsulum. The suborder contains only two different families, the solitary Thalassosphærida (or Beloidea monozoa) and the associated Sphærozoida (or Beloidea polyzoa). Both families are very nearly allied, and differ only in one single character: the solitary life of the former, the social union of the {29}latter. It seems to be merely a consequence of this difference that the cleavage of the nucleus commonly takes place very late in the former, very early in the latter.

Commonly, therefore, the full-grown Thalassosphærida (until immediately before their propagation) exhibit one single nucleus in the centre of the capsule, whilst in the Sphærozoida the capsule is distended with numerous small nuclei. In these latter the centre of the capsule usually contains one large oil-globule, whilst in the former oil-globules are either wanting or scattered in large numbers in the endoplasm, or disposed in one layer on the inside of the capsule membrane.

In the solitary Thalassosphærida each capsule is enclosed in its own peculiar spherical calymma, whilst in the associated Sphærozoida all the capsules of the colony are united into one common, very voluminous, alveolated calymma.

Family III. #THALASSOSPHÆRIDA#, Haeckel, 1862, (Pl. 2).

Thalassosphærida, Monogr. d. Radiol., p. 255.

Definition.--#Beloidea# solitaria.

The family Thalassosphærida comprises all solitary SPUMELLARIA with an imperfect skeleton, composed of numerous solid needles or spicula, scattered around the central capsule in the calymma. The structure of the unicellular soft body is quite the same as in the Thalassicollida; it differs from these only in the possession of the extracapsular skeleton. All needles of this skeleton are solid siliceous spicula, never hollow, as in the similar Cannorrhaphida among the PHÆODARIA. In the special structure and form of the skeleton the Thalassosphærida agree perfectly with the well-known, colony-building Sphærozoida; they differ from these only by their hermit-like life and by some peculiarities derived from this solitary development.

The oldest known form of this family is probably the first Radiolarian, observed in the living state, described in 1834 by Meyen as Physematium atlanticum (see p. 35). A second form was figured in my Monograph (1862) as Thalassosphæra bifurca (p. 260, Taf. xii. fig. 1). A third form was there described under the name Thalassosphæra morum; this remarkable form was first observed by Johannes Müller, and figured under the name Thalassicolla morum (1858, Abhandl., p. 28, Taf. vii. figs. 1, 2). The same form was afterwards observed living by myself in the Mediterranean, as well as in the Atlantic, and in great numbers by the late Sir Wyville Thomson in the Pacific. The latter gave a good figure of it with some valuable remarks in his excellent work, The Atlantic (1877, vol. i. p. 233, fig. 51). He called this peculiar Rhizopod Calcaromma calcarea, on account of the very peculiar calcareous bodies "looking in outline like the rowels of spurs," which are accumulated in great quantity around the central capsule, in the calymma. Further investigations have convinced me that these peculiar stellate {30}bodies of carbonate of lime, for which we propose the name "Calcastrella," are not parts of the skeleton produced by the Radiolarian, but foreign bodies picked up by its extracapsular sarcode (in the same way as the Coccoliths are picked up by Thalassicolla sanguinolenta = Myxobrachia!). These Calcastrella occur also in the calymma of some Discoidea and other Radiolaria; they are either unicellular calcareous Algæ, or foreign bodies of other origin. The Collodarium, however, described as Thalassicolla morum and Calcaromma calcarea, seems to be a simple Actissa, which has picked up a number of Calcastrella.

The Challenger collection has yielded a number of other true Thalassosphærida, which partly agree with Thalassosphæra in the simple structure of the unicellular body (resembling Actissa), and partly differ from it in the development of alveoles, either within or without the central capsule (similar to Thalassolampe and Thalassicolla). The solid siliceous spicula, which occur in great numbers scattered in the calymma, agree perfectly in form with the spicula of the colony-building Sphærozoida. A characteristic difference between the social and the solitary #Beloidea# seems to be determined by the cleavage of the nucleus, which takes place in the latter very late, in the former very early. Therefore in the large central capsule of the mature solitary Thalassosphærida, we commonly find one large nucleus in the centre, and a number of oil-globules around it in the endosarc, or disposed in one layer on the inside of the capsule-membrane (Pl. 2, figs. 2, 5); whereas in the much smaller associated capsules of the Sphærozoida one large oil-globule is placed commonly in the centre, and a great number of small nuclei scattered in the endoplasm (compare above, p. 24).

Synopsis of the Genera of Thalassosphærida.

A. Alveoles neither within { Spicula simple, 7. Thalassosphæra. nor without the { central capsule. { Spicula branched, 8. Thalassoxanthium.

B. Numerous large alveoles } within the central } Spicula simple, 9. Physematium. capsule (not in the } calymma). }

C. Numerous large alveoles { Spicula simple, 10. Thalassoplancta. within the calymma (not { in the central capsule). { Spicula branched, 11. Lampoxanthium.

Genus 7. Thalassosphæra,[14] Haeckel, 1862, Monogr. d. Radiol., p. 259.

Definition.--Thalassosphærida without alveoles, with simple, unbranched, needle-shaped spicula in the calymma.

The genus Thalassosphæra was founded by me in 1862 for those solitary #Collodaria# in which the simple central capsule is surrounded by scattered solid spicula. {31}I described these two different species, the new Thalassosphæra bifurca and the Thalassosphæra morum, which J. Müller had formerly called Thalassicolla morum. This latter form is characterised by peculiar calcareous bodies "looking in outline like the rowels of spurs, scattered irregularly in the gelatinous envelope," and was therefore afterwards called "Calcaromma calcarea" by Sir Wyville Thomson.[15] As already mentioned above, these calcareous rowels are foreign bodies, picked up by an Actissa (see p. 29). I here confine the genus Thalassosphæra to those solitary #Beloidea# in which the body exhibits no alveoles, and the siliceous solid spicula in the calymma are quite simple needles.

Thalassosphæra belonium, n. sp.

Spicula thin cylindrical rods, more or less curved, pointed at both ends, with smooth surface (similar to the needles of Rhaphidozoum italicum). Central capsule spherical, three times as large as the central nucleus, without larger oil-globules.

Dimensions.--Diameter of the central capsule 0.1 to 0.12, length of the spicula 0.04 to 0.08.

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

Thalassosphæra rhaphidium, n. sp.

Spicula thick cylindrical rods, more or less curved, pointed at both ends, covered with numerous strong conical thorns, perpendicular to the axis. Central capsule spherical, four times as broad as the central nucleus, with twenty to thirty large oil-globules on the inside of the membrane.

Dimensions.--Diameter of the central capsule 0.2, length of the spicula 0.12 to 0.16.

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

Genus 8. Thalassoxanthium,[16] Haeckel, 1881, Prodromus, p. 470.

Definition.--Thalassosphærida without alveoles, with numerous branched or compound spicula in the calymma.

The genus Thalassoxanthium differs from the foregoing Thalassosphæra, by the ramification of the spicula, and has therefore the same relation to it as Sphærozoum to Belonozoum. The soft unicellular body is as simple as in Actissa, and exhibits alveoles neither in the capsule nor in the calymma.

Subgenus 1. Thalassoxanthella, Haeckel.

Definition.--Spicula not geminate, but simply radiate, consisting of three, four, or more needles or shanks, radiating in different directions from one and the same point; shanks now simple or needle-like, now furcate or branched.

{32}1. Thalassoxanthium triactinium, n. sp.

Spicula all (or nearly all) triradiate, composed of three (or sometimes in a few spicula four) needle-like shanks of equal length, diverging from one common point. Shanks straight or somewhat curved, smooth, pointed. Central capsule pellucid, twice as broad as its dark nucleus, without larger oil-globules. Jelly-envelope very thin, with numerous xanthellæ.

Dimensions.--Diameter of the central capsule 0.1, of its nucleus 0.05, length of the spicule-shanks 0.6 to 0.8.

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

2. Thalassoxanthium triradiatum, n. sp.

Spicula all (or nearly all) triradiate, composed of three (or sometimes in a few spicula four) needle-like shanks of different length, diverging from one common point. Shanks curved or bent, covered with small conical thorns. Central capsule dark, three times as large as the nucleus, with numerous large oil-globules. Jelly-envelope thick, without xanthellæ.

Dimensions.--Diameter of the capsule 0.2, of the nucleus 0.07, length of the spicule-shanks 0.1 to 0.15.

Habitat.--South Pacific, Station 302, surface.

3. Thalassoxanthium medusinum, n. sp. (Pl. 2, fig. 5).

Spicula all (or nearly all) quadriradiate, irregular, composed of four (or sometimes in a few spicula three) needle-like shanks (mostly of unequal length), diverging from one common point. Shanks curved, pointed, thorny, covered with small spinules. Central capsule dusky, twice to three times as large as its dark central nucleus. On the inside of the membrane numerous large oil-globules. Jelly-envelope thin, with numerous xanthellæ.

Dimensions.--Diameter of the central capsule 0.45 to 0.5, of its nucleus 0.18 to 0.2.

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

4. Thalassoxanthium hexactinium, n. sp.

Spicula all (or nearly all) hexaradiate, composed of six (or sometimes in a few spicula three) needle-like shanks, diverging in two opposite hemispheres (three needles upwards, three needles downwards). Shanks somewhat curved, pointed, smooth. Central capsule yellowish-brown, dark, four times as broad as its dark central nucleus. Jelly-envelope thick (about twice as broad as the capsule), with very numerous xanthellæ.

Dimensions.--Diameter of the central capsule 0.3 to 0.4, of its nucleus 0.1 to 0.12.

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

{33}5. Thalassoxanthium cervicorne, n. sp. (Pl. 2, figs. 3, 4).

Spicula all triradiate, trichotomously branched, with three equal shanks, which diverge from one common point, and are again provided each with three branches on the distal end. These nine branches are commonly once or twice forked (each fork rarely provided with three ramules). The ramules are thin, unequal, curved, or bent, and the ramification nearly resembles a stag's horn. Central capsule transparent, without oil-globules, two to three times as broad as the dark nucleus, which contains one single long central nucleolus. Calymma thin, scarcely as thick as the radius of the nucleus.

Dimensions.--Diameter of the central capsule 0.2 to 0.25, of the nucleus 0.08 to 0.1, length of the spicula 0.05 to 0.15.

Habitat.--Central Pacific, Stations 271, 274, surface.

Subgenus 2. Thalassoxanthomma, Haeckel.

Definition.--Spicula all or partly geminate, consisting of one middle or axial rod, from the two poles of which diverge two, three, or more shanks in different directions. Shanks or needle-rays sometimes simple, needle-like, sometimes bifurcated or branched.

6. Thalassoxanthium furcatum, n. sp.

Spicula all (or nearly all) geminate and simply forked, composed of a simple axial rod and two simple, needle-like shanks on each end of it. Shanks straight, pointed, smooth, somewhat shorter than the middle rod. Central capsule yellowish, dark, three times as broad as its central dark nucleus; besides this a single oil-globule, nearly of the same size.

Dimensions.--Diameter of the central capsule 0.1, of its nucleus 0.03; length of the axial rod of the spicula 0.04, of its shanks 0.03.

Habitat.--Cape Verde Islands.

7. Thalassoxanthium bifurcum, Haeckel.

Thalassosphæra bifurca, Haeckel, 1862, Monogr. d. Radiol., p. 260, Taf. xii. fig. 1.

Sphærozoum bifurcum, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 845.

Spicula all geminate and double forked, composed of a simple axial rod and two forked branches on each end; these branches are again forked, so that each spiculum exhibits eight thin distal ends. All branches are thin, slender and straight. Central capsule red, four times as broad as the central nucleus, containing between the red pigment-granules numerous, peculiar, violin-shaped bodies (fat-corpuscles?). Compare fig. 1, loc. cit.

Dimensions.--Diameter of the central capsule 0.08, of the nucleus 0.02, length of the spicula 0.05 to 0.08.

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

{34}8. Thalassoxanthium ovodimare, n. sp.

Spicula all geminate, composed of a simple, very short axial rod and three diverging shanks or branches on each end of it; the shanks are very thin, straight, or little curved, and eight to ten times as long as the axial rod. The spicula are quite smooth, as in the similar Sphærozoum ovodimare (in which, however, the axial rod is much longer). Central capsule transparent, without oil-globules, twice as broad as the nucleus.

Dimensions.--Diameter of the capsule 0.4, of the nucleus 0.2, length of the spicula 0.1 to 0.2.

Habitat.--Central Pacific, Station 273, surface.

9. Thalassoxanthium punctatum, n. sp.

Spicula all geminate-triradiate, composed of a simple middle rod and of three diverging shanks on each end of it; the shanks are thorny with small spinules and shorter than the axial rod, very similar to the common Sphærozoum punctatum. Central capsule dark, with numerous (twenty to thirty) oil-globules on the inside of the membrane, three times as broad as the nucleus.

Dimensions.--Diameter of the capsule 0.3, of the nucleus 0.1, length of the spicula 0.05 to 0.2.

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

10. Thalassoxanthium octoceras, n. sp. (Pl. 2, fig. 6).

Spicula all geminate-quadriradiate, composed of a simple short middle rod and of four diverging shanks on each end of it; the shanks are quite smooth, irregularly curved or bent, and four to eight times as long as the middle rod. Central capsule dark, filled with pigment-granules, without oil-globules, four times as large as the nucleus.

Dimensions.--Diameter of the capsule 0.5, of the nucleus 0.12, length of the spicula 0.2 to 0.4.

Habitat.--Indian Ocean, Madagascar, Rabbe.

Genus 9. Physematium,[17] Meyen, 1834, Nova Acta Acad. Nat. Curios., vol. xvi., Suppl., p. 286 (p. 162).

Definition.--#Thalassosphærida# with large numerous alveoles within the central capsule (not in the calymma), and with numerous simple, needle-shaped spicula in the calymma.

The genus Physematium is, together with the colony-forming Sphærozoum, the first Radiolarian which was observed in the living state, described in 1834 by Meyen. It is most nearly allied to Thalassolampe, and has the same large roundish alveoles within the central capsule, which reaches therefore an extraordinary size, 5 to 10 mm. It {35}differs from the latter by the possession of spicula in the calymma. The peculiar "centripetale Zell-gruppen" on the inside of the capsule-membrane are probably due to radial cleavages of the endoplasm; as also occurs in other #Collodaria#.

1. Physematium mülleri, Schneider.

Physematium mülleri, Schneider, 1858, Archiv. f. Anat. u. Physiol., p. 38, Taf. iii. B, figs. 1-5.

Physematium mülleri, Haeckel, 1862, Monogr. d. Radiol., p. 256, Taf. iii. figs. 6-9.

Spherical body limpid, somewhat opalescent, sometimes a little yellowish or brownish, rather soft. Central capsule with a thin, but firm, transparent membrane, its diameter eight to ten times as large as that of the central spherical nucleus. Membrane of the nucleus thick, porous, on its inside with some nucleoli. In the protoplasmic network between the large intracapsular alveoles, numerous large, pale, yellowish, or orange oil-globules. On the inside of the membrane numerous conical bodies, centripetally directed with the apex towards the centre; every conical body ("kegelförmige centripetale Zellgruppe") composed of three to nine (commonly four or five) nucleated cells (mother-cells of the spores?); in the axis of the cone there is often a yellowish, orange, or brown oil-globule. Extracapsular jelly-envelope thin, with short pseudopodia. Xanthellæ scarce or wanting. Spicula scattered in the jelly numerous, small, simple needles, commonly C- or S-like curved, smooth.

Dimensions.--Diameter of the whole jelly-sphere 3 to 6 mm., of the central capsule 1 to 5 mm., of the nucleus 0.1 to 0.5, length of the spicula 0.05 to 0.1.

Habitat.--Mediterranean, Messina; Schneider, Haeckel; surface.

2. Physematium atlanticum, Meyen.

Physematium atlanticum, Meyen, 1834, Nova Acta Acad. Nat. Curios., vol. xvi., Suppl., p. 286 (162), Taf. xxxviii. (xxviii.) figs. 1-3.

Spherical body opalescent, pearl-like, with a violet or purple lustre, very soft. Central capsule with a strong, semi-transparent membrane, its diameter six to eight times as large as that of the central spherical nucleus. Membrane of the nucleus very thick, porous, on its inside with many small nucleoli. In the protoplasmic network between the alveoles very numerous, small, purple oil-globules. On the inside of the membrane a continuous simple layer of small nuclei, enclosed in radially striped protoplasm (mother-cells of the spores?). No centripetal conical bodies. Extracapsular jelly-envelope very thin, with short pseudopodia. No xanthellæ. Spicule scattered in the jelly numerous, small needles, straight or slightly curved, thorny owing to numerous small vertical spinules. This species and Thalassolampe maxima (p. 17) possess the largest central capsule.

Dimensions.--Diameter of the whole jelly-sphere 8 to 12 mm., of the central capsule 5 to 10 mm., of the nucleus 1 to 2 mm., length of the spicula 0.1 to 0.3.

Habitat.--Eastern Atlantic, between Canary Islands and Cape Verde Islands, Meyen; Lanzerote, Haeckel.

{36}Genus 10. Thalassoplancta,[18] Haeckel, 1862, Monogr. d. Radiol., p. 261.

Definition.--#Thalassosphærida# with numerous large alveoles in the calymma (but not in the central capsule), and with numerous simple, needle-shaped spicula around the central capsule.

The genus Thalassoplancta was founded by me in 1862 for a Radiolarian with simple hollow needles in the calymma, which was afterwards recognised as a Phæodarium, belonging to Cannorrhaphis. We here retain this name for a true Thalassosphærid, very similar to the latter, but distinguished by the absence of the phæodium and the solid--not hollow--needle-shaped spicula, which are scattered in the alveolated calymma. Thalassoplancta can be regarded as the solitary form of the social Belonozoum.[19]

1. Thalassoplancta longispicula, n. sp.

Spicula long and thin, cylindrical, smooth, more or less bent, pointed at both ends, similar to those of Thalassoplancta cavispicula. Central capsule thin-walled, without oil-globules, four times as broad as the nucleus, which encloses one single nucleolus.

Dimensions.--Diameter of the capsule 0.6, of the nucleus 0.15, of the calymma 4 mm.

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

2. Thalassoplancta brevispicula, n. sp. (Pl. 2, fig. 2).

Lampoxanthium brevispiculum, Haeckel, 1882, Atlas.

Spicula short and thick, thorny, irregularly curved, pointed at both ends, very numerous. In the observed specimen all spicula were aggregated in the outer part of the voluminous calymma, whilst the inner alveolated part was devoid of them. Central capsule thick walled, with a layer of large oil-globules on its inner surface, twice as broad as the large nucleus which contains numerous nucleoli.

Dimensions.--Diameter of the central capsule 0.5, of the nucleus 0.2, of the calymma 2.5.

Habitat.--South Atlantic, Station 334, surface.

Genus 11. Lampoxanthium,[20] n. gen.

Definition.--#Thalassosphærida# with numerous large alveoles in the calymma (but not in the central capsule), and with numerous branched or compound spicula in the calymma.

{37}The genus Lampoxanthium differs from the foregoing, Thalassoplancta, by the composite form of the spicula, which are not simple needles, but radiate or geminate, or branched in different forms; the former stands therefore in the same relation to the latter as the social Belonozoum to Sphærozoum. The spicula of some species of Lampoxanthium are identical with those of some species of Sphærozoum, so that the latter may be derived from the former by forming colonies. The large central capsule is enveloped by a very voluminous alveolated calymma, and includes a large central nucleus with numerous nucleoli.

Subgenus 1. Lampoxanthella, Haeckel.

Definition.--Spicula all (or nearly all) of one kind, radiate.

1. Lampoxanthium tetractinium, n. sp.

Spicula all (or nearly all) tetraradiate, with four thorny, straight, pointed shanks, radiating from one common point. (Intermingled with these are often some few, thorny, triradiate spicula.) On the inside of the capsule a layer of large oil-globules as in Thalassoplancta, Pl. 2, fig. 2.

Dimensions.--Diameter of the central capsule 0.2, of the nucleus 0.08, of the calymma 0.8.

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

Subgenus 2. Lampoxanthomma, Haeckel.

Definition.--Spicula all (or nearly all) of one kind, geminate-radiate, with a simple middle rod and two to four diverging shanks on each end of it.

2. Lampoxanthium punctatum, n. sp.

Spicula all geminate-triradiate, thorny, of the same form as in the common Sphærozoum punctatum, of which this species is the large solitary representative. The spicula are aggregated in a very condensed layer on the surface of the large calymma.

Dimensions.--Diameter of the capsule 0.8, of the nucleus 0.6, of the calymma 2.0.

Habitat.--North Pacific, Station 248, surface.

3. Lampoxanthium octoceras, n. sp.

Spicula all geminate-quadriradiate, with a very short simple middle rod and four very long divergent shanks on both ends of it; the shanks are smooth, five to ten times as long as the middle {38}rod, irregularly bent and curved. (Differs from the similar Thalassoxanthium octoceras, Pl. 2, fig. 6, by slender, more curved shanks, and by the voluminous calymma, there entirely wanting.)

Dimensions.--Diameter of the capsule 0.5, of the nucleus 0.2, of the calymma 3.0.

Habitat.--South Atlantic, Station 331, surface.

Subgenus 3. Lampoxanthura, Haeckel.

Definition.--Spicula of two or three different kinds, simple, radiate, and geminate-radiate mixed.

4. Lampoxanthium pandora, n. sp. (Pl. 2, fig. 1).

Spicula mixed, of three different kinds--simple, radiate and geminate-radiate; all three kinds partly smooth, partly thorny. The simple needles short, thin spindle-shaped, often curved. The radiate spicula commonly with three or four, rarely five or six, unequal rays, straight or curved. The radiate-geminate spicula commonly with three, rarely four, shanks on each end, often different on both ends of the middle rod. The size, number, and form of the irregular spicula are here quite as variable as in the social Rhaphidozoum pandora, of which it is the solitary representative. The wall of the large central capsule is very thick, with evident pore-canals, separated by a clear interval from the coagulated and vacuolated endoplasm, which contains no oil-globules. Nucleus with numerous nucleoli.

Dimensions.--Diameter of the central capsule 0.5 to 0.6, of the nucleus 0.1 to 0.2, of the calymma 2 to 4 mm.

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

Family IV. #SPHÆROZOIDA#, Haeckel (Pl. 4).

Sphærozoida, Haeckel, 1862, Monogr. d. Radiol., p. 521.

Definition.--#Beloidea# socialia.

The family #Sphærozoida# comprises all associated or colony-forming Radiolaria, which are provided with an imperfect skeleton, composed of numerous solid needles or spicula, scattered around the central capsule in the calymma. The structure and form of this skeleton is quite the same as in the preceding solitary Thalassosphærida, but on the other hand, the structure and form of the colonies and of the included numerous central capsules is the same as in the skeletonless Collozoida.

The oldest well-known form of Sphærozoida is the common cosmopolitan Sphærozoum punctatum, probably first observed in 1834 by Meyen, and called Sphærozoum fuscum, afterwards more accurately described by Huxley in 1851.

{39}Other forms were afterwards described by Müller and by myself in 1862.[21] Further investigations have shown me that some species of this family are among the most common Radiolaria, and occur in astonishing numbers on the surface of all warmer seas. But the number of species is comparatively small, and their distinction is very difficult, as all the different forms are very variable and connected by intermediate forms--a truly "transformistic" group.

The only character sufficient for the constitution of genera in this transformistic group is found in the form and composition of the spicula; the very variable form of the jelly-calymma and the enclosed central capsule being without value for this purpose. But also the form of the spicula is very variable, and not always constant. In some species the particular form of the spicula is transmitted by constant heredity, whilst in others it is very inconstant, even in one and the same individual. (Compare the remarks on variability in the general introduction.)

As the number of various forms is rather great, it seems to be advisable to distinguish the three following genera.

Synopsis of the Genera of Sphærozoida.

A. Spicula all of one kind, simple or needle-shaped, 12. Belonozoum. B. Spicula all of one kind, branched or radiate, or geminate, 13. Sphærozoum. C. Spicula of two more different kinds, partly simple, partly branched, 14. Rhaphidozoum.

Genus 12. Belonozoum,[22] n. gen.

Definition.--#Sphærozoida# with simple needle-shaped spicula, which are neither radiate nor branched.

The genus Belonozoum comprises the Sphærozoida with simple needle-shaped spicula, and may be regarded as the colonial form of Thalassosphæra or Thalassoplancta, derived from these solitary #Beloidea# by multiplication of the capsules and union in a common calymma.

1. Belonozoum bacillosum, n. sp.

Sphærozoum bacillosum, Haeckel, 1881, Manuscript.

Spicula all simple rods, straight cylindrical, obtuse at both ends, quite smooth. Central capsule pellucid, with one single central oil-globule.

Dimensions.--Diameter of the central capsule 0.08 to 0.12, length of the spicula 0.05 to 0.08.

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

{40}2. Belonozoum spinulosum, Haeckel.

Sphærozoum spinulosum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 54, Taf. viii. fig. 4.

Sphærozoum spinulosum, Haeckel, 1862, Monogr. d. Radiol., p. 527, Taf. xxxiii. figs. 3, 4.

Spicula all simple rods, straight cylindrical, obtuse on both ends, thorny with numerous small spines, placed vertically on the rods.

Dimensions.--Diameter of the central capsule 0.08 to 0.1, length of the spicula 0.05 to 0.2.

Habitat.--Mediterranean, Nice, J. Müller; Messina, Haeckel; Naples, Brandt; surface.

3. Belonozoum italicum, Haeckel.

Sphærozoum italicum, Haeckel, 1862, Monogr. d. Radiol., p. 526, Taf. xxxiii. figs. 1, 2.

Spicula all simple rods, more or less curved or bent, pointed at both ends, quite smooth. Central capsule with a variable number (commonly five to twenty) of oil-globules.

Dimensions.--Diameter of the central capsule 0.1 to 0.3, length of the spicula 0.05 to 0.2.

Habitat.--Mediterranean, Nice, Naples, Messina, Haeckel, surface.

4. Belonozoum atlanticum, n. sp.

Sphærozoum atlanticum, Haeckel, 1881, Manuscript.

Spicula all together simple rods, more or less curved or bent, pointed at both ends, thorny from numerous small spines, placed vertically on the rods.

Dimensions.--Diameter of the central capsule 0.1 to 0.2, length of the spicula 0.07 to 0.15.

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

Genus 13. Sphærozoum,[23] Meyen, 1834, Nova Acta Acad. Nat. Curios., Bd. xvi., Suppl., p. 287 (p. 163).

Definition.--#Sphærozoida# with branched or radiate spicula of one kind.

The genus Sphærozoum, with Physematium one of the two oldest Radiolaria, observed in the living state, was founded 1834 by Meyen for one of the social #Beloidea#, which was probably the common cosmopolitan Sphærozoum punctatum, the true type of this genus. Johannes Müller described a number of species, which were partly skeletonless (Collozoum), partly armed with simple or with compound spicula. The species with simple spicula we refer here to Belonozoum, the species with two or more different kinds of spicula to Rhaphidozoum, while we unite in Sphærozoum all species with one kind of branched or compound spicula. The two following species are incompletely known:--Sphærozoum orientale, Dana, 1863, Ann. and Mag. Nat. Hist., vol. xii. p. 54. Sphærozoum sanderi, Doenitz, 1871, L. N. 60, p. 71.

{41}Subgenus 1. Sphærozonactis, Haeckel.

Definition.--Spicula radiate, not geminate, consisting of three, four, or more needles or shanks, radiating in different directions from one common central point.

1. Sphærozoum triactinium, n. sp.

Spicula all (or nearly all) triradiate, composed of three (or sometimes in few spicula four) needle-like shanks, diverging from one common point. Shanks straight or somewhat curved, smooth, pointed. Central capsules spherical, with one central oil-vesicle. This species may be regarded as the social form of Thalassoxanthium triactinium.

Dimensions.--Diameter of the central capsules 0.1 to 0.12, length of the spicula-shanks 0.05 to 0.1.

Habitat.--South Pacific, Station 295, surface.

2. Sphærozoum medusinum, n. sp.

Spicula all (or nearly all) quadriradiate, composed of four (or sometimes in few spicula three) needle-like shanks (mostly of unequal length), diverging from one common point. Shanks slightly curved, pointed, thorny, covered with small spinules. Central capsules ellipsoidal, containing several (four to eight) oil-vesicles. This species may be regarded as the social form of the solitary Thalassoxanthium medusinum (Pl. 2, fig. 5).

Dimensions.--Diameter of the central capsules 0.15 to 0.18, length of the spicula-shanks 0.08 to 0.12.

Habitat.--North Pacific, Station 236, surface.

3. Sphærozoum hamatum, n. sp.

Spicula all (or nearly all) quadriradiate, composed of four (or sometimes in few spicula three) needle-like shanks, mostly of very different size, diverging from one common point. Shanks strong, straight, curved, or hook-like; thorny, covered with small spinules on the distal extremity. Central capsules ellipsoidal, large, containing many (ten to twenty) oil-globules. This large species is distinguished by the very irregular form and size of the spicula.

Dimensions.--Diameter of the central capsules 0.2 to 0.25, length of the spicula-shanks 0.12 to 0.18.

Habitat.--Central Pacific, Station 265, surface.

4. Sphærozoum hexactinium, n. sp.

Spicula all (or nearly all) hexaradiate, composed of six (or sometimes in few spicula five or seven) needle-like shanks, mostly of equal size, diverging from one common point in two opposite hemispheres (three needles upwards, three needles downwards). Shanks somewhat curved, pointed, {42}smooth. Central capsules spherical, small, with one central oil-globule. This species may be regarded as the social form of Thalassoxanthium hexactinium.

Dimensions.--Diameter of the central capsule 0.06 to 0.08, length of the spicula-shanks 0.05 to 0.06.

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

Subgenus 2. Sphærozonoceras, Haeckel.

Definition.--Spicula all geminate-radiate, consisting of one middle rod, which bears an equal and constant number of rays (two, three, or four) at each end.

5. Sphærozoum furcatum, n. sp.

Spicula all (or nearly all) geminate and simply forked, composed of a simple axial rod and two simple needle-like shanks on each end of it. Shanks straight, pointed, smooth, commonly somewhat longer than the middle rod.

Dimensions.--Diameter of the central capsules 0.1 to 0.15, length of the axial rod of the spicula 0.03, of its shanks 0.04 to 0.06.

Habitat.--Tropical zone of the Atlantic, near Ascension Island, Station 344, surface.

6. Sphærozoum furculosum, n. sp.

Spicula all (or nearly all) geminate and simply forked, composed of a simple axial rod and two simple needle-like shanks on each end of it. Shanks curved or bent, pointed, thorny, with many small spinules, commonly somewhat shorter than the middle rod.

Dimensions.--Diameter of the central capsules 0.2 to 0.25, length of the axial rod of the spicula 0.1, of its shanks 0.05 to 0.08.

Habitat.--South Atlantic, near Tristan da Cunha, Station 334, surface.

7. Sphærozoum ovodimare, Haeckel.

Sphærozoum ovodimare, Haeckel, 1862, Monogr. d. Radiol., p. 527, Taf. xxxiii. figs. 5, 6.

Sphærozoum punctatum, var., Brandt, 1881, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, Taf. i. fig. 54.

Spicula all (or nearly all) geminate and triradiate, composed of a long simple axial rod and three simple needle-like shanks on each end of it. Shanks straight, pointed, smooth, commonly shorter than the middle rod. (Often few furcate or four-rayed spicula are intermixed, or few spicula are not smooth, but thorny.)

Dimensions.--Diameter of the central capsules 0.05 to 0.2, length of the middle rod of the spicula 0.02 to 0.06, of its shanks 0.01 to 0.04.

Habitat.--Mediterranean, Naples, Messina, Haeckel; Atlantic, Canary Islands, Cape Verde Islands, West Coast of Africa, Stations 351 to 354; surface.

{43}8. Sphærozoum trigeminum, n. sp.

Spicula all (or nearly all) geminate-triradiate, composed of a short simple axial middle rod and three simple needle-like shanks on each end of it. Shanks curved or bent, very thin, smooth, commonly much longer than the middle rod. (Often few quadriradiate or few thorny triradiate spicules are interspersed among the others.)

Dimensions.--Length of the middle rod of the spicula 0.02 to 0.04, of its shanks 0.03 to 0.09.

Habitat.--North Pacific, Stations 244 to 248, surface.

9. Sphærozoum punctatum, J. Müller.

Sphærozoum punctatum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 54, Taf. viii. figs. 1, 2.

Sphærozoum punctatum, Haeckel, 1862, Monogr. d. Radiol., p. 528, Taf. xxxiii. figs. 7-9.

Sphærozoum fuscum, Meyen, 1834, Nova Acta Acad. Nat. Cur., vol. xvi. Taf. xxxviii. fig. 7.

Thalassicolla punctata, Huxley, 1851, Ann. and Mag. Nat. Hist., ser. 2, vol. viii. p. 434, pl. xvi. figs. 1, 2, 3.

Spicula all (or nearly all) geminate-triradiate, composed of a long simple axial middle rod and three simple needle-like shanks on each end of it. Shanks straight, pointed, thorny, with many small spines, commonly somewhat shorter than the middle rod. (Often few furcate or four-rayed spicula are intermingled, or some of the spicula are smooth.) This cosmopolitan species is extremely variable, and produces interesting transitional forms to many other species of the genus. Compare also the general remarks on the genus, and the chapter on "Transformation" in the general introduction.

Dimensions.--Length of the middle rod of the spicula 0.02 to 0.06, of its shanks 0.01 to 0.05.

Habitat.--Cosmopolitan, common in nearly all warmer seas, Mediterranean, Atlantic, Indian Ocean, Pacific; surface.

10. Sphærozoum armatum, n. sp. (Pl. 4, fig. 9).

Spicula all geminate-triradiate, with a stout and short middle rod and three arborescent shanks on each end of it. Shanks longer than the middle rod, very stout, straight, pine-shaped, with six to twelve irregular, spinulated, lateral branches.

Dimensions.--Diameter of the central capsules 0.04 to 0.08, length of the middle rod of the spicula 0.02 to 0.03, of its shanks 0.05 to 0.08.

Habitat.--North Pacific, Japan, Station 239, surface.

11. Sphærozoum alveolatum, n. sp. (Pl. 4, figs. 2, 3).

Spicula all together geminate-triradiate, with a simple stout middle rod and three arborescent shanks on each end of it. Shanks more or less curved, slender, pine-shaped, with four to eight short, thorny lateral branches. In all coenobia of this remarkable species the central capsules are enclosed in large thick-walled alveoles (of three times their breadth), and in each alveole is placed besides {44}the capsule one single very large spiculum, whilst the others are much smaller (fig. 3). All the alveolated capsules are placed in one single stratum on the surface of the jelly-like spherical coenobium, comparable to the blastoderm-cells of a blastula.

Dimensions.--Diameter of the central capsules 0.08 to 0.1, of the alveoles 0.2 to 0.4, length of the spicula 0.1 to 0.3.

Habitat.--South Pacific (Juan Fernandez), Station 300, surface.

12. Sphærozoum verticillatum, n. sp. (Pl. 4, fig. 7).

Spicula all geminate-triradiate, with a short simple middle rod and three much longer arborescent shanks on each end of it. Shanks straight, slender, pine-shaped, each in the distal half with three to four elegant verticils of thorny lateral branches.

Dimensions.--Diameter of the capsules 0.1 to 0.12, middle rod of the spicula 0.03 to 0.05, shanks 0.1 to 0.15.

Habitat.--Indian Ocean, Ceylon, Haeckel; Madagascar, Rabbe; surface.

13. Sphærozoum octoceras, n. sp.

Spicula all geminate-quadriradiate, with a short simple middle rod and four diverging shanks on each end of it. Shanks smooth, irregularly curved or bent, three to six times as long as the middle rod. It may be regarded as the social form of Thalassoxanthium octoceras (Pl. 2, fig. 6).

Dimensions.--Diameter of the capsules 0.12 to 0.16, middle rod of the spicula 0.02, shanks 0.01.

Habitat.--Australia, south coast, Faber; Station 163, surface.

14. Sphærozoum quadrigeminum, n. sp.

Spicula all geminate-quadriradiate, with a long thick middle rod and four shorter diverging shanks on each end of it. Shanks straight, thorny.

Dimensions.--Diameter of the capsules 0.06 to 0.08, length of the spicula 0.05 to 0.15.

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

15. Sphærozoum araucaria, n. sp.

Spicula all geminate-quadriradiate, with stout straight middle rod and four longer diverging shanks on each end of it. Shanks arborescent, with six to twelve thorny lateral branches.

Dimensions.--Diameter of the capsules 0.1 to 0.15, length of the spicula 0.05 to 0.1.

Habitat.--South Atlantic, coast of Brazil, Rabbe; surface.

16. Sphærozoum arborescens, n. sp. (Pl. 4, fig. 8).

Spicula all geminate-quadriradiate, with a stout straight middle rod and four longer diverging shanks on each end of it. Shanks arborescent, pine-shaped, with four to six verticils of lateral branches, which again are ramified and thorny.

{45}Dimensions.--Diameter of the capsules 0.16 to 0.18, length of the spicula 0.1 to 0.2.

Habitat.--South Atlantic (Tristan da Cunha), Station 332, surface.

Subgenus 3. Sphærozonura, Haeckel.

Definition.--Spicula all geminate-radiate, but with a different and variable number of shanks on each end of the middle rod.

17. Sphærozoum stellatum, n. sp.

Spicula all geminate-radiate, with a strong middle rod and a variable number of shorter radiating shanks on the two ends of it. Shanks straight, nearly conical, smooth; for the most part three or four shanks on each end, but sometimes also five or six; very often this number is unequal on the two ends.

Dimensions.--Diameter of the central capsules 0.1 to 0.2, length of the spicula 0.05 to 0.15.

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

18. Sphærozoum geminatum, n. sp. (Pl. 4, fig. 4).

Spicula all geminate-radiate, with a strong middle rod and a variable number of longer radiant shanks on each end of it. Shanks straight, conical, in the distal half thorny; commonly either three or four shanks on each end of the middle rod, often also three on one end, four on the other end; rarely five or six rays on one end.

Dimensions.--Diameter of the capsules 0.15 to 0.2, length of the spicula 0.05 to 0.1.

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

19. Sphærozoum circumtextum, n. sp.

Spicula all geminate-radiate, with a very variable number of rays (two to six) on each end of the thin middle rod. All spicula very thin and delicate, smooth, with curved or bent shanks, densely covering the central capsule like a cobweb. The number of rays on each end is usually different, generally four or five, often also two or three, rarely six.

Dimensions.--Diameter of the capsule 0.1 to 0.2, length of the spicula 0.04 to 0.12.

Habitat.--Southeast part of the Indian Ocean, Station 160, surface.

20. Sphærozoum variabile, n. sp. (Pl. 4, fig. 5).

Spicula all geminate-radiate, with a short middle rod and a variable number of shanks on each end of it. Shanks four to eight times as long as the middle rod, curved or bent, in the distal half thorny; their number is commonly different on the two ends of it, three or five, often also four or six, rarely two; their size and form very variable.

{46}Dimensions.--Diameter of the capsules 0.1 to 0.3, length of the spicula 0.1 to 0.2.

Habitat.--North Pacific, Station 248, surface.

Genus 14. Rhaphidozoum,[24] Haeckel, 1862, Monogr. d. Radiol., p. 529.

Definition.--Sphærozoida with two or more different kinds of spicula; one kind simple, needle-shaped; the other kinds compound, radiate, or branched.

The genus Rhaphidozoum differs from Sphærozoum by the composition of the skeleton of two or more different kinds of spicula, and has therefore the same relation to it as the solitary Lampoxanthura to Lampoxanthella.

In some species nearly all the different forms, which characterise the numerous species of #Beloidea#, may be united in one and the same individual.

Subgenus 1. Rhaphidonactis, Haeckel.

Definition.--Spicula of two different kinds; one kind simple, needle-shaped, the other radiate (composed of three, four, or more shanks, diverging from one common point).

1. Rhaphidozoum pelagicum, n. sp.

Spicula of two different kinds; one kind simple thin needles, a little curved or bent, the other kind triradiate, with three thin, curved shanks. Both kinds smooth, without thorns. Resembles a combination of Belonozoum italicum and Sphærozoum triactinium.

Dimensions.--Diameter of the central capsules 0.1 to 0.12, length of the spicula 0.05 to 0.15.

Habitat.--Central Pacific, Station 267, surface.

2. Rhaphidozoum pacificum, n. sp.

Spicula of two different kinds; one kind simple needles, stout and straight, pointed at both ends, the other kind triradiate, with three straight and stout shanks. Both kinds thorny.

Dimensions.--Diameter of the central capsule 0.06 to 0.08, length of the spicula 0.05 to 0.1.

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

3. Rhaphidozoum acuferum, Haeckel.

Rhaphidozoum acuferum, Haeckel, 1862, Monogr. d. Radiol., p. 529, Taf. xxxii. figs. 9-11.

Sphærozoum acuferum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 54, Taf. viii. fig. 3.

Thalassicolla acufera, J. Müller, 1855, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 237.

Spicula of two different kinds, simple needles and quadriradiate; both strong, thorny, covered with small spinules. Simple needles mostly curved, C-shaped. Four shanks of the quadriradiate {47}spicula now straight, now curved, commonly of very different size. (Often one single quadriradiate spiculum is distinguished by its extraordinary size.) For the detailed description of this species compare my Monograph (loc. cit.).

Dimensions.--Diameter of the central capsules 0.05 to 0.35, length of the simple needles 0.05 to 0.25, shanks of the quadriradiate spicula 0.05 to 0.15.

Habitat.--Mediterranean, Messina, Naples, Nice.

4. Rhaphidozoum arachnoides, n. sp.

Spicula of two different kinds; one kind simple, needle-like, the other quadriradiate; both very thin and slender, smooth, without spicules. Simple needles curved, C-shaped. Four shanks of the quadriradiate spicula also curved, commonly of nearly equal size. The numerous thread-like spicula of this species are so densely packed around the central capsule, that they extend all around its surface like the network round a balloon.

Dimensions.--Diameter of the central capsules 0.12 to 0.15, length of the simple needles 0.1 to 0.12, shanks of the quadriradiate spicula 0.06 to 0.08.

Habitat.--Tropical Atlantic, Station 345, surface.

5. Rhaphidozoum asperum, n. sp.

Spicula of two different kinds; one kind simple, needle-shaped, stout, and straight, the other kind hexaradiate; its six shanks about half as long as the former, conical. Both kinds very thorny, covered with short conical spinules.

Dimensions.--Diameter of the capsules 0.06 to 0.08, length of the simple needles 0.05 to 0.07, shanks of the hexaradiate spicula 0.03 to 0.04.

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

Subgenus 2. Rhaphidoceras, Haeckel.

Definition.--Spicula of two different kinds; one kind simple, needle-shaped, the other kind geminate-radiate, with rays on both poles of a middle rod.

6. Rhaphidozoum neapolitanum, Haeckel.

Sphærozoum neapolitanum, C. Brandt, 1881, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 390, Taf. i. figs. 14, 16-18.

Spicula mixed, of two different kinds; simple needles and geminate-forked. Simple rods, like those of Belonozoum italicum, more or less curved, pointed at both ends, smooth (sometimes a little thorny at both ends). Geminate spicula simply forked, like those of Sphærozoum furcatum, composed of a short, simple, axial rod, and two simple, smooth, straight shanks on each end of it, commonly somewhat longer than the middle rod. This species, which I have observed myself in Spezzia in great quantity, is quite as variable as all the other species of the genus, and has not more claim to specific rights than the others. Commonly the simple needles are much more numerous {48}than the geminate-forked, but sometimes the contrary is the case. On their variability compare the general remarks on the genus, and the chapter on "Transformation" in the general introduction.

Dimensions.--Length of the simple spicula 0.05 to 0.1, of the middle rod of the forked spicule 0.05 to 0.08, of their shanks 0.01 to 0.03.

Habitat.--Mediterranean, Naples, Spezzia, surface.

7. Rhaphidozoum patagonicum, n. sp.

Spicula mixed, of two different kinds, simple needles and geminate-triradiate. Simple rods, like those of Belonozoum spinulosum, straight, thorny, pointed at both ends. Geminate spicula double-triradiate, like those of Sphærozoum punctatum, composed of a simple, short, axial rod and three simple pointed shanks on each end of it. Shanks straight, thorny, with many small spinules, commonly somewhat longer than the middle rod. (Often some of the spicula of both kinds are smooth, not thorny, or not straight, but a little curved, or a few forked or four-radiated geminate spicula are mingled with the others.)

Dimensions.--Diameter of the central capsules 0.08 to 0.2, length of the simple spicula 0.1 to 0.15, of the geminate 0.08 to 0.16.

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

8. Rhaphidozoum ascensionis, n. sp.

Spicula mixed, of two different kinds, simple needles and geminate-triradiate; both kinds thin, smooth, without spinules. Simple needles somewhat curved, C- or S-shaped. Geminate spicula double-triradiate, composed of a simple, short, straight axial rod and three slender curved shanks on each end of it. Shanks two to four times longer than the middle rod. (Sometimes few simple hexaradiate and geminate tetraradiate spicula are mingled.)

Dimensions.--Diameter of the central capsules 0.12 to 0.15, length of the simple spicula 0.1, of the double-triradiate 0.05 to 0.2.

Habitat.--South Atlantic, off Ascension Island, Station 342, surface.

9. Rhaphidozoum capense, n. sp.

Spicula of two different kinds; one kind simple, needle-shaped, straight, pointed at both ends, the other kind geminate-quadriradiate, with a stout short middle rod and four longer bent shanks on each end of it. Both kinds smooth.

Dimensions.--Diameter of the capsules 0.2 to 0.25, length of the simple needles 0.01 to 0.3, of the geminate spicula 0.05 to 0.15.

Habitat.--Cape of Good Hope (Agulhas), Station 142, surface.

10. Rhaphidozoum australe, n. sp.

Spicula of two different kinds; one kind simple, needle-shaped, curved, thin; the other kind geminate, with a variable number of shanks on both ends of the shorter middle rod, often {49}different on the two poles of it. The prevalent number of rays on each end is three or four, often also two or five, rarely six. All spicula smooth, more or less bent.

Dimensions.--Diameter of the capsules 0.1 to 0.2, length of the spicula 0.05 to 0.15.

Habitat.--South West Pacific, Station 165, surface.

Subgenus 3. Rhaphidonura, Haeckel.

Definition.--Spicula of three different kinds: one kind simple, needle-shaped; the second kind radiate, with three to six shanks radiating from a common central point; the third kind geminate-radiate, with rays on both poles of a middle rod.

11. Rhaphidozoum polymorphum, n. sp.

Spicula of three different kinds; simple needles, radiate, and geminate mixed. The simple needles straight and stout. The radiate spicula commonly with three or six, rarely four or five, rays. The geminate-radiate spicula prevalent, with three or four, rarely two or five, shanks on each end of the middle rod. Number very variable. All shanks straight and smooth.

Dimensions.--Diameter of the capsule 0.1 to 0.2, length of the spicula 0.05 to 0.15.

Habitat.--South Pacific, Station 295, surface.

12. Rhaphidozoum pandora, n. sp. (Pl. 4, fig. 6).

Spicula of three different kinds; simple needles, radiate and geminate mixed. The simple needles thin spindle-shaped, often curved. The radiate spicula commonly with three or four, rarely five or six, curved rays. The geminate-radiate spicula commonly with three or four, rarely two or five, shanks on each end, often different on the two ends of the middle rod. Number and form very variable. All or most of the shanks more or less bent and thorny.

Dimensions.--Diameter of the capsule 0.1 to 0.3, length of the spicula 0.05 to 0.2.

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

----

Order II. SPHÆRELLARIA, Haeckel, 1881.

Sphærellaria, Haeckel, 1881, Prodromus, p. 421. Sphæridea vel Peripylea, Hertwig, 1879, Organismus der Radiol., p. 133.

Definition.--SPUMELLARIA with latticed or spongy shell.

The order #Sphærellaria#, the second order of Radiolaria, comprises all those SPUMELLARIA in which the skeleton is a latticed or fenestrated, often more or less spongy, siliceous shell. Originally this shell is a simple extracapsular lattice-sphere, in which the central capsule is included; from this simple ancestral form an enormous {50}mass of different and often very complicated forms is derived; this order is by far the largest, and in morphological respects the most important and most interesting, of all Radiolaria. It contains not less than twenty-eight different families, three hundred and five genera, and more than sixteen hundred species.

In my Monograph (1862) seven families appertaining to this group are described--the Ethmosphærida, Cladococcida, Ommatida, Spongurida, Discida, Lithelida, and Collosphærida. The astonishing increase of this group by the detection of a large series of new and interesting forms, and particularly of important connecting forms between very different branches of it, now enables me to give a much better arrangement. I discern now four suborders or sections of #Sphærellaria#, according to the different geometrical form of the central capsule and of the latticed shell enveloping it. The first of these, and the common ancestral group of the whole order, is the #Sphæroidea#, with spherical capsule; in the #Prunoidea# it becomes ellipsoidal or cylindrical by prolongation of one axis; in the #Discoidea# lenticular or discoidal by shortening of one axis; in the #Larcoidea# lentelliptical, or triaxon-ellipsoid, by different growth of the capsule in three different "dimensive axes."

Synopsis of the Four Suborders of #Sphærellaria#.

Central capsule { Shell a simple sphere or a spherical. { system of concentric spheres, 1. #Sphæroidea#.

Central capsule { Shell a simple ellipsoid or a ellipsoidal or { cylinder with annular cylindrical. { transverse constrictions, 2. #Prunoidea#.

Central capsule lenticular or { Shell a biconvex lens or a discoidal. { flat disk, 3. #Discoidea#.

Central capsule lentelliptical or { Shell a triaxon-ellipsoid, with triaxon. { three different axes, 4. #Larcoidea#.

----

Suborder I. SPHÆROIDEA, Haeckel.

Sphæroida, Sphæridea, Sphærida, Haeckel, 1878, Protistenreich, p. 103. Sphæridea, R. Hertwig, 1879, Organismus der Radiol., p. 39.

Definition.--SPUMELLARIA with spherical central capsule (very rarely somewhat modified, or allomorphous); with spherical fenestrated siliceous shell (often an endospherical polyhedron, very rarely of more modified, subspherical form or allomorphous). Growth of the shell in the three dimensive axes equal.

The suborder #Sphæroidea#, the first and most important of the four of the #Sphærellaria#, comprises those SPUMELLARIA in which the original geometrical {51}spherical form is quite constantly preserved in the central capsule, and commonly also in the fenestrated shell enveloping the latter, although in many forms the sphere is more or less modified; very frequently it is an "endospherical polyhedron," i.e., a polyhedron all the angles (or the nodes of the network) of which lie upon the surface of a geometrical sphere; more rarely the spherical form is more or less modified and irregular. In the great majority of #Sphæroidea# there is no external indication of the three dimensive axes; but in many forms they are indicated by the regular position of certain external radial spines or internal radial beams. However, in no case are those three axes expressed in the form of the shell itself and of the enclosed spherical central capsule; this is the main character by which the #Sphæroidea# differ from the following sections:--#Prunoidea#, #Discoidea#, #Larcoidea#, all three of which arise from them.

The section #Sphæroidea#, in the sense here restricted, was founded by me in my Protistenreich (1878, p. 103) and adopted by Hertwig (1879) in his Organismus der Radiolarien (p. 39). The different groups appertaining to this large section were characterised more accurately in my Prodromus (1881, pp. 448-456); there I gave the characters of six subfamilies with thirty tribes, containing ninety-three genera. Formerly, in my Monograph (1862), the #Sphæroidea# were disposed in five different families:--Ethmosphærida, Cladococcida, Ommatida, Spongosphærida, Collosphærida. At that time I could not separate them sufficiently from some ACANTHARIA and PHÆODARIA, which have a similar spherical lattice-shell.

As the number of different genera and species in the #Sphæroidea# is much greater than in all other sections of SPUMELLARIA, many forms were already described by former authors. In the oldest system of Ehrenberg (1847, loc. cit., p. 53) they represent one part of his Haliommatina (with four genera, Haliomma, Chilomma, Stylosphæra, Spongosphæra). Most species, however, of these genera are #Discoidea#. Also in the latest system of Ehrenberg (1875, loc. cit., p. 157) his Haliommatina are a confused conglomeration of different SPUMELLARIA (#Sphæroidea#, #Discoidea#, and #Prunoidea#).

The section #Sphæroidea# is the largest division of #Sphærellaria#, comprising not less than one hundred and seven genera and six hundred and fifty species. This enormous number (easily to be augmented by further investigations) requires a careful disposition in different families and subfamilies. For this disposition two different principles only can be employed: firstly, the number and disposition of the radial spines; secondly, the number of the concentric latticed spheres, which are connected by radial beams. I give here the preference to the first principle, whilst in my Prodromus (1881) I had preferred the second. The question, which of the two principles is more important for the classification of #Sphæroidea#, is very difficult to answer; probably in many cases the former, in many the latter is more important for their phylogeny.

{52}Regarding the number of the concentric shells which compose the latticed carapace of the #Sphæroidea#, we can distinguish six families, viz.:--

I. Monosphærida (with one single shell). II. Dyosphærida (with two concentric shells). III. Triosphærida (with three concentric shells). IV. Tetrasphærida (with four concentric shells). V. Polysphærida (with five or more concentric shells). VI. Spongosphærida (with spongy shells).

On the other hand, regarding the number of the radial spines and their regular disposition on the shell-surface, we can distinguish five families, viz.:--

I. Liosphærida (without radial spines). II. Stylosphærida (with two radial spines, opposite in one axis). III. Staurosphærida (with four radial spines, opposite in pairs in two axes, perpendicular one to another). IV. Cubosphærida (with six radial spines, opposite in pairs in the three dimensive axes). V. Astrosphærida (with numerous--eight, twelve, twenty, or more--radial spines, often more than a hundred).

All five latter groups contain representatives of all six former groups; therefore we get together not less than thirty different subfamilies of #Sphæroidea#, already enumerated in my Prodromus, 1881, p. 449. I repeat them here to give a better survey of the system there employed.

{53}The #Monosphærida# comprise all those #Sphæroidea# in which the carapace is represented only by one single lattice-shell. Originally this shell is probably everywhere an extracapsular or "cortical shell," which is developed on the outside of the jelly-veil enveloping the central capsule, and serves as a protective carapace for these soft enclosed parts. But with the progress of growth the central capsule becomes larger than the including shell, and sends out through its pores club-shaped prolongations or cæcal-sacs (Pl. 11, figs. 1, 5; Pl. 19, figs. 2, 3, 5; Pl. 20, fig. 1_a_; Pl. 27, fig. 3). These protruded sacs may fuse together again outside the shell and form a spherical bladder, now enveloping the smaller shell; the latter now becomes an intracapsular or "medullary shell."

As #Pliosphærida# (or Sphæroidea concentrica) we can oppose to the simple Monosphærida all other #Sphæroidea#, the lattice-shell of which is composed of two or more concentric shells, connected by radial beams. Probably all Pliosphærida (or at least the greater part of them) arise from the Monosphærida by centrifugal growth; two or more radial spines are developed from the surface of the simple lattice-sphere, and are united together by communicating lateral branches, developed at equal distances from the centre; and this same process may be repeated, two, three, four, or more times. In this way originate the characteristic systems of concentric spheres, all united by piercing radial beams which arise from the surface of the innermost sphere (not from its centre). Regarding this mode of growth, we can distinguish the innermost as "original" or "primary" shell, and all subsequent ones as "apposed" or "secondary" shells; if the number of concentric shells amount to three or more, commonly both innermost shells lie within the central capsule and are medullary shells, whilst all others lie outside it and are therefore cortical shells. This difference can be commonly recognised also in the isolated shell, without its central capsule; the distance between the cortical and the medullary shells being commonly much larger than the distance between the two medullary shells.

The #Dyosphærida#, or the #Sphæroidea# with two concentric shells, are the most numerous among the Pliosphærida. Commonly in this group the inner or primary shell lies within the central capsule as a true "medullary shell," whilst the outer lies outside it as a "cortical shell"; therefore the radial beams, connecting both, pierce the wall of the capsule. But in several forms, mainly in the peculiar group of Diplosphærida, both concentric shells remain outside the central capsule, and both are therefore "cortical shells."

The #Triosphærida#, or the #Sphæroidea# with three concentric shells, are also very rich in different forms, though not so numerous by far as the Dyosphærida. Commonly in the Triosphærida both inner shells lie within the central capsule as "medullary shells," whilst the third lies outside it as a "cortical shell"; therefore the central capsule remains intermediate in size between the outer and the middle shell. But in some genera (e.g., Rhodosphæra) both outer shells are cortical and only the {54}innermost is a medullary shell. In this case the size of the capsule remains intermediate between the inner and the middle shell.

The #Tetrasphærida#, or the #Sphæroidea# with four concentric shells, are in general not frequent, and not rich in different forms. In most of the observed species two inner shells are medullary, two outer cortical shells, the former within, the latter without, the central capsule; and the wall of the capsule, pierced by the connecting radial beams, lies between the two middle shells. But there are some Tetrasphærida in which all four shells seem to be external or cortical shells.

The #Polysphærida#, or the #Sphæroidea# with five or more concentric shells, seem of course to offer the greatest possibility for the development of very different forms; but in reality this group is the poorest and smallest of all; and only one part of it, the Arachnosphærida, is rather common. In this peculiar division the shell is composed of five to ten or more, very delicate, cobweb-like concentric shells, which are connected by radial beams; all are cortical shells, and lie outside the central capsule. Much more rare are those Polysphærida, in which both innermost shells, as true medullary shells, lie within the central capsule, all others being outside it. The total number of concentric shells in this group is commonly between five and ten, rarely more.

The #Spongosphærida# are distinguished from all other #Sphæroidea# by the spongy structure of the spherical shell, which is composed wholly or partially of an irregular spongy framework. The relation of this group to the other groups of #Sphæroidea# is probably rather complicated, for in some Spongosphærida the whole shell is composed of massive spongy reticulation, whilst in others it contains a spherical central cavity, and in a third group this cavity is filled up by one or two concentric lattice-shells, connected by radial beams. Many of these Spongosphærida are very common, and of considerable size.

The #Collosphærida# form a peculiar separate group of #Sphæroidea#, distinguished from all others by their social life or aggregation in colonies (coenobia). They represent the only group of #Sphærellaria# in which this association of numerous individual capsules or cells is realised. The shell is almost constantly simple, without regularly disposed radial spines; therefore they may be called "social Monosphærida," or better "polyzoic Ethmosphærida." Only in one small group (Clathrosphærida) the shell, enveloping every central capsule, is double or surrounded by an external mantle; these may be compared to the Diplosphærida (or better to a part of the Carposphærida, Liosphæra, p. 76). In most of the Collosphærida the lattice-shell is more or less irregular in form and structure.

The Lattice Work of the fenestrated shells is in the #Sphæroidea# of the greatest variability, and its innumerable modifications serve mainly for the distinction of species. In general we can distinguish as the most important modifications a regular network (with equal size, form, and distance of the pores or meshes) and an irregular network (with {55}differences in the size, form, or distance of the meshes or pores). In both groups the pores may be either angular or round; so that there may exist together four different main forms of network--(A) regular lattice with equal hexagonal pores; (B) regular lattice with equal circular pores; (C) irregular lattice with unequal polygonal pores; (D) irregular lattice with unequal roundish pores. Besides these modifications, the pores may be prolonged into tubules which are directed radially towards the outside (rarely towards the inside) of the sphere. In other cases they are surrounded by elevated or honeycomb-like frames.

The Radial Spines exhibit in the #Sphæroidea# the greatest variety in form, size, disposition, &c., and their numerous modifications serve mainly for the distinction of genera, their peculiar formation and size also for the distinction of species. In general we may distinguish as the most important modifications primary and secondary spines. The primary spines or "main spines" are commonly direct outward prolongations of the internal radial beams, connecting the concentric shells. The secondary or "by-spines" arise only from the surface of the lattice-shell, without reference to the internal beams. The by-spines are commonly smaller, and much more numerous than the main spines. Regarding the form, the radial spines are either roundish (cylindrical or conical, often also club-shaped, rarely spindle-shaped) or angular (commonly three-sided, prismatic or pyramidal). The spines are constantly solid, never hollow; the "internal canals," described by some authors, are only microscopic views of the transparent edges. In many cases the spines are branched or forked. The most important difference in the variable shape of the spines is their regular or irregular number and disposition, which afford characters for the distinction of our five families.

The Three Dimensive Axes--or the three diameters of the sphere, perpendicular one to another--are in the great majority of the #Sphæroidea# significant in the promorphological consideration of the body, and are indicated either by the position of the external radial spines, or at least of the internal radial beams, connecting the concentric spheres. Commonly two radial spines are placed opposite in each axis. The most perfect group in this respect seems to be that of the Cubosphærida, in which the three axes are represented by three pairs of spines. Next come the Staurosphærida, in which two axes in cross-form are exhibited by two pairs of spines. The most simple group are the Stylosphærida, in which only one pair of spines is developed, indicating one single axis. These three families form together a continuous natural series,--the #Sphæroidea# with real dimensive axes,--and exhibit at the same time relations to the three other suborders of #Sphærellaria#, the #Larcoidea#, #Discoidea#, and #Prunoidea# respectively. At both ends of this series stand two other families, on one side the Liosphærida, without any radial spines on the surface of the sphere, on the other side the Astrosphærida, in which the radial spines are developed in great and variable numbers, at least eight to twelve, commonly twenty to forty, often more than a hundred or even a thousand.

{56}The #Liosphærida# comprise all those #Sphæroidea# in which the surface of the shell is smooth, without radial spines (Pls. 12, 20). The simplest of these are the Ethmosphærida, with one single lattice-shell, enveloping the spherical central capsule. Cenosphæra, the most simple form of the Ethmosphærida, may be regarded as the common ancestral form of all #Sphæroidea#, in an ontogenetical as well as in a phylogenetical and morphological sense. From this simple lattice sphere all other #Sphæroidea# can be derived either by radial or by tangential growth. If the radial beams, arising from the surface of the simple fenestrated sphere, become connected (at equal distances from the centre) by tangential beams, we get the compound shells of the "Liosphærida concentrica" (with two, three, four, or more concentric spheres). The radial beams connecting these exhibit in many Liosphærida the same regular disposition and number as the external radial spines in the Astrosphærida. Perhaps these forms in a "natural system" would be better united (e.g., Liosphærida with twelve or twenty internal radial beams, and Astrosphærida with twelve or twenty external radial spines); but in many cases (mainly for higher numbers) the certain determination of their number and disposition is very difficult or quite impossible.

The #Cubosphærida# (Pls. 21-25) represent the large and very important family of #Sphæroidea#, in which all three dimensive axes are equally distinguished by pairs of spines, corresponding to three axes of a cube or of a regular octahedron, agreeing therefore also with the three axes of the cubic or regular crystalline system. In the majority of the Cubosphærida the six radial spines are accurately opposite each other in pairs in three axes, perpendicular one to another, and commonly they are of equal size and form; but in some genera the three pairs of spines become differentiated, whilst both spines of each pair remain equal. Either one pair is larger than the two others (which are equal), corresponding to the axes of the quadratic crystalline system; or all three pairs are different (corresponding to the three unequal axes of the rhombic crystalline system); the former nearer to the #Discoidea#, the latter to the #Larcoidea#. We may suppose with some probability, that the Cubosphærida are for the most part the common ancestral group of those #Sphæroidea#, in which a certain number of radial spines or beams is disposed in a regular order; the Staurosphærida may be derived from them by loss of one pair of spines, the Stylosphærida by loss of two pairs of spines, and most Astrosphærida by multiplying the radial spines, six to fourteen or more secondary spines being added to the six primary "dimensive spines." However, in many Astrosphærida (e.g., in those with eight spines, Centrocubus, Octodendron, &c.) the regular geometrical disposition of the radial spines seems to follow another mathematical order, quite independent of the Cubosphærida.

The #Staurosphærida# (Pl. 15) are distinguished by the possession of four radial spines, opposite in pairs in two axes, perpendicular one to another. This rectangular cross determines a certain plane, the "equatorial plane," and this brings the Staurosphærida near {57}to the #Discoidea#, mainly to those which also bear on the periphery of the circular equatorial plane four crossed spines (such as Staurodisculus, Stethostaurus, Staurodictya, &c.). But in these cruciform #Discoidea# the shell and the enclosed central capsule are discoidal or lenticular, whilst in the Staurosphærida they remain spherical. Commonly the cross is quite regular, with four right angles and four equal beams; but often also it becomes more or less irregular. In some genera one pair of equal opposite spines is larger than the other pair. These forms represent the three different axes of the rhombic crystal system, whilst the common regular Staurosphærida represent those of the quadratic crystal system. The latter can be derived from the Cubosphærida (representing the regular crystal system) by reduction of one axis and loss of its pair of spines. In general the number of species (and particularly of the individuals) is much smaller in the Staurosphærida than in all other families of #Sphæroidea#.

The #Stylosphærida# (Pls. 13-17) can be derived from the Cubosphærida by reduction of two dimensive axes and loss of two pairs of spines. Therefore, here one pair of spines only is developed, opposite in one single axis. This "monaxonial" form brings the Stylosphærida very near to the ellipsoidal #Prunoidea# (mainly to many two-spined forms of Ellipsida and Druppulida); but they differ from these by the spherical (not ellipsoidal) form of the central capsule and of the enclosing lattice-shell. In the greater part of the Stylosphærida both spines are of equal size and form, accurately opposite in the "main axis." But in many forms both spines become unequal in size or form, often very different. More rarely they are not accurately opposed, but placed in two different axes, intersecting at a small variable angle. The small group of Saturnalida presents a very remarkable and peculiar structure, in which both spines (at equal distances from the centre) are united by a circular or elliptical ring (Pl. 13, figs. 15, 16; Pl. 16, figs. 16, 17).

The #Astrosphærida# are distinguished from the other #Sphæroidea# by the great and variable number of their external radial spines (Pls. 11, 18-20, 26-30). Commonly this number amounts to from twelve to twenty, rarely to only eight to ten, very often to thirty-two to forty or more; in many species more than one hundred are present. As already mentioned above, it would be important to distinguish between primary spines (as outer prolongations of the inner radial beams) and secondary spines (developed from the surface of the shell), but in many cases this distinction is difficult or impossible. More practical is the distinction between larger "main spines" and smaller "by-spines." The size and form of the radial spines is extremely variable. Much more important is their number and disposition. In general we can here distinguish the following different cases:--(A) radial spines are developed from all the nodal points of the network on the shell surface; (B) the number of the spines is smaller than that of the nodal points, but they are irregularly scattered; (C) the radial spines exhibit a limited number and a certain regular disposition. In this latter case the following modes of distribution seem to be the most important:--(a) eight spines placed in the four diagonal axes of the {58}regular cube (Pl. 18, figs. 1-3); (b) twelve spines (placed in the corner axes of the regular icosahedron); (c) fourteen spines (six placed in the three dimensive axes of the regular octahedron, eight in the centres of its eight faces); (d) twenty spines (placed either in the same order as in many #Larcoidea# and ACANTHARIA [?], or in the twenty corners of the regular dodecahedron); (e) thirty-two spines (twelve placed in the twelve corners of the regular icosahedron, twenty in the centre of its triangular faces). Besides these most important and quite geometrical modes of disposition there also seem to occur in the Astrosphærida the following subregular (or symmetrical?) modes: 9, 10, 16, 18, 24, 40, 60, 80. But it is very difficult to give a correct account of these modes. In every case this manifold and regular disposition of the radial spines is of the highest interest for the study of general "Promorphology."

The Central Capsule is in all #Sphæroidea# (without any exception) a perfect sphere in the geometrical sense, even in those forms in which the enclosing lattice-shell is more or less irregular (i.e., many Collosphærida). This is the most important character, which separates the #Sphæroidea# from all other #Sphærellaria#. For in the #Prunoidea# the capsule is ellipsoidal, with one prolonged axis; in the #Discoidea# lenticular, with one shortened axis; in the #Larcoidea# lentelliptical, with three different dimensive axes. The central capsule is originally always enclosed by the lattice-shell; but in many cases with increasing growth this relation becomes inverted; the capsule sending out many club-shaped blind sacs through the meshes of the lattice-shell, and these melting together outside the latter, a new membrane is formed, enclosing a "medullary shell."

The Nucleus of the cell exhibits a very different shape in the solitary and the social #Sphæroidea#. In the solitary or monozoic #Sphæroidea# the centre of the central capsule is occupied by a large spherical concentric nucleus, with or without nucleoli; also this nucleus is originally always within the innermost lattice-shell, but with increasing size may overgrow and enclose it. A short time before the formation of the vibratile spores the central nucleus becomes resolved into many small nuclei. In the social or polyzoic #Sphæroidea#--the Collosphærida--commonly the simple central nucleus very early (a long time before the formation of the spores) is divided into a great number of small nuclei, whilst the centre of the capsule becomes filled with a large oil-globule. Therefore we find the same difference between the solitary and social forms in the #Sphæroidea# as in the #Colloidea#. Here also the calymma, or the jelly-mantle, enveloping the central capsule, is in the social forms very large and voluminous, differentiated into alveoles, whilst in the solitary forms it is much smaller, without alveoles.

{59}Synopsis of the Families of #Sphæroidea#.

{ A. Liosphærida { Spherical shell { monozoa. { commonly { Single cells { quite regular, { (each with shell) { simple, or Surface of { living solitary. { composed of the spherical { { two or more shell smooth, { { concentric rough, or { { spheres, 5. LIOSPHÆRIDA. thorny, but { not armed { B. Liosphærida { Spherical shell with radial { polyzoa. { commonly spines. { Aggregated cells { more or less { (each with { irregular, { shell) living { simple (rarely { in colonies. { composed of { { two concentric { { spheres), 6. COLLOSPHÆRIDA.

Surface of { Two radial main-spines, opposite in the spherical { one axis of the shell 7. STYLOSPHÆRIDA. shell armed { with two, { Four radial main-spines, opposite in four, or six { pairs in two dimensive axes, radial main { perpendicular one to another, 8. STAUROSPHÆRIDA. spines, { opposite in { Six radial main-spines, opposite in pairs in one, { pairs in three dimensive two, or three { axes (perpendicular one to dimensive { another), 9. CUBOSPHÆRIDA. axes (always { solitary). {

Surface of the spherical shell covered with numerous (commonly irregularly disposed) radial spines, often also twelve to twenty, more or less regularly disposed, 10. ASTROSPHÆRIDA.

Family V. #LIOSPHÆRIDA#, Haeckel, 1881.

Liosphærida, Haeckel, 1881, Prodromus, p. 449.

Definition.--#Sphæroidea# without radial spines on the surface of the spherical shell; living solitary (not associated in colonies).

The family #Liosphærida# comprises all those solitary #Sphæroidea# in which the surface of the spherical shell is not armed with radial spines. Nearly the half of this large group is formed by the Ethmosphærida, in which the carapace is a quite simple, spherical lattice-shell; this subfamily is probably the common ancestral group from which all other #Sphæroidea#, or even all #Sphærellaria#, can be derived in a phylogenetical as well as in a morphological sense. The central capsule in this first subfamily is constantly enclosed by the fenestrated shell, and separated from it by the jelly-veil. The shell is therefore an extracapsular or medullary shell.

To these simple Ethmosphærida all other subfamilies can be opposed as "Liosphærida concentrica," as their carapace is composed of two or more concentric lattice-shells; two in the Carposphærida, three in the Thecosphærida, four in the Cromyosphærida, five or more in the Caryosphærida. In all these four subfamilies the concentric shells are simple (not spongy) fenestrated shells. In a sixth subfamily, in the Plegmosphærida, the shell is wholly or partially composed of spongy wicker-work, with or without a latticed medullary shell in the centre.

The internal radial beams, in the "Liosphærida composita" connecting the concentric spheres, exhibit in their number and disposition similar important differences, such as the external radial spines in the Astrosphærida. The following eight {60}different cases of regular disposition were observed:--(A) two opposite beams in one axis; (B) four beams, opposite in pairs in two axes perpendicular one to another; (C) six beams, opposite in pairs in the three dimensive axes; (D) eight beams, opposite in pairs in the four diagonals of the regular cube; (E) twelve beams corresponding to the twelve axes of the regular icosahedron; (F) fourteen beams quite regularly disposed (six corresponding to the three axes of the regular octahedron, eight to the central points of its faces); (G) twenty beams (probably corresponding to the twenty corners of a regular dodecahedron); (H) thirty-two beams, regularly disposed. Rarely the number of the radial beams is intermediate between these eight cases, and rarely it is higher; then commonly the disposition is irregular. The regularity of their disposition in the great majority of cases is very remarkable and evident.

Synopsis of the Genera of Liosphærida.

------------------------------------------------------------------------- I. Subfamily Ethmosphærida. (Shell one single latticed sphere.) ------------------------------------------------------------------------- {Shell cavity { simple, 15. Cenosphæra. Pores of the { shell simple, {Shell cavity not prolonged { with radial into free tubuli. { beams united { in the { centre, 16. Stigmosphæra.

Pores prolonged {Tubuli external, into free { centrifugal, 17. Ethmosphæra. conical or { cylindrical {Tubuli internal, tubuli. { centripetal, 18. Sethosphæra. ------------------------------------------------------------------------- II. Subfamily Carposphærida. (Two concentric spheres.) ------------------------------------------------------------------------- One shell medullary (intracapsular), the other cortical (extracapsular), 19. Carposphæra.

Both shells cortical (near together), 20. Liosphæra. ------------------------------------------------------------------------- III. Subfamily Thecosphærida. (Three concentric spheres.) ------------------------------------------------------------------------- Two shells medullary (intracapsular), one shell cortical (extracapsular), 21. Thecosphæra.

One shell medullary (intracapsular), two shells cortical (extracapsular), 22. Rhodosphæra. ------------------------------------------------------------------------- IV. Subfamily Cromyosphærida. (Four concentric spheres.) ------------------------------------------------------------------------- Two inner medullary shells (intracapsular), and two outer cortical shells (extracapsular), 23. Cromyosphæra. ------------------------------------------------------------------------- V. Subfamily Caryosphærida. (Five or more concentric spheres.) ------------------------------------------------------------------------- Two inner medullary shells, and three or more outer cortical shells, 24. Caryosphæra. ------------------------------------------------------------------------- VI. Subfamily Plegmosphærida. (Spherical shell wholly or partially of spongy structure.) ------------------------------------------------------------------------- Spongy sphere {Sphere solid, 25. Styptosphæra. without latticed { medullary shell {Sphere with a in the centre. { central cavity, 26. Plegmosphæra.

Spongy sphere with {One single one or two { medullary shell, 27. Spongoplegma. latticed { medullary shells {Two concentric in the centre. { medullary { shells, 28. Spongodictyon.

{61}Subfamily ETHMOSPHÆRIDA,[25] Haeckel, 1862, Monogr. d. Radiol., p. 348 (sensu restricto).

Definition.--#Liosphærida# with one single spherical lattice-shell; living solitary, not aggregated in colonies.

Genus 15. Cenosphæra,[26] Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 237.

Definition.--#Liosphærida# with one single latticed sphere, with simple shell-pores (not prolonged into free tubuli) and with simple shell-cavity (without internal radial beams).

The genus Cenosphæra is the most simple form of all SPHÆROIDEA, and may be regarded as the common ancestral form of this order. The siliceous latticed shell, in which the central capsule is enclosed, represents a simple regular sphere, with simple cavity. The pores of the shell-wall are simple, not prolonged into radial tubuli (as in Ethmosphæra and Sethosphæra). According to the different form of the pores, the numerous species of this genus can be disposed in four different subgenera. Some species may be easily confounded with isolated shells of the corresponding social Collosphæra; but in this latter the spherical shell-form is commonly more or less irregular, in Cenosphæra quite regular.

Subgenus 1. Phormosphæra, Haeckel, 1881, Prodromus, p. 448.

Definition.--Pores of the shell regular or subregular, hexagonal or circular, with hexagonal frames or lobes; all nearly of equal size and form.

1. Cenosphæra primordialis, n. sp.

Shell very thin walled, smooth. Pores hexagonal, regular, or subregular; twelve to fifteen on the half meridian of the shell; bars between them extremely delicate (only visible when three hundred or four hundred times enlarged). Diameter of the shell nine to ten times that of the meshes. This species is remarkable for the extreme delicacy of the arachnoidal network of the simple spherical shell; it may be regarded as the common ancestral form of all #Sphæroidea#. The shell equals that of Heliosphæra tenuissima (figured in my Monograph, 1862, pl. ix. fig. 2), but differs from it by the smooth surface and the absence of all spines or thorns. I observed this species living in the Indian Ocean, near Ceylon, in 1882; the spherical diameter of the central capsule is about one-third of that of the shell; the contents of the central capsule are colourless {62}and transparent, except the central dark globular nucleus. The same shells also occur in some mounted preparations of surface organisms from the Challenger.

Dimensions.--Diameter of the shell 0.12, of the pores 0.012.

Habitat.--Indian Ocean, Ceylon, Haeckel; Central Pacific, Stations 266, 271, surface.

2. Cenosphæra inermis, Haeckel.

Heliosphæra inermis, Haeckel, 1862, Monogr. d. Radiol., p. 351, Taf. ix. fig. 1.

Surface of the thin-walled shell smooth. Pores regular, hexagonal, twelve to fifteen times as broad as the bars, seven to nine on the quadrant.

Dimensions.--Diameter of the shell 0.08 to 0.12, pores 0.012 to 0.015, bars 0.001.

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

3. Cenosphæra hexagonalis, n. sp.

Surface of the thick-walled shell smooth. Pores regular, hexagonal, five to six times as broad as the bars, six to eight on the quadrant.

Dimensions.--Diameter of the shell 0.1 to 0.15, pores 0.01 to 0.012, bars 0.002.

Habitat.--Central Pacific, Stations 265 to 274, at various depths.

4. Cenosphæra mellifica, n. sp. (Pl. 12, fig. 9).

Surface of the thick-walled shell smooth. Pores regular, circular, with thin hexagonal frames, four times as broad as the bars, six to eight on the quadrant.

Dimensions.--Diameter of the shell 0.2, pores 0.12, bars 0.003.

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

5. Cenosphæra favosa, n. sp. (Pl. 12, fig. 10).

Surface of the thick-walled shell rough. Pores regular, circular, with thin hexagonal frames, three times as broad as the bars, ten to twelve on the quadrant.

Dimensions.--Diameter of the shell 0.2, pores 0.09, bars 0.003.

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

6. Cenosphæra vesparia, n. sp. (Pl. 12, fig. 11).

Surface of the thick-walled shell smooth. Pores regular, circular, with thick hexagonal frames, twice as broad as the bars, ten to twelve on the quadrant.

Dimensions.--Diameter of the shell 0.25, pores 0.016, bars 0.008.

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

{63}7. Cenosphæra bombus, n. sp.

Shell thick walled, rough. Pores regular, circular, with thin hexagonal frames, of the same breadth as the bars, twenty to twenty-two on the quadrant.

Dimensions.--Diameter of the shell 0.3, pores and bars 0.005.

Habitat.--Tropical Atlantic, Station 347, depth 2250 fathoms.

8. Cenosphæra melecta, n. sp.

Shell thick walled, papillate. Pores regular, circular, double-edged, with thick hexagonal frames, of the same breadth as the bars; a short conical papilla in the corner of each hexagon; fourteen to sixteen pores on the quadrant.

Dimensions.--Diameter of the shell 0.2, pores and bars 0.008.

Habitat.--Fossil in Barbados.

9. Cenosphæra anthophora, n. sp.

Shell thick walled, papillate. Pores regular, circular, with an elegant six-lobed frame and a coronal of six short papillæ; the latter alternating with the six lobes (quite as in Pl. 28, fig. 1_b_). Pores twice as broad as the bars, ten to twelve on the quadrant.

Dimensions.--Diameter of the shell 0.13, pores 0.01, bars 0.005.

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

10. Cenosphæra rosetta, n. sp.

Shell thin walled, smooth. Pores regular, circular, with an elegant six-lobed outer opening, without papillæ. Pores of the same breadth as the bars, six to eight on the quadrant.

Dimensions.--Diameter of the shell 0.1, pores and bars 0.006.

Habitat.--South Atlantic, Station 323, depth 1900 fathoms.

Subgenus 2. Circosphæra, Haeckel.

Definition.--Pores of the spherical shell regular or subregular, circular, without hexagonal frames or lobes, all nearly of equal size and form.

11. Cenosphæra porophæna, Ehrenberg.

Cenosphæra porophæna, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 31.

Shell thin walled, smooth. Pores regular, circular, six to eight times as broad as the bars, five to six on the quadrant.

Dimensions.--Diameter of the shell 0.1, pores 0.012, bars 0.002.

Habitat.--Mediterranean (Crete, depth 1100 fathoms; Corfu, surface).

{64}12. Cenosphæra setosa, Ehrenberg.

Cenosphæra setosa, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. vii. fig. 1.

Shell thin walled, covered with very short and numerous bristles. Pores regular, circular, five to six times as broad as the bars, six to eight on the quadrant.

Dimensions.--Diameter of the shell 0.17, pores 0.2, bars 0.03.

Habitat.--West Tropical Pacific, 3300 fathoms; Philippine Sea, Station 200, depth 250 fathoms.

13. Cenosphæra plutonis, Ehrenberg.

Cenosphæra plutonis, Ehrenberg, 1854, Mikrogeol., Taf. xxxv. B, B. iv. fig. 20.

Shell thin walled, covered with short conical papillæ. Pores regular, circular, twice as broad as the bars, eight to nine on the quadrant.

Dimensions.--Diameter of the shell 0.09, pores 0.006, bars 0.003.

Habitat.--North Atlantic, Station 353, depth 2965 fathoms.

14. Cenosphæra proserpinæ, n. sp.

Shell thin walled, smooth. Pores regular, circular, four times as broad as the bars, five to six on the quadrant.

Dimensions.--Diameter of the shell 0.08, pores 0.008, bars 0.002.

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

15. Cenosphæra eridani, n. sp.

Shell thin walled, smooth. Pores regular, circular, three times as broad as the bars, eleven to twelve on the quadrant.

Dimensions.--Diameter of the shell 0.16, pores 0.01, bars 0.003.

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

16. Cenosphæra lethe, n. sp.

Shell thick walled, smooth. Pores regular, circular, double-edged, five times as broad as the bars, sixteen to eighteen on the quadrant.

Dimensions.--Diameter of the shell 0.25, pores 0.01, bars 0.002.

Habitat.--North Atlantic, Station 64, depth 2700 fathoms.

17. Cenosphæra elysia, n. sp. (Pl. 12, fig. 8).

Shell thick walled, rough. Pores regular, circular, double-edged, twice as broad as the bars, twelve to fourteen on the quadrant.

Dimensions.--Diameter of the shell 0.2, pores 0.01, bars 0.005.

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

{65}18. Cenosphæra nirwana, n. sp.

Shell thick walled, smooth. Pores regular, circular, twice as broad as the bars, twenty-four to twenty-five on the quadrant.

Dimensions.--Diameter of the shell 0.25, pores 0.004, bars 0.002.

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

19. Cenosphæra maxima, n. sp.

Shell thick walled, smooth. Pores regular, circular, twice as broad as the bars, thirty to thirty-three on the quadrant.

Dimensions.--Diameter of the shell 0.3 to 0.4, pores 0.012, bars 0.006.

Habitat.--West Tropical Pacific, Station 225, depth 4475; also fossil in Barbados.

20. Cenosphæra compacta, n. sp. (Pl. 12, fig. 7).

Shell very thick walled, rough (its wall one-fourth to one-third as thick as the radius). Pores subregular, circular, of the same breadth as the bars, seven to eight on the quadrant.

Dimensions.--Diameter of the shell 0.15, pores and bars 0.012.

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

Cenosphæra radiata, Zittel, 1876 (L. N. 29, p. 84, Taf. ii. figs. 7, 8), a fossil Cretaceous species, is closely allied to Cenosphæra compacta.

21. Cenosphæra crassa, n. sp.

Shell very thick walled, rough (its wall nearly half as thick as the radius). Pores tubular, double-edged, regular, circular, ten times as broad as the thin united bars, twelve to fourteen on the quadrant.

Dimensions.--Diameter of the shell 0.14, pores 0.01, bars 0.001.

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

22. Cenosphæra solida, n. sp.

Shell very thick walled, covered with innumerable short bristles (its wall one-third as thick as the radius). Pores regular, circular, four times as broad as the bars, tubular, eight to ten on the quadrant.

Dimensions.--Diameter of the shell 0.2, pores 0.02, bars 0.005.

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

Subgenus 3. Cyrtidosphæra, Haeckel, 1862, Monogr. d. Radiol., p. 348.

Definition.--Pores of the spherical shell irregularly polygonal, of unequal size or form, sometimes roundish with polygonal frames.

{66}23. Cenosphæra reticulata, Haeckel.

Cyrtidosphæra reticulata, Haeckel, 1862, Monogr. d. Radiol., p. 349, Taf. xi. fig. 2.

Shell very thin walled, smooth. Pores irregular, polygonal, two to eight times as broad as the bars, fifteen to twenty on the quadrant (groups of four to eight smaller meshes are scattered on the surface, and separated by reticular rows of larger meshes).

Dimensions.--Diameter of the shell 0.16, pores 0.004 to 0.016, bars 0.002.

Habitat.--Mediterranean (Messina), surface.

24. Cenosphæra tenerrima, n. sp.

Shell extremely thin walled, smooth, like a cobweb. Pores very irregular and small, polygonal with thread-like bars, thirty to forty on the quadrant.

Dimensions.--Diameter of the shell 0.25, pores 0.002 to 0.008, bars under 0.001.

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

25. Cenosphæra polygonalis, n. sp.

Shell thin walled, smooth, with irregular, polygonal pores, three to four times as broad as the bars, eight to ten on the quadrant.

Dimensions.--Diameter of the shell 0.2, pores 0.012 to 0.02, bars 0.005.

Habitat.--North Pacific, Station 236, surface.

26. Cenosphæra papillata, n. sp.

Shell thick walled, covered with short conical papillæ. Pores irregular, polygonal, three to five times as broad as the bars, fourteen to sixteen on the quadrant.

Dimensions.--Diameter of the shell 0.12, pores 0.004 to 0.007, bars 0.0015.

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

27. Cenosphæra cristata, n. sp.

Shell thick walled, rough. Pores irregular, roundish, surrounded by polygonal crested frames two to three times as broad as the bars, eight to twelve on the quadrant.

Dimensions.--Diameter of the shell 0.16, pores 0.006 to 0.01, bars 0.003.

Habitat.--North Pacific, Station 254, surface.

28. Cenosphæra perforata, n. sp. (Pl. 26, fig. 10).

Ceriosphæra perforata, Haeckel, 1881, Prodromus et Atlas, loc. cit.

Shell thick walled, rough. Pores irregular, roundish, surrounded by high polygonal funnel-shaped frames, which are solid in the inner half, perforated by numerous very small pores in the {67}outer half, sieve-shaped. Pores one to three times as broad as the bars, of very different size, four to six on the quadrant.

Dimensions.--Diameter of the shell 0.15, pores 0.01 to 0.02, bars 0.005 to 0.01.

Habitat.--Tropical Atlantic, Station 347, depth 2250 fathoms.

29. Cenosphæra coronata, n. sp. (Pl. 26, fig. 11).

Shell thick walled, rough. Pores irregular, roundish, surrounded by high polygonal frames bearing on their sharp crest a series of small papillæ, so that each pore is surrounded by a coronal of such spinules. Pores four to eight times as broad as the bars, four to five on the quadrant.

Dimensions.--Diameter of the shell 0.15, pores 0.01 to 0.03, bars 0.002 to 0.008.

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

Subgenus 4. Porosphæra, Haeckel.

Definition.--Pores of the spherical shell irregular, roundish, without polygonal frames, of unequal size or form.

30. Cenosphæra antiqua, Haeckel.

Cenosphæra plutonis, var., Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 25, Taf. iv. figs. 47, 48.

Cenosphæra plutonis, var., Stöhr, 1880, Palæontogr. xxvi. p. 85, Taf. i. fig. 1.

Shell thin walled, smooth. Pores irregular, roundish, two to eight times as broad as the bars, ten to fifteen on the quadrant.

Dimensions.--Diameter of the shell 0.15 to 0.2, pores 0.007 to 0.015, bars 0.002 to 0.008.

Habitat.--Fossil in the Jurassic, Cretaceous, and Tertiary formations; living in the depths of the Atlantic and Pacific; Station 332, depth 2200 fathoms; Station 225, depth 4475 fathoms, &c.

31. Cenosphæra gigantea, n. sp.

Shell thick walled, smooth. Pores irregular, roundish, two to five times as broad as the bars, thirty to forty on the quadrant.

Dimensions.--Diameter of the shell 0.4 to 0.5, pores 0.004 to 0.01, bars 0.002.

Habitat.--Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

32. Cenosphæra marginata, n. sp.

Shell very thick walled, smooth. Pores irregular, roundish, double-edged, three to eight times as broad as the bars, six to eight on the quadrant.

{68}Dimensions.--Diameter of the shell 0.12, pores 0.01 to 0.03, bars 0.004.

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

33. Cenosphæra aspera, Stöhr.

Cenosphæra aspera, Stöhr, 1880, Palæontogr. Bd. xxvi. p. 85, Taf. i. fig. 2.

Shell thick walled, rough, covered with short conical papillæ. Pores irregular, roundish, of about the same breadth as the bars, eight to twelve on the quadrant.

Dimensions.--Diameter of the shell 0.17, pores and bars 0.01 to 0.04.

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

34. Cenosphæra hirsuta, Ehrenberg.

Cenosphæra hirsuta, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss., Berlin, p. 287, Taf. x. fig. 18.

Shell thin walled, rough, covered with innumerable very short bristles. Pores very irregular, roundish, of about the same breadth as the bars.

Dimensions.--Diameter of the shell 0.11, pores and bars 0.002 to 0.012.

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

Genus 16. Stigmosphæra,[27] Haeckel, n. gen.

Definition.--#Liosphærida# with one single latticed sphere, with simple shell-pores (not prolonged into free tubuli); in the central point of the spherical shell-cavity are united a number of radial beams, which become forked and inserted into the inner surface of the shell by their distal ends.

The genus Stigmosphæra differs from Cenosphæra (and from all other Monosphærida) by internal radial beams, which are united in the centre of the simple spherical shell; these beams are branched, and the distal ends of the branches inserted on the internal surface of the shell. I have observed only two, nearly identical specimens of this genus, both with regular, hexagonal pores and thin bars; the beams were implanted in the corners of the hexagons. In one specimen the surface was covered with short radial bristles, whilst these in the other specimen were prolonged into radial spines (like Acanthosphæra). Possibly this peculiar genus is derived from Carposphæra, by reduction and loss of a central medullary shell.

Stigmosphæra actinocentra, n. sp.

Shell very thin walled, rough, with regular circular, hexagonally framed pores, six times as broad as the bars, eight to ten on the quadrant; in the corner of each hexagon a small bristle. In {69}the central point of the shell are united about twelve (?) thin and straight radial beams, which are forked, with dichotomous branches; the distal ends of the branches are inserted in the corners of the hexagons on the inside of the shell.

Dimensions.--Diameter of the shell 0.15, pores 0.02, bars 0.003.

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

Genus 17. Ethmosphæra,[28] Haeckel, 1862, Monogr. d. Radiol., p. 349.

Definition.--#Liosphærida# with one single latticed sphere, with simple shell-cavity; with shell-pores which are prolonged on the outside in centrifugal, conical, or cylindrical tubuli.

The genus Ethmosphæra differs from the simple Cenosphæra, its ancestral form, by the peculiar formation of the shell-pores; in all observed species of the genus these are quite regular, of nearly equal size and form; their base in the spherical shell-face is hexagonal, but on the outside prolonged into centrifugal, external, radial tubuli, which are either conical or cylindrical (in the latter case both openings of the tubes being equal, in the former the outer opening being smaller than the inner). The solitary Ethmosphæra corresponds to the social Siphonosphæra; but in the former the formation of the shell and of its tubuli is quite regular, in the latter more or less irregular.

Subgenus 1. Ethmosphærella, Haeckel.

Definition.--Tubuli conical, their outer opening smaller than the inner.

1. Ethmosphæra siphonophora, Haeckel.

Ethmosphæra siphonophora, Haeckel, 1862, Monogr. d. Radiol., p. 350, Taf. xi. fig. 1.

Tubuli conical, their outer opening half as broad as the inner and three times as broad as their height. Five to six pores on the quadrant. Diameter of the outer pores one and a half times as large as their distance from each other.

Dimensions.--Diameter of the shell 0.1, outer pores 0.01, their distance 0.007.

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

2. Ethmosphæra conosiphonia, n. sp. (Pl. 12, figs. 5, 5_a_).

Tubuli conical, their outer opening two thirds as broad as the inner, and scarcely broader than their height. Ten to twelve pores on the quadrant. Diameter of the outer pores twice as large as their distance from each other.

Dimensions.--Diameter of the shell 0.17, outer pores 0.01, their distance 0.005.

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

{70}3. Ethmosphæra polysiphonia, n. sp. (Pl. 12, fig. 6).

Tubuli conical, their outer opening three-fourths as broad as the inner and three times as broad as their height. Sixteen to eighteen pores on the quadrant. Diameter of the outer pores three times as large as their distance apart.

Dimensions.--Diameter of the shell 0.2, outer pores 0.008, their distance 0.003.

Habitat.--West Tropical Pacific, Station 225, depth 4475 fathoms; also fossil in Barbados and in Sicily.

Subgenus 2. Ethmosphæromma, Haeckel.

Definition.--Tubuli cylindrical, their outer opening about as large as the inner.

4. Ethmosphæra stenosiphonia, n. sp.

Tubuli cylindrical, short, quite contiguous, so that their diameter is six times as large as their distance apart, but about equal to their height. Nine to ten pores on the quadrant.

Dimensions.--Diameter of the shell 0.14, outer pores 0.012, their distance 0.002.

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

5. Ethmosphæra pachysiphonia, n. sp.

Tubuli cylindrical, twice as long as broad, very thick-walled, and nearly contiguous, so that their diameter is five times as large as their distance apart. The thickness of their wall is equal to their lumen. Twelve to fourteen pores on the quadrant.

Dimensions.--Diameter of the shell 0.16, outer pores 0.01, their distance 0.002.

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

6. Ethmosphæra leptosiphonia, n. sp.

Tubuli cylindrical, short, about as long as broad, very thin-walled and fragile, separated by wide distances, which are three times as large as their diameter. Six to seven pores on the quadrant. (Very similar to Siphonosphæra cyathina, Pl. 6, fig. 10, but quite regular, all tubuli retaining the same size and distance.)

Dimensions.--Diameter of the shell 0.12, outer pores 0.01, their distance 0.03.

Habitat.--North Atlantic, Færöe Channel, John Murray; surface.

7. Ethmosphæra macrosiphonia, n. sp.

Tubuli cylindrical, very elongated, four times as long as broad; their bases separated by distances which are equal to their breadth. Eight to ten tubuli on the quadrant. (The tubes are similar to those of Siphonosphæra serpula, Pl. 6, fig. 6, but quite regular, straight, not curved, all of the same size and at equal distances apart.)

{71}Dimensions.--Diameter of the shell 0.1, length of the tubes 0.04, breadth 0.01, basal distance 0.01.

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

Genus 18. Sethosphæra,[29] Hæckel, 1881, Prodromus, p. 452 (sensu emendato).

Definition.--#Liosphærida# with one single latticed sphere, with simple shell-cavity; with shell-pores, which are prolonged on the inside into centripetal, conical, or cylindrical tubuli.

The genus Sethosphæra differs from its ancestral form, Cenosphæra, by the production of internal, centripetal, radial tubuli on the inside of the shell (the contrary of the preceding genus Ethmosphæra). It corresponds therefore to the social Pharyngosphæra; but in the latter the formation of the shell and its tubes is more or less irregular, whilst in the former each regular pore is prolonged into a regular tubule.

1. Sethosphæra entosiphonia, n. sp.

Shell with smooth surface and regular circular pores, separated by hexagonal frames, twice as broad as the bars. Six to eight on the quadrant. Each pore is prolonged on the inside of the shell in a short conical centripetal tube, twice as long as its diameter.

Dimensions.--Diameter of the shell 0.15, outer pores 0.008, bars 0.004, length of the tubuli 0.015.

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

2. Sethosphæra entosolenia, n. sp.

Shell with smooth surface and regular circular pores, without hexagonal frames, of about the same breadth as the bars. Ten to twelve on the quadrant. Each pore is prolonged on the inside of the shell into a thin cylindrical centripetal tube, three times as long as its diameter.

Dimensions.--Diameter of the shell 0.2, outer pores and bars 0.006, length of the tubuli 0.02.

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

Subfamily CARPOSPHÆRIDA,[30] Haeckel, 1881, Prodromus, p. 449.

Definition.--#Liosphærida# with two concentric spherical lattice-shells, which are united by radial beams.

Carposphæra,[31] Haeckel, 1881, Prodromus, p. 451.

Definition.--Liosphærida with one medullary (intracapsular) and one cortical (extracapsular) shell, both connected by radial beams piercing the central capsule.

{72}The genus Carposphæra comprises a large number of double-shelled #Sphæroidea#, formerly united with Haliomma, but different from this genus by the absence of radial spines. The shell is composed of two concentric latticed spheres, the inner of which (or the medullary shell) is situated within the central capsule, the other (or the cortical shell) outside it. Both shells are connected by radial beams which pierce the wall of the central capsule. The distance between the shells is at least as large as (commonly much larger than) the radius of the inner shell, whilst in the following genus, Liosphæra, that distance is much smaller than this radius.

Subgenus 1. Melittosphæra, Haeckel, 1881, Prodromus, p. 451.

Definition.--Pores of the cortical shell regular, hexagonal (or circular, with hexagonal frames or lobes), all of nearly equal size and form.

1. Carposphæra capillacea, n. sp.

Cortical shell very delicate, four times as broad as the similarly constructed medullary shell, with regular hexagonal meshes (twenty to twenty-five on the quadrant) and very thin thread-like bars. Both shells connected by twenty (?) very thin radial beams. (Similar to Heliosoma radians, Pl. 28, fig. 3, 3_a_, but with smooth surface, without any radial spines.)

Dimensions.--Diameter of the outer shell 0.2, inner 0.05, pores 0.01, bars below 0.001.

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

2. Carposphæra cubaxonia, n. sp.

Cortical shell smooth, three times as broad as the medullary shell, with regular hexagonal pores, four times as broad as the bars. Eight to ten pores on the quadrant. Medullary shell with regular circular pores, twice as broad as the bars. Both shells connected by six radial beams, which are three-sided prismatical, opposite in pairs in the three dimensive axes.

Dimensions.--Diameter of the outer shell 0.15, inner 0.05; outer pores 0.01, inner 0.005.

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

3. Carposphæra infundibulum, Haeckel.

Haliomma infundibuliforme, Stöhr, 1880, Palæontogr. Bd. xxvi. p. 87, Taf. i. fig. 6.

Cortical shell very thick-walled, two and a half times as broad as the medullary shell, with rough surface and regular hexagonal, funnel-shaped pores, of about the same breadth as the bars. Five to six on the quadrant.

Dimensions.--Diameter of the outer shell 0.1, inner 0.04, outer pores and bars 0.01.

Habitat.--North Atlantic, Station 354; fossil in Tertiary rocks (Barbados and Sicily).

{73}4. Carposphæra melissa, n. sp.

Cortical shell thick walled, four times as broad as the medullary shell, with regular circular, hexagonally framed pores, three times as broad as the bars. Eight to ten pores on the quadrant. Medullary shell with simple circular pores.

Dimensions.--Diameter of the outer shell 0.16, inner 0.04, outer pores 0.012, bars 0.004.

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

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

Melitomma melittosphæra, Haeckel, 1881; Prodromus et Atlas, loc. cit.

Cortical shell thick walled, with thorny surface, two and a half times as broad as the medullary shell. Its pores regular, circular, twice as broad as the bars, elegantly six-lobed, separated by crested hexagonal frames; in each hexagon-corner a short conical papilla (alternating with a lobe). Eight to ten pores on the quadrant. Medullary shell with small simple circular pores.

Dimensions.--Diameter of the outer shell 0.17, inner 0.07, outer pores 0.01, bars 0.005, inner pores 0.005.

Habitat.--Central Pacific, Stations 266 to 274, in various depths.

Subgenus 2. Cerasosphæra, Haeckel, 1881, Prodromus, p. 451.

Definition.--Pores of the cortical shell regular, circular, without hexagonal frames, all of nearly equal size and form.

6. Carposphæra cerasus, n. sp.

Cortical shell thin walled, smooth, twice as broad as the medullary shell; both with regular circular pores, six times as broad as the bars. Twelve to fifteen pores on the quadrant. Outer pores twice as large as the inner.

Dimensions.--Diameter of the outer shell 0.24, inner 0.12; outer pores 0.016, inner 0.008.

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

7. Carposphæra apiculata, Haeckel.

? Haliomma apiculatum, Ehrenberg, 1872; Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 313.

Cortical shell thin-walled, covered with numerous short conical thorns, three times as broad as the medullary shell. Pores regular, circular, four times as broad as the bars. Six to eight pores on the quadrant.

Dimensions.--Diameter of the outer shell 0.15, inner 0.05, outer pores 0.012, bars 0.03.

Habitat.--North Pacific, California, depth 2000 fathoms; Station 254, depth 3025 fathoms.

{74}8. Carposphæra entactinia, Haeckel.

Haliomma entactinia, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, Taf. xxvi. fig. 4.

Cortical shell thick walled, rough, twice as broad as the medullary shell; both shells with regular circular pores, twice as broad as the bars. Six to eight pores on the quadrant. Outer pores half as broad as the inner. Both shells connected by very numerous (twenty-four to forty-eight or more) radial beams.

Dimensions.--Diameter of the outer shell 0.12, inner 0.06, outer pores 0.008, bars 0.004, inner pores 0.004.

Habitat.--Cosmopolitan; Atlantic and Pacific, in various depths; fossil in Barbados and Sicily.

9. Carposphæra modesta, Haeckel.

Haliomma modestum, Stöhr, 1880, Palæontogr. Bd. xxvi. p. 86, Taf. i. fig. 5.

Cortical shell thick walled, rough, three times as broad as the medullary shell, with regular circular pores of the same breadth as the bars. Eight to twelve pores on the quadrant. (Very common, like the preceding species, and connected with it by numerous intermediate forms.)

Dimensions.--Diameter of the outer shell 0.12 to 0.2, inner 0.04 to 0.07, pores and bars 0.006 to 0.008.

Habitat.--Atlantic and Pacific, from many Stations and at various depths; fossil in Barbados and Sicily.

10. Carposphæra belladonna, n. sp.

Cortical shell thick walled, smooth, five times as broad as the medullary shell, with regular circular pores of the same breadth as the bars. Twenty to twenty-two pores on the quadrant.

Dimensions.--Diameter of the outer shell 0.3, inner 0.06, outer pores and bars 0.004.

Habitat.--North Atlantic, Færöe Channel, John Murray.

11. Carposphæra areca, n. sp.

Cortical shell very thick walled, rough, twice as broad as the medullary shell, with regular circular pores half as broad as the bars. Eight to ten pores on the quadrant.

Dimensions.--Diameter of the outer shell 0.12, inner 0.06, outer pores 0.03, bars 0.006.

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

Subgenus 3. Prunosphæra, Haeckel, 1881, Prodromus, p. 451.

Definition.--Pores of the cortical shell irregular polygonal, of unequal size or dissimilar form.

12. Carposphæra prunulum, n. sp.

Cortical shell thin walled, smooth, four times as broad as the medullary shell, with large irregular polygonal pores, four to eight times as broad as the bars. Connecting beams between them numerous.

{75}Dimensions.--Diameter of the outer shell 0.24, inner 0.06, outer pores 0.008 to 0.016, bars 0.002.

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

13. Carposphæra corypha, n. sp.

Cortical shell thin walled, rough, three times as broad as the medullary shell, with irregular polygonal pores, three to six times as broad as the bars. Connecting beams between the two shells twenty, regularly disposed.

Dimensions.--Diameter of the outer shell 0.15, inner 0.05, outer pores 0.01 to 0.02, bars 0.003.

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

14. Carposphæra borassus, n. sp.

Cortical shell thick walled, smooth, three times as broad as the medullary shell, with irregular polygonal pores, two to four times as broad as the bars. Connecting beams between the two shells six, opposite by pairs in the three dimensive axes. (Similar to Hexalonche aristarchi, Pl. 22, fig. 3, but without external radial spines.)

Dimensions.--Diameter of the outer shell 0.12, inner 0.04, outer pores 0.01 to 0.02, bars 0.005.

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

Subgenus 4. Phoenicosphæra, Haeckel.

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

15. Carposphæra nobilis, Haeckel.

Haliomma nobile, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 268; Abhandl., 1875, Taf. xxvii. fig. 6.

Cortical shell thin walled, rough, twice as broad as the medullary shell, with irregular roundish pores, two to four times as broad as the bars.

Dimensions.--Diameter of the outer shell 0.1, inner 0.05, outer pores 0.01 to 0.02, bars 0.006.

Habitat.--Cosmopolitan; Atlantic, Indian, Pacific, at various depths; fossil in Jurassic, Cretaceous, and Tertiary rocks.

16. Carposphæra micrococcus, n. sp.

Cortical shell thin walled, rough, seven times as broad as the medullary shell, with irregular roundish pores, three to six times as broad as the bars.

Dimensions.--Diameter of the outer shell 0.2, inner 0.03, outer pores 0.012 to 0.025, bars 0.004.

Habitat.--South Atlantic, Station 330, surface.

{76}17. Carposphæra maxima, n. sp.

Cortical shell thin walled, smooth, five times as broad as the medullary shell, with irregular roundish pores, of about the same breadth as the bars.

Dimensions.--Diameter of the outer shell 0.4, inner 0.08, pores and bars 0.004 to 0.008.

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

18. Carposphæra nodosa, n. sp. (Pl. 28, figs. 2, 2_a_).

Anthomma nodosum, Haeckel, 1879, Atlas, loc. cit.

Cortical shell thick walled, covered with forty to fifty scattered pyramidal nodules, two and a half times as broad as the medullary shell, connected with it by very numerous thin radial beams. Outer and inner pores irregular roundish or polygonal, two to three times as broad as the bars. (This species in consequence of the cortical nodules may represent a peculiar genus, analogous to Conosphæra, called Anthomma.)

Dimensions.--Diameter of the outer shell 0.13, inner 0.05, inner and outer pores 0.008 to 0.012, bars 0.004.

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

Genus 20. Liosphæra,[32] Haeckel, 1881, Prodromus, p. 449.

Definition.--#Liosphærida# with two cortical (extracapsular) shells (without a medullary or intracapsular shell).

The genus Liosphæra agrees with the preceding Carposphæra in the possession of two concentric latticed spheres; but whilst in the latter genus the inner sphere is a medullary one (intracapsular), the outer a cortical shell (extracapsular), both connected by radial beams piercing the capsule-wall, here in Liosphæra the central capsule lies freely within the inner lattice shell and is not pierced by radial beams. Therefore both shells are here cortical shells, both separated by a distance, which is constantly much smaller than the radius of the inner shell; whereas in Carposphæra this distance is at least as large as that radius (commonly much larger). In Carposphæra the number of pores in both shells is never the same; in several species of Liosphæra this number is the same, each outer regular hexagonal pore exactly corresponding to an inner; the six corners of each connected by six short radial beams.

Subgenus 1. Melitomma, Haeckel.

Definition.--Pores of both shells regular, in each shell all of nearly equal size and form.

1. Liosphæra hexagonia, n. sp. (Pl. 20, fig. 3).

Both shells with the same number of pores, exactly corresponding, about ten on the quadrant. {77}All pores regular, or subregular, hexagonal; the outer twice as broad as the inner. Outer bars very thin, thread-like; inner bars thick, one-third as broad as the pores. Surface smooth. Both shells connected by numerous radial beams, their distance one-third as large as the radius of the inner shell.

Dimensions.--Diameter of the outer shell 0.16, inner 0.12, distance of both 0.02; outer pores 0.014, inner pores 0.007.

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

2. Liosphæra rhodococcus, n. sp.

Both shells with the same number of pores, exactly corresponding, about twelve on the quadrant. All pores regular or subregular; the inner circular, with elegant six-lobed frames, twice as broad as the bars; the outer hexagonal, with very thin thread-like bars. All corners of the outer and inner hexagons connected by thin, bristle-shaped radial beams. (Similar to Haliomma rhodococcus, Pl. 19, fig. 6; but with smooth surface and regular hexagonal pores of the outer shell.)

Dimensions.--Diameter of the outer shell 0.2, inner 0.16, distance of both 0.02; outer pores 0.03, inner 0.01.

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

3. Liosphæra porulosa, n. sp.

Both shells with regular hexagonal pores; their number in the outer shell seven times as great as in the inner. Pores of the stout inner shell large, three times as broad as the bars, about eight on the quadrant. From each hexagon-corner arises one bristle-shaped radial beam; their distal ends are united by threads (three from each), forming the large meshes of the delicate outer shell. Each of these is divided by very thin threads into seven small circular porules, one central and six around it.

Dimensions.--Diameter of the outer shell 0.25, inner 0.2, distance of both 0.025; outer pores 0.04, their porules 0.012, inner pores 0.15.

Habitat.--Indian Ocean, Sunda Strait, Rabbe; surface.

Subgenus 2. Craspedomma, Haeckel.

Definition.--Pores of both shells irregular, in each shell differing either in form or size.

4. Liosphæra peridromium, n. sp.

Both shells with the same number of large, polygonal, very irregular pores, exactly corresponding (about eight to ten on the quadrant); both with a very delicate thin framework. From the thread-like bars of the inner, very large and thin-walled, sphere arise perpendicularly innumerable short bristles of equal length, which are united at equal distances by tangential thread-like bars, parallel to the former, composing the outer shell. Each mesh is, therefore, surrounded by a delicate ballister or rail.

{78}Dimensions.--Diameter of the outer shell 0.42, inner 0.4, distance of both 0.01; diameter of the meshes 0.02 to 0.06.

Habitat.--North Pacific, Station 250, surface.

5. Liosphæra polypora, n. sp. (Pl. 20, fig. 2).

Both shells with small irregular roundish pores, of about the same size as the bars between them; twenty to thirty on the quadrant. The pores of the outer shell somewhat smaller, therefore much more numerous than the pores of the inner shell. Distance between the two shells about one-third as great as the radius of the inner. Both shells connected by numerous thin radial beams. Surface smooth or a little rough.

Dimensions.--Diameter of the outer shell 0.18, inner 0.14, distance of both 0.02; pores and bars 0.003 to 0.005.

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

Subfamily THECOSPHÆRIDA,[33] Haeckel, 1881, Prodromus, pp. 449, 452.

Definition.--#Liosphærida# with three concentric spherical lattice-shells, which are united by radial beams.

Genus 21. Thecosphæra,[34] Haeckel, 1881, Prodromus, p. 452.

Definition.--#Liosphærida# with two medullary (intracapsular) shells and one cortical (extracapsular) shell.

The genus Thecosphæra comprises a large number of triple-shelled #Sphæroidea#, formerly united with Actinomma, but different from this genus in the absence of radial spines. The latticed shell is composed of three concentric spheres, two of which lie within the central capsule (medullary shells), and one outside (cortical shell). This latter is connected with the former by radial beams piercing the wall of the central capsule. From the following Rhodosphæra (with one medullary and two cortical shells) Carposphæra differs also by the distance of the three shells. In the former the distance between the two outer shells is much smaller, in the latter much larger, than the distance between the inner shells.

Subgenus 1. Thecosphærantha, Haeckel.

Definition.--Pores of the cortical shell regular, hexagonal, or circular, with hexagonal frames or lobes, all of nearly equal size and form.

{79}1. Thecosphæra triplodictyon, n. sp.

Cortical shell thin walled, smooth, with regular, hexagonal pores, four times as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 8. Both medullary shells with regular circular pores, twice as broad as the bars, the inner half as broad as the outer. All three shells connected by six thin radial beams, opposite in pairs in the three dimensive axes.

Dimensions.--Diameter of the outer shell 0.2, middle 0.05, inner 0.025; cortical pores 0.012, bars 0.003.

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

2. Thecosphæra phænaxonia, n. sp.

Cortical shell thick walled, rough, with regular, circular, hexagonally framed pores, twice as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 6. Both medullary shells with regular hexagonal pores and thin bars. All three shells connected by six prismatic radial beams, opposite in pairs in the three dimensive axes. (Shell similar to Hexacontium sceptrum, Pl. 24, fig. 1, 1_a_, but without external spines.)

Dimensions.--Diameter of the outer shell 0.12, middle 0.04, inner 0.02; cortical pores 0.01, bars 0.005.

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

3. Thecosphæra favosa, n. sp.

Cortical shell thick walled, thorny, with regular, circular, hexagonally framed pores, of the same breadth as the bars. Radial proportion of the three spheres = 1 : 3 : 10. Both medullary shells with regular circular pores, connected with the former by twelve short prismatic, regularly disposed radial beams.

Dimensions.--Diameter of the outer shell 0.2, middle 0.06, inner 0.02; cortical pores and bars 0.008.

Habitat.--Central Pacific, Station 268, surface; also fossil in Barbados.

4. Thecosphæra floribunda, n. sp.

Cortical shell thick walled, smooth, with regular, elegantly six-lobed pores, three times as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 4. Both medullary shells with simple regular circular pores, connected with the former by six dimensive radial beams. (Similar to Hexacontium floridum, Pl. 24, fig. 4, but without external spines.)

Dimensions.--Diameter of the outer shell 0.12, middle 0.06, inner 0.03; cortical pores 0.01, bars 0.0033.

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

{80}Subgenus 2. Thecosphærella, Haeckel.

Definition.--Pores of the cortical shell regular, circular, without hexagonal frames or lobes, all of nearly equal size and form.

5. Thecosphæra inermis, Haeckel.

Actinomma inerme, Haeckel, 1862, Monogr. d. Radiol., p. 440, Taf. xxiv. fig. 5.

Haliomma inerme, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 815.

Cortical shell thin walled, rough, with regular circular pores, twice as broad as the bars. Radial proportion of the three spheres and of their circular regular pores = 1 : 2 : 4. All three spheres connected by twelve regularly disposed radial beams.

Dimensions.--Diameter of the outer shell 0.1, middle 0.05, inner 0.025; cortical pores 0.006, bars 0.003.

Habitat.--Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, at many Stations and at various depths.

6. Thecosphæra æquorea, Haeckel.

Haliomma æquorea, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 83; Mikrogeol., 1854, Taf. xxii. fig. 35.

Actinomma æquorea, Haeckel, 1862, Monogr. d. Radiol., p. 443.

Cortical shell thick walled, smooth, with regular circular pores of the same breadth as the bars. Radial proportion of the three spheres and of their regular pores = 1 : 2 : 6 or = 1 : 3 : 9; they are connected by six radial beams, opposite by pairs in the three dimensive axes.

Dimensions.--Diameter of the outer shell 0.08 to 0.12, middle 0.03 to 0.04, inner 0.09 to 0.12; cortical pores and bars about 0.006.

Habitat.--Mediterranean, Corfu, surface; fossil in Greece and Sicily.

7. Thecosphæra medusa, Haeckel.

Haliomma medusa, Ehrenberg, 1838, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 130; Mikrogeol., 1854, Taf. xxii. figs. 33, 34.

Actinomma medusa, Haeckel, 1862, Monogr. d. Radiol., p. 444.

Actinomma medusa, Stöhr, 1880, Palæontogr., Bd. xxvi. p. 90, Taf. ii. fig. 3.

Cortical shell thick walled, rough or thorny, with regular circular pores of the same breadth as the bars. Radial proportion of the three spheres = 1 : 2 : 4 (or 1 : 2.5 : 6); they are connected by four radial beams, crossed by pairs in two diameters, perpendicular one to another.

Dimensions.--Diameter of the outer shell 0.08 to 0.12, middle 0.04 to 0.06, inner 0.02 to 0.025; cortical pores and bars in average 0.005.

Habitat.--Fossil in Tertiary rocks of Barbados and the Mediterranean.

{81}8. Thecosphæra entactinia, n. sp.

Cortical shell thick walled, smooth, with regular circular pores of the same breadth as the bars. Radial proportion of the three spheres = 1 : 3 : 12; they are connected by very numerous (forty to fifty, or more) thin radial beams.

Dimensions.--Diameter of the outer shell 0.24, middle 0.06, inner 0.02; cortical pores and bars 0.008.

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

9. Thecosphæra micropora, n. sp.

Cortical shell thin walled, smooth, with very small and numerous, regular, circular pores, half as broad as the bars. Radial proportion of the three shells = 1 : 2 : 5; they are connected by twenty regularly disposed radial beams.

Dimensions.--Diameter of the outer shell 0.2, middle 0.08, inner 0.04; cortical pores 0.002, bars 0.004.

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

Subgenus 3. Thecosphærina, Haeckel.

Definition.--Pores of the cortical shell irregular polygonal, of unequal size or dissimilar form.

10. Thecosphæra capillacea, n. sp.

Cortical shell thin walled, smooth, with irregular polygonal pores, three to six times as broad as the bars. Both medullary shells with similar, but smaller, pores. Radial proportion of the three spheres = 1 : 3 : 8; they are connected by very numerous (sixty to eighty or more) thin radial beams. (Similar to Actinomma capillaceum, Pl. 29, fig. 6, but without external spines.)

Dimensions.--Diameter of the outer shell 0.2, middle 0.075, inner 0.025; cortical pores 0.006 to 0.012, bars 0.002.

Habitat.--North Pacific, Station 250, surface.

11. Thecosphæra diplococcus, n. sp.

Cortical shell thick walled, rough, with large irregular polygonal pores, two to three times as broad as the bars. Both medullary shells with small regular circular pores. Radial proportion of the three spheres = 1 : 2 : 6; they are connected by twenty (?) stout radial beams.

Dimensions.--Diameter of the outer shell 0.12, middle 0.04, inner 0.02; cortical pores 0.008 to 0.012, bars 0.004.

Habitat.--South Atlantic, Station 330, surface.

Subgenus 4. Thecosphæromma, Haeckel.

Definition.--Pores of the cortical shell irregular, roundish, of unequal size or dissimilar form.

{82}12. Thecosphæra dodecactis, n. sp.

Cortical shell thin walled, smooth, with large irregular roundish pores, two to eight times as broad as the bars. Both medullary shells with regular circular pores, twice as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 5; they are connected by twelve regularly disposed stout radial beams.

Dimensions.--Diameter of the outer shell 0.2, middle 0.08, inner 0.04; cortical pores 0.004 to 0.016, bars 0.002.

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

13. Thecosphæra icosactis, n. sp.

Cortical shell thin walled, with small irregular roundish pores, two to four times as broad as the bars. Both medullary shells with similar but smaller pores. Radial proportion of the three spheres = 1 : 3 : 8; they are connected by twenty thin radial beams.

Dimensions.--Diameter of the outer shell 0.32, middle 0.12, inner 0.04; cortical pores 0.005 to 0.012, bars 0.003.

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

14. Thecosphæra maxima, n. sp.

Cortical shell thin walled, with small irregular roundish pores, two to six times as broad as the bars. Both medullary shells with similar, but smaller, pores. Radial proportion of the three spheres = 1 : 3 : 9; they are connected by numerous (forty to sixty or more) thin radial beams.

Dimensions.--Diameter of the outer shell 0.45, middle 0.15, inner 0.05; cortical pores 0.008 to 0.024, bars 0.004.

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

Genus 22. Rhodosphæra,[35] Haeckel, 1881, Prodromus, p. 452.

Definition.--#Liosphærida# with one medullary (intracapsular) shell and two cortical (extracapsular) shells.

The genus Rhodosphæra differs from the preceding Thecosphæra in the same manner in which, among the Dyosphærida, Liosphæra differs from Carposphæra. The cortical shell is double, composed of two not far distant shells, lying outside the central capsule. The distance between the shells is much smaller than the radius of the inner shell. This is connected by radial beams (piercing the central capsule) with the small central medullary shell.

Subgenus 1. Rhodosphærella, Haeckel.

Definition.--Pores of both cortical shells regular, in each shell all of nearly equal size and form.

{83}1. Rhodosphæra hexagonia, n. sp.

Both cortical shells with the same number of regular hexagonal pores; the inner four times as broad as the bars, and half as broad as the outer pores, which are separated by thread-like bars. Medullary shell only one-fourth as broad as the inner cortical shell, with regular hexagonal pores of half the size. (Differs from the similar Liosphæra hexagonia, Pl. 20, fig. 3, by the possession of a medullary shell.)

Dimensions.--Diameter of the outer shell 0.2, middle 0.16, inner 0.04; outer pores 0.013, middle 0.008, inner 0.004.

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

2. Rhodosphæra melitomma, n. sp.

Both cortical shells with the same number of regular pores; the inner regular, circular, twice as broad as the bars, with elegant hexagonal frames and six roundish lobes alternating with the six radial spines which arise from the hexagon-corners; these short conical spines are connected at the distal end (at equal distances from the centre) by delicate threads (three from each spine), which form the delicate external shell. Medullary shell one-third as broad as the inner cortical shell, with small, simple, regular circular pores. (If in Carposphæra melitomma, Pl. 20, fig. 4, the distal ends of the spines became united by a cobweb-like outer shell, this species would be formed.)

Dimensions.--Diameter of the outer shell 0.22, middle 0.18, inner 0.06; outer pores 0.025, middle 0.0125, inner 0.005.

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

Subgenus 2. Rhodosphæromma, Haeckel.

Definition.--Pores of both cortical shells irregular, in each shell of unequal size or dissimilar form.

3. Rhodosphæra palliata, n. sp.

Both cortical shells with an unequal number of irregular roundish pores; the outer pores somewhat smaller and much more numerous than the inner pores; the bars between the latter are thicker. Medullary shell about one quarter as broad as the inner cortical shell, with regular circular pores.

Dimensions.--Diameter of the outer shell 0.4, middle 0.36, inner 0.08; outer pores on an average 0.008, middle 0.012, inner 0.004.

Habitat.--Fossil in Barbados.

4. Rhodosphæra pentaphylla, n. sp.

Both cortical shells with unequal number of irregular roundish pores; the inner pores large, three to four times as broad as the bars; to each inner pore corresponds a group of five smaller {84}outer pores, like the five petals of a flower. Medullary shell half as broad as the inner cortical shell, with regular circular pores.

Dimensions.--Diameter of the outer shell 0.25, middle 0.2, inner 0.1; outer pores on an average 0.006, middle 0.012, inner 0.004.

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

Subfamily CROMYOSPHÆRIDA,[36] Haeckel, 1881, Prodromus, pp. 449, 453.

Definition.--#Liosphærida# with four concentric spherical latticed shells, united by radial beams.

Genus 23. Cromyosphæra,[37] Haeckel, 1881, Prodromus, p. 453.

Definition.--#Liosphærida# with two intracapsular (medullary) shells and two extracapsular (cortical) shells; the former united with the latter by radial beams piercing the wall of the central capsule.

The genus Cromyosphæra is the only known genus of Cromyosphærida, or of such #Sphæroidea#, the smooth shell of which is composed of two medullary and two cortical shells. There may possibly be other Cromyosphærida, in which the shell is composed of one simple medullary and three cortical shells, or only of four extra-capsular cortical shells; but such have not as yet been observed. Caryosphæra polysphærica, Bütschli, 1882 (L. N. 41, Taf. xxiii. fig. 12) is probably a Cromyosphæra (fossil in Barbados).

1. Cromyosphæra quadruplex, n. sp. (Pl. 30, fig. 9).

Radial proportion of the four spheres = 1 : 2 : 4 : 5. Outer cortical shell smooth, with large regular hexagonal pores, ten times as broad as the bars; inner cortical shell with irregular polygonal pores, five times as broad as the bars. Both medullary shells with regular circular pores of the same breadth as the bars.

Dimensions.--Diameter of the four spheres--(A) 0.16, (B) 0.12, (C) 0.06, (D) 0.03.

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

2. Cromyosphæra rosetta, n. sp.

Radial proportion of the four spheres = 1 : 2 : 8 : 10. Outer cortical shell smooth, with regular hexagonal pores and very thin bars; inner cortical shell with the same number of exactly corresponding, regular circular, hexagonally framed pores, twice as broad as the bars; the corners of the outer and inner hexagons united by radial bristles. Both medullary shells with regular circular pores, twice as broad as the bars.

Dimensions.--Diameter of the four spheres--(A) 0.2, (B) 0.16, (C) 0.04, (D) 0.02.

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

{85}3. Cromyosphæra bigemina, n. sp.

Radial proportion of the four spheres = 1 : 2 : 7 : 8. Outer cortical shell smooth, with regular hexagonal pores and very thin bars; inner cortical shell with the same number of exactly corresponding, regular circular pores. Both medullary shells with regular circular pores of the same breadth as the bars. (Somewhat similar to Hexacromyon elegans, Pl. 24, fig. 9, also with six inner radial beams, but without external radial spines.)

Dimensions.--Diameter of the four spheres--(A) 0.2, (B) 0.17, (C) 0.05, (D) 0.025.

Habitat.--North Pacific, Station 241, depth 2300 fathoms.

4. Cromyosphæra cepa, n. sp.

Radial proportion of the four spheres = 1 : 2 : 4 : 5. All four shells of the same structure, thick-walled, with regular circular pores, two to four times as broad as the bars; the size of the pores increases gradually from the inner to the outer shell. Surface thorny. Distance between the second and third shells twice as great as that between the others.

Dimensions.--Diameter of the four spheres--(A) 0.125, (B) 0.1, (C) 0.05, (D) 0.025.

Habitat.--Fossil in Barbados.

5. Cromyosphæra scorodonium, n. sp.

Radial proportion of the four spheres = 1 : 2 : 3 : 4. All four shells of the same structure, thin-walled, with irregular roundish pores, two to four times as broad as the bars; the size of the pores increasing gradually from the inner to the outer shell. Surface smooth. Distance between each two shells equal to the diameter of the innermost.

Dimensions.--Diameter of the four spheres--(A) 0.12, (B) 0.09, (C) 0.06, (D) 0.03.

Habitat.--Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

6. Cromyosphæra antarctica, n. sp..

Radial proportion of the four spheres = 1 : 2 : 5 : 7. Both cortical shells with irregular polygonal roundish pores; the outermost with thinner bars and rough surface, the inner with thicker bars. Both medullary shells with irregular roundish pores.

Dimensions.--Diameter of the four spheres--(A) 0.18, (B) 0.12, (C) 0.05, (D) 0.025.

Habitat.--Antarctic Ocean; in very large number, together with Rhizosphæra antarctica, in the diatomaceous ooze of Station 157 (3rd March 1874); depth 1950 fathoms.

Subfamily CARYOSPHÆRIDA,[38] Haeckel, 1881, Prodromus, pp. 449, 454.

Definition.--#Liosphærida# with numerous (five or more) concentric spherical latticed shells, united by radial beams.

{86}Genus 24. Caryosphæra,[39] Haeckel, 1881, Prodromus, p. 454.

Definition.--#Liosphærida# with two intracapsular (medullary) shells and three or more extracapsular (cortical) shells; the former united with the latter by radial beams piercing the wall of the central capsule.

The genus Caryosphæra, the only observed form of this subfamily, comprises those #Liosphærida# in which the shell is composed of two medullary and three or more cortical shells. Such forms (without radial spines) are very rare; I observed only two species, one with five, the other with six shells. They are derived from Cromyosphæra by further apposition of outer cortical shells.

1. Caryosphæra pentalepas, n. sp.

Shell composed of five concentric spheres, with radial proportion = 1 : 2 : 8 : 10 : 12. Both medullary shells with regular circular pores, twice as broad as the bars. First cortical shell with regular, circular, hexagonally framed pores, three times as broad as the bars; second cortical shell with regular hexagonal pores, four times as broad as the bars; third (outermost) cortical shell with regular hexagonal pores and very thin thread-like bars. Surface smooth.

Dimensions.--Diameter of the five shells--(A) 0.02, (B) 0.04, (C) 0.16, (D) 0.2, (E) 0.24.

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

2. Caryosphæra hexalepas, n. sp.

Shell composed of six concentric spheres, with the radial proportion = 1 : 2 : 4 : 5 : 6 : 8. All six shells with regular circular pores, two to four times as broad as the bars, with increasing size from the centrum against the smooth surface.

Dimensions.--Diameter of the six shells--(A) 0.025, (B) 0.05, (C) 0.1, (D) 0.13, (E) 0.16, (F) 0.2.

Habitat.--Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

Subfamily PLEGMOSPHÆRIDA,[40] Haeckel, 1881, Prodromus, p. 455.

Definition.--#Liosphærida# with spongy spherical shell, with or without latticed medullary shell in the centre.

Genus 25. Styptosphæra,[41] Haeckel, 1881, Prodromus, p. 455.

Definition.--#Liosphærida# forming a solid sphere of spongy framework, without enclosed medullary shell, and without central cavity.

{87}The genus Styptosphæra presents a spherical shell with smooth or rough surface (without radial spines), the whole mass of which is composed of looser or denser spongy wicker-work.

1. Styptosphæra spumacea, n. sp.

Spongy framework of the solid sphere loose, with large polygonal meshes of slightly different size, ten to twenty times as broad as the bars. Structure of the whole spongy sphere the same. Central capsule filled with crystals. Surface smooth.

Dimensions.--Diameter of the sphere 0.32, of the central capsule 0.26, meshes 0.01 to 0.02, bars 0.001.

Habitat.--North Pacific, Station 236, surface.

2. Styptosphæra spongiacea, n. sp.

Spongy framework in the central part of the solid sphere much more compact than in the peripheral part, becoming gradually looser towards the rough surface. Meshes in the centre three to five times, in the periphery fifteen to twenty times as broad as the bent bars.

Dimensions.--Diameter of the sphere 0.45, inner meshes 0.006 to 0.01, outer meshes 0.03 to 0.04, bars 0.002.

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

3. Styptosphæra stupacea, n. sp.

Spongy framework of the solid sphere rather compact, everywhere of the same structure, with roundish, nearly equal meshes, six to eight times as broad as the bars. Surface rough with prominent thorns.

Dimensions.--Diameter of the sphere 0.22, meshes 0.01 to 0.012, bars 0.0015.

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

Genus 26. Plegmosphæra, Haeckel,[42] 1881, Prodromus, p. 455.

Definition.--#Liosphærida# forming a hollow sphere of spongy framework, without a medullary shell in the central cavity.

The genus Plegmosphæra develops a large hollow sphere, the wall of which is composed of looser or denser spongy wicker-work. On the inner as well as on the outer face of the spongy shell-wall may be present a simple lattice-sphere from which the threads of the framework arise; but in some species these lattice-plates are quite absent.

{88}Subgenus 1. Plegmosphærantha, Haeckel.

Definition.--Inside and outside of the spongy shell-wall smooth, closed by a lattice-plate with polygonal meshes.

1. Plegmosphæra maxima, n. sp.

Radius of the spherical shell-cavity eight to ten times as great as the thickness of the thin spongy wall. Inside and outside of the wall smooth, closed by a lattice-plate with irregular polygonal meshes. Only three or four meshes in the thickness of the wall.

Dimensions.--Diameter of the spongy sphere 0.8 to 1.0 mm., of its inner cavity 0.7 to 0.8, meshes 0.01 to 0.02, bars 0.002 to 0.003, central capsule 0.5 to 0.6, nucleus 0.1 to 0.15.

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

2. Plegmosphæra coelopila, n. sp.

Radius of the spherical shell-cavity eight to ten times as great as the thickness of the spongy wall. Inside and outside of the wall closed by a smooth lattice-plate with irregular polygonal meshes, five to ten times as broad as the bars.

Dimensions.--Diameter of the shell 0.32, of its cavity 0.26, meshes 0.01 to 0.02, bars 0.002.

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

3. Plegmosphæra pachypila, n. sp.

Radius of the spherical shell-cavity about equal to the thickness of the spongy wall. Inside and outside of the wall closed by a smooth lattice-plate with irregular polygonal meshes, three to six times as broad as the bars.

Dimensions.--Diameter of the shell 0.24, of its cavity 0.12.

Habitat.--North Pacific, Station 250, surface.

Subgenus 2. Plegmosphærella, Haeckel.

Definition.--Inside of the spongy shell-wall closed by a smooth lattice-plate, outside rough, spongy, with prominent thorns.

4. Plegmosphæra entodictyon, n. sp.

Radius of the spherical shell-cavity half as great as the thickness of the spongy wall. Inside of the wall closed by a smooth lattice-plate, outside rough, spongy.

Dimensions.--Diameter of the shell 0.24, of its cavity 0.08.

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

{89}5. Plegmosphæra leptodictyon, n. sp.

Radius of the spongy shell-cavity six times as great as the thickness of the spongy wall. Inside of the wall closed by a smooth lattice-plate, outside rough spongy.

Dimensions.--Diameter of the shell 0.44, of its cavity 0.36.

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

Subgenus 3. Plegmosphæromma, Haeckel.

Definition.--Inside of the spongy shell-wall rough spongy, without lattice-plate, outside closed by a smooth lattice-plate.

6. Plegmosphæra exodictyon, n. sp. (Pl. 18, fig. 8).

Radius of the spongy shell-cavity only one-fourth as great as the thickness of the spongy shell-wall. Outside of the wall closed by a smooth lattice-plate, inside rough, spongy.

Dimensions.--Diameter of the shell 0.4, of its cavity 0.08.

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

Subgenus 4. Plegmosphærusa, Haeckel.

Definition.--Inside and outside of the spongy shell-wall rough, with spongy or spiny surface, without lattice-plate.

7. Plegmosphæra leptoplegma, n. sp.

Radius of the spherical shell-cavity half as great as the thickness of the loose spongy shell-wall. Inside and outside of the wall rough spongy, not closed by a lattice-plate. Meshes ten to twenty times as broad as the bars.

Dimensions.--Diameter of the shell 0.3, of its cavity 0.088.

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

8. Plegmosphæra pachyplegma, n. sp.

Radius of the spherical shell-cavity about equal to the thickness of the dark and dense spongy shell-wall. Inside and outside of the wall rough spongy, not closed by a lattice-plate. Meshes three to five times as broad as the bars.

Dimensions.--Diameter of the shell 0.2, of its cavity 0.1.

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

Genus 27. Spongoplegma,[43] Haeckel, 1881, Prodromus, p. 455.

Definition.--#Liosphærida# forming a sphere of spongy framework, which encloses in the centre one single latticed medullary shell.

{90}The genus Spongoplegma may be regarded as a Carposphæra, in which the simple latticed cortical shell is represented by an irregular spongy framework, immediately enclosing the simple latticed medullary shell.

1. Spongoplegma antarcticum, n. sp.

Cortical shell with loose spongy framework and rough surface, four to six times as broad as the enclosed simple medullary shell. Pores of the latter regular circular, twice as broad as the bars. From its surface arise numerous (forty to fifty or more) short radial beams, which become forked and compose, by communication of lateral branches, the spongy cortical shell.

Dimensions.--Diameter of the spongy cortical shell 0.2 to 0.3 of the latticed medullary shell 0.05 to 0.06.

Habitat.--Antarctic Ocean, in large number, together with Cromyosphæra antarctica; in the Diatom ooze of Station 157 (depth 1950 fathoms).

Genus 28. Spongodictyon,[44] Haeckel, 1862, Monogr. d. Radiol., p. 459.

Definition.--#Liosphærida# forming a sphere of spongy framework, which encloses in the centre a double latticed concentric medullary shell.

The genus Spongodictyon can be regarded as a Thecosphæra, in which the simple latticed cortical shell is represented by an irregular spongy framework, which immediately encloses the double latticed medullary shell. Sometimes this latter appears triple, the inner surface of the spongy cortical shell forming a smooth spherical lattice-plate, separated by an interval from the double medullary shell.

Subgenus 1. Dictyoplegma, Haeckel, 1862, Monogr. d. Radiol, p. 458.

Definition.--Spongy cortical shell enveloping immediately the double medullary shell.

1. Spongodictyon spongiosum, Haeckel.

Dictyosoma spongiosum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 31, Taf. ii. figs. 9-11.

Dictyoplegma spongiosum, Haeckel, 1862, Monogr. d. Radiol., p. 458.

Spongy framework of the cortical shell loose, with large, polygonal roundish meshes, on an average as large as the double medullary shell, which is immediately enveloped by it. Both concentric medullary shells with subregular roundish pores, twice as broad as the bars.

Dimensions.--Diameter of the cortical shell 0.2 to 0.3 or more; of the outer medullary shell 0.03, inner 0.01.

Habitat.--Mediterranean (French south coast, surface), J. Müller.

{91}2. Spongodictyon cavernosum, n. sp.

Spongy framework of the cortical shell rather compact in the inner part, which immediately envelops the double medullary shell; very loose, with large caverns in the outer part, caverns of the surface larger than the medullary shell. Both medullary shells with regular circular pores, three times as broad as the bars.

Dimensions.--Diameter of the cortical shell 0.3 to 0.4, outer medullary shell 0.1, inner 0.03.

Habitat.--Tropical Atlantic, Station 338, surface.

Subgenus 2. Spongodictyoma, Haeckel.

Definition.--Spongy cortical shell on the inner surface with a smooth lattice-plate (or third medullary shell), which is connected by radial beams with the inner double medullary shell.

3. Spongodictyon trigonizon, Haeckel.

Spongodictyon trigonizon, Haeckel, 1862, Monogr. d. Radiol., p. 459, Taf. xxvi. figs. 4-6.

Dictyosoma trigonizon, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 841.

Spongy framework of the cortical shell very loose, with very large, for the most part triangular meshes, which are two to six times as large as the enclosed double medullary shell. From the surface of the latter arise numerous radial beams, which are connected by a spherical lattice-plate, forming the smooth inner surface of the spongy sphere (or a third medullary shell). The structure of the framework reminds one of the PHÆODARIUM Sagena (Pl. 108). Pores of both medullary shells regular circular, twice as broad as the bars.

Dimensions.--Diameter of the cortical shell 0.5 to 1.15, outer medullary 0.05, inner 0.035.

Habitat.--Mediterranean, Messina, surface.

4. Spongodictyon arcadophoron, n. sp.

Spongy framework of the cortical shell in the inner part very loose, in the outer part more compact; outer meshes scarcely as large as the inner medullary shell (or only half as large), inner meshes two to four times as large. From the surface of the double medullary shell arise numerous radial beams, which are forked at equal distances from the centre; the fork branches are curved and united together by dichotomous branches, like elegant arcades; and these arcades form together the large polygonal meshes on the inside of the cortical shell (or a third medullary shell). Both medullary shells with regular circular pores, of the same breadth as the bars.

Dimensions.--Diameter of the cortical shell 0.2, outer medullary shell 0.04, inner 0.02.

Habitat.--Tropical Atlantic, Station 349, surface.

{92}Family VI. #COLLOSPHÆRIDA#, J. Müller[45] (Pls. 5-8).

Definition.--#Sphæroidea# living associated in colonies, united by an alveolar jelly-body, and connected by the network of anastomosing pseudopodia.

The family #Collosphærida# comprises all polyzous or social #Sphæroidea#, and constitutes the only polyzoic group among the SPHÆRELLARIA. This group was first constituted by J. Müller as "Radiolaria polyzoa with shells."[46] Formerly following his authority, in my Monograph I had separated them from the other #Sphæroidea# and united them with the social Collodaria (Sphærozoida).[47] Also R. Hertwig in his Organismus der Radiolarien[48] united them with his Sphærozoea. In my Prodromus[49] I had retained this isolated position. But a further careful study has convinced me that this isolation is not truly natural, and that the Collosphærida are only "social Ethmosphærida" which have arisen from this solitary subfamily by adaptation to colonial life. There are some forms of Collosphærida which are nearly identical with some forms of Ethmosphærida, only differing from the latter by their association in colonies; and in some forms of both groups it is quite impossible to decide whether the isolated shells appertain to one or to the other family.

The isolated shell of the Collosphærida is almost constantly (with few exceptions) a simple extracapsular lattice-shell, as in the Monosphærida; only the small group of Clathrosphærida (with the genera Clathrosphæra and Xanthiosphæra) exhibit an exception, the simple lattice-shell being overgrown by an external mantle or veil of very thin, cobweb-like, irregular lattice-work (Pl. 8, figs. 6-11). Therefore these Clathrosphærida bear to the Acrosphærida (or the common simple Collosphærida) a relation similar to that which Liosphæra (p. 76) bears to Cenosphæra; both shells are extracapsular "cortical shells" at a very short distance apart. In the Collosphærida true concentric medullary shells never occur; the central capsule always lies quite freely in the simple or double cortical shell, separated from it by a jelly-veil.

Although a well marked difference in the simple lattice-shell of the social Collosphærida and the solitary Ethmosphærida does not exist, nevertheless in most cases the two shells can be distinguished by a practiced observer. The simple fenestrated shells of the monozoic Ethmosphærida are commonly quite regular spheres in a mathematical sense, or regular "endospherical polyhedra"; whereas in the Collosphærida they are commonly more or less irregular, often to an extraordinary degree (Pls. 5-8). Some species of Collosphærida, however, also possess quite regular spherical shells. Another difference is often shown in the lattice-work of the shells, which in the Collosphærida is nearly always very irregular, and exhibits a peculiar tendency to the {93}production of radial, conical, or cylindrical tubules. These occur as well on the inside as on the outside of the shell, and the tubules are now more conical, now more cylindrical; their wall either solid or pierced by pores (Pls. 5-8). The tubules are commonly very irregular in form, size, and disposition; distinguished, however, by a number of hereditary peculiarities, which are sufficient for the distinction of genera. Similar tubules occur also in some genera of solitary Ethmosphærida (Coscinomma, Ethmosphæra, Conosphæra, &c., Pl. 12); but the tubules are here much more regular and not so highly developed.

Besides the tubules of the fenestrated shells, in some genera of Collosphærida the surface is armed with irregular thorns, rarely with more regular radial spines. But these spines obtain constantly the character of accessory by-spines, and remain short and thin. In this family typical radial spines never occur in a regular and characteristic disposition, corresponding to dimensive axes, as is the case in nearly all solitary #Sphæroidea#, only excepting the Liosphærida. Commonly these spines or thorns serve as protective arms for the shell-meshes, surrounding them often in the form of coronels. Often the lattice-plate of the irregular roundish shell is tubercular, elevated into irregular protuberances, bearing on the top a short spine or thorn (Pl. 8).

The Central Capsule of the Collosphærida is always a regular sphere, as in all other #Sphæroidea#; it is constantly placed within the lattice-shell, and commonly much smaller than it, separated from it by a thick jelly-veil. A remarkable difference from the solitary #Sphæroidea# is shown in the early division of the nucleus. Commonly the central capsule of the Collosphærida contains in its centre a large oil-globule, surrounded by very numerous small nuclei. R. Hertwig estimated this difference as so important, that he separated the social "Sphærozoea" and the solitary "Peripylea" as two different orders. As already shown above (p. 7, 24), we cannot support this separation, and are now convinced that this difference in the development of the spores--just as in the #Collodaria#--is the consequence of an adaptation to social life.

The common jelly-body, in which the numerous central capsules and their enveloping shells are united, exhibits in the Collosphærida quite the same characters as in the other social Radiolaria, the Collozoida and Sphærozoida. The jelly-body is very voluminous, commonly spherical, often cylindrical, of considerable size; constantly containing numerous large alveoles. Often each shell is enclosed in a separate alveole with rather solid wall (Pl. 6, fig. 2). Sometimes in the dead colonies all shells are united in the central part of the jelly-body, whilst its peripheral part is composed of a stratum of large alveoles (Pl. 8, fig. 11); at other times no alveoles are visible (Pl. 7, fig. 11). In many living colonies I found a very large spherical alveole with thick wall in the centre of the spherical colony, surrounded by many strata of delicate thin-walled alveoles (Pl. 5, fig. 1). In this case often the inner younger capsules were naked, {94}without shells, the outer only surrounded by shells. Already in my Monograph I had described the same peculiar formation.[50]

Synopsis of the Genera of Collosphærida.

------------------------------------------------------------------------- I. Subfamily Acrosphærida. (Lattice-shell simple, without an external mantle of network.) ------------------------------------------------------------------------- {Inside {Inside smooth, 29. Collosphæra. Outside of { without { the shell { tubuli. {Inside spiny, 30. Tribonosphæra. smooth, { without { {Tubuli spines or {Inside with { imperforated, 31. Pharyngosphæra. tubuli. { centripetal { { tubuli. {Tubuli { { fenestrated, 32. Buccinosphæra.

{Spines { irregularly { scattered on { the surface, 33. Acrosphæra. { Outside of the shell armed {Each larger with solid spines, but { pore with one with hollow tubuli. { single spine, 34. Odontosphæra. { {Each larger { pore with { a coronal of { spines, 35. Choenicosphæra.

{Mouth of the { tubuli { truncated, { smooth, 36. Siphonosphæra. { Outside of {Tubuli {Mouth with the shell { simple, not { one single with { branched. { large tooth, 37. Mazosphæra. irregular { { radial { {Mouth with a tubuli, { { coronal of the wall of { { teeth, 38. Trypanosphæra. which is { solid, not {Tubuli irregularly branched, fenestrated.{ each with two to four or { more openings, 39. Caminosphæra.

{Mouth of the { tubuli { truncated, { smooth, 40. Solenosphæra. Outside of the shell with { irregular radial tubuli, {Mouth with one open on both ends, { single large with fenestrated wall. { tooth, 41. Otosphæra. { {Mouth with a { coronal of { teeth, 42. Coronosphæra. ------------------------------------------------------------------------- II. Subfamily Clathrosphærida. (Lattice-shell double, with an external mantle of network.) ------------------------------------------------------------------------- Surface of the outer shell smooth, 43. Clathrosphæra.

Surface of the outer shell thorny, 44. Xanthiosphæra.

Subfamily ACROSPHÆRIDA, Haeckel, 1881, Prodromus, p. 471.

Definition.--#Collosphærida# with one simple lattice-shell around every central capsule of the coenobium.

{95}Genus 29. Collosphæra,[51] J. Müller, 1855.

Definition.--#Collosphærida# with simple shells, smooth on the inside and on the outside, without any spines or tubuli.

The genus Collosphæra is the most simple form of all Collosphærida, and must be regarded as the common ancestral form of this family. As the lattice-shell is quite a simple sphere, without any spines, tubules, or other peculiar productions, it agrees perfectly with Cenosphæra, and represents the social or polyzoid aggregate of this solitary or monozoid genus. Therefore a certain distinction between the isolated shells of the two genera is often very difficult or even impossible; but commonly this distinction is possible owing to the circumstance, that in the majority of the Collosphæræ the shell is more or less irregular roundish or polyhedral, not quite spherical, as in Cenosphæra. Dermatosphæra, Ehrenberg, is a Collosphæra with small pores (compare L. N. 16, p. 533).

Subgenus 1. Eucollosphæra, Haeckel.

Definition.--Shell a regular or subregular sphere.

1. Collosphæra primordialis, n. sp.

Shell a regular sphere, with very delicate and regular network of hexagonal meshes. Six to eight meshes in the half meridian of the shell. Diameter of the meshes ten to fifteen times as broad as the thin bars between them. Can be regarded as social form of Cenosphæra primordialis.

Dimensions.--Diameter of the shell 0.1 to 0.12, of the pores 0.008.

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

2. Collosphæra regularis, n. sp.

Shell a regular sphere, with a perfectly regular network of circular meshes, all of the same size. Ten to twelve meshes in the half meridian of the shell. Diameter of the meshes the same as that of the bars between them.

Dimensions.--Diameter of the shell 0.1 to 0.12, of the pores 0.005 to 0.006.

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

3. Collosphæra globularis, n. sp.

Shell a regular sphere, with subregular network of circular meshes of different sizes; few large pores between many smaller pores. Ten to twenty meshes in the half meridian of the shell. Diameter of the meshes from half to twice as broad as that of the bars.

{96}Dimensions.--Diameter of the shell 0.1 to 0.12, of the pores 0.002 to 0.008, breadth of the bars 0.004 to 0.008.

Habitat.--Tropical and subtropical zone of both hemispheres, widely distributed; Canaries, Azores, Cape Verde Islands, Guinea Coast, Brazil Coast, Indian Ocean, Madagascar, Ceylon, surface.

Subgenus 2. Dyscollosphæra, Haeckel.

Definition.--Shell not a regular sphere, but irregular roundish, in all degrees of variation between subspherical and polyhedral or quite irregular forms.

4. Collosphæra huxleyi, J. Müller.

Collosphæra huxleyi, J. Müller, 1855, Abhandl. d. k. Akad. d. Wiss. Berlin, pp. 55-59, Taf. viii. figs. 6-9.

Collosphæra huxleyi, Haeckel, 1862, Monogr. d. Radiol., p. 534, Taf. xxxiv.

Collosphæra huxleyi, Cienkowski, 1871, Archiv f. mikrosk. Anat., Bd. vii. p. 374, Taf. xxix. figs. 1-6.

Collosphæra ligurina, J. Müller, 1856, Monatsber. d. k. Akad. d. Wiss. Berlin, p. 481.

Thalassicolla punctata, var., Huxley, 1851, Ann. and Mag. Nat. Hist., ser. 2, vol. viii. p. 434, pl. xvi. fig. 6.

Shell subspherical, somewhat irregular, sometimes with more or less superficial impressions, with irregular network of roundish meshes. Eight to sixteen meshes in the half meridian of the shell, one to three times as broad as their bars. Very variable, with direct transition-forms to other species of this genus, especially to Collosphæra globularis, Collosphæra tuberosa, Collosphæra pyriformis, and Collosphæra polyedra.

Dimensions.--Diameter of the shell 0.1 to 0.16, of the pores 0.004 to 0.012, of the bridges 0.003 to 0.006.

Habitat.--Cosmopolitan; common in the greater part of the warmer seas, surface.

5. Collosphæra polygona, n. sp. (Pl. 5, fig. 13).

Collosphæra huxleyi var., Haeckel, 1862, Monogr. d. Radiol., Taf. xxxiv. fig. 5.

Shell irregular polygonal, with very delicate, irregular network of polygonal meshes, four to twelve times as broad as the bars. Ten to twenty pores on the half meridian of the shell.

Dimensions.--Diameter of the shell 0.1 to 0.2, of the pores 0.012 to 0.004, of the bars 0.001 to 0.002.

Habitat.--Mediterranean, Atlantic, surface; Stations 348 to 354.

6. Collosphæra pyriformis, Haeckel, n. sp.

Shell irregular, rounded, ovate or pear-shaped, with irregular network of rounded or nearly polygonal meshes. Ten to twenty meshes in the half meridian of the shell, one to three times as broad as the bars. Commonly one large opening (two to three times as broad as the largest {97}meshes) on the thinner end of the ovate shell (corresponding to the insertion of a pear-stalk); sometimes two or three such large openings.

Dimensions.--Diameter of the shell 0.1 to 0.15, of the pores 0.008 to 0.016, of the bridges 0.004 to 0.008.

Habitat.--Tropical zone--Cape Verde Islands, Ceylon; Central Pacific, Stations 266 to 272, 348 to 352, &c.

7. Collosphæra polyedra, n. sp.

Trisolenia zanguebarica, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 301, Taf. x. fig. 11.

Shell irregular, polyhedral, with even or somewhat vaulted sides, and obtuse ridges between them. Network more or less irregular, with small rounded meshes, quite as broad or twice as broad as their bars. Besides these small pores constantly some large round openings (commonly three to six), situated on the corners of the polyhedral shell, four to six times as large as the pores. Often an acute tooth on the edge of each large opening. Transition-form between Collosphæra and Solenosphæra or Odontosphæra.

Dimensions.--Diameter of the shell 0.1 to 0.15, of the pores 0.004 to 0.008, of their bridges 0.004, of the large openings 0.24 to 0.032.

Habitat.--Tropical zone of the Pacific and the Indian Ocean; Stations 266 to 272, surface.

8. Collosphæra tuberosa, n. sp.

Collosphæra huxleyi, var., Haeckel, 1862, Monogr. d. Radiol., Taf. xxxiv. figs. 3, 9.

Shell very irregular, between subspherical and polyhedral in form, but always with irregular impressions, boils or bosses, and between these different rounded prominent tubercles and ridges. Network irregular, strong, with rounded, subcircular or nearly polygonal meshes. Ten to thirty pores in the half meridian of the shell. Diameter of the meshes half to four times as broad as that of the thick bars.

Dimensions.--Diameter of the shell very variable in the same coenobium, 0.05 to 0.2, of the pores 0.002 to 0.008, breadth of the bridges 0.004 to 0.006.

Habitat.--Cosmopolitan, common in all warmer seas, surface.

9. Collosphæra irregularis, n. sp.

Collosphæra huxleyi, var., Haeckel, 1862, Monogr. d. Radiol., Taf. xxxiv. fig. 8.

Shell quite irregular, knotty or bulbous, with irregular impressions, and prominent knobs or bulbs between them. Network thin, fragile, quite irregular, with polygonal meshes of most unequal size and form. Five to twenty pores in the half meridian of the shell. Diameter of the meshes two to ten times as broad as that of the thin bars.

Dimensions.--Diameter of the shell very variable in the same coenobium, 0.04 to 0.24, of the pores 0.005 to 0.05, of the bridges 0.002 to 0.004.

Habitat.--Mediterranean, Atlantic, not common; Stations 348, 352, &c., surface.

{98}Genus 30. Tribonosphæra,[52] Haeckel, 1881, Prodromus, p. 471.

Definition.--#Collosphærida# with simple shells, on the inside with radial centripetal beams.

The genus Tribonosphæra differs from Collosphæra by a very peculiar and rare character, the development of centripetal radial sticks on the internal face of the shell; these beams are not united in the centrum, but finish freely in a certain distance from it.

1. Tribonosphæra centripetalis, n. sp. (Pl. 5, fig. 12).

Shell roundish or subspherical, with numerous small circular or roundish pores, about twice as broad as the bars. Twenty to thirty pores on the half meridian of the shell. Outside of the shell smooth, inside a variable number (ten to twenty) of thin, radial, centripetal sticks or spines, one-third or one-half as long as the radius of the shell. (In the central capsule many very large crystals, resting after the destruction of the capsule.)

Dimensions.--Diameter of the shell 0.1 to 0.12, of the pores 0.003 to 0.005, of the bridges 0.001 to 0.002; length of the inner centripetal sticks 0.02 to 0.03.

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

Genus 31. Pharyngosphæra,[53] n. gen.

Definition.--#Collosphærida# with simple shells, having on the inside radial centripetal tubes, the walls of which are solid.

The genus Pharyngosphæra differs from Collosphæra by the development of radial tubules on the inside of the shell, which are directed centripetally towards its centre. The wall of the tubule is solid, not latticed as in the following genus.

1. Pharyngosphæra stomodæa, n. sp. (Pl. 5, fig. 10).

Shell irregular polyhedral, with ten to fifteen polygonal faces and rounded edges. Pores very small, circular, irregularly scattered, smaller than the bars. Twelve to fifteen pores on the half meridian of the shell. On the inside of every shell-face one short, nearly cylindrical, centripetal tubule, twice as long as broad, and about one-third as long as the shell radius. Outer umbilical mouth of the tubules somewhat wider than the inner truncated mouth.

Dimensions.--Diameter of the shell 0.11 to 0.12, of the pores 0.003 to 0.005, of the bars 0.01 to 0.02; length of the inner tubuli 0.02, breadth of them 0.01.

Habitat.--South Pacific, Station 288, depth 2600 fathoms.

{99}Genus 32. Buccinosphæra,[54] n. gen.

Definition.--#Collosphærida# with simple shells, having on the inside radial centripetal tubes, the walls of which are fenestrated.

The genus Buccinosphæra exhibits, on the inner surface of the shell, radial centripetal tubules similar to those of the foregoing Pharyngosphæra; but the walls of these tubes are here latticed, not solid; they represent therefore true invaginations of the whole shell-wall.

1. Buccinosphæra invaginata, n. sp. (Pl. 5, fig. 11).

Shell irregular roundish or nearly polyhedral, with a variable number of umbilical depressions, which are prolonged on the inside into cylindrical or somewhat conical, centripetal, fenestrated tubes, about one-third as long as the shell radius. Inner mouth of the tubes narrower, scarcely half as broad as the outer mouth, about equal to one-fourth the shell radius, truncated. Pores of the tubes and of the shell small, roundish, irregular in size and distribution, about as broad as the bars. Twenty-five to thirty pores in the half meridian of the shell. In all observed specimens the spherical central capsule (half as broad as the shell) contained a large number of crystals.

Dimensions.--Diameter of the shell 0.1 to 0.12, of the pores 0.001 to 0.003, of the bars 0.002 to 0.003; length of the tubuli 0.02; outer mouth 0.026, inner mouth 0.013; crystals in the central capsule 0.002 to 0.004, sometimes 0.008.

Habitat.--Philippine Islands (Samboangan), Station 213, surface.

2. Buccinosphæra tubaria, n. sp.

Shell irregular polyhedral with rounded edges, with a variable number of umbilical depressions, which are prolonged on the inside into large, nearly cylindrical, centripetal, fenestrated tubes, half as long as the shell radius. In the middle the tubes are somewhat constricted and narrower. Inner mouth of the tubes dilated, nearly as broad as the outer mouth, about equal to one-half the shell-radius, truncated. Pores of the tubes and of the shell large, roundish polygonal, irregular in size and distribution, three to four times as broad as the bars. Fifteen to twenty pores in the half meridian of the shell.

Dimensions.--Diameter of the shell 0.12 to 0.14, of the pores 0.008 to 0.012, of the bars 0.002 to 0.004; length of the tubuli 0.03; outer mouth 0.04, inner mouth 0.03.

Habitat.--North coast of New Guinea, Station 217, surface.

Genus 33. Acrosphæra,[55] Haeckel, 1881, Prodromus, p. 471.

Definition.--#Collosphærida# with simple shells, the outer surface of which is covered with radial, irregularly scattered spines.

{100}The genus Acrosphæra differs from its ancestral genus Collosphæra by the development of spines on the outer surface of the shell. These are either short, straight, radial spines, or oblique and often curved; their base is often inflated; they are irregularly scattered on the whole surface between the pores.

1. Acrosphæra erinacea, n. sp.

Shell a regular sphere, everywhere covered with small, very numerous, straight radial spines, regularly scattered between the pores. In the half meridian of the shell ten to twelve circular pores, all of the same form and size, double as broad as the bars. Spines bristle-shaped, very thin, solid, about as long as the diameter of the pores.

Dimensions.--Diameter of the shell 0.1 to 0.12, of the pores 0.008 to 0.012; length of the spines 0.01.

Habitat.--Tropical zone of the Atlantic, coast of Brazil, Rabbe, surface.

2. Acrosphæra echinoides, n. sp. (Pl 8, fig. 1).

Shell a regular sphere, covered with numerous, straight, radial spines, irregularly scattered over the whole surface. In the half meridian of the shell twenty to thirty irregular roundish pores of variable size, one to four times as broad as the bars. Spines conical, strong, quite radial, at the top of small conical elevations, which are perforated by from three to six pores.

Dimensions.--Diameter of the shell 0.12 to 0.15, of the pores 0.002 to 0.008; length of the spines 0.015, of their basal zones 0.01.

Habitat.--South-east corner of the Pacific, Valparaiso, Station 298, surface.

3. Acrosphæra setosa, Haeckel.

Polysolenia setosa, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 299, Taf. viii. fig. 10.

Shell a regular sphere, covered with numerous bristle-shaped radial spines, irregularly scattered between the pores. In the half meridian of the shell two to four very large circular pores (equal to one-third the radius), and between them numerous very small, point-like pores.

Dimensions.--Diameter of the shell 0.05 to 0.08, of the large pores 0.01, of the small 0.001; length of the spines 0.01 to 0.02.

Habitat.--West Tropical Pacific, Philippine Sea, Station 206, depth 2100 fathoms.

4. Acrosphæra spinosa, Haeckel.

Collosphæra spinosa, Haeckel, 1862, Monogr. d. Radiol., p. 536, Taf. xxxiv. figs. 12, 13.

Collosphæra spinosa, Cienkowsky, 1871, Archiv f. mikrosk. Anat., vii. p. 374, Taf. xxix. figs. 7-17.

Shell a regular or subregular sphere, covered with numerous, obliquely standing spines, irregularly scattered over the surface. In the half meridian of the shell fifteen to twenty irregular {101}roundish pores of very different form and size, one to four times as broad as their bars. Spines conical, irregularly diverging and curved, their hollow base perforated by several pores, not longer than the diameter of the largest pores.

Dimensions.--Diameter of the shell 0.1 to 0.2, of the pores 0.001 to 0.04; length of the spines 0.01 to 0.02.

Habitat.--Mediterranean, Messina; Canary Islands, Haeckel.

5. Acrosphæra collina, n. sp. (Pl. 8, fig. 2).

Shell quite irregular, polyhedrical, hilly, with a variable number (eight to sixteen) of large conical hill-like prominences; every cone or hill about as high as broad, perforated by the same pores as the shell, on its top bearing a larger irregular roundish pore, and on its edge one single bristle-like spine, not larger than the diameter of this pore, obliquely inserted. In the half meridian of the shell twenty to thirty irregular roundish pores of very different size, one to six times as broad as the bars. A very characteristic species, closely resembling the following Odontosphæra.

Dimensions.--Diameter of the shell 0.15 to 0.25, of the pores 0.005 to 0.02; length of the spines 0.01 to 0.02, height of the hills from which they rise 0.03 to 0.04.

Habitat.--North coast of New Guinea, Station 218, surface.

6. Acrosphæra inflata, n. sp. (Pl. 5, fig. 7).

Mazosphæra inflata, Haeckel, 1879, Atlas, loc. cit.

Shell more or less irregular, polyhedral, hilly, with a variable number (six to twelve) of large pyramidal, hill-like prominences; every hill about as high as broad, on the top a strong conical, radial, or obliquely inserted spine, inflated, with three to six very large polygonal meshes, much larger than the other pores between the hills, which are also polygonal, two to six times as broad as the bars. Ten to fifteen pores on the half meridian.

Dimensions.--Diameter of the shell 0.1 to 0.14, of the largest pores 0.05, of the smallest 0.005; length of the spines 0.02 to 0.03.

Habitat.--North Atlantic, Station 64, surface.

Genus 34. Odontosphæra,[56] n. gen.

Definition.--#Collosphærida# with simple shells, the outside of which bears single scattered spines, one single spine on the margin of each larger pore.

The genus Odontosphæra is distinguished from the foregoing Acrosphæra by the peculiar disposition of the spines, which are not scattered on the outside of the shell between the pores, but so disposed that each larger pore is protected by one single spine, obliquely placed over it.

{102}1. Odontosphæra monodon, n. sp. (Pl. 5, fig. 5).

Shell spherical or subspherical, with very small and numerous circular pores, much smaller than the bars. Twelve to fifteen pores on the half meridian of the shell. Between them a variable number of larger roundish apertures (mostly twelve to sixteen) irregularly scattered, one-fourth to one-fifth as broad as the shell radius. On the margin of every larger aperture a single (rarely two or three) sharp conical tooth, about as long as the diameter of the aperture, and obliquely laid over them.

Dimensions.--Diameter of the shell 0.1 to 0.13, of the pores 0.001 to 0.003, of the bars 0.01 to 0.02, of the larger apertures 0.01 to 0.02.

Habitat.--Sunda Archipelago, Station 192, surface.

2. Odontosphæra cyrtodon, n. sp. (Pl. 5, fig. 6).

Shell spherical or subspherical, with numerous roundish pores of very irregular size and distribution, mostly larger than the bars. Ten to twelve pores on the half meridian of the shell. Between them a variable number (mostly six to nine) of large roundish pores, about half as broad as the shell radius, armed on one side of the margin with one single large tooth, about as long as the diameter of the aperture, hook-like, curved, and obliquely laid over them.

Dimensions.--Diameter of the shell 0.12 to 0.14, of the pores 0.01 to 0.02, of the bars 0.003 to 0.006, of the larger apertures 0.03 to 0.04.

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

Genus 35. Choenicosphæra,[57] n. gen.

Definition.--#Collosphærida# with simple shells, armed on the outside with radial spines, forming elegant coronals around the larger pores.

The genus Choenicosphæra is characterised by the peculiar disposition of its radial spines, which form protective coronals around the larger pores, or even around all pores of the shell.

Subgenus 1. Choenicosphærula.

Definition.--A coronal of spines around every pore of the shell.

1. Choenicosphæra murrayana, n. sp. (Pl. 8, fig. 4).

Shell spherical, with large circular or roundish pores of unequal size, two to four times as broad as the bars. Ten to twelve pores in the half meridian of the shell. Margin of every pore {103}with a coronal of six to nine short and acute spines, not longer than the half diameter of the pore. No spines between the pores.

Dimensions.--Diameter of the shell 0.16 to 0.2, of the pores 0.02 to 0.03; length of the spines 0.008 to 0.012.

Habitat.--Færöe Channel (Gulf Stream), common. Expedition of H.M.S. "Triton," John Murray.

2. Choenicosphæra flosculenta, n. sp.

Shell spherical, with large circular or roundish pores of different size, three to six times as broad as the bars. Six to eight pores in the half meridian of the shell. Margin of every pore somewhat prominent, with a coronal of ten to twenty parallel acute spines of different length, the largest somewhat longer than the diameter of the pore. No spines between the pores.

Dimensions.--Diameter of the shell 0.12 to 0.15, of the pores 0.02 to 0.04; length of the spines 0.02 to 0.05.

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

Subgenus 2. Choenicosphærium.

Definition.--A coronal of spines only around the larger pores, not around the smaller.

3. Choenicosphæra nassiterna, n. sp. (Pl. 8, fig. 3).

Shell spherical, with circular or roundish pores of very different size. The smaller pores very numerous, without coronal of spines, roundish, about as broad as the bridges. Twenty to thirty pores in the half meridian of the shell. Between them, irregularly scattered, a small number (eight to twelve) of very large circular pores, one-third to one-half as broad as the radius of the shell, armed with a coronal of six to nine parallel, straight, acute spines, about half as long as the radius of the shell.

Dimensions.--Diameter of the shell 0.1 to 0.13, of the smaller pores 0.002 to 0.004, of the larger armed pores 0.02 to 0.03; length of the spines 0.03 to 0.04.

Habitat.--Philippine Islands, Mindanao, Station 213, depth 2050 fathoms.

4. Choenicosphæra flammabunda, n. sp. (Pl. 8, fig. 5).

Shell spherical, with circular or roundish pores of very different size. The smaller pores very numerous and unequal, very irregularly scattered, hardly one-fourth to one-half as broad as the bridges between them. Twelve to twenty-four pores in the half meridian of the shell. Between them, irregularly scattered, a variable number (ten to twenty) of very large circular pores, about one-fourth as broad as the radius of the shell. The margin of these large pores is armed with a very irregular coronal of four to twelve unequal, curved acute spines, partly simple, partly branched like {104}a deer-horn, one-fourth to one-half as long as the radius of the shell. Some other small spines irregularly scattered over the shell.

Dimensions.--Diameter of the shell 0.12 to 0.16, of the smaller pores 0.001 to 0.004, of the larger armed pores 0.016 to 0.024; length of the spines 0.02 to 0.04.

Habitat.--Central area of the Tropical Pacific, Stations 266 to 272, depth 2425 to 2925 fathoms.

Genus 36. Siphonosphæra,[58] J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 59.

Definition.--#Collosphærida# with simple shells, the pores of which are prolonged into external simple radial tubuli with solid wall; outer mouth of the tubuli truncated, smooth.

The genus Siphonosphæra is, next to Collosphæra, the most common of all Collosphærida, and rich in different species; all agreeing in the tubular prolongation of the pores, and corresponding therefore to Ethmosphæra among the simple Liosphærida.

Subgenus 1. Holosiphonia, Haeckel.

Definition.--All the pores or apertures of the shell prolonged into tubules.

1. Siphonosphæra pansiphonia, n. sp.

Shell a regular sphere, everywhere occupied by short, regular cylindrical tubes, all of the same size and form. Length of the tubules equal to their breadth and to the intervals between them. Ten to twelve tubules in the half meridian of the shell. This most regular species is nearly allied to Collosphæra regularis, and may be derived from it by tubular prolongation of all the regular pores.

Dimensions.--Diameter of the shell 0.1 to 0.12, length and breadth of the tubules 0.005 to 0.006.

Habitat.--Indian Ocean, Sunda Strait, Rabbe, surface.

2. Siphonosphæra marginata, n. sp.

Shell a regular or subregular sphere, occupied by numerous short cylindrical tubules of different sizes. Six to eight tubules in the half meridian of the shell. Diameter of the tubules about equal to their distance apart, but two to four times as large as their length.

Dimensions.--Diameter of the shell 0.1 to 14; length of the tubules 0.004 to 0.006, breadth of the tubules and the intervals 0.01 to 0.02.

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

{105}3. Siphonosphæra tubulosa, J. Müller (Pl. 6, fig. 4).

Siphonosphæra tubulosa, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 59.

Siphonosphæra tubulosa, Haeckel, 1862, Monogr. d. Radiol., p. 532.

Collosphæra tubulosa, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 59.

Thalassicolla punctata, var., Huxley, 1851, Ann. and Mag. Nat. Hist., ser. 2, vol. viii. p. 435, pl. xvi. fig. 5.

Shell subspherical or roundish, somewhat irregular, occupied by a small number (five to ten) of short cylindrical tubules, irregularly scattered at great distances; intervals between the tubules very large, two to four times as broad as the length of the tubules, which is equal to their breadth and about one-fifth or one-sixth of the shell diameter. Only two or three tubules in the half meridian of the shell.

Dimensions.--Diameter of the shell 0.12 to 0.15, length and breadth of the tubules 0.02 to 0.03.

Habitat.--Equatorial zone of the Pacific, Stations 225, 265, 268, surface.

4. Siphonosphæra cyathina, n. sp. (Pl. 6, fig. 10).

Shell a regular sphere, everywhere occupied by short cup-like tubules of somewhat different size. In the half meridian of the shell about ten to twelve tubules, nearly cylindrical, but constricted in the middle. Inner and outer aperture of the tubule of the same size; their diameter equal to their length and distance.

Dimensions.--Diameter of the shell 0.1 to 0.12, length and breadth of the tubules 0.005 to 0.01.

Habitat.--West coast of Tropical Africa, Stations 348 to 352, surface.

5. Siphonosphæra patinaria, n. sp. (Pl. 6, figs. 7, 8).

Shell a regular or subregular sphere, occupied by numerous broad cup-like tubules of very different sizes. In the half meridian of the shell about six to eight tubules, very flat, circular or subcircular, much constricted in the middle. Diameter of the inner aperture larger than that of the middle stricture, smaller than that of the outer aperture of the tubule; outer diameter two to four times as great as their length.

Dimensions.--Diameter of the shell 0.1 to 0.15, of the pores 0.01 to 0.04; length of the tubules 0.01, breadth 0.02 to 0.04.

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

6. Siphonosphæra infundibulum, n. sp.

Shell subspherical or irregular rounded, occupied by a small number (six to twelve) of large funnel-like tubules of very different size, scattered irregularly at great distances. Intervals between the tubules larger than their length, which surpasses the radius of the shell. Outer opening of the funnels three to four times as broad as the inner.

Dimensions.--Diameter of the shell 0.15; length of the tubules 0.05 to 0.09.

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

{106}7. Siphonosphæra conifera, n. sp. (Pl. 6, fig. 9).

Shell subspherical, everywhere occupied by irregular conical tubules, the length of which nearly reaches the shell radius. Inner aperture of the cones two to three times as large as the outer. Four to five tubules in the half meridian of the shell. Distances between the bases of the cones small and irregular.

Dimensions.--Diameter of the shell 0.06 to 0.08, length of the tubules 0.03 to 0.04; inner aperture of the cones 0.01 to 0.02, outer aperture 0.008 to 0.01.

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

8. Siphonosphæra fragilis, n. sp.

Shell quite irregular roundish or nearly ovate, very thin and fragile, everywhere occupied by irregular, short, and broad cylindrical or conical tubes. Six to ten tubes in the half meridian of the shell. Diameter of the tubules about one-eighth that of the shell, three to four times as large as the length of the tubules, and the distance apart of their bases.

Dimensions.--Diameter of the shell 0.16 to 0.24, of the tubules 0.02 to 0.03; length of the tubules 0.006 to 0.008, distance of them 0.005 to 0.009.

Habitat.--East coast of Australia, Sydney, Faber; Station 165, surface.

Subgenus 2. Merosiphonia, Haeckel.

Definition.--Only part of the shell apertures prolonged in tubules, the others simple.

9. Siphonosphæra socialis, n. sp. (Pl. 6, figs. 1, 2).

Shell a regular or subregular sphere, bearing only a small number (one to four, commonly two to three) of short and broad cylindrical tubules, irregularly scattered. Between them many small circular or subcircular pores of different sizes, double as broad as their bars. Eight to ten pores in the half meridian of the shell. Tubules three to six times as broad as the pores, about as long as broad, now quite cylindrical, now somewhat dilated at the outer opening. (Although the shells and cells of this common species are among the smallest, their colonies are among the largest, often containing more than one hundred social individuals, often enclosed in alveoles.)

Dimensions.--Diameter of the shell 0.04 to 0.05, of the pores 0.002 to 0.004, of the tubules 0.015 to 0.02; length of them about the same.

Habitat.--Tropical and subtropical part of the Eastern Atlantic, Cape Verde Islands, Canaries, very common, Haeckel; Stations 338 to 353, surface.

10. Siphonosphæra polysiphonia, n. sp.

Shell a regular or subregular sphere, bearing twelve to sixteen circular pores in its half meridian. Nearly one half the pores simple, very small; the other half prolonged into short cylindrical tubules, {107}half as long as broad, two to four times as broad as the pores and their intervals. This species is nearly related to the foregoing, which it represents in the western tropical part of the Atlantic, but differs constantly in the double size of the shell and the much larger number of the tubules.

Dimensions.--Diameter of the shell 0.06 to 0.09, of the pores 0.002 to 0.004, of the tubules 0.01 to 0.012; their length 0.006 to 0.008, surface.

Habitat.--Tropical and subtropical part of the Western Atlantic, coast of Brazil, &c., Rabbe.

11. Siphonosphæra macrosiphonia, n. sp.

Shell a regular sphere, with numerous very small pores of equal size and distribution. Twelve to sixteen pores in its half meridian. Bars (between the pores) three to four times as broad as their diameter. Only a small number (two to four) of very long cylindrical tubes, irregularly scattered, nearly as long or somewhat longer than the shell diameter; now quite straight, now somewhat curved. Diameter of the cylinders four to six times as large as that of the pores.

Dimensions.--Diameter of the shell 0.1 to 0.12, of the pores 0.002 to 0.004, of the tubules 0.015 to 0.018; length of the tubules 0.08 to 0.16.

Habitat.--Central Tropical Pacific, Station 266 to 272, surface.

12. Siphonosphæra serpula, n. sp. (Pl. 6, fig. 6).

Shell a regular sphere, with numerous very small pores of equal size and distribution. Eight to ten pores in its half meridian; bars between them three to four times as broad as their diameter. Only a small number (six to eight) of very long and snake-like, contorted, cylindrical tubes, irregularly scattered. The shape of the latter is very much like that of the calcareous tubes of some species of Serpula; they are nearly as long as, or longer than, the shell diameter, and four to six times as broad as the pores.

Dimensions.--Diameter of the shell 0.12 to 0.14, of the pores 0.003 to 0.005, of the tubules 0.02 to 0.022; length of the tubules 0.1 to 0.2.

Habitat.--North Eastern Pacific, Station 252 to 262, Sandwich Islands, Haltermann.

13. Siphonosphæra chonophora, n. sp. (Pl. 6, fig. 5).

Shell a regular or subregular sphere, with numerous very small pores of equal size and distribution, ten to twelve in its half meridian. Bars between the pores four to six times their diameter. Only a small number (two to six) of very large funnel-like tubules, irregularly scattered. The inner half of these tubules is a short cylindrical tube, of the same thickness as the shell, three to four times as broad as the pores; the outer half is an irregular funnel, suddenly expanded, with siliceous walls of the utmost tenuity and fragility, often irregularly folded and contorted, like a decayed flower-calyx, often half as large as the shell.

Dimensions.--Diameter of the shell 0.1 to 0.12, of the pores 0.003 to 0.005, inner half of the tubules 0.015 to 0.02, outer funnel-like half 0.05 to 0.08.

Habitat.--South Pacific, Stations 285 to 295, surface.

{108}14. Siphonosphæra pipetta, n. sp. (Pl. 6, fig. 3).

Shell more or less irregularly roundish or subspherical, occupied in part by very small pores, in part by very large cylindrical tubules, inflated in the middle. Number, form, and size of the tubes very irregular; commonly there are five to ten, half as long or as long as the shell radius; their inner and outer aperture about half as broad as their inflated middle part; three to nine times as broad as the pores. A very irregular and variable species.

Dimensions.--Diameter of the shell 0.1 to 0.15, of the pores 0.001 to 0.005, of the tubules 0.015 to 0.03; length of the tubules 0.03 to 0.08.

Habitat.--North Pacific, Stations 242 to 253, surface.

Genus 37. Mazosphæra,[59] Ehrenberg, 1860.

Mazosphæra, Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 833.

Definition.--#Collosphærida# with simple shells, the pores of which are prolonged into external simple radial tubuli with solid wall; outer mouth of each tubulus armed with a single tooth.

The genus Mazosphæra is intermediate between Siphonosphæra and Odontosphæra, agreeing with the former in the tubular prolongation of the pores, with the latter in the possession of a single large protective tooth on the outer opening.

1. Mazosphæra hippotis, n. sp. (Pl. 5, fig. 8).

Shell spherical, with circular pores of irregular size and distribution, scarcely half as broad as the bars; fifteen to twenty on the half meridian of the shell. Between them, irregularly distributed, a variable number (ten to fifteen) of short cylindrical radial tubules, about twice as long as broad, and half as long as the shell radius. Mouth of the tubuli obliquely truncated, having on one side a strong acute tooth.

Dimensions.--Diameter of the shell 0.11 to 0.12, of the pores 0.002 to 0.004, of the bridges 0.006 to 0.009; length of the tubuli 0.03, breadth of them 0.01 to 0.015.

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

2. Mazosphæra lagotis, n. sp. (Pl. 5, fig. 9).

Shell spherical, with circular pores of irregular size and distribution, about as broad as the bars; twelve to sixteen on the half meridian. Between them, irregularly distributed, a variable number (eight to twelve) of long, cylindrical, curved tubules, three to six times as long as broad, and about as long as the shell radius; their external mouth lateral, obliquely truncated, ovate, having on one side a strong conical tooth.

{109}Dimensions.--Diameter of the shell 0.1 to 0.12, of the pores 0.002 to 0.01; length of the tubuli 0.05 to 0.07.

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

3. Mazosphæra lævis, Ehrenberg.

Mazosphæra lævis, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. vii. fig. 7.

Shell spherical, with very small pores, scarcely one-fourth as broad as the bars. Fifteen to twenty pores on the half meridian of the shell. Between them, irregularly distributed, a variable number (fifteen to twenty) of short conical tubules, about as long as broad, only one-fifth to one-sixth as long as the shell radius. Mouth of the tubuli truncated, with an obtuse short tooth on one side.

Dimensions.--Diameter of the shell 0.08 to 0.09, of the pores 0.001 to 0.002, of the bridges 0.005 to 0.008; length of the tubuli 0.01 to 0.02, breadth of them the same.

Habitat.--Philippine Islands (depth 3300 fathoms), Ehrenberg; Station 206, depth 2100 fathoms; Station 225, depth 4575 fathoms.

4. Mazosphæra apicata, Ehrenberg.

Mazosphæra apicata, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 316.

Shell spherical, without small pores, only with a variable number (ten to twenty) of short conical tubules, twice as long as broad, and half as long as the shell radius. Mouths of the tubuli obliquely truncated, with a strong acute tooth on one side. (This species differs from the two preceding by the want of the small pores between the tubules.)

Dimensions.--Diameter of the shell 0.08 to 0.1, of the tubules 0.01.

Habitat.--Philippine Islands (depth 3300 fathoms), Ehrenberg; north coast of New Guinea, depth 2000 fathoms; Station 217.

Genus 38. Trypanosphæra,[60] n. gen.

Definition.--#Collosphærida# with simple shells, the pores of which are prolonged into external simple radial tubuli with solid walls; outer mouth of each tubulus armed with a coronal of spines.

The genus Trypanosphæra is intermediate between Siphonosphæra and Choenicosphæra agreeing with the former in the tubular prolongation of the pores, with the latter in the possession of a coronal of teeth on their outer opening.

Subgenus 1. Trypanosphærula, Haeckel.

Definition.--All pores of the shell prolonged into short coronated tubules.

{110}1. Trypanosphæra trepanata, n. sp. (Pl. 5, fig. 4).

Shell regular spherical, with regular circular pores of nearly equal size, at unequal distances, one to four times as broad as the bars. Eight to ten pores on the half meridian. All the pores prolonged into short cylindrical tubuli about as long as broad, armed on the external mouth with an elegant coronal of twenty to thirty straight bristle-shaped, parallel teeth.

Dimensions.--Diameter of the shell 0.12 to 0.14, of the pores 0.015 to 0.02; length of the tubuli 0.02.

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

2. Trypanosphæra dentata, n. sp.

Shell regular spherical, with regular circular pores of equal size, but at very different distances. Only three to four pores on the half meridian. All the pores prolonged into irregular curved, cylindrical tubuli, about as long as the shell radius, with a coronal of ten to twelve short conical teeth on the distal end.

Dimensions.--Diameter of the shell 0.08 to 0.09; length of the tubuli 0.04, breadth 0.02.

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

Subgenus 2. Trypanosphærium, Haeckel.

Definition.--Only part of the shell-pores prolonged into coronated tubules.

3. Trypanosphæra coronata, n. sp. (Pl. 5, fig. 3).

Shell regular spherical, with irregular roundish pores of very different sizes. On the half meridian four to six large and twelve to sixteen very small pores. About half of the large pores prolonged into short cylindrical tubuli, the outer mouth of each being armed with an elegant coronal of ten to twenty thin irregular teeth.

Dimensions.--Diameter of the shell 0.1 to 0.12, of the large pores 0.01 to 0.02, of the small pores 0.001; length of the tubuli 0.012.

Habitat.--North Pacific, Station 241, depth 2300 fathoms.

4. Trypanosphæra terebrata, n. sp.

Shell irregular roundish, with unequal, small, roundish pores. Sixteen to twenty pores on the half meridian. Six to eight larger pores are prolonged into curved cylindrical tubuli, about as long as the shell radius, with a coronal of ten to twelve strong conical straight teeth on the distal end.

Dimensions.--Diameter of the shell 0.15, of the pores 0.001 to 0.003; length of the tubuli 0.08, breadth 0.02.

Habitat.--West Tropical Pacific, Station 225, depth 4575 fathoms.

{111}5. Trypanosphæra transformata, n. sp. (Pl. 5, figs. 1, 2).

Shell quite irregular, of very variable, roundish, or polyhedral form, with small irregular roundish pores, two to four times as broad as the bars. Ten to thirty on the half meridian. The different form of the shell depends upon the variable number of tubuli, which arise at irregular distances from the shell; commonly three to four, often also five to six, more rarely one or two. The tubuli are now more conical, now more cylindrical, about as long as the shell radius, at other times scarcely one-half or one-third as long, with a coronal of ten to twenty more or less curved teeth on the narrower distal mouth. All the different forms are to be found in one and the same colony, as shown in fig. 1. This coenobium, which I observed living in Ceylon, exhibited the same peculiar formation as I figured in Collosphæra huxleyi in my Monograph 1862 (Taf. xxxiv. fig. 1). In the centre of the jelly-sphere lies a large globular alveole, surrounded by numerous small, young central capsules without shell; whilst in the surface lies one layer of older capsules, enclosed in shells. Some of the younger capsules exhibit self-division.

Dimensions.--Diameter of the shells 0.08 to 0.12, pores 0.002 to 0.006; length and breadth of the tubuli 0.03 to 0.05.

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

Genus 39. Caminosphæra,[61] n. gen.

Definition.--#Collosphærida# with simple shells, the pores of which are prolonged into external branched radial tubuli with solid wall.

The genus Caminosphæra differs from Siphonosphæra (and from all other Collosphærida) in the ramification of the tubuli, which arise from the pores; the walls of the tubuli are solid, not fenestrated.

1. Caminosphæra furcata, n. sp.

Shell spherical or subspherical, with a variable number (four to eight) of short cylindrical tubes, irregularly scattered, about as long as the radius of the shell. Every tube forked, with two cylindrical branches of the same size as the simple basal part of the tube. Mouth of the branches truncated, not dilated. Pores of the shell between the tubes very small, all of the same size, half as broad as their bars. Fifteen to twenty pores in the half meridian of the shell.

Dimensions.--Diameter of the shell 0.1 to 0.12, of the pores 0.001 to 0.002; length of the tubules 0.05 to 0.06, breadth of them 0.012 to 0.015.

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

2. Caminosphæra elongata, n. sp.

Shell spherical, with a large number (twelve to twenty) of long cylindrical tubes, irregularly formed and scattered, somewhat longer than the diameter of the shell. Every tube forked at {112}the distal end, with two or three short irregular branches of unequal size and form; branches much shorter than the undivided basal part of the tube. Mouth of the branches narrowed, truncated. Pores of the shell between the tubes about half as broad, irregularly roundish or polygonal, two to three times as broad as their bars. Ten to twelve pores in the half meridian of the shell.

Dimensions.--Diameter of the shell 0.05 to 0.07, of the pores 0.006 to 0.009; length of the tubules 0.06 to 0.09, breadth of them 0.015 to 0.02.

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

3. Caminosphæra dichotoma, n. sp. (Pl. 7, fig. 2).

Shell spherical, with a variable number (ten to fifteen) of cylindrical tubes, irregularly scattered, about as long as the radius of the shell. Every tube furcated, with two cylindrical branches of the same size as the simple basal part of the tube. Mouth of the branches dilated, funnel-like, twice as broad as the tube; the edges irregularly dentated or lacerated. Pores between the tubes small, one-third to one-sixth as broad as these, half as broad as their bars. Ten to twelve pores in the half meridian of the shell.

Dimensions.--Diameter of the shell 0.12 to 0.14, of the pores 0.003 to 0.005; length of the tubules 0.06 to 0.08, breadth of them 0.02 to 0.03.

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

4. Caminosphæra dendrophora, n. sp. (Pl. 7, fig. 1).

Shell spherical, with a variable number (eight to twelve) of long cylindrical tubes, irregularly branched and scattered, nearly as long as the diameter of the shell. Every tube with two to six (commonly three to four) branches of different sizes. Mouth of the branches dilated, funnel-like; the edges irregularly dentated or lacerated. Pores between the tubes half as broad as these, irregularly roundish, twice as broad as their bars. Ten to twelve pores in the half meridian of the shell.

Dimensions.--Diameter of the shell 0.12 to 0.15, of the pores 0.006 to 0.01; length of the tubules 0.1 to 0.13, breadth of them 0.02 to 0.025.

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

Genus 40. Solenosphæra,[62] n. gen.

Definition.--#Collosphærida# with simple shells, the pores of which are prolonged into external simple radial tubuli with fenestrated wall; outer mouth of the tubuli truncated, smooth.

The genus Solenosphæra differs from Siphonosphæra in the fenestration of the external radial tubes. A large number of shells, appertaining to this genus, were already described by Ehrenberg, and disposed in five different genera corresponding to the {113}different numbers of the tubuli:--Disolenia with two tubes, Trisolenia with three tubes, Tetrasolenia with four tubes, Pentasolenia with five tubes, Polysolenia with six or more tubes. All these five genera are without value, as those different numbers of tubes occur frequently intermingled in the individual cells of one and the same colony, wherever the form and structure of the tubes is inherited with sufficient constancy to determine the species.

Subgenus 1. Solenosphactra, Haeckel.

Definition.--Tubuli of the shell cylindrical or nearly cylindrical, the outer and inner apertures nearly of the same size.

1. Solenosphæra variabilis, Haeckel.

Tetrasolenia quadrata, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. x. fig. 20.

Shell quite irregular roundish or polyhedral, with roundish pores of different size. Ten to fifteen pores in the half meridian of the shell, two to three times as broad as the bars. Porous tubuli of the shell in variable number (in one and the same colony), three to nine, mostly four to six; cylindrical or subcylindrical or somewhat conical, two to three times as broad as long, not longer than the half radius of the shell. Inner aperture of the tubuli commonly as broad as the half radius of the shell (or somewhat smaller), about as large as the truncated outer aperture. This species is closely related to Collosphæra polyedra (p. 97), and may be derived from it by a short tube-like prolongation of the larger apertures.

Dimensions.--Diameter of the shell 0.1 to 0.16, of the pores 0.005 to 0.015; length of the tubules 0.02 to 0.03, breadth of them 0.04 to 0.06.

Habitat.--Central area of the Tropical Pacific, Stations 270, 271, 272, depths 2425 to 2925 fathoms.

2. Solenosphæra pandora, n. sp. (Pl. 7, figs. 10, 11).

Shell irregular roundish or subglobular, with roundish pores of different sizes, mostly somewhat broader than the bars. About twelve to sixteen pores on the half meridian of the shell. Porous tubuli of the shell of variable number (in one and the same colony), one to six, mostly three to four; cylindrical or nearly cylindrical, somewhat longer than broad, not longer than the radius of the shell. Inner aperture of the tubuli commonly as broad as the half radius of the shell, and a little smaller than the truncated outer aperture.

Dimensions.--Diameter of the shell 0.07 to 0.1, of the pores 0.003 to 0.006; length of the tubuli 0.03 to 0.05, breadth of them 0.02 to 0.03.

Habitat.--Central area of the Tropical Pacific, Stations 266 to 274, depths 2350 to 2925 fathoms.

{114}3. Solenosphæra megalactis, Haeckel.

Trisolenia megalactis, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 301, Taf. viii. fig. 19.

Shell irregularly polyhedrical, with very small roundish pores, scarcely half as broad as the bars. Only eight to ten pores on the half meridian of the shell. Porous tubuli of the shell of variable number (in one and the same colony), two to five, mostly three or four; cylindrical, about as long as the radius of the shell. Inner aperture of the tubuli commonly as broad as the half radius of the shell, and quite as broad as the truncated outer aperture.

Dimensions.--Diameter of the shell 0.07 to 0.09, of the pores 0.002 to 0.004, of the bars 0.005 to 0.009; length of the tubuli 0.03 to 0.04, breadth of them 0.02.

Habitat.--Pacific; California, Philippine Sea, Ehrenberg; Stations 256 to 285, depths 310 to 3000 fathoms.

4. Solenosphæra serpentina, n. sp. (Pl. 7, fig. 7).

Shell nearly spherical, with very small circular pores, scarcely one-third or one-fourth as broad as the bars. Only five to seven pores in the half meridian of the shell. Porous tubuli of the shell of variable number (in one and the same colony), two to nine, mostly seven or eight; cylindrical, somewhat curved or contorted, once and a half or twice as long as the diameter of the shell, with few very small and widely scattered pores. Inner and outer aperture of the tubuli have the same diameter, about one-fifth or one-fourth that of the shell. (This species is closely allied to Siphonosphæra serpula, but is distinguished from it by the long tortuous tubuli and the small scarce pores.)

Dimensions.--Diameter of the shell 0.08 to 0.1, of the pores 0.001 to 0.002, of the bars 0.004 to 0.008; length of the tubuli 0.12 to 0.18, breadth of them 0.02 to 0.025.

Habitat.--North-eastern Pacific, between Sandwich Islands and California, Haltermann, surface.

Subgenus 2. Solenosphenia, Haeckel.

Definition.--Tubuli of the shell more or less conical, the inner aperture much larger than the outer aperture.

5. Solenosphæra venosa, Haeckel.

Tetrasolenia venosa, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 301, Taf. vii. fig. 22.

Shell irregular polyhedral or roundish, with a delicate network of large irregular polyhedral meshes, five to ten times as broad as the thin bars. Eight to twelve meshes on the half meridian of the shell. Fenestrated tubuli of the shell of variable number (in one and the same colony), one to five, commonly three or four, shaped like a short truncated cone, about half as long as broad on its base, shorter than the radius of the shell. Inner aperture of the cone nearly as broad as the half radius of the shell, about twice as broad as the truncated outer aperture.

{115}Dimensions.--Diameter of the shell 0.07 to 0.12, of the pores 0.008 to 0.016, of the bars 0.001; length of the tubuli 0.02 to 0.03, inner aperture 0.03 to 0.04, outer aperture 0.02 to 0.03.

Habitat.--Indian Ocean, Sunda Strait, Rabbe.

6. Solenosphæra ascensionis, n. sp. (Pl. 7, fig. 9).

Shell somewhat irregular, subspherical, with polygonal pores of different size. Twelve to fifteen pores in the half meridian of the shell, two to eight times as broad as their bars. Porous tubuli of the shell of variable number (in one and the same colony), three to nine, mostly five to seven; conical or nearly cylindrical, irregular, about as long as broad at their base. Inner aperture of the tubuli two to four times as broad as the broadest pores, and double as broad as the truncated circular outer aperture.

Dimensions.--Diameter of the shell 0.1 to 0.12, of the pores 0.004 to 0.018, of the bars 0.002, length of the tubuli 0.04, inner aperture 0.04, outer 0.02.

Habitat.--South Atlantic, near Ascension Island, Station 343, surface.

Subgenus 3. Solenosphyra, Haeckel.

Definition.--Tubuli of the shell funnel-like, the outer aperture much larger than the inner.

7. Solenosphæra cornucopia, n. sp. (Pl. 7, fig. 8).

Shell spherical or subspherical, with roundish pores of different size. Ten to twelve pores in the half meridian of the shell, two to three times as broad as the bars. Porous tubuli of the shell of variable number (in one and the same colony), four to eight, mostly five to seven, funnel-like, about as long as the diameter of the shell. Inner aperture of the tubuli commonly two-thirds or three-fourths as broad as the radius of the shell (or somewhat smaller), only one-half or two-thirds as broad as the dilated and truncated outer aperture.

Dimensions.--Diameter of the shell 0.07 to 0.09, of the pores 0.006 to 0.018; length of the tubuli 0.06 to 0.08, diameter of the inner aperture 0.04 to 0.05, of the outer 0.06 to 0.08.

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

8. Solenosphæra amalthea, n. sp.

Shell irregular roundish or spherical, with small circular pores of different size. Fifteen to twenty pores in the half meridian of the shell, but still not as broad as the bars. Porous tubuli of the shell of variable number (in one and the same colony), three to six, commonly four or five, funnel-like, about as long as the radius of the shell. Inner aperture of the tubuli about half as broad as the radius of the shell, only one-half or one-third as broad as the truncated outer aperture. (This species is intermediate between the preceding and Siphonosphæra chonophora, Pl. 6, fig. 5.)

{116}Dimensions.--Diameter of the shell 0.09 to 0.11, of the pores 0.002 to 0.004, of the bars 0.003 to 0.006; length of the tubuli 0.05 to 0.06; diameter of the inner aperture 0.02 to 0.03, of the outer aperture 0.05 to 0.07.

Habitat.--Western part of the South Atlantic, Station 325, surface.

Genus 41. Otosphæra,[63] n. gen.

Definition.--#Collosphærida# with simple shells, the pores of which are prolonged into external simple radial tubuli with fenestrated walls; outer mouth of the tubuli armed with a single tooth.

The genus Otosphæra differs from Solenosphæra by the single tooth on the external mouth of the tubuli, from Mazosphæra by the fenestration of the walls of the tubuli.

1. Otosphæra polymorpha, n. sp. (Pl. 7, fig. 6).

Shell quite irregular, polyhedral or roundish, very variable in size and form, with numerous very small pores, much smaller than the bars. Twenty to thirty pores in the half meridian of the shell. Porous tubuli of the shell commonly in variable number (one to four), but sometimes constant in number (one, two, three, or four) in the one and same colony. Tubuli irregular conical, commonly about as long as the radius of the shell; their outer aperture obliquely truncated, on one side prolonged into one large, prominent, bill-like, curved, acute tooth.

Dimensions.--Diameter of the shell 0.12 to 0.15, of the pores 0.001 to 0.002; length of the tubuli 0.06 to 0.08, inner aperture 0.03, outer aperture 0.02.

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

2. Otosphæra auriculata, n. sp. (Pl. 7, fig. 5).

Shell quite irregular, of extremely variable form, now inclining to roundish, now to polyhedral, with very numerous small pores, irregularly formed and distributed. Twelve to twenty-four pores in the half meridian of the shell, of very different size, for the most part larger than the bars. Porous tubuli of the shell of variable number (in one and the same colony), one to five, mostly three or four, of conical form, irregularly formed and scattered, commonly about half as long as the radius of the shell. Outer aperture of the tubuli obliquely truncated, with one large prominent, often curved, acute tooth.

Dimensions.--Diameter of the shell 0.1 to 0.2, of the pores 0.003 to 0.005; length of the tubuli 0.01 to 0.05, inner aperture 0.04, outer aperture 0.03.

Habitat.--Central Tropical Pacific, Stations 268 to 272, depths 2425 to 2925 fathoms.

{117}Genus 42. Coronosphæra,[64] n. gen.

Definition.--#Collosphærida# with simple shells, the pores of which are prolonged into external simple radial tubuli with fenestrated walls; outer mouth of the tubuli armed with a coronal of spines.

The genus Coronosphæra differs from Solenosphæra by the coronated mouth of the tubuli, from Trypanosphæra by the fenestration of the walls of the tubuli.

1. Coronosphæra diadema, n. sp. (Pl. 7, fig. 3).

Shell spherical or subspherical, with a variable number (fifteen to twenty) of short, coronal-like tubules, irregularly scattered, about half as long as the radius of the shell. Outer aperture of the tubuli irregularly dentated, a little dilated, and not much broader than the inner aperture, one-half or one-third as broad as the shell radius. Pores of the shell and of the tubuli circular or roundish, very irregularly scattered, mostly one-half or one-third as broad as the bars.

Dimensions.--Diameter of the shell 0.11 to 14, of the pores 0.002 to 0.004, of the bars 0.006 to 0.012; length of the tubuli 0.03, inner aperture 0.02 to 0.03, outer aperture 0.03 to 0.04.

Habitat.--Central Pacific, Stations 268 to 270, depths 2550 to 2925 fathoms.

2. Coronosphæra calycina, n. sp. (Pl. 7, fig. 4).

Shell spherical or subspherical, with a variable number (eight to twelve) of large, funnel-like tubules, irregularly scattered, about as long as the radius of the shell. Outer aperture of the tubuli irregularly dentated, much dilated, somewhat broader than the shell radius, three to four times as broad as the inner circular aperture. Pores of the shell and of the tubuli circular or roundish, of very different size, one to three times as broad as the bars.

Dimensions.--Diameter of the shell 0.1 to 0.3, of the pores 0.003 to 0.01, of the bars 0.002 to 0.004; length of the tubuli 0.1, inner aperture 0.02 to 0.03, outer aperture 0.06 to 0.18.

Habitat.--Central Pacific, Stations 271, 272, depths 2425 and 2600 fathoms respectively.

3. Coronosphæra convolvulus, n. sp.

Shell irregular roundish, with a variable number (five to ten) of long, curved tubules, about as long as the shell diameter. The inner half of the tubuli is narrow, cylindrical; the outer half funnel-like dilated, similar to the flower of Convolvulus. The outer aperture is elegantly dentated, five to six times as broad as the inner aperture. Pores of the shell and of the tubuli very irregular roundish, about as broad as the bars.

Dimensions.--Diameter of the shell 0.08 to 0.09, of the pores and bars 0.004 to 0.008; length of the tubuli 0.07 to 0.1, inner aperture 0.01, outer aperture 0.05.

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

{118}Subfamily CLATHROSPHÆRIDA, Haeckel, 1881, Prodromus, p. 472.

Definition.--#Collosphærida# with a double lattice-shell around every central capsule of the coenobium; both concentric shells connected by irregular or subradial beams, commonly solid or lamellar staffs, rarely hollow tubes.

Genus 43. Clathrosphæra,[65] Haeckel, 1881, Prodromus, p. 472.

Definition.--#Collosphærida# with a double lattice-shell around every central capsule of the coenobium; surface of the outer shell smooth.

The genus Clathrosphæra (with smooth surface) and the following Xanthiosphæra (with spiny surface) form together the small subfamily, Clathrosphærida, different from the other Collosphærida by the double lattice-shell. From the surface of the inner primary shell arise either solid spines or hollow tubes, which unite by the anastomosis of irregular branches and so form the outer secondary shell, often very incomplete and irregular. All Clathrosphærida seem to inhabit great depths.

Subgenus 1. Clathrosphærula, Haeckel.

Definition.--The connecting staffs between both shells are hollow tubes (derived from Siphonosphæra).

1. Clathrosphæra circumtexta, n. sp. (Pl. 8, fig. 6).

Inner shell spherical, with irregular roundish large meshes, now broader now smaller than their bars. Eight to ten meshes in the half meridian of the shell. All these meshes are prolonged into short cylindrical hollow tubes, about as long as broad, somewhat constricted in the middle. From the margins of the outer openings of these tubes proceed very numerous and delicate siliceous filaments, which all lie on the same spherical face, branch, anastomose, and twine over the openings and the intervals between them, forming a very thin, arachnoid spherical outer shell. The meshes of this are quite irregular polygonal, of very different size and form. The radius of the inner shell bears to that of the outer a ratio = 5 : 6.

Dimensions.--Diameter of the inner shell 0.11 to 0.13, of the outer 0.13 to 0.16; meshes of the inner shell 0.005 to 0.02, of the outer 0.005 to 0.04.

Habitat.--North Pacific, Stations 238 to 253, depths 2050 to 3950 fathoms.

Subgenus 2. Clathrosphærium, Haeckel.

Definition.--The connecting staffs between the two shells are solid rods or lamellar spines (derived from Acrosphæra).

{119}2. Clathrosphæra arachnoides, n. sp. (Pl. 8, fig. 7).

Inner shell spherical, with irregular roundish meshes, two or three times as broad as the bars. Ten to twelve meshes in the half meridian of the shell. From its surface arise numerous conical radial spines (with base often fenestrated), which at equal distances from the surface send out lateral branches. All these branches lie on a spherical face, and form by communications the irregular, very delicate, arachnoid network of the outer shell, quite unlike that of the inner, with large polygonal meshes of very different size. Eight to sixteen meshes in the half meridian of the shell. Surface of the outer shell nearly spherical, somewhat uneven, like a spider's web. The radius of the inner shell bears to that of the outer a ratio = 3 : 4.

Dimensions.--Diameter of the inner shell 0.12 to 0.14, of the outer 0.15 to 0.18; pores of the inner shell 0.003 to 0.02, of the outer 0.01 to 0.04.

Habitat.--Central area of the Tropical Pacific, Station 268, depth 2900 fathoms.

3. Clathrosphæra lamellosa, n. sp. (Pl. 8, fig. 8).

Inner shell spherical or subspherical, with irregular roundish meshes, about half as broad as the bars. Twelve to sixteen meshes in the half meridian of the shell. From its surface arise numerous oblique irregular staffs or broad and thin lamellæ, which branch quite irregularly, and by communications of the branches form the thin outer shell. This is quite irregular roundish or subspherical, very unlike the inner, with large polygonal meshes of different size, six to twelve in the half meridian of the shell. Bridges between the meshes very variable, now very thin filamentous, now very broad lamellar. Outer surface very uneven or tuberculated, but not spinous. The radius of the inner shell bears to that of the outer a ratio = 5 : 6.

Dimensions.--Diameter of the inner shell 0.1 to 0.13, of the outer 0.12 to 0.18; pores of the inner shell 0.003 to 0.009, of the outer 0.01 to 0.04.

Habitat.--Central area of the Tropical Pacific, Stations 270 to 274, depths 2350 to 2925 fathoms.

Genus 44. Xanthiosphæra,[66] Haeckel, 1881, Prodromus, p. 472.

Definition.--#Collosphærida# with a double lattice-shell around every central capsule of the coenobium; surface of the outer shell thorny or spiny.

The genus Xanthiosphæra differs from the foregoing Clathrosphæra by spines or thorns arising from the surface of the outer shell, commonly very irregular.

1. Xanthiosphæra capillacea, n. sp.

Inner shell spherical, with irregular polygonal meshes, three to five times as broad as their narrow bars. Six to eight meshes in the half meridian of the shell. From its surface arise at the nodes of the network numerous thin radial spines, which, at equal distances from the surface, {120}send out lateral branches. All these branches lie on a spherical face, and form by communications the irregular delicate network of the outer shell, very like that of the inner, with large polygonal meshes, six to eight meshes in the half meridian of the shell. Surface of the outer shell covered with numerous straight spines, prolongations of the inner spines, but only half as long as these. The radius of the inner shell bears to that of the outer a ratio = 3 : 5.

Dimensions.--Diameter of the inner shell 0.1 to 0.12, of the outer 0.15 to 0.19; pores of the inner shell 0.02 to 0.04 to 0.06, of the outer 0.04 to 0.06 to 0.08; length of the outer spines 0.01 to 0.02.

Habitat.--Central area of the Tropical Pacific, Station 263, depth 2650 fathoms.

2. Xanthiosphæra erinacea, n. sp. (Pl. 8, fig. 9).

Inner shell spherical, with irregular roundish meshes, one-half to two times as broad as the bars. Fifteen to twenty meshes in the half meridian of the shell. From its surface arise numerous thin radial spines, which at equal distances from the surface send out lateral branches. All these branches lie on the face of a sphere, and form by communications the irregular delicate network of the outer shell, very unlike that of the inner, with large polygonal meshes, twelve to twenty-four in the half meridian of the shell. Surface of the outer shell covered with numerous straight spines, prolongations of the inner spines, and of the same length. The radius of the inner shell bears to that of the outer a ratio = 3 : 4.

Dimensions.--Diameter of the inner shell 0.1 to 0.12, of the outer 0.13 to 0.16; pores of the inner shell 0.002 to 0.008, of the outer 0.01 to 0.03; length of the outer spines 0.02 to 0.03.

Habitat.--Central area of the Tropical Pacific, Stations 270, 272, depth 2925 and 2600 fathoms respectively.

3. Xanthiosphæra lappacea, n. sp. (Pl. 8, figs. 10, 11).

Inner shell spherical or subspherical, with very small roundish pores, quite irregularly scattered, one-fourth to three-fourth as broad as their bars. Ten to twenty pores in the half meridian of the shell. From its surface arise in an extremely irregular and variable manner numerous oblique spines, often curved, often lamellar, and perforated by pores, sometimes hollow, fenestrated cones. At different distances from the surface these spines send out lateral curved branches, which by communications form the delicate and very irregular network of the outer shell. This network is often incomplete and very unlike that of the inner shell, with large polygonal meshes, six to eighteen in the half meridian of the shell. Surface of the outer shell covered with numerous small, curved, and oblique spines, prolongations of the inner spines, but scarcely one-third to one-half as long as these. The radius of the inner shell bears to that of the outer a ratio = 3 : 4.

Dimensions.--Diameter of the inner shell 0.08 to 0.12, of the outer 0.11 to 0.15; pores of the inner shell 0.001 to 0.009, of the outer 0.01 to 0.04; length of the outer spines 0.005 to 0.009.

Habitat.--Central area of the Tropical Pacific, Stations 263 to 274, depths 2350 to 3000 fathoms.

{121}Family VII. #STYLOSPHÆRIDA#, Haeckel (Pls. 13-17).

Stylosphærida, Haeckel, 1881, Prodromus, p. 449.

Definition.--#Sphæroidea# with two radial spines on the surface of the spherical shell, opposite in one axis; living solitary (not associated in colonies).

The family #Stylosphærida# comprises a large number of very common #Sphæroidea#, and is distinguished from all others by the possession of two radial spines which are placed in one axis of the spherical shell.[67] By the expression of this "main axis" as a solid rod they form the transition to the #Prunoidea#, in which the whole shell is more or less transformed according to this "monaxial growth." But in these latter the shell, as well as the central capsule, becomes ellipsoidal, prolonged in one axis, whilst in the former they remain spherical. However, the distinction of both nearly allied groups is sometimes difficult.

The most simple Stylosphærida are the Xiphostylida, with one single spherical lattice-shell. To this ancestral group all other subfamilies can be opposed as "Stylosphærida concentrica," as their carapace is composed of two or more concentric lattice-shells: two in the Sphærostylida, three in the Amphistylida, four in the Cromyostylida, five or more in the Caryostylida. In all these four subfamilies the concentric shells are simple (not spongy) fenestrated spheres. In a sixth subfamily, in the Spongostylida, the shell is wholly or partially composed of a spongy irregular wicker-work, with or without a medullary shell in the centre.

Both the radial spines in all Stylosphærida are opposed normally in one axis; but in many species besides the normal form occur individual abnormalities, in which the two spines are not accurately opposed in this main axis, but placed in two different axes, intersecting at a smaller or larger angle. In the majority of the Stylosphærida both opposite spines have the same size and form; but in some genera they are more or less different, often in a very striking degree. The same differences occur in the nearly allied groups of #Prunoidea#, in the Ellipsida and Druppulida.

The distal ends of both spines are commonly free; but in the small group of Saturnalida (Saturnalis with one single shell, Saturnulus with two concentric shells, Saturninus with three concentric shells) the distal ends of both spines are united, at equal distances from the centre, by a circular or elliptical ring. This remarkable peculiarity occurs in no other group of #Sphæroidea#, and consequently brings the Saturnalida into close relation with the #Discoidea#.

{122}Synopsis of the Genera of Stylosphærida.

{ {Both spines {Polar spines { equal, 45. Xiphosphæra. { free, without{ I. Subfamily { connecting {Spines Xiphostylida. { ring on the { different (Spherical shell{ distal ends. { in size simple.) { { or form, 46. Xiphostylus. { {Both polar spines united by { a circular or elliptical { ring, 47. Saturnalis.

{ {Both spines { { equal, 48. Stylosphæra. {Polar spines { II. Subfamily { free. {Spines Sphærostylida.{ { different in (Two concentric { { size or spheres.) { { form, 49. Sphærostylus. { {Both polar spines united by { a circular or elliptical { ring, 50. Saturnulus.

{ {Both spines { { equal, 51. Amphisphæra. {Polar spines { III. Subfamily { free. {Spines Amphistylida. { { different in (Three { { size or concentric { { form, 52. Amphistylus. spheres.) { {Both polar spines united by { a circular or elliptical { ring, 53. Saturninus.

IV. Subfamily } {Both spines Cromyostylida.}Polar spines { equal, 54. Stylocromyum. (Four concentric} free. { spheres.) } {Spines } { different, 55. Cromyostylus.

V. Subfamily } Caryostylida. }Polar spines {Both spines (Five or more } free. { equal, 56. Caryostylus. concentric } spheres.) }

{Shell a solid spongy sphere { without central medullary { shell, 57. Spongolonchis. VI. Subfamily { Spongostylida.{ {One central (Spherical shell{ { medullary partially or {In the centre { shell, 58. Spongostylus. wholly of a { of the spongy{ spongy { sphere one or{Two structure.) { two medullary{ concentric { shells. { medullary { { shells, 59. Spongostylidium.

Subfamily XIPHOSTYLIDA, Haeckel, 1881, Prodromus, pp. 449, 450.

Definition.--#Stylosphærida# with one simple spherical lattice-shell.

Genus 45. Xiphosphæra,[68] Haeckel, 1881, Prodromus, p. 450.

Definition.--#Stylosphærida# with one single lattice-sphere and two free spines of equal size and form.

The genus Xiphosphæra is the most simple form of all Stylosphærida, and may be regarded as the common ancestral form of this family. On the surface of a simple {123}spherical lattice-shell, enclosing the central capsule, arise two equal, free, radial spines, opposite to each other on the poles of one axis.

Subgenus 1. Xiphosphærantha, Haeckel.

Definition.--Pores of the spherical shell regular, of nearly equal size and form; surface smooth or a little rough, without spines or thorns (other than the two polar spines).

1. Xiphosphæra planeta, n. sp.

Pores regular, hexagonal, eight to nine times as broad as the thin bars. Ten to twelve pores on the half equator. Shell very thin walled; surface smooth. Polar spines three-sided pyramidal, about as long as the axis of the sphere, as broad at the base as one pore.

Dimensions.--Diameter of the sphere 0.12 to 0.13, pores 0.016 to 0.018, bars 0.002; length of the polar spines 0.1 to 0.15, basal thickness 0.02.

Habitat.--Pacific, central area, surface; Stations 271 to 274, depths 2425 to 2750 fathoms.

2. Xiphosphæra gæa, n. sp. (Pl. 14, fig. 5).

Pores regular, circular, with prominent hexagonal crests between them. On the half equator ten to twelve pores, of the same breadth as the crested bars. Shell thin walled; surface smooth. Polar spines three-sided prismatic, about twice as long as the axis of the sphere, twice as broad at the base as one pore.

Dimensions.--Diameter of the sphere 0.07 to 0.09, pores and bars 0.005; length of the polar spines 0.15 to 0.2, basal thickness 0.01.

Habitat.--Pacific, central area, Station 274, depth 2750 fathoms.

3. Xiphosphæra venus, n. sp. (Pl. 14, fig. 2).

Pores regular, circular, with prominent hexagonal frames. On the half equator fifteen to eighteen pores, of the same breadth as the bars. Shell very thick walled; surface smooth, honeycomb-like. Polar spines conical, smooth, about as long as the axis of the shell, twice as broad at the base as one pore.

Dimensions.--Diameter of the sphere 0.12 to 0.13, pores and bars 0.005; thickness of the shell wall 0.013; length of the polar spines 0.12 to 0.15, basal breadth 0.01.

Habitat.--Pacific, central area, Station 272, depth 2600 fathoms.

4. Xiphosphæra luna, n. sp.

Pores regular, circular, hexagonally lobed or rosette-shaped, three times as broad as the bars. Ten to twelve pores on the half equator. Shell thick walled; surface smooth. Polar spines three-sided pyramidal, one to two times as long as the axis of the shell, as broad at the base as one pore {124}(very similar to Xiphostylus phasianus, Pl. 13, fig. 9, but different in the equal size and similar form of the two large polar spines).

Dimensions.--Diameter of the sphere 0.12, pores 0.015, bars 0.005; length of the polar spines 0.1 to 0.2, basal breadth 0.02.

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

5. Xiphosphæra hebe, n. sp.

Pores regular, circular, three times as broad as the bars. On the half equator sixteen to twenty pores. Shell thick walled; surface smooth. Polar spines conical or nearly cylindrical, about as long as the axis of the sphere, as broad at the base as two pores.

Dimensions.--Diameter of the sphere 0.1 to 0.13, pores 0.006, bars 0.002; polar spines 0.1 to 0.15 long, 0.01 thick.

Habitat.--Pacific, central area, Stations 265 to 268, depths 2700 to 2900 fathoms.

6. Xiphosphæra maxima, n. sp.

Pores regular, circular, twice as broad as the bars, funnel-shaped. Twenty to thirty pores on the half equator. Shell very thick walled; surface smooth. Polar spines three-sided pyramidal, about as long as the radius of the sphere, as broad at the base as two pores.

Dimensions.--Diameter of the sphere 0.22 to 0.35, pores 0.008 to 0.01, bars 0.005; polar spines 0.1 to 0.15 long, 0.02 thick.

Habitat.--Equatorial Atlantic, Station 347, depth 2250 fathoms.

7. Xiphosphæra euphrosyne, n. sp.

Pores regular, circular, about as broad as the bars, double contoured. Eight to ten on the half equator. Shell thin walled; surface smooth. Polar spines conical, about as long as the radius of the sphere, as broad at the base as one pore.

Dimensions.--Diameter of the sphere 0.12 to 0.15, pores and bars 0.02; polar spines 0.06 to 0.09 long, 0.02 thick.

Habitat.--South Atlantic, Station 323, depth 1900 fathoms.

Subgenus 2. Xiphosphærella, Haeckel.

Definition.--Pores of the spherical shell regular, of nearly equal size and form; surface thorny or spiny, covered with regularly distributed papillæ or thorns (in addition to the two large polar spines).

8. Xiphosphæra pallas, n. sp. (Pl. 14, fig. 4).

Pores regular, circular, separated by hexagonal elevated frames, the sharp crest of which is elegantly denticulated; in each corner of the hexagons (between three pores) is a short radial spine, {125}about as long as one pore. On the half equator sixteen to twenty pores, of the same breadth as the bars. Shell thick walled; whole surface spiny. Polar spines cylindrical, at the apex conical, about as long as the axis of the sphere, three to four times as broad as one pore.

Dimensions.--Diameter of the sphere 0.1, pores and bars 0.005; length of the polar spines 0.07 to 0.11, thickness 0.015 to 0.02.

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

9. Xiphosphæra flora, n. sp.

Pores regular, circular, with hexagonal frames, twice as broad as the bars. Ten to twelve pores on the half equator. Shell thin walled, with spiny surface; in each corner of the hexagons is one bristle-like radial spine twice as long as one pore. Polar spines three-sided prismatic, at the apex pyramidal, nearly twice as long as the axis of the sphere, as broad at the base as two pores (similar to Ellipsoxiphus palliatus, Pl. 14, fig. 7).

Dimensions.--Diameter of the sphere 0.15, pores 0.01, bars 0.005; length of the polar spines 0.2 to 0.25, breadth 0.02.

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

10. Xiphosphæra juno, n. sp.

Pores regular, circular, as broad as the bars, funnel-shaped. Fifteen to twenty pores on the half equator. Shell thick walled, covered with bristle-like spines, about twice as long as one pore. Polar spines conical, thick, about as long as the axis of the sphere, twice as broad at the base as one pore.

Dimensions.--Diameter of the sphere 0.12, pores and bars 0.01; length of the polar spines 0.14, basal breadth 0.02.

Habitat.--Fossil in the Barbados rocks; living in the greatest depth of the Tropical Pacific, Station 225, depth 4475.

11. Xiphosphæra gigantea, n. sp.

Pores regular, circular, two to three times as broad as the bars; twenty-eight to thirty-two on the half equator. Shell thick walled, covered with short conical thorns. Polar spines three-sided pyramidal, about as long as the radius of the sphere, as broad at the base as three pores.

Dimensions.--Diameter of the sphere 0.25 to 0.3, pores 0.01, bars 0.004; polar spines 0.1 to 0.15 long, 0.03 broad.

Habitat.--Fossil in the Tertiary rocks of Barbados and Sicily (Cattanisetta).

Subgenus 3. Xiphosphærissa, Haeckel.

Definition.--Pores of the spherical shell irregular, of different size or form; surface smooth or a little rough, without spines or thorns (other than the polar spines).

{126}12. Xiphosphæra ceres, n. sp.

Pores irregular, roundish, of different sizes, two to four times as broad as the bars. Sixteen to twenty pores on the half equator. Shell thin walled, with smooth surface. Polar spines conical, about as long as the axis of the sphere, very thick at the base.

Dimensions.--Diameter of the sphere 0.15 to 0.2, pores 0.004 to 0.008, bars 0.002; polar spines 0.18 to 0.24 long, at the base 0.02 thick.

Habitat.--North Atlantic, Station 353, surface.

13. Xiphosphæra clavigera, n. sp.

Pores irregular, roundish, double contoured, of very unequal size, two to seven times as broad as the bars; ten to twelve on the half equator. Shell thick walled; surface a little rough. Polar spines club-shaped, with prominent edges, about half as long as the axis of the sphere; thinner at both ends than in the middle. (Differs from Ellipsoxiphus claviger, Pl. 14, fig. 3, in the spherical shell and shorter spines.)

Dimensions.--Diameter of the sphere 0.2, pores 0.005 to 0.02, bars 0.003; polar spines 0.06 long, 0.02 broad.

Habitat.--Pacific, central area, Station 274, depth 2750 fathoms.

Subgenus 4. Xiphosphæromma, Haeckel.

Definition.--Pores of the spherical shell irregular, of different size or form; surface thorny or spiny (besides the two large polar spines).

14. Xiphosphæra vesta n. sp. (Pl. 14, fig. 6).

Pores irregular, roundish, three to five times as broad as the bars; fourteen to sixteen on the half equator. Scattered on the surface of the thick-walled shell are from twenty to thirty strong three-sided pyramidal spines of unequal size, the largest twice as long as the largest pores. Polar spines very strong, nearly three-sided prismatic, with curved edges, nearly as long as the axis of the sphere and twice as broad as the largest pores.

Dimensions.--Diameter of the sphere 0.17, pores 0.01 to 0.02, bars 0.004; length of the polar spines 0.13, thickness 0.02 to 0.03.

Habitat.--Pacific, central area. Station 266, depth 2750 fathoms,

15. Xiphosphæra astræa, n. sp.

Pores irregular, roundish, one to two times as broad as the bars; ten to twelve on the half equator. Surface of the thick-walled shell covered with numerous short conical thorns. Polar spines cylindro-conical, one and a half to two times as long as the axis of the sphere.

{127}Dimensions.--Diameter of the sphere 0.18, pores 0.01 to 0.015, bars 0.008; length of the polar spines 0.25 to 0.3, thickness 0.02.

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

Genus 46. Xiphostylus,[69] Haeckel, 1881, Prodromus, p. 450.

Definition.--#Stylosphærida# with one single lattice-sphere and two free spines of different size or form.

The genus Xiphostylus differs from the foregoing Xiphosphæra in the unequal size or form of both polar spines, which become more or less differentiated.

Subgenus 1. Xiphostylantha, Haeckel.

Definition.--Pores of the spherical shell regular, of nearly equal size and form; surface smooth or a little rough, without spines or thorns.

1. Xiphostylus alcedo, n. sp. (Pl. 13, fig. 4).

Pores regular, circular, with elevated hexagonal frames, twice as broad as the bars. Eight to ten pores on the half equator. Surface smooth. Polar spines three-sided pyramidal, as broad at the base as one hexagon; the major spine four to five times as long as the minor, which is about equal to the radius of the sphere.

Dimensions.--Diameter of the sphere 0.12, pores 0.012, bars 0.006; length of the major polar spine 0.16 to 0.2, of the minor 0.04 to 0.06, basal breadth 0.02.

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

2. Xiphostylus phasianus, n. sp. (Pl. 13, fig. 9).

Pores regular, circular, twice as broad as the bars. Eight to ten pores on the half equator. Outer opening of each pore elegantly lobed, with eight indentations. Surface a little rough. Polar spines very unequal; major spine sword-like, sharply edged, about as long as the diameter of the sphere; minor spine scarcely half so long, pommel-shaped, with nine (?) wing-like edges.

Dimensions.--Diameter of the sphere 0.13, inner circular opening of the pores 0.01, outer eight-lobed opening 0.015, bars 0.005; length of the major polar spine 0.14, of the minor 0.06, breadth 0.03.

Habitat.--Australian Sea, Station 162, surface.

3. Xiphostylus motacilla, n. sp.

Pores regular, circular, three times as broad as the bars; sixteen to twenty on the half equator. Surface smooth. Polar spines compressed, two-edged, at the base three to four times as broad as {128}one pore; the major spine somewhat longer than the diameter of the shell, the minor scarcely one-third or one-half as long.

Dimensions.--Diameter of the sphere 0.14, pores 0.006, bars 0.002; length of the major spine 0.16 to 0.18, of the minor 0.05 to 0.07, basal breadth 0.02.

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

4. Xiphostylus gallus, n. sp.

Pores regular, circular, five times as broad as the bars. Twelve to sixteen pores on the half equator. Surface smooth. Polar spines very unequal; the major conical spine one and a half to three times as long as the diameter of the sphere; the minor pommel-shaped, scarcely one-third as long (length of both spines very variable).

Dimensions.--Diameter of the sphere 0.13, pores 0.01, bars 0.002; length of the major spine 0.2 to 0.4, of the minor 0.05 to 0.08.

Habitat.--Pacific, central area, Station 268, depth 2900 fathoms.

5. Xiphostylus alauda, n. sp. (Pl. 14, fig. 15).

Lithomespilus alauda, Haeckel, 1881, Prodrom. et Atlas, loc. cit.

Pores subregular, circular, three to four times as broad as the bars; fifteen to eighteen on the half equator. Surface a little rough. Polar spines irregularly conical or pyramidal, scarcely as long as the radius of the sphere; one spine simple, the other composed of a bunch of four or five spines united at the base.

Dimensions.--Diameter of the sphere 0.11, pores 0.01, bars 0.003; length of the polar spines 0.03 to 0.05, basal breadth 0.02.

Habitat.--Pacific, central area, Station 272, depth 2600 fathoms.

6. Xiphostylus anhinga, Haeckel.

Rhabdolithis pipa, Bury, 1862, Polycystins of Barbados, pl. iii. fig. 4.

Pores subregular, circular, about the same breadth as the bars; eight to ten on the half equator. Surface smooth or a little rough. Polar spines cylindrical, very irregularly curved like S or contorted, the major three to six times as long as the diameter of the sphere, the minor scarcely one-fourth as long as the former, at the end truncated.

Dimensions.--Diameter of the sphere 0.07, pores and bars 0.005; length of the major polar spine 0.2 to 0.4, of the minor 0.06 to 0.09, basal breadth 0.01.

Habitat.--Fossil in the Barbados rocks.

Subgenus 2. Xiphostyletta, Haeckel.

Definition.--Pores of the spherical shell regular, of nearly equal size and form; surface thorny or spiny (other than the two large polar spines).

{129}7. Xiphostylus cuculus, n. sp.

Pores regular, circular, hexagonally framed, three times as broad as the bars; ten to twelve on the half equator. Surface thorny, between every three pores a short conical thorn. Polar spines three-sided prismatic, the major somewhat longer than the diameter of the sphere, the minor scarcely one-third as long, pommel-shaped.

Dimensions.--Diameter of the sphere 0.17, pores 0.012, bars 0.004; length of the major polar spine 0.2, of the minor 0.05, basal breadth 0.015.

Habitat.--South Atlantic, surface; Station 335, depth 1425 fathoms.

8. Xiphostylus trochilus, n. sp. (Pl. 13, fig. 10).

Pores regular, circular, four times as broad as the bars; eight to nine on the half equator. Polar spines cylindrical, the major somewhat longer than the axis of the sphere, the minor shorter, surrounded by a group of from four to eight shorter conical spines. Surface of the opposite hemisphere smooth, without by-spines.

Dimensions.--Diameter of the sphere 0.07 to 0.08, pores 0.01, bars 0.0025.

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

9. Xiphostylus picus, n. sp. (Pl. 14, fig. 13).

Lithomespilus picus, Haeckel, 1881, Prodrom. et Atlas.

Pores regular, circular, twice as broad as the bars; sixteen to eighteen on the half equator. Polar spines cylindrical, conical at the apex, the major once and a half to twice as long as the diameter of the shell, the minor scarcely half so long; around the latter a group of twelve to twenty shorter conical spines, irregularly scattered. Surface of the other hemisphere smooth.

Dimensions.--Diameter of the sphere 0.13, pores 0.006, bars 0.003; length of the major polar spine 0.2 to 0.24, of the minor 0.08 to 0.09, basal breadth 0.02.

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

Subgenus 3. Xiphostylissa, Haeckel.

Definition.--Pores of the spherical shell irregular, of unequal size or form; surface smooth or a little rough, without thorns.

10. Xiphostylus trogon, n. sp. (Pl. 14, fig. 12).

Lithomespilus trogon, Haeckel, 1881, Prodrom. et Atlas.

Pores irregular, roundish or subcircular, two to three times as broad as the bars; ten to twelve on the half equator. Surface smooth. Major polar spine three-sided prismatic, once and a half to twice as long as the axis of the sphere; minor spine quite rudimentary, scarcely longer than broad, but surrounded by a group of from three to six similar short spines.

{130}Dimensions.--Diameter of the sphere 0.1, pores 0.005 to 0.015, bars 0.005 to 0.008; length of the major spine 0.15 to 0.18, of the minor 0.01 to 0.02, basal breadth 0.02.

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

11. Xiphostylus falco, n. sp. (Pl. 13, fig. 14).

Pores irregular, roundish, two to five times as broad as the bars; sixteen to eighteen on the half equator. Surface smooth. Polar spines cylindrical, very stout, nearly half as thick as the radius of the shell; major spine two to four times as long as the diameter of the shell; minor spine obliquely inserted, scarcely longer than the diameter, divided at the end into two short, hook-shaped, curved branches.

Dimensions.--Diameter of the sphere 0.08, pores 0.002 to 0.005, bars 0.001; breadth of the spines 0.02, length of the major spine 0.15 to 0.2, of the minor 0.09.

Habitat.--South Pacific, Station 302, depth 1450 fathoms.

12. Xiphostylus alca, n. sp. (Pl. 13, fig. 13).

Pores irregular, roundish, two to six times as broad as the bars; six to eight on the half equator. Each pore with three to six lobes, composed of three to six confluent smaller pores. Surface smooth. Major spine conical, curved, somewhat longer than the axis of the sphere; minor spine somewhat shorter, pommel-like, edged.

Dimensions.--Diameter of the sphere 0.07, pores 0.01 to 0.02, bars 0.003; length of the major spine 0.08, of the minor 0.06, basal thickness 0.02.

Habitat.--Indian Ocean, Sunda Strait, Rabbe, surface.

13. Xiphostylus edolius, n. sp. (Pl. 13, fig. 5).

Pores irregular, roundish, composed of two to six smaller confluent pores. On the half equator six to eight large pores, and twenty to thirty small pores; bars between the smaller very thin. Surface a little rough. Major polar spine conical, S-shaped, about twice as long as the axis of the shell; minor spine pommel-shaped, edged, scarcely as long as its radius.

Dimensions.--Diameter of the sphere 0.12, large pores 0.01 to 0.03, small pores 0.004 to 0.008, bars 0.001 to 0.004; length of the major spine 0.2, of the minor 0.05, basal breadth 0.02.

Habitat.--Central Pacific, Station 273, surface.

Subgenus 4. Xiphostylomma, Haeckel.

Definition.--Pores of the spherical shell irregular, of different size or form; surface thorny or spiny.

{131}14. Xiphostylus emberiza, n. sp. (Pl. 13, fig. 11).

Pores irregular, roundish, one to four times as broad as the bars; six to eight on the half equator. Polar spines very unequal; major cylindrical, twice as long as the axis of the sphere; minor scarcely half as long, obliquely inserted, like a bird's head, surrounded by a group of ten to twenty smaller conical spines. Opposite hemisphere smooth.

Dimensions.--Diameter of the sphere 0.005, pores 0.002 to 0.008, bars 0.002; length of the major spine 0.09, of the minor 0.05, basal breadth 0.01.

Habitat.--South Atlantic, Station 332, surface.

15. Xiphostylus ardea, n. sp.

Pores irregular, roundish, one to three times as broad as the bars; twelve to sixteen on the half equator. Whole surface spiny. Major polar spine three-sided pyramidal, somewhat longer than the diameter of the sphere; minor scarcely so long as its half radius, pommel-like, edged.

Dimensions.--Diameter of the sphere 0.12, pores 0.003 to 0.01, bars 0.003; length of the major polar spine 0.15, of the minor 0.03, basal breadth 0.02.

Habitat.--North Atlantic, Station 64, surface.

Genus 47. Saturnalis,[70] Haeckel, 1881, Prodromus, p. 450.

Definition.--#Stylosphærida# with one single lattice-sphere and two equal opposite spines, connected at the distal end by a circular or elliptical ring.

The genus Saturnalis (with simple lattice-sphere) and the two similar genera Saturnulus (with two concentric spheres) and Saturninus (with three spheres) form together the small peculiar group of Saturnalida, distinguished by a remarkable circular or elliptical ring, connecting the distal ends of the two equal opposite polar spines. This ring indicates a certain equatorial plane, and therefore brings these #Sphæroidea# into relation with the #Discoidea#.

Subgenus 1. Saturnalina, Haeckel.

Definition.--Ring smooth, without spines or thorns.

1. Saturnalis circularis, n. sp.

Pores of the spherical shell regular, circular, hexagonally framed, twice as broad as the bars. Ten to twelve pores on the half equator. Ring circular, smooth, its diameter three times as great as that of the sphere.

{132}Dimensions.--Diameter of the sphere 0.07, pores 0.005, bars 0.0025; diameter of the circular ring 0.2, thickness of the axial beams and the ring 0.01.

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

2. Saturnalis annularis, n. sp. (Pl. 13, fig. 16).

Pores of the spherical shell regular, circular, with elevated hexagonal frames, of the same breadth as the bars. Sixteen to twenty pores on the half equator. Ring elliptical, smooth, somewhat constricted at the poles of the axis, its diameter three times as great as that of the sphere.

Dimensions.--Diameter of the sphere 0.09, pores and bars 0.005, major axis of the elliptical ring 0.27 to 0.3, minor axis 0.19 to 0.2; thickness of the ring and of the axial beams 0.01.

Habitat.--Pacific, central area, Stations 270 to 274, surface.

3. Saturnalis cyclus, n. sp.

Lithocircus mesocena, Bury, 1862, Polycystins of Barbados, pl. iii. fig. 1.

Pores of the spherical shell regular, circular, without hexagonal frames, twice as broad as the bars. Eight to ten pores on the half equator. Ring circular, smooth, its diameter four times as great as that of the sphere.

Dimensions.--Diameter of the sphere 0.07, pores 0.006, bars 0.003; diameter of the circular ring 0.28, thickness of the ring and both axial beams 0.01.

Habitat.--Fossil in the Barbados rocks.

4. Saturnalis circoides, n. sp. (Pl. 13, fig. 12).

Pores of the spherical shell irregular, roundish, often somewhat lobed, one to three times as broad as the bars; fifteen to twenty on the half equator. Ring circular, smooth, with four prominent edges, its diameter twice as great as that of the sphere. (The figured specimen is a young or not fully developed one; afterwards I found in the same locality other specimens with quite perfect rings, similar to the edged ring of Saturnulus annulus, Pl. 16, fig. 17.)

Dimensions.--Diameter of the sphere 0.09 to 0.1, pores 0.003 to 0.01, bars 0.004; diameter of the circular ring 0.2 to 0.24, thickness of the ring and the polar beams 0.01.

Habitat.--Indian Ocean; fossil in the Nicobar rocks; living at great depths near Zanzibar, 2200 fathoms, Pullen.

Subgenus 2. Saturnalium, Haeckel.

Definition.--Ring armed on the periphery with numerous spines or thorns.

5. Saturnalis trochoides, n. sp.

Haliomma species, Bury, 1862, Polycystins of Barbados, pl. xx. fig. 2.

Pores of the spherical shell subregular, circular, twice as broad as the bars. Twelve to sixteen pores on the half equator. Ring circular, armed with ten to twelve strong conical, irregular spines, its diameter twice as great as that of the sphere.

{133}Dimensions.--Diameter of the sphere 0.08, pores 0.006, bars 0.003; diameter of the circular ring 0.16; length of the radial spines 0.02 to 0.04; thickness of the ring and the axial beams 0.01.

Habitat.--Fossil in the Barbados rocks.

6. Saturnalis rotula, n. sp. (Pl. 13, fig. 15).

Pores of the spherical shell regular, circular, twice as broad as the bars; sixteen to twenty on the half equator. Ring circular, armed with fifteen to twenty strong, conical, irregular spines, partly simple, partly divided into two or three irregular branches; diameter of the ring two and a half times as great as that of the sphere.

Dimensions.--Diameter of the sphere 0.08, pores 0.004, bars 0.002; diameter of the circular ring 0.2, length of its spines 0.02 to 0.03; thickness of the ring and the radial beams 0.01.

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

Subfamily SPHÆROSTYLIDA, Haeckel, 1881, Prodromus, pp. 449, 451.

Definition.--#Stylosphærida# with two concentric, spherical lattice-shells.

Genus 48. Stylosphæra,[71] Ehrenberg, 1847, Monatsber. d. Berlin Akad., p. 54.

Definition.--#Stylosphærida# with two concentric lattice-spheres and two free spines of equal size and similar form.

The genus Stylosphæra, the most simple form of the Sphærostylida, can be derived either from Xiphosphæra by duplication of the spherical shell, or from Carposphæra by development of two opposite polar spines. The inner or medullary shell is enclosed in the central capsule, whilst the outer or cortical shell lies outside it; the two are connected by two or more radial beams, piercing the wall of the capsule.

Subgenus 1. Stylosphærantha, Haeckel.

Definition.--Pores of the cortical shell regular, of nearly equal size and similar form; surface smooth or a little rough, without spines or thorns.

1. Stylosphæra musa, n. sp.

Radial proportion of the two concentric spheres = 3 : 1. Cortical shell thin walled, smooth, with regular, hexagonal pores, three times as broad as the thin bars; twelve on the half equator. Polar spines three-sided pyramidal, as long as the axis of the cortical shell, one-tenth as broad at the base.

Dimensions.--Diameter of the outer shell 0.2, pores 0.01, bars 0.003; diameter of the inner shell 0.06; length of the polar spines 0.2, basal breadth 0.02.

Habitat.--Tropical Atlantic, Station 347, depth 2250 fathoms.

{134}2. Stylosphæra urania, n. sp.

Radial proportion of the two shells = 4 : 1. Cortical shell thin walled, smooth; pores regular, circular, hexagonally framed, twice as broad as the bars; ten on the half equator. Polar spines conical, as long as the radius of the outer shell.

Dimensions.--Diameter of the cortical shell 0.24, pores 0.012, bars 0.006; medullary shell 0.06; length of the polar spines 0.12, basal breadth 0.024.

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

3. Stylosphæra calliope, n. sp. (Pl. 16, fig. 6).

Radial proportion of the two shells = 3 : 1. Cortical shell thick walled, smooth; pores regular, circular, three times as broad as the bars. Each pore on its outer opening with eight regular lobules, flower-like. Nine to ten pores on the half equator. Polar spines three-sided pyramidal, with three strong prominent edges, about as long as the axis, as broad as one pore. (Sometimes, as in the figured specimen, one spine is smaller than the other; this variety, otherwise identical, may be called Sphærostylus calliope.)

Dimensions.--Diameter of the outer shell 0.12, pores 0.015, bars 0.005; inner shell 0.04; length of the polar spine 0.08 to 0.12, breadth 0.02.

Habitat.--Pacific, central area, Station 268, depth 2900 fathoms.

4. Stylosphæra clio, n. sp. (Pl. 16, fig. 7).

Radial proportion of the two shells = 2 : 1. Cortical shell thick walled, smooth; pores regular, circular, three times as broad as the bars; fourteen to sixteen on the half equator. Polar spines three-sided pyramidal, very robust, with thick prismatic edges, about as long as the axis of the cortical shell, one-third as broad at the base. (Sometimes, as in the figured specimen, one spine is greater than the other; this form may be called Sphærostylus clio.)

Dimensions.--Diameter of the outer shell 0.12, pores 0.01, bars 0.003; inner shell 0.06; length of the polar spines 0.08 to 0.12, basal breadth 0.03 to 0.04.

Habitat.--Pacific, central area; Station 272, depth 2600 fathoms.

5. Stylosphæra polyhymnia, n. sp.

Radial proportion of the two spheres = 3 : 1. Cortical shell very thin walled, smooth, with regular, circular pores, three times as broad as the bars; sixteen to twenty on the half equator. Polar spines cylindrical, pointed, once and a half to twice as long as the axis of the outer sphere, scarcely broader than one pore. The two spheres are connected only by the two opposite beams.

Dimensions.--Diameter of the outer shell 0.12 to 0.16, pores 0.006 to 0.009, bars 0.002 to 0.003; inner shell 0.04 to 0.05; length of the polar spines 0.18 to 0.22, breadth 0.01.

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

{135}6. Stylosphæra dixyphos, Haeckel.

Haliomma dixyphos, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 83; Mikrogeol., Taf. xxii. fig. 31.

Haliomma dixyphos, Haeckel, 1862, Monogr. d. Radiol. p. 433.

Radial proportion of the two spheres = 2 : 1. Cortical shell thin walled, smooth, with regular, circular pores, twice as broad as the bars; ten to twelve on the half equator. Polar spines about as long as the axis of the outer shell, three-sided pyramidal, at the base twice as broad as one pore. (The two spheres connected by four beams, two opposite in the main axis, two opposite in the equatorial axis.)

Dimensions.--Diameter of the outer shell 0.1, pores 0.01, bars 0.05; inner shell 0.05; length of the polar spines 0.08 to 0.1, basal breadth 0.02.

Habitat.--South Atlantic, Station 332, surface; fossil in Tertiary rocks of Sicily.

Subgenus 2. Stylosphærella, Haeckel.

Definition.--Pores of the cortical shell regular, of nearly equal size and similar form; surface thorny or spiny.

7. Stylosphæra setosa, Ehrenberg, 1872.

Stylosphæra setosa, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 320; Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. viii. fig. 15.

Radial proportion of the two shells = 2 : 1. Cortical shell thin walled, spiny; pores regular, hexagonal, four times as broad as the bars. Six to eight pores on the half equator. Polar spines conical, thin, scarcely as long as the radius of the cortical shell.

Dimensions.--Diameter of the cortical shell 0.1, pores 0.002, bars 0.005; medullary shell 0.05; length of the polar spines 0.04, basal breadth 0.01.

Habitat.--Philippine Sea, depth 3300 fathoms, Ehrenberg; Station 206, depth 2100 fathoms.

8. Stylosphæra euterpe, n. sp.

Radial proportion of the two shells = 3 : 1. Cortical shell thin walled, spiny; pores regular, circular, with hexagonal frames, twice as broad as the bars; eight to ten on the half equator. Polar spines conical, as thick as one pore at the base, about as long as the axis of the cortical shell.

Dimensions.--Diameter of the cortical shell 0.12, pores 0.012, bars 0.006; medullary shell 0.04; length of the polar spines 0.1, basal breadth 0.012.

Habitat.--South Pacific, Station 302, depth 1450 fathoms.

9. Stylosphæra melpomene, n. sp. (Pl. 16, fig. 1).

Radial proportion of the two shells = 3 : 1. Cortical shell thin walled, spiny, with regular, circular pores, four times as broad as the bars; eight to ten on the half equator. Polar spines three-sided prismatic, pointed, as broad as one pore, only one-third as long as the axis of the sphere (the two shells connected by four thin beams, two opposite in the main axis, two in the equatorial axis).

{136}Dimensions.--Diameter of the outer shell 0.12, pores 0.012, bars 0.003; inner shell 0.04; length of the polar spines 0.04, thickness 0.013.

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

10. Stylosphæra hispida, Ehrenberg, 1854.

Stylosphæra hispida, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 246; Mikrogeol, Taf. xxxvi. fig. 26.

Haliomma hispidum, Haeckel, 1862, Monogr. d. Radiol., p. 433.

Radial proportion of the two spheres = 3 : 1. Cortical shell thick walled, spiny, with regular, circular pores of the same breadth as the bars; ten to fifteen on the half equator. Polar spines three-sided prismatic, pointed, about as long as the axis of the outer sphere, nearly as broad at the base as the inner sphere. (Compare Sphærostylus hispidus; also Ehrenberg, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, 1874, p. 259.)

Dimensions.--Diameter of the outer shell 0.1 to 0.12, pores and bars 0.004; inner shell 0.04; length of the polar spines 0.1 to 0.15, basal breadth 0.03.

Habitat.--Fossil in the Tertiary rocks of Sicily, Barbados, Nicobars, &c.

11. Stylosphæra liostylus, Ehrenberg, 1875.

Stylosphæra liostylus, Ehrenberg, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xxv. fig. 3.

Radial proportion of the two spheres = 3 : 1. Cortical shell thick walled, thorny, with regular, circular pores, three times as broad as the bars; eight to ten on the half equator. Polar spines conical, once and a half to twice as long as the axis of the outer sphere, half as broad at the base as its radius. (This species, common in the Barbados rocks, is different from Sphærostylus liostylus, loc. cit., fig. 2, which Ehrenberg believed identical.)

Dimensions.--Diameter of the outer shell 0.1, pores 0.01, bars 0.0035; inner shell 0.03; length of the polar spines 0.14 to 0.18, basal breadth 0.02.

Habitat.--Fossil in the Barbados rocks; living in the depths of the North Atlantic, Gulf Stream, Florida.

Subgenus 3. Stylosphærissa, Haeckel.

Definition.--Pores of the cortical shell irregular, of different size or form; surface smooth or a little rough, without thorns or spines.

12. Stylosphæra nana, n. sp. (Pl. 16, figs. 12, 13).

Radial proportion of the two spheres = 2 : 1. Cortical shell thick walled, somewhat irregular, smooth, with irregular, roundish pores, one to three times as broad as the bars; eight to ten on the half equator. Polar spines three-sided pyramidal, scarcely as long as the axis of the outer sphere, and nearly as broad at the base as its radius. (A very variable and irregular form.)

Dimensions.--Diameter of the outer shell 0.07 to 0.09, pores 0.003 to 0.009, bars 0.003; inner shell 0.03 to 0.04; length of the polar spines 0.04 to 0.07, basal breadth 0.03.

Habitat.--North Pacific, Stations 241 to 253, surface.

{137}13. Stylosphæra jugata, n. sp.

Radial proportion of the two shells = 2 : 1. Cortical shell thick walled, smooth, with irregular, roundish, double-contoured pores, confluent in groups of two to six. On the half equator six to nine groups and fifteen to twenty pores; bars between them of very variable breadth. Polar spines very strong, three-sided pyramidal, twice as long as the axis of the outer sphere, half as broad at the base as its radius. (Nearly allied to Lithatractus jugatus, Pl. 16, fig. 2, but differs in the truly spherical form of both shells and the double length of the polar spines.)

Dimensions.--Diameter of the outer shell 0.15, pores 0.005 to 0.02; inner shell 0.07; length of the polar spines 0.25 to 0.3, basal breadth 0.03.

Habitat.--Western Tropical Pacific, Station 224, depth 1850 fathoms.

14. Stylosphæra terpsichore, n. sp.

Radial proportion of the two shells = 3 : 1 or 4 : 1. Cortical shell thick walled, smooth, with irregular, roundish pores, one to three times as broad as the bars; fifteen to twenty-five on the half equator. Polar spines conical, about as long as the axis of the outer sphere, as broad at the base as the inner shell.

Dimensions.--Diameter of the outer shell 0.15 to 0.2, pores 0.005 to 0.02, bars 0.004 to 0.008; inner shell 0.05; length of the polar spines 0.15 to 0.25, basal breadth 0.05.

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

Subgenus 4. Stylosphæromma, Haeckel.

Definition.--Pores of the cortical shell irregular, of different size or form; surface spiny or thorny.

15. Stylosphæra thalia, n. sp.

Radial proportion of the two shells = 2 : 1. Cortical shell thin walled, thorny, with irregular, roundish pores, two to four times as broad as the bars; eight to twelve on the half equator. Polar spines conical, one to one and a half times as long as the axis of the outer sphere, one-fourth to one-sixth as thick at the base. (Resembles Sphærostylus ophidium, Pl. 16, fig. 14, but differs in the straight regular conical polar spines, both of equal length and similar form.)

Dimensions.--Diameter of the outer shell 0.12, pores 0.01 to 0.02, bars 0.005; inner shell 0.06; polar spines 0.1 to 0.16 long, 0.03 broad.

Habitat.--South Pacific, Station 302, depth 1450 fathoms.

16. Stylosphæra erato, n. sp.

Radial proportion of the two shells = 3 : 1. Cortical shell thick walled, thorny, with irregular, roundish pores, two to five times as broad as the bars; fourteen to eighteen on the half equator. {138}Polar spines three-sided pyramidal, about as long as the axis of the outer sphere, one-fourth as broad as its radius. (Similar to Xiphosphæra vesta, Pl. 14, fig. 6.)

Dimensions.--Diameter of the outer shell 0.15, pores 0.008 to 0.015, bars 0.003; inner shell 0.05; polar spines 0.12 long, 0.02 broad.

Habitat.--South Atlantic, Station 335, depth 1425 fathoms.

Genus 49. Sphærostylus,[72] Haeckel, 1881, Prodromus, p. 451.

Definition.--#Stylosphærida# with two concentric lattice-spheres and two free spines, of different size or form.

The genus Sphærostylus differs from Stylosphæra in the different size or form of the two polar spines, and therefore has the same relation to it that Xiphostylus bears to Xiphosphæra.

Subgenus 1. Sphærostylantha, Haeckel.

Definition.--Pores of the cortical shell regular, of nearly equal size and similar form; surface smooth or a little rough, without thorns.

1. Sphærostylus liostylus, Haeckel.

Stylosphæra liostylus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xxv. fig. 2.

Cortical shell thin walled, with rough surface, three times as broad as the medullary shell. Pores of the cortical shell regular, circular, twice as broad as the bars; ten to twelve on the half equator. Polar spines cylindrical, as broad as one pore, with conical apex; the minor spine about as long as the axis of the outer shell, the major three to four times as long.

Dimensions.--Diameter of the outer sphere 0.12, pores 0.12, bars 0.006; diameter of the inner sphere 0.04; length of the major polar spine 0.3 to 0.4, of the minor 0.1 to 0.15, breadth 0.012.

Habitat.--Fossil in the Barbados rocks.

2. Sphærostylus flexuosus, Haeckel.

Stylosphæra flexuosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xxv. fig. 5.

Cortical shell thick walled, with rough surface, three times as broad as the medullary shell. Pores of the cortical shell regular circular, of the same breadth as the bars; eight to ten on the half equator. Polar spines cylindrical, S-like curved, irregular; the minor scarcely as long as the axis of the outer sphere, the major two to three times as long. (In the figure of Ehrenberg the spines are broken off; I have found them myself constantly irregular and of unequal length, sometimes with conical apex.)

{139}Dimensions.--Diameter of the outer sphere 0.08, pores and bars 0.006; inner sphere 0.03; length of the major polar spine 0.15 to 0.25, of the minor 0.07 to 0.09, breadth 0.02.

Habitat.--Fossil in the Barbados rocks.

3. Sphærostylus clio, n. sp.

Cortical shell thick walled, with smooth surface, twice as broad as the medullary shell; its network has regular, circular pores, three times as broad as the bars; sixteen to twenty on the half equator. Polar spines very strong, three-sided pyramidal; the major nearly twice as long as the axis of the outer sphere, the minor scarcely as long as its radius. (Nearly related to Stylosphæra clio, Pl. 16, fig. 7, but differs in the slender form and unequal length of the polar spines.)

Dimensions.--Diameter of the outer sphere 0.14, pores 0.01, bars 0.03; inner sphere 0.07; length of the major spine 0.25, of the minor 0.06, basal breadth 0.02.

Habitat.--Pacific, central area, Station 274, depth 2750 fathoms.

4. Sphærostylus hippocampus, n. sp. (Pl. 16, figs. 10, 11).

Cortical shell thick walled, with smooth surface and regular network; the pores circular, hexagonally-lobed, three times as broad as the bars; ten to twelve on the half equator. Medullary shell half as large, with very small circular pores, eight to ten on the half equator. Major polar spine scarcely as long as the axis of the outer shell, curved like a horn; minor spine scarcely half as long, pommel-like, edged. (Sometimes, by prolongation of the main axis, the spherical shells become ellipsoidal and thus the species is transformed into Druppatractus hippocampus.)

Dimensions.--Diameter of the outer sphere 0.08, pores 0.009, bars 0.003; inner sphere 0.04; length of the major spine 0.07, of the minor 0.03, breadth 0.02.

Habitat.--Pacific, central area, Station 270, depth 2925 fathoms.

Subgenus 2. Sphærostyletta, Haeckel.

Definition.--Pores of the cortical shell regular, of nearly equal size and form; surface spiny or thorny.

5. Sphærostylus diadema, n. sp.

Cortical shell thick walled, spiny, twice as broad as the medullary shell, with regular, circular pores, twice as broad as the bars; eight to ten on the half equator. Major polar spine about as long as the axis of the outer sphere, three-sided pyramidal; minor spine scarcely half as long, pommel-shaped, edged. (Similar in general form to Xiphatractus glyptodon, Pl. 17, figs. 9, 10; but differs in the simple medullary shell, the spherical form of both shells, and the simple circular regular pores.)

{140}Dimensions.--Diameter of the outer sphere 0.12, pores 0.014, bars 0.007; inner sphere 0.06; length of the major spine 0.13, of the minor 0.05, greatest breadth 0.04.

Habitat.--Southern Pacific, surface, Station 289.

Subgenus 3. Sphærostylissa, Haeckel.

Definition.--Pores of the cortical shell irregular, of different size or form; surface smooth or a little rough.

6. Sphærostylus cottus, n. sp.

Cortical shell thick walled, smooth, about twice as broad as the medullary shell, with irregular, roundish pores, scarcely larger than the bars; fifteen to twenty on the half equator. Polar spines conical, the major once and a half to twice as long as the axis of the outer sphere, the minor scarcely as long as its radius.

Dimensions.--Diameter of the outer sphere 0.14, pores and bars 0.008 to 0.012; inner sphere 0.065; length of the major spine 0.2 to 0.3, of the minor 0.05 to 0.07, basal breadth 0.03.

Habitat.--Northern Atlantic, Færöe Channel, surface, John Murray.

7. Sphærostylus trigla, n. sp.

Cortical shell thin walled, smooth, three times as broad as the medullary shell, with irregular, roundish pores, two to three times as broad as the bars; ten to twelve on the half equator. Polar spines very unequal; the major three-sided pyramidal, one and a half times as long as the axis of the outer sphere; the minor scarcely as long as its radius, edged, pommel-like.

Dimensions.--Diameter of the outer sphere 0.12, pores 0.01 to 0.015, bars 0.005; inner sphere 0.04; length of the major spine 0.2, of the minor 0.05, breadth 0.03.

Habitat.--Northern Pacific, Station 241, depth 2300 fathoms.

Subgenus 4. Sphærostylomma, Haeckel.

Definition.--Pores of the cortical shell irregular, of different size or form; surface spiny or thorny.

8. Sphærostylus ophidium, n. sp. (Pl. 16, figs. 14, 15).

Stylosphæra ophidium, Haeckel, 1878, Atlas, loc. cit.

Cortical shell thin walled, thorny, twice as broad as the medullary shell, with irregular, roundish pores; eight to ten on the half equator. Polar spines conical, more or less curved or S-shaped; the minor scarcely as long as the axis of the outer sphere, the major two to three times as long.

{141}Dimensions.--Diameter of the outer sphere 0.11, pores 0.01 to 0.017, bars 0.003 to 0.007; diameter of the inner sphere 0.06, pores 0.005 to 0.008, bars 0.002 to 0.004; length of the major polar spine 0.25, of the minor 0.1, basal breadth 0.03.

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

Genus 50. Saturnulus,[73] Haeckel, 1881, Prodromus, p. 451.

Definition.--#Stylosphærida# with two concentric lattice-spheres and two equal opposite spines, the distal ends of which are connected by a circular or elliptical ring.

The genus Saturnulus differs from the similar Saturnalis by the duplication of the spherical lattice-shell; the inner lies within, the outer without the central capsule.

1. Saturnulus circulus, n. sp.

Cortical shell smooth, twice as broad as the medullary shell, with regular, circular, hexagonally framed pores, of the same breadth as the bars; fourteen to sixteen on the half equator. Ring circular, smooth, without edges, its diameter three times as great as that of the sphere.

Dimensions.--Diameter of the outer sphere 0.08, pores and bars 0.004; of the inner sphere 0.04, of the ring 0.24.

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

2. Saturnulus annulus, n. sp.

Cortical shell smooth, three times as broad as the medullary shell, with regular, circular, hexagonally framed pores, of the same breadth as the bars; eighteen to twenty on the half equator. Ring elliptical, smooth, without edges, somewhat constricted at the poles of the minor axis, its major diameter four times as great as that of the sphere. Differs from Saturnalis annularis, Pl. 13, fig. 16, mainly in the possession of a medullary shell.

Dimensions.--Diameter of the outer sphere 0.1, pores and bars 0.005; inner sphere 0.033; major axis of the ring 0.4, minor 0.3.

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

3. Saturnulus ellipticus, n. sp. (Pl. 16, fig. 16).

Cortical shell smooth, three times as broad as the medullary shell, with regular, circular pores, three times as broad as the bars; sixteen to eighteen on the half equator. Ring elliptical, smooth, without edges, its major diameter three times as great as that of the sphere.

Dimensions.--Diameter of the outer sphere 0.09, pores 0.006, bars 0.002; inner sphere 0.03; major axis of the elliptical ring 0.28, minor 0.24; thickness of the ring and the axial beams 0.008.

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

{142}4. Saturnulus planetes, n. sp. (Pl. 16, fig. 17).

Cortical shell smooth, twice as broad as the medullary shell, with regular, circular pores, of the same breadth as the bars; sixteen to eighteen on the half equator. Ring elliptical, smooth, with strong prominent edges, constricted at the poles of the minor axis, its major diameter three times as great as that of the outer sphere.

Dimensions.--Diameter of the outer sphere 0.08, pores and bars 0.005; inner sphere 0.035; major axis of the ring 0.25, minor axis 0.2; thickness of the ring and the axial beams 0.012.

Habitat.--Indian Ocean, Sunda Strait, Rabbe; Station 200, surface.

Subfamily AMPHISTYLIDA, Haeckel, 1881, Prodromus, pp. 449, 452.

Definition.--#Stylosphærida# with three concentric spherical lattice-shells.

Genus 51. Amphisphæra, Haeckel,[74] 1881, Prodromus, p. 452.

Definition.--#Stylosphærida# with three concentric lattice-spheres and two free spines of equal size and similar form.

The genus Amphisphæra differs from its probable ancestral form, Stylosphæra, in the triple spherical lattice-shell. Commonly two of these lie within the central capsule (medullary shell), whilst the third lies outside it (cortical shell). But sometimes this order is inverted, the cortical shell being double, the medullary shell simple; and perhaps these forms may better represent a peculiar genus, Amphisphæridium.

Subgenus 1. Amphisphærantha, Haeckel.

Definition.--Pores of the cortical shell regular, of nearly equal size and similar form; surface smooth or a little rough, without spines or thorns.

1. Amphisphæra neptunus, n. sp.

Radial proportion of the three concentric spheres = 4 : 2 : 1. Cortical shell thick walled, smooth, with regular, circular, hexagonally framed pores, of the same breadth as the bars; twelve to fifteen on the half equator. Polar spines three-sided pyramidal, with strong prominent edges, about as long as the radius of the outer shell, half as broad at the base. (Similar to Stylatractus neptunus, Pl. 17, fig. 6, but differs in the purely spherical form of the three concentric shells and the regular form of the network and of the polar spines.)

Dimensions.--Diameter of the outer shell 0.16, middle shell 0.08, inner shell 0.04; pores and bars of the cortical shell 0.008; length of the polar spines 0.08, basal breadth 0.04.

Habitat.--Pacific, central area, Station 271, depth 2425 fathoms.

{143}2. Amphisphæra uranus, n. sp.

Radial proportion of the three spheres = 4 : 2 : 1. Cortical shell thick walled, smooth, with regular, circular pores, three times as broad as the bars; ten to twelve on the half equator. Polar spines three-sided pyramidal, about as long as the diameter of the outer shell, twice as broad at the base as one pore.

Dimensions.--Diameter of the outer shell 0.12, middle 0.06, inner 0.03; pores of the cortical shell 0.012, bars 0.004; length of the polar spines 0.1, basal breadth 0.024.

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

3. Amphisphæra jupiter, n. sp.

Radial proportion of the three spheres = 10 : 3 : 2. Cortical shell thick walled, smooth, with regular, circular pores, twice as broad as the bars; twenty to twenty-five on the half equator. Polar spines cylindro-conical, nearly as long as the axis of the outer shell, twice as broad at the base as one pore.

Dimensions.--Diameter of the outer shell 0.2, middle 0.06, inner 0.04; pores of the cortical shell 0.01, bars 0.005; length of the polar spines 0.15 to 0.18, breadth 0.02.

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

Subgenus 2. Amphisphærella, Haeckel.

Definition.--Pores of the cortical shell regular, of nearly equal size and similar form; surface thorny or spiny.

4. Amphisphæra apollo, n. sp.

Radial proportion of the three spheres = 3 : 1.5 : 1. Cortical shell thick walled, spiny, with regular, circular, hexagonally framed pores, of the same breadth as the bars; twenty to twenty-two on the half equator. In each hexagon-corner (between three pores) a bristle-like radial spine. Polar spines cylindrical, with conical apex; one to one and a half times as long as the axis of the outer shell, as broad as three pores at the base. (Resembles closely Xiphosphæra pallas, Pl. 14, fig. 4, but differs in the presence of two medullary shells and the absence of the fine denticulations on the hexagonal crests.)

Dimensions.--Diameter of the outer shell 0.12, middle 0.06, inner 0.04; pores and bars of the cortical shell 0.006; length of the polar spines 0.15, breadth 0.02.

Habitat.--Western Tropical Pacific, Station 224, depth 1850 fathoms.

5. Amphisphæra mercurius, n. sp.

Radial proportion of the three spheres = 3 : 2 : 1. Cortical shell thin walled, spiny, with regular, circular pores, twice as broad as the bars; fifteen to eighteen on the half equator; between {144}them short bristle-like radial spines. Polar spines three-sided pyramidal, about as long as the radius of the outer shell, one-third as broad at the base.

Dimensions.--Diameter of the outer shell 0.15, middle 0.09, inner 0.05; pores of the cortical shell 0.01, bars 0.005; length of the polar spines 0.09, basal breadth 0.03.

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

Subgenus 3. Amphisphærissa, Haeckel.

Definition.--Pores of the cortical shell irregular, of different size or form; surface smooth or a little rough, without spines or thorns.

6. Amphisphæra cronos, n. sp. (Pl. 17, fig. 5).

Radial proportion of the three spheres = 3 : 2 : 1. Cortical shell thin walled, smooth, with irregular, roundish pores, two to four times as broad as the bars; eight to ten on the half equator. Outer medullary shell similar, but with pores of half the size, connected with the cortical shell by numerous radial beams; inner medullary shell with very small pores. Polar spines three-sided pyramidal, as long as the axis of the inner medullary shell, half as broad at the base.

Dimensions.--Diameter of the outer shell 0.12, middle 0.08, inner 0.04; pores of the cortical shell 0.01 to 0.02, bars 0.05; length of the polar spines 0.04, basal breadth 0.02.

Habitat.--South Atlantic, Station 330, surface.

7. Amphisphæra pluto, n. sp. (Pl. 17, figs. 7, 8).

Radial proportion of the three spheres about = 4 : 2 : 1 (or 11 : 7 : 3). Cortical shell thick walled, smooth, with very irregular, roundish pores, two to four times as broad as the bars; eight to ten on the half equator; often two to four pores confluent. Margin of their outer aperture double. Polar spines conical, double contoured, as long as the radius of the outer shell, one-third as broad at the base.

Dimensions.--Diameter of the outer shell 0.11, middle shell 0.07, inner shell 0.03; pores of the cortical shell 0.01 to 0.02, bars 0.06, length of the polar spines 0.06, basal breadth 0.02.

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

Subgenus 4. Amphisphæromma, Haeckel.

Definition.--Pores of the cortical shell irregular, of different size or form; surface spiny or thorny.

8. Amphisphæra mars, n. sp.

Radial proportion of the three spheres = 10 : 3 : 2. Cortical shell thin walled, thorny, with irregular, roundish pores, one to three times as broad as the bars; sixteen to twenty on the {145}half equator. Irregularly scattered between them short conical thorns. Polar spines conical, about as long as the axis of the outer shell, as broad at the base as the inner shell.

Dimensions.--Diameter of the outer shell 0.2, middle shell 0.06, inner shell 0.04; pores of the cortical shell 0.005 to 0.02, bars 0.006; length of the polar spines 0.17, basal breadth 0.04.

Habitat.--North Atlantic, Gulf Stream, near Florida, depth 1500 fathoms, Schaffner.

Genus 52. Amphistylus,[75] Haeckel, 1881, Prodromus, p. 452.

Definition.--#Stylosphærida# with three concentric lattice-spheres and two free spines of different size or form.

The genus Amphistylus differs from its ancestral form, Amphisphæra, by the differentiation of both polar spines, and exhibits therefore the same relation to it that Sphærostylus bears to Stylosphæra.

1. Amphistylus clio, n. sp.

Radial proportion of the three spheres = 4 : 2 : 1. Cortical shell thick walled, smooth; its pores regular, circular, three times as broad as the bars; eighteen to twenty on the half equator. Polar spines three-sided pyramidal, very stout, as broad at the base as the inner medullary shell; major spine somewhat longer than the diameter of the cortical shell; minor spine scarcely half as long. (Similar to Stylosphæra clio, Pl. 16, fig. 7, but different in the double medullary shell and the different length of the polar spines.)

Dimensions.--Diameter of the outer sphere 0.15, middle 0.08, inner 0.04; pores of the outer shell 0.01, bars 0.003; length of the major spine 0.17, minor 0.07, basal breadth 0.04.

Habitat.--Pacific, central area, Station 265, depth 2900 fathoms.

2. Amphistylus hippocampus, n. sp.

Radial proportion of the three spheres = 3 : 2 : 1. Cortical shell thick walled, smooth; its pores regular, circular, hexagonally lobed, three times as broad as the bars; twelve to fifteen on the half equator. Major polar spine three-sided pyramidal, about as long as the axis of cortical shell; minor spine pommel-like, edged, scarcely one-third as long. (Similar to Sphærostylus hippocampus, Pl. 16, figs. 10, 11, but differs in the larger size, the double medullary shell, and the straight, not curved, major spine.)

Dimensions.--Diameter of the outer sphere 0.11, middle 0.07, inner 0.035; pores of the outer shell 0.011, bars 0.004; length of the major spine 0.12, of the minor 0.04, breadth 0.03.

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

3. Amphistylus glyptodon, n. sp.

Radial proportion of the three spheres = 6 : 3 : 1. Cortical shell thick walled, spiny, with irregular, roundish pores, two to four times as broad as the bars; ten to twelve on the half equator. {146}Inner aperture of each pore closed by a thin fenestrated lamella with five to seven small pores. Major polar spine three-sided pyramidal, longer than the diameter of the outer sphere; minor polar spine scarcely as long as its radius, pommel-shaped. (Similar to Xiphatractus glyptodon, Pl. 17, figs. 9, 10, but differs in the spherical, not ellipsoidal, form of the three shells and the size of the polar spines.)

Dimensions.--Diameter of the outer sphere 0.12, middle 0.06, inner 0.02; pores and spines of the outer shell 0.01 to 0.02, bars and porules 0.006; length of the major polar spine 0.15, of the minor 0.05, breadth 0.04.

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

Genus 53. Saturninus,[76] n. gen.

Definition.--#Stylosphærida# with three concentric lattice-spheres and two equal opposite spines, connected at the distal end by a circular or elliptical ring.

The genus Saturninus differs from the similar Saturnulus by the triplication of the spherical lattice-shell; the inner shell is enclosed in the central capsule, whilst both the others lie outside it.

1. Saturninus triplex, n. sp.

Radial proportion of the three spheres = 4 : 3 : 1. Inner cortical shell with regular, circular pores, of the same breadth as the bars, sixteen to eighteen on the half equator; outer cortical shell connected with the inner by numerous bristle-like radial spines, network very delicate, cobweb-shaped, with irregular polygonal meshes. Ring elliptical, two and a half times as broad as the outer shell.

Dimensions.--Diameter of the inner sphere 0.03, middle 0.09, outer 0.12; pores and bars of the middle shell 0.004; major axis of the elliptical ring 0.3, minor 0.25; thickness of the ring and the axial beams 0.008.

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

Subfamily CROMYOSTYLIDA, Haeckel, 1881, Prodromus, pp. 449, 453.

Definition.--#Stylosphærida# with four concentric spherical lattice-shells (two medullary and two cortical).

Genus 54. Stylocromyum,[77] Haeckel, 1881, Prodromus, p. 453.

Definition.--#Stylosphærida# with four concentric lattice-spheres and two free spines of equal size and similar form.

{147}The genus Stylocromyum differs from its probable ancestral form, Amphisphæra, by the duplication of the cortical shell; two opposite radial beams, piercing the wall of the central capsule, connect it with the double medullary shell, and are prolonged outside into two equal spines.

1. Stylocromyum amphiconus, n. sp.

Surface of the shell smooth. Radial proportion of the four spheres = 1 : 2 : 8 : 9. Two medullary shells inside the central capsule, two cortical shells outside it. Interval between the second and third shells the greatest. Pores of all the shells regular, circular, two to four times as broad as the bars. Both polar spines equal, conical, about as long as the axis of the outermost sphere, as broad at the base as the innermost.

Dimensions.--Diameter of the four spheres--(A) inner medullary shell 0.03, (B) outer medullary shell 0.06, (C) inner cortical shell 0.25, (D) outer cortical shell 0.28; length of the polar spines 0.3, basal breadth 0.03.

Habitat.--Central Pacific, Station 273, depth 2350 fathoms.

2. Stylocromyum amphipyramis, n. sp.

Surface of the shell smooth. Radial proportion of the four spheres = 2 : 3 : 6 : 8. Both medullary shells with regular, circular pores, twice as broad as the bars. Both cortical shells with irregular, roundish, much larger pores, three to six times as broad as the bars. Both polar spines equal or nearly equal, three-sided pyramidal, about as long as the axis of the third shell.

Dimensions.--Diameter of the four spheres--(A) 0.04, (B) 0.06, (C) 0.12, (D) 0.16; length of the polar spines 0.11, basal breadth 0.02.

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

Genus 55. Cromyostylus,[78] Haeckel, 1881, Prodromus, p. 453.

Definition.--#Stylosphærida# with four concentric lattice-spheres and two free spines of different size or form.

The genus Cromyostylus differs from its ancestral form, Stylocromyum, in the differentiation of the two unequal polar spines.

1. Cromyostylus gladius, n. sp.

Surface of the shell smooth. Radial proportion of the four spheres = 1 : 3 : 10 : 12. Both medullary shells with regular, circular, simple pores. Inner cortical shell with regular, circular, hexagonally framed pores, twice as broad as the bars. From each hexagon-corner arises a {148}bristle-shaped radial spine, which at the distal end gives off three thread-like branches; by communication of these threads (at equal distances from the centre) the delicate outer medullary shell is formed. The polar spines very different; major spine six-sided pyramidal, longer than the diameter of the shell; minor pommel-shaped, shorter than the radius (similar to Xiphatractus glyptodon, Pl. 17, figs. 9, 10, but different in the double spherical cortical shell).

Dimensions.--Diameter of the four spheres--(A) 0.02, (B) 0.06, (C) 0.2, (D) 0.24; length of the major spine 0.3, of the minor 0.1.

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

Subfamily CARYOSTYLIDA, Haeckel, 1881, Prodromus, pp. 449, 454.

Definition.--#Stylosphærida# with five or more concentric, spherical lattice-shells.

Genus 56. Caryostylus, Haeckel, 1881, Prodromus, p. 454.

Definition.--#Stylosphærida# with five to six or more concentric lattice-shells and two free opposite spines of equal size and similar form.

The genus Caryostylus differs from its ancestral form, Stylocromyum, by the multiplication of the concentric spheres, the number of which amounts to five or six or more. I have only observed one single species of this genus. Some similar forms which in my Prodromus (1881, p. 454) were annexed to it, and disposed in three nearly allied genera (Caryoxiphus, Caryodoras, Caryolonche), have now been proved to belong to other groups, mainly ellipsoidal Druppulida.

1. Caryostylus hexalepas, n. sp.

Surface of the spherical shell smooth. Radial proportion of the component six concentric shells = 1 : 2 : 7 : 9 : 12 : 15. Both medullary shells connected only by six radial beams, opposite in pairs in the three dimensive axes. Between second and third shell numerous (twenty regularly disposed?) radial beams. Four cortical shells connected by very numerous (sixty to eighty or more?) short radial beams. Pores of all six shells regular, circular, the size increasing towards the surface, two to three times as broad as the bars. Two opposite polar spines very large, of equal size, three times as long as the shell radius, cylindrical, club-shaped at the thicker distal end. (The whole shell structure is similar to Pl. 15, fig. 2, but the shells are spherical, not ellipsoidal.)

Dimensions.--Diameter of the six spheres--(A) 0.02, (B) 0.04, (C) 0.15, (D) 0.18, (E) 0.24, (F) 0.3; length of the spines 0.5.

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

Subfamily SPONGOSTYLIDA, Haeckel, 1881, Prodromus, pp. 449, 455.

Definition.--#Stylosphærida# with spherical spongy shell (with or without enclosed latticed medullary shells).

{149}Genus 57. Spongolonchis,[79] Haeckel, 1881, Prodromus, p. 455.

Definition.--#Stylosphærida# with a solid sphere of spongy framework, and with two opposite free radial spines.

The genus Spongolonchis differs from its probable ancestral form, Styptosphæra, by the development of two opposite radial spines situated in one axis.

1. Spongolonchis compacta, n. sp.

Spongy framework of the spherical shell very compact, with small meshes, three to four times as broad as the bars. Surface rough, but not spiny. Two polar spines pyramidal, only as long as the radius of the shell, one-third as broad at the base.

Dimensions.--Diameter of the shell 0.2; length of the spines 0.1, basal breadth 0.03.

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

2. Spongolonchis laxa, n. sp.

Spongy framework loose, with large meshes, ten to twelve times as broad as the bars. Surface spiny. Two polar spines three-sided prismatic, longer than the diameter of the shell (broken off in the observed specimen).

Dimensions.--Diameter of the shell 0.5; length of the spine 0.6 and more, breadth 0.02.

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

Genus 58. Spongostylus,[80] Haeckel, 1881, Prodromus, p. 455.

Definition.--#Stylosphærida# with spongy spherical cortical shell, enclosing in the centre a simple latticed medullary shell, and with two opposite free radial spines.

The genus Spongostylus may probably be derived from Spongoplegma by development of two opposite radial spines in one axis.

1. Spongostylus hastatus, n. sp.

Spongy cortical shell with compact framework, twice as broad as the enclosed medullary shell, the pores of which are regular, circular, twice as broad as the bars. Two polar spines, three times as long as the radius of the shell, in the basal two-thirds cylindrical, in the distal third compressed, two-edged, spear-shaped.

Dimensions.--Diameter of the cortical shell 0.1, medullary shell 0.05; length of the spines 0.15.

Habitat.--South Atlantic, Station 335, depth 1425 fathoms.

{150}2. Spongostylus gladiatus, Haeckel.

Stylosphæra holosphæra, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 299, Taf. viii. fig. 14.

Spongy cortical shell with rather compact framework, four times as broad as the enclosed medullary shell, the pores of which are irregular, roundish, three to four times as broad as the bars. Two polar spines sword-shaped, two-edged, as long as the shell diameter.

Dimensions.--Diameter of the cortical shell 0.24, medullary shell 0.06; length of the spines 0.25.

Habitat.--Central Pacific, Station 268, depth 2900 fathoms; Philippine Sea, depth 3300 fathoms.

3. Spongostylus serratus, n. sp.

Spongy cortical shell with lax framework, ten to twelve times as broad as the enclosed medullary shell, the pores of which are irregular, roundish, once and a half to twice as broad as the bars. Two polar spines longer than the shell diameter (broken off in the observed specimen), three-sided prismatical, with three straight serrated edges.

Dimensions.--Diameter of the cortical shell 0.5, medullary shell 0.04; length of the spines 0.6 or more.

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

Genus 59. Spongostylidium,[81] Haeckel, 1881, Prodromus, p. 455.

Definition.--#Stylosphærida# with spongy spherical cortical shell, enclosing two concentric spherical latticed medullary shells, and with two opposite, free radial spines.

The genus Spongostylidium differs from Spongostylus by duplication of the latticed medullary shell, and therefore bears the same relation to it as Spongodictyon to Spongoplegma.

1. Spongostylidium streptacanthum, n. sp.

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, four times as broad as the outer medullary shell. Two polar spines very large, four times as long as the diameter of the outer shell; as broad as the inner medullary shell, with three dentated, spirally contorted edges. (Very similar to the common Spongosphæra streptacantha and to Hexadoridium streptacanthum, but with only two opposite spines in one axis.)

Dimensions.--Diameter of the cortical shell 0.16, of the outer medullary shell 0.04, inner 0.02; length of the spines 0.7 and more, breadth 0.02.

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

{151}Family VIII. #STAUROSPHÆRIDA#, Haeckel (Pl. 15).

Staurosphærida, Haeckel, 1881, Prodromus, p. 449.

Definition.--#Sphæroidea# with four radial spines on the surface of the spherical shell, forming a regular cross, being opposite in pairs in two axes perpendicular to one another; living solitary (not associated in colonies).

The family #Staurosphærida# is distinguished from the other #Sphæroidea# by the possession of four radial spines, which are opposite in pairs in two perpendicularly crossed axes. By these "two main axes" an equatorial plane is determined, which approximates them to the #Discoidea#. But in the latter the shells as well as the central capsule become more or less flattened, lenticular, or discoidal, whilst in the former they remain spherical. However, some forms of both groups are very similar, and inspection from different sides (and mainly from the margin of the equatorial plane) is required to determine the spherical (not compressed) shell-form of the Staurosphærida. As a rule the species of this family are much rarer, and much less numerous, than those of all the other #Sphæroidea#.

The most simple Staurosphærida are the Staurostylida, with one single spherical lattice-shell. To this ancestral group all other subfamilies can be opposed as "Staurosphærida concentrica," since their carapace is composed of two or more concentric lattice-shells; two in the Staurolonchida, three in the Stauracontida, four in the Staurocromyida, five or more in the Staurocaryida. In all these four subfamilies the concentric shells are simple (not spongy) fenestrated spheres. In a sixth subfamily, in the Staurodorida, the shell is wholly or partially composed of irregular spongy wickerwork, with or without a medullary shell in the centre.

The Four Radial Spines in all Staurosphærida are normally opposed in pairs in two axes perpendicular one to another, and therefore together form a rectangular cross. But in many species besides this normal form individual abnormalities occur, in which the four spines in the equatorial plane are not quite accurately opposed, so that the four angles between them are not right angles, but more or less unequal. More rarely also their position in the equatorial plane is not accurately retained, so that they are placed in two, three, or four different meridian planes, intersecting at very small variable angles.

In the greater part of Staurosphærida all four radial spines are quite equal, and of the same size and form. But in some genera there takes place a more or less considerable differentiation of the four spines, commonly in pairs, so that the two opposite spines of each pair are equal, but the pairs different (Staurostylus, Staurolonchidium). More rarely also both spines of one pair become unequal, whilst those of the other pair remain equal (Stauroxiphos). Very rarely all four spines assume a different size or form.

{152}Synopsis of the Genera of Staurosphærida.

I. Subfamily {All four spines equal, 60. Staurosphæra. Staurostylida. { (Shell one single {Four spines different lattice-sphere.) { in pairs, 61. Staurostylus. { {One spine larger than the { three others, 62. Stylostaurus.

II. Subfamily {All four spines {Simple, 63. Staurolonche. Staurolonchida. { equal, { (Shell with { {Branched, 64. Staurancistra. two concentric { lattice-spheres.) {Four spines different 65. { in pairs, Staurolonchidium. { {One spine larger than { the three others, 66. Stauroxiphos.

III. Subfamily }All four spines equal, Stauracontida. } simple, 67. Stauracontium. (Shell with three } concentric spheres.) }

IV. Subfamily }All four spines {Simple, 68. Staurocromyum. Staurocromyida. } equal, { (Shell with four } {Branched, 69. Cromyostaurus. concentric spheres.) }

V. Subfamily }All four spines equal, 70. Staurocaryum. Staurocaryida. } (Shell with five } or more concentric } spheres.) }

VI. Subfamily }Solid spongy sphere Staurodorida. } without medullary shell, 71. Staurodoras. (Shell a spongy } sphere.) }

Subfamily STAUROSTYLIDA,[82] Haeckel, Prodromus, 1881, pp. 449, 450.

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

Genus 60. Staurosphæra,[83] Haeckel, 1881, Prodromus, p. 450.

Definition.--#Staurosphærida# with a single lattice-sphere and four crossed equal spines.

The genus Staurosphæra may be regarded as the common ancestral form of this subfamily, since it represents their most simple and primitive form. From the surface of the simple lattice-sphere, enclosing the central capsule, arise four equal, simple, radial spines, opposite in pairs in two diameters, perpendicular one to another. Staurosphæra may be derived phylogenetically either from Cenosphæra by production of the four spines, or from Hexastylus by reduction of two opposite spines.

{153}Subgenus 1. Staurosphærantha, Haeckel.

Definition.--Pores regular, all of nearly equal size and similar form; surface smooth.

1. Staurosphæra cruciata, n. sp.

Shell thin walled, smooth, with regular, hexagonal pores, four times as broad as the bars; ten to twelve on the quadrant. Four crossed radial spines three-sided pyramidal, as long as the diameter of the shell, as broad at the base as one pore (very similar to Hexastylus phænaxonius, Pl. 21, fig. 3, but with only four spines).

Dimensions.--Diameter of the shell 0.12, of the pores 0.008, bars 0.002.

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

2. Staurosphæra christiana, n. sp.

Shell thick walled, smooth, with regular, circular, hexagonally framed pores, three times as broad as the bars; six to eight on the quadrant. Four crossed spines six-sided pyramidal, as long as the radius, as broad as one mesh.

Dimensions.--Diameter of the shell 0.13, pores 0.012, bars 0.004.

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

3. Staurosphæra johannis, n. sp.

Shell thick walled, smooth, with regular, circular pores, four times as broad as the bars; five to six on the quadrant. Four spines six-sided pyramidal, half as long as the radius, as broad as one mesh.

Dimensions.--Diameter of the shell 0.15, pores 0.02, bars 0.005.

Habitat.--North Pacific, Station 241, depth 2300 fathoms.

4. Staurosphæra pauli, n. sp.

Shell very thick walled, smooth, with regular, circular, double-edged pores, four times as broad as the bars; eight to ten on the quadrant. Four spines conical, as long as the radius, as broad as one mesh.

Dimensions.--Diameter of the shell 0.15, pores 0.016, bars 0.004.

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

5. Staurosphæra petri, n. sp.

Shell thin walled, smooth, with regular, circular pores, three times as broad as the bars; twenty to twenty-two on the quadrant. Four spines conical, half as long as the radius, as broad as one mesh.

Dimensions.--Diameter of the shell 0.22, pores 0.006, bars 0.002.

Habitat.--South Atlantic, Station 325, depth 2650 fathoms; also fossil in Barbados.

{154}6. Staurosphæra jacobi, n. sp.

Shell thick walled, smooth, with regular, circular pores, twice as broad as the bars; eleven to twelve on the quadrant. Four spines cylindrical, three times as long as the radius, three times as broad as one mesh.

Dimensions.--Diameter of the shell 0.1, pores 0.006, bars 0.003.

Habitat.--North Atlantic, Station 353, depth 2965 fathoms.

7. Staurosphæra simonis, n. sp.

Haliomma with four spines, Bury, 1862, Polycystins of Barbados, pl. iv. fig. 4.

Shell thick walled, smooth, with regular, circular pores, of the same breadth as the bars; eight to ten on the quadrant. Four spines cylindrical, twice as long as the radius, five times as broad as one mesh.

Dimensions.--Diameter of the sphere 0.1, pores and bars 0.003.

Habitat.--Fossil in Barbados.

Subgenus 2. Staurosphærella, Haeckel.

Definition.--Pores regular, all of nearly equal size and similar form; surface covered with by-spines or accessory thorns.

8. Staurosphæra philippi, n. sp. (Pl. 15, fig. 6).

Shell thin walled, covered with bristle-shaped by-spines, as long as the radius. Pores regular, circular, twice as broad as the bars; six to eight on the quadrant. Four main spines cylindrical, five to ten times as long as the radius, as broad as one mesh.

Dimensions.--Diameter of the shell 0.08, pores 0.006, bars 0.003.

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

9. Staurosphæra andreæ, n. sp.

Shell thick walled, with regular, circular, hexagonally framed pores, three times as broad as the bars; nine to ten on the quadrant. From each hexagon-corner arises a bristle-shaped by-spine, half as long as the radius. Four main spines three-sided pyramidal, with spirally contorted edges, as long as the radius (very similar to Hexastylus solonis, Pl. 21, fig. 11, but with only four spines).

Dimensions.--Diameter of the shell 0.16, pores 0.01, bars 0.003.

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

{155}10. Staurosphæra thomæ.

Shell thick walled, with regular, circular pores, twice as broad as the bars; twelve to fourteen on the quadrant; surface covered with short conical by-spines. Four main spines conical, twice as long as the radius, twice as broad as one mesh.

Dimensions.--Diameter of the sphere 0.2, pores 0.012, bars 0.006.

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

Subgenus 3. Staurosphærissa, Haeckel.

Definition.--Pores irregular, of different size or form; surface smooth.

11. Staurosphæra judæ, n. sp.

Shell thin walled, smooth, with irregular, polygonal pores, twice to four times as broad as the bars; six to ten on the quadrant. Four main spines three-sided pyramidal, as long as the radius.

Dimensions.--Diameter of the sphere 0.15, pores 0.006 to 0.012, bars 0.003.

Habitat.--Central Pacific, Station 273, depth, 2350 fathoms.

12. Staurosphæra crassa, Dunikowski.

Staurosphæra crassa, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 27, Taf. v. figs. 52-55.

Shell thick walled, smooth, with irregular, roundish pores, scarcely broader than the bars; eight to ten on the quadrant. Four spines three-sided pyramidal, nearly as long as the shell diameter.

Dimensions.--Diameter of the sphere 0.19, pores and bars 0.015.

Habitat.--Fossil in the Alpine Lias (Schafberg near Salzburg, Dunikowski).

13. Staurosphæra apostolorum, Haeckel.

? Cenosphæra megapora, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. iii. fig. 1.

? Cenosphæra micropora, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. iii. fig. 2.

Shell thin walled, smooth, with large, irregular, roundish pores, twice to six times as broad as the bars; four to six on the quadrant. Four spines conical, very stout, about as long as the shell diameter, often more or less irregularly disposed.

Dimensions.--Diameter of the sphere 0.12 to 0.2, pores 0.01 to 0.03, bars 0.005.

Habitat.--Fossil in Barbados.

{156}Subgenus 4. Staurosphæromma, Haeckel.

Definition.--Pores irregular, of different size or form; surface covered with by-spines or accessory thorns.

14. Staurosphæra bartholomæi, n. sp.

Shell thin walled, with irregular, polygonal pores, three times as broad as the bars; six to eight on the quadrant; surface covered with short bristle-shaped by-spines. Four main spines three-sided pyramidal, twice as long as the radius.

Dimensions.--Diameter of the shell 0.14, pores 0.008 to 0.016, bars 0.003 to 0.005.

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

15. Staurosphæra thaddæi, n. sp.

Shell thick walled, with irregular, roundish, polygonally framed pores, twice to three times as broad as the bars; five to seven on the quadrant; surface covered with bristle-shaped spines, half as long as the radius. Four main spines pyramidal, as long as the radius.

Dimensions.--Diameter of the shell 0.12, pores 006 to 0.012, bars 0.004.

Habitat.--Central Pacific, Station 266, depth 2750 fathoms; also fossil in Barbados.

16. Staurosphæra matthæi, n. sp.

Shell thick walled, with irregular, roundish pores, twice to five times as broad as the bars; ten to twelve on the quadrant; surface covered with short conical thorns or by-spines. Four main spines conical, as long as the radius.

Dimensions.--Diameter of the shell 0.15, pores 0.004 to 0.01, bars 0.002.

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

Genus 61. Staurostylus,[84] Haeckel, 1881, Prodromus, p. 450.

Definition.--#Staurosphærida# with one single lattice-sphere and four crossed spines which are arranged in opposite pairs, one pair opposite being larger than the other.

The genus Staurostylus has been developed from Staurosphæra by differentiation of the four crossed spines in pairs; two opposite spines growing much more strongly than the other two.

1. Staurostylus græcus, n. sp.

Shell thick walled, smooth, with regular, circular, hexagonally framed pores, twice as broad as the bars; six to eight on the quadrant. Spines three-sided prismatic, pointed, as broad as {157}one mesh; two opposite larger spines as long as the diameter of the shell, two smaller only as long as the radius.

Dimensions.--Diameter of the shell 0.15, pores 0.01, bars 0.005; length of the major spines 0.16, minor 0.08.

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

2. Staurostylus latinus, n. sp.

Shell thin walled, smooth, with regular, circular, double-edged pores, three times as broad as the bars; twelve to fourteen on the quadrant. Spines conical, twice as broad at the base as one mesh; two opposite larger spines as long as the radius of the shell, two smaller only one-third as long.

Dimensions.--Diameter of the shell 0.24, pores 0.012, bars 0.004; length of the major spines 0.12, minor 0.04.

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

3. Staurostylus germanicus, n. sp.

Shell thick walled, covered with bristle-shaped by-spines, half as long as the radius. Pores regular, circular, hexagonally framed, twice as broad as the bars; eight to ten on the quadrant. From each hexagon-corner arises one short by-spine. Four main spines three-sided pyramidal, as broad at the base as one mesh; two opposite larger spines one and a half times as long as the radius, two smaller two-thirds as long.

Dimensions.--Diameter of the shell 0.16, pores 0.008, bars 0.004; length of the major spines 0.12, minor 0.08.

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

Genus 62. Stylostaurus,[85] 1881, Prodromus, p. 450.

Definition.--#Staurosphærida# with one single lattice-sphere and four crossed spines, one of which is much larger than the other three.

The genus Stylostaurus differs from the preceding in the extraordinary development of one of the four spines, which is much longer than the other three; these may be equal or different.

1. Stylostaurus caudatus, n. sp. (Pl. 13, fig. 7).

Shell thick walled, smooth, with regular, circular, hexagonally framed pores, twice as broad as the bars; five to six on the quadrant. Spines three-sided pyramidal, as broad at the base as {158}one mesh; one of the spines longer than the shell diameter, the opposite spine nearly as long as the shell radius; both lateral spines scarcely one-third as long.

Dimensions.--Diameter of the shell 0.1, pores 0.01, bars 0.005; length of the major spine 0.14, of the opposite 0.04, of both lateral spines 0.012.

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

2. Stylostaurus gladiatus, n. sp.

Shell thick walled, smooth, with regular, circular pores, three times as broad as the bars; nine to ten on the quadrant. Spines three-sided prismatic, as broad at the base as one mesh; one of the spines longer than the shell diameter, and much larger than the other three, which are nearly equal (half as long as the radius).

Dimensions.--Diameter of the shell 0.2, pores 0.015, bars 0.005; length of the major spine 0.25, of the three others 0.005.

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

Subfamily STAUROLONCHIDA,[86] Haeckel, 1881, Prodromus, pp. 449, 451.

Definition.--#Staurosphærida# with two concentric spherical lattice-shells.

Genus 63. Staurolonche,[87] Haeckel, 1881, Prodromus, p. 451.

Definition.--#Staurosphærida# with two concentric lattice-spheres and four crossed, equal, simple spines.

The genus Staurolonche may be derived either from Staurosphæra by the duplication of the lattice-sphere, or from Carposphæra by the production of four crossed radial spines, lying in one meridional plane, or from Hexalonche by the reduction of two opposite spines.

Subgenus 1. Staurolonchantha, Haeckel.

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

1. Staurolonche hexagona, n. sp.

Haliomma hexagonum, Ehrenberg, 1854, Mikrogeol., Taf. xxxvb., Bd. iv. fig. 17.

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

Cortical shell thin walled, smooth, three times as broad as the medullary shell, with regular, hexagonal pores, four times as broad as the bars; seven to eight on the quadrant. Four spines three-sided pyramidal, somewhat longer than the radius, as broad at the base as one mesh.

{159}Dimensions.--Diameter of the outer shell 0.12, inner 0.04; cortical pores 0.012, bars 0.003; length of the spines 0.08.

Habitat.--North Atlantic, Station 64, depth 2700 fathoms.

2. Staurolonche spinozæ, n. sp.

Cortical shell thick walled, smooth, twice as broad as the medullary shell, with regular, circular, hexagonally framed pores, three times as broad as the bars; five to six on the quadrant. Four spines three-sided pyramidal, half as long as the radius, as broad at the base as one mesh.

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

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

3. Staurolonche aperta, Haeckel.

Haliomma apertum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, Taf. xxviii. fig. 5.

Cortical shell thin walled, smooth, three times as broad as the medullary shell; pores regular, circular, five times as broad as the bars; four to five on the quadrant. Four spines conical, as long as the radius, as broad as one mesh.

Dimensions.--Diameter of the outer shell 0.1, inner 0.03; cortical pores 0.015, bars 0.003; length of the spines 0.05.

Habitat.--Fossil in Barbados.

4. Staurolonche brunonis, n. sp.

Cortical shell thick walled, smooth, twice as broad as the medullary shell, with regular, circular pores, three times as broad as the bars; eight to ten on the quadrant. Four spines cylindro-conical, longer than the diameter, twice as broad as one mesh.

Dimensions.--Diameter of the outer shell 0.08, inner 0.04; cortical pores 0.006, bars 0.002; length of the spines 0.12.

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

5. Staurolonche pertusa, n. sp. (Pl. 15, figs. 5, 5_a_).

Cortical shell thin walled, smooth, three times as broad as the medullary shell, with regular, circular pores, three times as broad as the bars; eight to ten on the quadrant. Pores of the medullary shell only one-third as large, also circular. Four spines three-sided prismatic, three times as long as the radius; each of their three thin wings perforated by a single row of small pores.

Dimensions.--Diameter of the outer shell 0.1, inner 0.033; cortical pores 0.01, bars 0.003; length of the spines 0.15.

Habitat.--North Atlantic, Station 353, surface.

{160}Subgenus 2. Staurolonchella, Haeckel.

Definition.--Pores of the cortical shell regular, and of nearly equal size and similar form; surface covered with by-spines or thorns.

6. Staurolonche straussii, n. sp.

Cortical shell thin walled, four times as broad as the medullary shell, and covered with numerous bristle-shaped by-spines, half as long as the radius. Pores regular, circular, hexagonally framed, twice as broad as the bars; six to eight on the radius. On each hexagonal frame twelve by-spines (six at the corners, six in the middle between them). Four main spines six-sided pyramidal, about as long as the radius, twice as broad as one mesh.

Dimensions.--Diameter of the outer shell 0.16, inner 0.04; cortical pores 0.016, bars 0.008; length of the spines 0.1.

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

7. Staurolonche feuerbachii, n. sp.

Cortical shell thick walled, five times as broad as the medullary shell, and covered with short conical by-spines. Pores regular, circular, twice as broad as the bars; twenty to twenty-two on the quadrant. Four main spines three-sided prismatic, with pyramidal apex, two to three times as long as the radius, twice as broad as one mesh.

Dimensions.--Diameter of the outer shell 0.27, of the inner 0.055; cortical pores 0.008, bars 0.004; length of the spines 0.3 to 0.4.

Habitat.--Fossil in Barbados.

8. Staurolonche moleschottii, n. sp.

Cortical shell thick walled, three times as broad as the medullary shell, and covered with short conical by-spines. Pores regular, circular, of the same breadth as the bars; fourteen to sixteen on the quadrant. Four main spines conical, as long as the radius, three times as broad at the base as one mesh.

Dimensions.--Diameter of the outer shell 0.15, inner 0.05; cortical pores and bars 0.004; length of the spines 0.08.

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

Subgenus 3. Staurolonchissa, Haeckel.

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

9. Staurolonche holbachii, n. sp.

Cortical shell thin walled, with smooth surface, three times as broad as the medullary shell. Pores irregular, polygonal, twice to four times as broad as the bars. Four main spines three-sided prismatic, longer than the shell diameter.

{161}Dimensions.--Diameter of the outer shell 0.12, inner 0.04; cortical pores 0.006 to 0.012, bars 0.003; length of the spines 0.15.

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

10. Staurolonche gassendii, n. sp.

Cortical shell thick walled, with smooth surface, four times as broad as the medullary shell. Pores irregular, roundish, three to five times as broad as the bars. Four main spines conical, as long as the radius.

Dimensions.--Diameter of the outer shell 0.2, inner 0.05; cortical pores 0.01 to 0.02, bars 0.004; length of the spines 0.1.

Habitat.--North Atlantic, Station 353, depth 2965 fathoms.

Subgenus 4. Staurolonchura, Haeckel.

Definition.--Pores of the cortical shell irregular, of different size or form; surface covered with by-spines or thorns.

11. Staurolonche epicurii, n. sp.

Cortical shell thick walled, five times as broad as the medullary shell, and covered with numerous bristle-shaped by-spines (half as long as the radius). Pores irregular, roundish, polygonally framed, twice to three times as broad as the bars. Four main spines pyramidal, as long as the radius.

Dimensions.--Diameter of the outer shell 0.22, inner 0.044; cortical pores 0.02 to 0.04, bars 0.012; length of the spines 0.1.

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

12. Staurolonche lucretii, n. sp.

Cortical shell thick-walled, three times as broad as the medullary shell, and covered with numerous short, conical thorns. Pores irregular, roundish, twice to four times as broad as the bars. Four main spines conical, half as long as the radius.

Dimensions.--Diameter of the outer shell 0.15, inner 0.05; cortical pores 0.015 to 0.03, bars 0.008; length of the spines 0.04.

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

Genus 64. Staurancistra,[88] Haeckel, 1881, Prodromus, p. 451.

Definition.--#Staurosphærida# with two concentric lattice-spheres and four crossed, equal, branched spines.

{162}The genus Staurancistra differs from its ancestral form, Staurolonche, in the ramification of the four crossed spines.

1. Staurancistra quadricuspis, n. sp.

Cortical shell thin walled, with rough, thorny surface, and irregular, roundish pores, twice to four times as broad as the bars; six to eight on the quadrant. Medullary shell one-third as large, with regular, circular pores; connected with the cortical shell by four crossed radial beams. These are prolonged outside into four strong three-sided prismatic spines, nearly as long as the shell diameter, each having three curved branches below the distal end. (Similar to Hexancistra quadricuspis, Pl. 22, fig. 11, but with only four spines.)

Dimensions.--Diameter of the cortical shell 0.16, of the medullary shell 0.05; pores of the former 0.06 to 0.012, bars 0.003; length of the spines 0.14, breadth 0.012.

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

Genus 65. Staurolonchidium,[89] n. gen.

Definition.--#Staurosphærida# with two concentric lattice-spheres and four crossed simple spines which are disposed in two different pairs, two opposite being larger than the other two.

The genus Staurolonchidium has arisen from Staurolonche by the stronger growth of the two opposite spines, the other two remaining stationary; both spines of each pair equal.

1. Staurolonchidium artioscelides, n. sp.

Cortical shell thin walled, with smooth surface, three times as broad as the medullary shell. Pores regular, circular, hexagonally framed, twice as broad as the bars; eight to ten on the quadrant. Four radial spines three-sided pyramidal, as broad as one mesh; two opposite larger spines three times as long as the two smaller, which are about equal to the radius.

Dimensions.--Diameter of the cortical shell 0.16, medullary shell 0.05; pores of the former 0.012, bars 0.006; length of the major spines 0.24, minor 0.08.

Habitat.--Central Pacific, Station 265, surface.

2. Staurolonchidium perspicuum, Haeckel.

Haliomma perspicuum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, Taf. xxix. fig. 1.

Cortical shell thin walled, covered with small conical by-spines, five times as broad as the medullary shell. Pores regular, circular, eight times as broad as the bars; three to four on the quadrant. Four radial spines three-sided pyramidal, scarcely one-third as broad as one mesh; two opposite larger spines four times as long as the two smaller, which are about equal to half the radius.

{163}Dimensions.--Diameter of the cortical shell 0.12, medullary shell 0.025; pores of the former 0.03, bars 0.004; length of the major spines 0.12, minor 0.03.

Habitat.--Fossil in Barbados.

Genus 66. Stauroxiphos,[90] n. gen.

Definition.--#Staurosphærida# with two concentric lattice-spheres and four crossed simple spines, one of which is much larger than the other three.

The genus Stauroxiphos differs from its ancestral form, Staurolonche, in the greater development of one single spine, and exhibits therefore the same relation to it that Stylostaurus bears to Staurosphæra.

1. Stauroxiphos gladius, n. sp. (Pl. 15, fig. 7).

Cortical shell thick walled, smooth, three times as broad as the medullary shell. Pores of the outer shell regular, circular, regularly six-lobed on the outer opening, four times as broad as the bars; about six on the quadrant. Pores of the inner shell only one-third as large, simple, circular. Three of the four radial spines of nearly equal size, pommel-shaped, with three prominent, dentated wings, somewhat shorter than the shell radius and about half as broad as long; the fourth spine much larger, sword-like, about three times as long as the shell radius.

Dimensions.--Diameter of the outer shell 0.12, of the inner 0.04; pores of the former 0.01, bars 0.0025; pores of the latter 0.003, bars 0.001; length of the major spine 0.18, of the three minor 0.04.

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

Subfamily STAURACONTIDA,[91] Haeckel, 1881, Prodromus, p. 52.

Definition.--#Staurosphærida# with three concentric spherical lattice-shells.

Genus 67. Stauracontium,[92] Haeckel, 1881, Prodromus, p. 452.

Definition.--#Staurosphærida# with three concentric lattice-spheres and four crossed, equal, simple spines.

The genus Stauracontium differs from its probable ancestral form, Staurolonche, in the duplication of the cortical shell.

Subgenus 1. Stauracontarium, Haeckel.

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

{164}1. Stauracontium cruciferum, n. sp.

Cortical shell thin walled, smooth, with regular, hexagonal pores, four times as broad as the bars; eight to ten on the quadrant. Radial proportion of the three spheres = 1 : 3 : 9. Connecting radial beams between them six (opposite in pairs in the three dimensive axes), but only four of them are prolonged outside into four stout three-sided prismatic spines, lying in one equatorial plane, as long as the shell diameter.

Dimensions.--Diameter of the outer shell 0.22, middle 0.07, inner 0.025; cortical pores 0.012, bars 0.003; length of the spines 0.2.

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

2. Stauracontium tetracanthum, Haeckel.

Haliomma tetracanthum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 295, Taf. x. figs. 7, 8.

Cortical shell thin walled, smooth, with regular, circular pores, three times as broad as the bars; five to six on the quadrant. Radial proportion of the three spheres = 1 : 3 : 12. Radial spines three-sided pyramidal, about as long as the shell diameter.

Dimensions.--Diameter of the outer shell 0.12, middle 0.03, inner 0.01; cortical pores 0.01, bars 0.003; length of the spines 0.1.

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

3. Stauracontium tetracontium, Haeckel.

Actinomma tetracanthum, Stöhr, 1880, Palæontogr. 26, p. 91, Taf. ii. fig. 6.

Cortical shell thin walled, rough, with regular, circular pores, of the same breadth as the bars; six to seven on the quadrant. Radial proportion of the three spheres = 1 : 2.5 : 8. Radial spines three-sided pyramidal, nearly as long as the shell diameter.

Dimensions.--Diameter of the outer shell 0.1, middle 0.03, inner 0.013; cortical pores and bars 0.006; length of the spines 0.08.

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

Subgenus 2. Stauracontellium, Haeckel.

Definition.--Pores of the cortical shell regular, and of nearly equal size and similar form; surface covered with numerous small thorns or by-spines.

4. Stauracontium daturæforme, Haeckel.

Actinomma daturæforme, Stöhr, 1880, Palæontogr. 26, p. 93, Taf. ii. fig. 13.

Cortical shell thick walled, covered with short thorns, and with regular, hexagonal pores, five times as broad as the bars; six to seven on the quadrant. Radial proportion of the three spheres = 1 : 3 : 3.5. Radial spines six-sided pyramidal, about half as long as the radius and one-fourth as broad.

{165}Dimensions.--Diameter of the outer shell 0.15, middle 0.13, inner 0.04; cortical pores 0.017, bars 0.003; length of the spines 0.03.

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

5. Stauracontium sparganium, n. sp.

Cortical shell thick walled, covered with very numerous, short, conical spines, and with regular, circular pores, five times as broad as the bars; sixteen to eighteen on the quadrant. Radial proportion of the three spheres = 2 : 3 : 9. Radial main spines three-sided prismatic, as long as the radius or longer.

Dimensions.--Diameter of the outer shell 0.275, middle 0.09, inner 0.06; cortical pores 0.01, bars 0.002; length of the spines 0.15.

Habitat.--Fossil in Barbados.

Subgenus 3. Stauracontidium, Haeckel.

Definition.--Pores irregular, of different size or form; surface smooth.

6. Stauracontium antarcticum, n. sp.

Cortical shell thin walled, smooth. Pores irregular, roundish, two to four times as broad as the bars. Radial proportion of the three spheres = 1 : 2 : 8. Radial spines conical, as long as the radius.

Dimensions.--Diameter of the outer shell 0.2, middle 0.05, inner 0.025; cortical pores 0.006 to 0.012, bars 0.003; length of the spines 0.1.

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

Subgenus 4. Stauracontonium, Haeckel.

Definition.--Pores irregular, of different size or form; surface covered with thorns or by-spines.

7. Stauracontium setosum, n. sp.

Cortical shell thin walled, covered with thin bristle-shaped by-spines, half as long as the radius. Pores irregular, polygonal, three to five times as broad as the bars. Proportion of the three spheres = 1 : 2 : 6. Radial main spines pyramidal, nearly as long as the shell diameter.

Dimensions.--Diameter of the outer shell 0.15, middle 0.05, inner 0.025; cortical pores 0.01 to 0.015, bars 0.003; length of the spines 0.12.

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

8. Stauracontium papillosum, n. sp.

Cortical shell thick walled, covered with short conical papillæ or by-spines. Pores irregular, roundish, two to four times as broad as the bars. Proportion of the three spheres = 1 : 3 : 12. Radial main spines conical, as long as the radius.

{166}Dimensions.--Diameter of the outer shell 0.24, middle 0.06, inner 0.02; cortical pores 0.007 to 0.015, bars 0.004; length of the spines 0.12.

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

Subfamily STAUROCROMYIDA,[93] Haeckel, 1881, Prodromus, pp. 449, 453.

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

Genus 68. Staurocromyum,[94] Haeckel, 1881, Prodromus, p. 453.

Definition.--#Staurosphærida# with four concentric lattice-spheres and four crossed, equal, simple spines.

The genus Staurocromyum has arisen probably from Stauracontium by duplication of the cortical shell, two concentric shells lying within, two others outside the central capsule.

1. Staurocromyum quadruplex, n. sp.

Radial proportion of the four spheres = 1 : 2 : 8 : 10. Both medullary shells with very small, regular, circular pores. Inner cortical shell with regular, circular, hexagonally-framed pores, twice as broad as the bars; from each hexagon-corner arises a small by-spine, and these, connected by tangential branches at equal distances from the centre, form the delicate outer cortical shell, with spiny surface. Four main spines three-sided pyramidal, as long as the shell radius.

Dimensions.--Diameter of the four shells--(A) 0.25, (B) 0.2, (C) 0.05, (D) 0.025; length of the spines 0.12.

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

2. Staurocromyum quadrispinum, n. sp.

Radial proportion of the four spheres = 1 : 3 : 9 : 12. Both medullary shells with small, regular, circular pores. Both cortical shells with irregular, roundish pores. Surface covered with short, conical by-spines. Four main spines cylindro-conical, somewhat longer than the shell diameter.

Dimensions.--Diameter of the four shells--(A) 0.24, (B) 0.18, (C) 0.06, (D) 0.02.

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

Genus 69. Cromyostaurus,[95] Haeckel, 1881, Prodromus, p. 453.

Definition.--#Staurosphærida# with four concentric lattice-spheres and four crossed, equal, branched spines.

{167}The genus Cromyostaurus differs from the preceding Staurocromyum, its ancestral form, in the ramification of the four crossed spines.

1. Cromyostaurus verticillatus, n. sp.

Radial proportion of the four spheres = 1 : 3 : 11 : 13. Both medullary shells with small, regular, circular pores; inner cortical shell with regular, hexagonal pores; from the hexagon-corners arise small, radial by-spines, which at equal distances from the centre send out forked tangential branches, three from each spine, and by communication of these form the outer, delicate, cortical shell. Four main spines nearly as long as the shell diameter, three-sided prismatic, with four to six verticils of ramified lateral branches, each verticil composed of three forked branches, which ramify again.

Dimensions.--Diameter of the four shells--(A) 0.26, (B) 0.22, (C) 0.06, (D) 0.02; length of the spines 0.24.

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

Subfamily STAUROCARYIDA,[96] Haeckel, 1881, Prodromus, pp. 449, 454.

Definition.--#Staurosphærida# with five or more concentric spherical lattice-shells.

Genus 70. Staurocaryum,[97] Haeckel, 1881, Prodromus, p. 454.

Definition.--#Staurosphærida# with five or more concentric lattice-spheres and four crossed, equal spines.

The genus Staurocaryum has arisen from the preceding Staurocromyum by the further multiplication of the concentric spheres; in the only observed form there are six, at nearly equal distances apart.

1. Staurocaryum arborescens, n. sp. (Pl. 15, fig. 8).

Shell composed of six concentric latticed spheres, at nearly equal distances apart, and with somewhat regular, circular pores, the size of which gradually increases from the first to the sixth shell. The surface of the outermost shell is densely covered with numerous arborescent by-spines, which bifurcate from three to four times, and are three-sided pyramidal at the base, and twice as long as the distance between each two shells. The six shells are connected only by four crossed, conical, radial beams, which increase in diameter from the centre, and are prolonged outside into very stout cylindrical, radial spines, irregularly covered with small thorns and forked ramules, and nearly as long as the shell diameter. Only a single specimen was observed.

{168}Dimensions.--Diameter of the whole shell 0.22; distance between each two shells 0.02; length of the by-spines 0.05, of the main spines 0.2.

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

Subfamily STAURODORIDA,[98] Haeckel, 1881, Prodromus, pp. 449, 455.

Definition.--#Staurosphærida# with spongy, spherical shell (with or without enclosed concentric lattice-shells).

Genus 71. Staurodoras,[99] Haeckel, 1881, Prodromus, p. 455.

Definition.--#Staurosphærida# with solid, spongy, spherical shell and four crossed simple spines.

The genus Staurodoras may be developed from Styptosphæra by the production of four crossed spines on the simple, spongy, spherical shell, which is composed of looser or denser irregular wicker-work, without enclosed medullary shell.

1. Staurodoras spongosphæra, n. sp.

Four crossed spines, two to three times as long as the diameter of the spongy sphere, three-sided prismatic, with three dentated and spirally contorted edges. (Form of Spongosphæra streptacantha, but without medullary shell and with four equal spines, crossed regularly at right angles.)

Dimensions.--Diameter of the sphere 0.25; length of the spines 0.4 to 0.7.

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

2. Staurodoras mojsisovicsi, Dunikowski.

Staurodoras mojsisovicsi, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 28, Taf. v. fig. 56.

Four crossed spines, one and a half times as long as the diameter of the spongy sphere, three-sided pyramidal, with three smooth edges. (What Dunikowski describes as "inner canals" of the spines are their edges.)

Dimensions.--Diameter of the sphere 0.14; length of the spines 0.18 to 0.2. basal breadth 0.04.

Habitat.--Fossil in the Alpine Lias (Schafberg near Salzburg).

3. Staurodoras liassica, Dunikowski.

Staurodoras liassica, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 28, Taf. v. fig. 57.

Four crossed spines, shorter than the diameter of the spongy sphere, conical or pyramidal (?).

Dimensions.--Diameter of the sphere 0.19; length of the spine 0.13, basal breadth 0.045.

Habitat.--Fossil in the Alpine Lias (Schafberg near Salzburg).

{169}4. Staurodoras wandae, Dunikowski.

Staurodoras wandae, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, Bd. xlv. p. 28, Taf. v. fig. 58.

Four crossed spines shorter than the radius of the spongy sphere, conical. (May be the young form of the preceding species.)

Dimensions.--Diameter of the sphere 0.14; length of the spines 0.06, basal breadth 0.05.

Habitat.--Fossil in the Alpine Lias (Schafberg near Salzburg).

Family IX. #CUBOSPHÆRIDA#, Haeckel (Pls. 21-25).

Cubosphærida, Haeckel, 1881, Prodromus, p. 449.

Definition.--#Sphæroidea# with six radial spines on the surface of the spherical shell, opposite in pairs in the three dimensive axes, perpendicular one to another; living solitary (not associated in colonies).

The family #Cubosphærida# is distinguished from the other #Sphæroidea# by the possession of six radial spines, which are opposite in pairs in three different axes, one perpendicular to the other two. These three axes are the typical "dimensive axes," which are more or less differentiated in the #Larcoidea#. But in these latter the shell itself and the enclosed central capsule become affected by the unequal growth in the three axes, whilst in the former the capsule constantly, and commonly also the shell, remains spherical. Sometimes the shell assumes the form of a regular octahedron, from the six corners of which arise the six radial spines, indicating its three axes.

The most simple Cubosphærida are the Hexastylida, with one single, spherical lattice-shell. To this ancestral group all other subfamilies can be opposed as "Cubosphærida concentrica," as their carapace is composed of two or more concentric lattice-shells--two in the Hexalonchida, three in the Hexacontida, four in the Hexacromyida, five or more in the Hexacaryida. In all these four subfamilies the concentric shells are simple (not spongy), fenestrated spheres. In a sixth subfamily, in the Hexadorida, the shell is wholly or partially composed of irregular, spongy wicker-work or loose reticulations, with or without a medullary shell in the centre.

The Six Radial Spines of the Cubosphærida are normally opposite in pairs in the three dimensive axes, each of which is perpendicular to the other two. But in many species besides this normal form occur individual abnormalities, in which the six spines are not quite accurately opposed, but more or less divergent; and often also the three dimensive planes (determined each by two axes) are not quite regular, but more or less uneven. More rarely the six spines appear disposed in quite an irregular manner.

In the greater part of the Cubosphærida all six spines are quite equal, of the same size and form. But in some genera a more or less considerable differentiation takes place, so {170}that two pairs or all three pairs of spines become different; very rarely, also both spines of one pair become unequal (probably only an individual abnormality). Those variations correspond to the differences between the crystalline systems. The common Cubosphærida, with three equal spine-pairs, correspond to the regular or cubic system, with three equal axes. The rarer forms (Hexastylarium, Hexaloncharium, Hexacontarium) exhibit two equal pairs and one different pair; they correspond to the quadratic system, with three perpendicular axes, two of which are equal, the third unequal. Still more rare are those forms (Hexastylidium, Hexalonchidium), in which all three pairs of spines are different, corresponding to the three unequal axes of the rhombic crystalline system.

Synopsis of the Genera of Cubosphærida.

{All six radial spines simple, I. Subfamily { of equal size, 72. Hexastylus. Hexastylida. { (Shell one {Six spines of {Two pairs equal, simple { different sizes,{ one pair latticed { all six simple. { different, 73. Hexastylarium. sphere.) { { { {All three pairs { { different, 74. Hexastylidium.

{All six radial {Spines simple, 75. Hexalonche. { spines of { II. Subfamily { equal size. {Spines branched, 76. Hexancistra. Hexalonchida. { (Shell composed {Six spines {Two pairs equal, of two { simple, in { one pair concentric { pairs of { different, 77. Hexaloncharium. latticed { different sizes. spheres.) { {All three pairs { { different, 78. Hexalonchidium.

{All six radial {Spines simple, 79. Hexacontium. III. Subfamily { spines of { Hexacontida. { equal size. {Spines branched, 80. Hexadendron. (Shell composed { of three {Six spines Two pairs equal, spheres.) { simple, of one pair { different sizes. different, 81. Hexacontarium.

IV. Subfamily }All six radial Spines simple, Hexacromyida. } spines of not branched, 82. Hexacromyum. (Four concentric} equal size. spheres.) }

V. Subfamily }All six radial {Spines simple, 83. Cubosphæra. Hexacaryida. } spines of { (Five or more } equal size. {Spines branched, 84. Hexacaryum. spheres.) }

{Without latticed { medullary VI. Subfamily }All six radial { shell, 85. Cubaxonium. Hexadorida. } spines of { (Shell a spongy } equal size, {With one single sphere, with } simple (not { medullary or without an } branched). { shell, 86. Hexadoras. enclosed } { central } {With two medullary } { medullary shell.) } { shells, 87. Hexadoridium.

{171}Subfamily HEXASTYLIDA,[100] Haeckel, 1881, Prodromus, pp. 449, 450.

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

Genus 72. Hexastylus,[101] Haeckel, 1881, Prodromus, p. 450.

Definition.--#Cubosphærida# with one simple lattice-sphere and six simple spines of equal size.

The genus Hexalonche is the most simple form of all Cubosphærida, and may be regarded as the common ancestral form of this family. It can be derived phylogenetically from Cenosphæra, by development of six radial spines on the surface of the simple spherical lattice-shell. These six simple spines are of equal size and opposite in pairs in the three dimensive axes, corresponding to the three equal axes of a cubic crystal.

Subgenus 1. Hexastylanthus, Haeckel.

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

1. Hexastylus phænaxonius, n. sp. (Pl. 21, fig. 3).

Shell thin walled, with smooth surface. Pores subregular, hexagonal, five to six times as broad as the bars; nine to ten on the radius. Six spines triangular pyramidal, as long as the radius of the shell, as broad at the base as one pore.

Dimensions.--Diameter of the shell 0.13, pores 0.008 to 0.01, bars 0.0015; length of the spines 0.07, basal breadth 0.008 to 0.012.

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

2. Hexastylus sapientum, n. sp.

Shell thin walled, with smooth surface. Pores regular, hexagonal, eight to ten times as broad as the bars; six to seven on the radius. Six spines bristle-shaped, longer than the diameter of the shell. (Lattice-work and spines similar to those of Heliosphæra actinota, Monogr. d. Radiol., Taf. ix. fig. 3.)

Dimensions.--Diameter of the shell 0.15, pores 0.016, bars 0.002; length of the spines 0.2, breadth 0.002.

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

{172}3. Hexastylus thaletis, n. sp. (Pl. 21, fig. 4).

Shell thin walled, with smooth surface. Pores subregular, circular, hexagonally framed, somewhat funnel-shaped, of the same breadth as the bars; eight to nine on the radius. Six spines triangular pyramidal, with prominent edges, as long as the radius, three to four times as broad at the base as one pore.

Dimensions.--Diameter of the shell 0.1, pores and bars 0.005; length of the spines 0.05, basal breadth 0.02.

Habitat.--Tropical Pacific, Station 225, depth 4575 fathoms.

4. Hexastylus favosus, n. sp.

Shell thick walled, with smooth surface. Pores regular, circular, hexagonally framed, deep funnel-shaped, of the same breadth as the bars; six to seven on the radius. Six spines triangular pyramidal, as long as the diameter, twice as broad at the base as one pore.

Dimensions.--Diameter of the shell 0.12, pores and bars 0.01; length of the spines 0.12, basal breadth 0.02.

Habitat.--South Atlantic, Station 320, surface.

5. Hexastylus longissimus, n. sp.

Shell thick walled, with smooth surface. Pores regular, circular, hexagonally framed, of the same breadth as the bars; five to six on the radius. Six spines triangular prismatic, extremely elongated, ten to twenty times as long as the diameter of the shell, twice as broad as one pore.

Dimensions.--Diameter of the shell 0.08, pores and bars 0.008; length of the spines 1.0 to 1.5, breadth 0.015.

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

6. Hexastylus minimus, n. sp. (Pl. 21, fig. 5).

Shell thin walled, with smooth surface. Pores subregular, circular, twice as broad as the bars; five to six on the radius. Six spines triangular pyramidal, scarcely as long as the radius, at the base half as broad as long.

Dimensions.--Diameter of the shell 0.05, pores 0.004, bars 0.002; length of the spines 0.02, basal breadth 0.01.

Habitat.--Tropical Pacific, Station 225, depth 4575 fathoms.

7. Hexastylus biantis, n. sp.

? Haliphormis hexacantha, Ehrenberg, 1872, L. N. 24, Taf. x. fig. 6.

Shell thin walled, smooth. Pores regular, circular, four times as broad as the bars; eight to nine on the radius. Six spines conical, as long as the radius, at the base as broad as one pore.

{173}Dimensions.--Diameter of the shell 0.12, pores 0.012, bars 0.003; length of the spines 0.06, basal breadth 0.012.

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

8. Hexastylus pittaci, n. sp.

Shell thin walled, smooth. Pores regular, circular, ten to twelve times as broad as the bars; six to seven on the radius. Six spines triangular pyramidal, as long as the radius, as broad as one pore.

Dimensions.--Diameter of the shell 0.12, pores 0.02, bars 0.002; length of the spines 0.06, basal breadth 0.02.

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

9. Hexastylus maximus, n. sp.

Shell thick walled, smooth. Pores regular, circular, twice as broad as the bars; twelve to sixteen on the radius. Six spines six-sided pyramidal, half as long as the radius, three times as broad as one pore.

Dimensions.--Diameter of the shell 0.3, pores 0.01, bars 0.005; length of the spines 0.08, basal breadth 0.03.

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

10. Hexastylus periandri, n. sp.

Shell thick walled, smooth. Pores regular, circular, double-edged, four times as broad as the bars; six to seven on the radius. Six spines conical, as long as the radius, twice as broad as one pore.

Dimensions.--Diameter of the shell 0.2, pores 0.012, bars 0.003; length of the spines 0.1, basal breadth 0.025.

Habitat.--Tropical Atlantic, Station 335, depth 1425 fathoms.

Subgenus 2. Hexastylettus, Haeckel.

Definition.--Pores regular or subregular, of nearly equal size and form; surface of the spherical shell spiny, covered with numerous conical or bristle-shaped radial by-spines.

11. Hexastylus solonis, n. sp. (Pl. 21, fig. 11).

Shell thick walled, covered with numerous bristle-shaped radial spines (one-third to one-half as long as the six main spines, arising from the lattice-knots). Pores regular, circular, enclosed by prominent, hexagonal frames, four to six times as broad as the bars; seven to eight on the radius. {174}Six main spines triangular pyramidal, with spirally contorted prominent edges, as long as the radius, as broad at the base as one pore.

Dimensions.--Diameter of the shell 0.13, pores 0.01, bars 0.002; length of the spines 0.06 to 0.8, basal breadth 0.01.

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

12. Hexastylus cochleatus, n. sp. (Pl. 21, fig. 1).

Shell thick walled, covered with numerous short, conical spines (about as large as one pore). Pores regular, circular, three times as broad as the bars; eight to nine on the radius. Six main spines triangular pyramidal, with prominent, spirally-twisted edges, as long as the diameter of the shell, and twice as broad at the base as one pore.

Dimensions.--Diameter of the shell 0.17, pores 0.015, bars 0.005; length of the spines 0.16, breadth 0.03.

Habitat.--Mediterranean, Corfu, Haeckel, surface.

13. Hexastylus setosus, Haeckel.

Acanthosphæra setosa, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 285, Taf. ix. fig. 11.

Shell thin walled, covered with numerous short, bristle-shaped spines (not larger than one pore). Pores regular, circular, four times as broad as the bars; thirteen to sixteen on the radius. Six main spines three-sided pyramidal, scarcely one-third as long as the radius. (In the figure of Ehrenberg, loc. cit., only four spines are in regular, crossed disposition, two others opposite in oblique direction; this is either an individual abnormality, or an error of drawing; the same species occurs with six spines exactly regularly disposed in the three dimensive axes.)

Dimensions.--Diameter of the shell 0.15; pores 0.008, bars 0.002; length of the spines 0.02 to 0.03, basal breadth 0.005.

Habitat.--Indian Ocean, Zanzibar, Pullen; Madagascar, Rabbe.

14. Hexastylus chilonis, n. sp.

Shell thin walled, covered with numerous bristle-shaped spines (as long as the radius). Pores regular, circular, twice as broad as the bars; eight to nine on the radius. Six main spines triangular pyramidal, with straight edges, as long as the diameter of the shell, as broad as two pores.

Dimensions.--Diameter of the shell 0.2, pores 0.02, bars 0.01; length of the spines 0.2, basal breadth 0.05.

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

15. Hexastylus cleobuli, n. sp.

Shell thick walled, covered with numerous short, conical spines (twice as large as one pore). Pores regular, circular, of the same breadth as the bars; twelve to thirteen on the radius. Six main spines conical, as long as the radius, three times as broad as one pore.

{175}Dimensions.--Diameter of the shell 0.24, pores and bars 0.005; length of the spines 0.12, basal breadth 0.016.

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

Subgenus 3. Hexastylissus, Haeckel.

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

16. Hexastylus triaxonius, n. sp. (Pl. 21, fig. 2).

Shell thin walled, with smooth surface. Pores irregular, polygonal, three to six times as broad as the bars; four to six on the radius. Six spines triangular pyramidal, as long as the diameter of the shell, as broad at the base as one pore.

Dimensions.--Diameter of the shell 0.05, pores 0.004 to 0.008, bars 0.0015; length of the spines 0.04, basal breadth 0.006.

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

17. Hexastylus dimensivus, n. sp. (Pl. 21, fig. 6).

Shell thin walled, with smooth surface. Pores irregular, polygonal, four to eight times as broad as the bars; eleven to thirteen on the radius. Six spines hexagonal pyramidal, as long as the radius, about three times as broad at the base as one pore.

Dimensions.--Diameter of the shell 0.13, pores 0.006 to 0.009, bars 0.0012; length of the spines 0.06, basal breadth 0.025.

Habitat.--North Pacific, Station 256, depth 2950 fathoms.

18. Hexastylus brevispinus, n. sp.

Shell thin walled, with smooth surface. Pores irregular, roundish, two to four times as broad as the bars; six to eight on the radius. Six spines triangular pyramidal, half as long as the radius, twice as broad as one pore.

Dimensions.--Diameter of the shell 0.2, pores 0.008 to 0.016, bars 0.004; length of the spines 0.05, basal breadth 0.025.

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

19. Hexastylus longispinus, n. sp.

Shell thick walled, smooth. Pores irregular, roundish, two to three times as broad as the bars; three to four on the radius. Six spines triangular prismatical, two to three times as long as the diameter of the shell.

{176}Dimensions.--Diameter of the shell 0.08, pores 0.008 to 0.012, bars 0.004; length of the spines 0.2, breadth 0.01.

Habitat.--North Atlantic, Station 353, surface.

20. Hexastylus marginatus, n. sp. (Pl. 21, fig. 10).

Shell thick walled, rough. Pores irregular, roundish, somewhat funnel-shaped double-edged, two to three times as broad as the bars; twelve to fourteen on the radius. Six spines three-sided pyramidal, somewhat longer than the radius, three times as broad as one pore.

Dimensions.--Diameter of the shell 0.15, pores 0.007 to 0.01, bars 0.004; length of the spines 0.1, basal breadth 0.025.

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

21. Hexastylus conifer, n. sp.

Shell thick walled, rough. Pores irregular, roundish, scarcely broader than the bars; fifteen to sixteen on the radius. Six spines conical, as long as the radius, five to seven times as broad as one pore.

Dimensions.--Diameter of the shell 0.18, pores and bars 0.004 to 0.006; length of the spines 0.1, basal breadth 0.03.

Habitat.--Indian Ocean, Sunda Strait, Rabbe, surface.

Subgenus 4. Hexastylurus, Haeckel.

Definition.--Pores irregular, of unequal size or form; surface of the spherical shell spiny, covered with numerous conical or bristle-shaped by-spines.

22. Hexastylus dictyotus, n. sp. (Pl. 21, figs. 8, 9).

Shell thin walled, spiny; short spines conical, smaller than the pore-breadth. Pores irregular, polygonal, five to seven times as broad as the bars; four to six on the radius. Six spines triangular pyramidal, longer than the radius, about as broad as one smaller pore.

Dimensions.--Diameter of the shell 0.09, pores 0.01 to 0.015, bars 0.002; length of the spines 0.06, basal breadth 0.01.

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

23. Hexastylus hirsutus, n. sp.

Shell thin walled, densely covered with bristle-shaped, radial spines, half as long as the six main spines. Pores irregular, polygonal, three to four times as broad as the bars; eight to ten on the radius. Six spines triangular pyramidal, as long as the radius, twice as broad as one pore.

{177}Dimensions.--Diameter of the shell 0.14, pores 0.005 to 0.008, bars 0.002; length of the spines 0.06, basal breadth 0.01.

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

24. Hexastylus contortus, n. sp. (Pl. 21, fig. 12).

Shell thick walled, covered with bristle-shaped, radial spines, half as long as the radius. Pores irregular, roundish, two to three times as broad as the bars; seven to eight on the radius. Six spines triangular prismatic, in the distal half spirally twisted like a cork-screw (fig. 12); longer than the diameter of the shell, about as broad as one pore.

Dimensions.--Diameter of the shell 0.12, pores 0.006 to 0.008, bars 0.003; length of the spines 0.15, breadth 0.015.

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

25. Hexastylus spiralis, n. sp. (Pl. 21, fig. 7).

Shell thick walled, covered with short conical spines. Pores irregular, roundish, two to three times as broad as the bars; five to six on the radius. Six spines triangular prismatic, with three thin, spirally contorted edges, two to three times as long as the diameter of the shell, about as broad as one large pore.

Dimensions.--Diameter of the shell 0.16, pores 0.01 to 0.02, bars 0.006; length of the spines 0.3 to 0.5, basal breadth 0.02.

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

Genus 73. Hexastylarium,[102] n. gen.

Definition.--#Cubosphærida# with one simple lattice-sphere and six simple spines of different sizes; one opposite pair larger than the other two.

The genus Hexastylarium differs from its probable ancestral form, Hexastylus, by the unequal growth of the six simple spines; two opposite spines of one pair being more strongly developed than the four others, which are equal. They correspond therefore to the three axes of a quadratic crystal.

1. Hexastylarium heteraxonium, n. sp.

Cortical shell thin walled, smooth, with regular, hexagonal pores, three times as broad as the bars; eight to ten on the radius. Six spines three-sided pyramidal, at the base as broad as one pore. Two opposite major spines longer than the shell diameter; four others scarcely as long as {178}the radius. (Similar to Hexastylus phænaxonius, Pl. 21, fig. 3, but differing in the unequal length of the spines.)

Dimensions.--Diameter of the shell 0.15, pores 0.12, bars 0.004; length of the two major spines 0.2, of the four minor 0.07.

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

2. Hexastylarium quadratum, n. sp.

Shell very delicate, with smooth surface, and irregular, polygonal pores, separated by very thin bars. The form of the shell is not, as commonly, a sphere, but a geometrical square octahedron, one axis (with two opposite major spines) being nearly twice as long as the other two dimensive axes; four spines, opposite by pairs in the latter, are only half as long. The eight sides of the octahedral shell are even, equilateral-triangular. Spines angular, thin.

Dimensions.--Diameter of the shell in the major axis 0.18, in the minor 0.1; length of the major spines 0.24, minor 0.12.

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

3. Hexastylarium elongatum, n. sp.

Shell thick walled, with spiny surface, and with irregular, roundish pores, two to four times as broad as the bars; eight to ten on the radius. Two opposite major spines, three to four times as long as the shell diameter, whilst the four other spines are very short, scarcely as long as the radius. All six spines at the base three-sided pyramidal, the two longer being cylindrical.

Dimensions.--Diameter of the shell 0.1; length of the major spines 0.3 to 0.4, of the minor 0.04, basal breadth 0.02.

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

Genus 74. Hexastylidium,[103] Haeckel, 1881, Prodromus, p. 450.

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

The genus Hexastylidium differs from its probable ancestral form, Hexastylus, by the unequal growth of the six simple spines; the two spines of each pair reaching the same dimensions, whilst the three pairs are different. They correspond therefore to the three axes of a rhombic crystal.

1. Hexastylidium rhomboides, n. sp.

Shell thin walled, smooth, with irregular, polygonal pores and very thin bars. Its form is not, as commonly, a sphere, but a rhombic octahedron. The radial proportion of the three unequal {179}dimensive axes = 1 : 2 : 4. The radial proportion of the three pairs of spines = 1 : 3 : 8. Spines thin cylindrical, at the base angular.

Dimensions.--Diameter of the major shell axis 0.2, middle 0.1, minor 0.05; length of the major spines 0.3, middle 0.12, minor 0.04.

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

2. Hexastylidium spirale, n. sp.

Shell thick walled, spherical, thorny, with irregular, roundish pores, three to five times as broad as the bars; six spines very stout, prismatic (as broad as one large pore), with three ring-like, spirally convoluted edges. Two opposite major spines of extraordinary length, ten to twelve times as long as the shell diameter, the two middle opposite spines being about as long as the latter, the two minor scarcely one-third as long. (Similar to Hexastylus spiralis, Pl. 21, fig. 7, but distinguished by the very unequal length of the spines.)

Dimensions.--Diameter of the shell 0.12; length of the major spines 1 to 1.5 mm., middle 0.15, minor 0.04.

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

Subfamily HEXALONCHIDA,[104] Haeckel, 1881, Prodromus, pp. 449, 451.

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

Genus 75. Hexalonche,[105] Haeckel, 1881, Prodromus, p. 451.

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

The genus Hexalonche is the most simple form, and probably the common ancestral form, of all Hexalonchida, or those Cubosphærida which possess two concentric latticed spheres, connected by six radial beams. Commonly one shell is intracapsular (medullary shell) and the other extracapsular (cortical shell); but sometimes also both shells are extracapsular, and these forms may perhaps be better separated as a peculiar genus Hexadilemma. In Hexalonche all six simple spines are of equal size, and opposite by pairs in three equal dimensive axes, corresponding to the three equal axes of a tesseral crystal. It can be derived from Hexastylus by duplication of the lattice-shell.

Subgenus 1. Hexalonchara, Haeckel.

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

{180}1. Hexalonche phænaxonia, n. sp.

Cortical shell thin walled, smooth; its pores regular, hexagonal, six to eight times as broad as the bars; eight to ten to twelve on the radius. Medullary shell one-third as broad, with regular, hexagonal pores of half size. Six spines triangular pyramidal, as long as the radius of the shell, at the base as broad as one pore. (Differs from Hexastylus phænaxonius, Pl. 21, fig. 3, only in the medullary shell and the six inner radial beams, connecting it with the cortical shell.)

Dimensions.--Diameter of the outer shell 0.15, pores 0.01 to 0.015, bars 0.015 to 0.02; inner shell 0.05; length of the spines 0.08, basal breadth 0.01.

Habitat.--Central Pacific, Stations 266 to 271, depth 2425 to 2925 fathoms.

2. Hexalonche rosetta, n. sp. (Pl. 25, figs. 3, 3_a_, 3_b_).

Cortical shell thick walled, smooth, two and a half time as broad as the medullary shell. Pores of the latter (fig. 3_a_) regular circular; eight to ten on the half meridian, about as broad as the bars between them. Pores of the outer shell regular, hexagonal, remarkable for a very peculiar form and arrangement. In the transverse section of the shell (fig. 3_b_) they appear as narrow, hexagonal prismatic canals, twice as high as broad, and four to five times as broad as the thin elevated bars between them. Every seven meshes form together a larger, regular hexagon (six pores surrounding one central pore). The periphery of these larger, rosette-like hexagons projects more strongly from the surface than the walls between the smaller hexagons. On the half meridian of the shell may be counted six to seven larger and eighteen to twenty smaller hexagons. The six radial beams between the two shells are thin, three-sided prismatic, not broader than the bars of the network, the prominent prolongations of which form six very strong spines of peculiar club-like shape (fig. 3), as long as the radius of the outer shell. The three wings of the club are lower in the inner, higher in the outer half; the broadest part of the spine (at the base and in the outer third) is as broad as a hexagonal rosette (equal to three meshes of the outer shell); its outer apex is pyramidal.

Dimensions.--Diameter of the outer shell 0.13, pores 0.008 to 0.01, bars 0.02; inner shell 0.05; length of the spines 0.07, distal breadth 0.03.

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

3. Hexalonche favosa, n. sp.

Cortical shell thick walled, smooth, four times as broad as the medullary shell. Pores of the former regular circular, hexagonally framed, deep funnel-shaped, of the same breadth as the bars; six to eight on the radius. Six spines triangular-pyramidal, as long as the radius, at the base twice as broad as one pore. (Differs from the similar Hexastylus favosus mainly in the possession of a medullary shell.)

Dimensions.--Diameter of the outer shell 0.16, pores and bars 0.012; inner shell 0.04; length of the spines 0.08, basal breadth 0.025.

Habitat.--Equatorial Atlantic, Station 348, depth 2450 fathoms; also fossil in Barbados.

{181}4. Hexalonche octahedra, n. sp. (Pl. 22, figs. 8, 8_a_).

Cortical shell a regular octahedron, thin walled, with twelve more or less rounded edges (between the bases of the spines), and with smooth surface, three times as broad as the spherical medullary shell. Pores of the former regular circular (three times as large as those of the latter), four times as broad as the bars; five to seven on the radius. Six spines three-sided prismatic, with thickened base and cuspidated end, somewhat longer than the radius, and once to twice as broad as one pore.

Dimensions.--Diameter of the outer shell 0.11, pores 0.01, bars 0.0025; inner shell 0.04; length of the spines 0.08, bars 0.01.

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

5. Hexalonche conicornis, n. sp. (Pl. 22, fig. 2).

Cortical shell thick walled, smooth, three times as broad as the medullary shell. Pores of both spheres regular circular, three to four times as broad as the bars; those of the thick walled outer shell six to seven on the radius, twice as large as those of the thin walled inner shell; six radial beams between the two spheres, very thin, cylindrical; six spines short, conical, scarcely as long as the radius of the outer shell, at the base twice as broad as one pore.

Dimensions.--Diameter of the outer shell 0.12 to 0.14, pores 0.01, bars 0.003; inner shell 0.04 to 0.05; length of the spines 0.04 to 0.06, basal breadth 0.02.

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

6. Hexalonche curvicornis, n. sp. (Pl. 25, fig. 4).

Cortical shell thick walled, smooth, not much larger than the medullary shell (= 4 : 3). Pores of both spheres regular circular, nearly of the same size, three times as broad as the bars between them; seven to nine on the radius. Six spines three-sided prismatic, inside and outside of the exterior shell of equal thickness, twice as broad as one pore, longer than the diameter of the outer shell, and in a singular manner curved like an ox horn; the three edges of each horn somewhat spirally twisted.

Dimensions.--Diameter of the outer shell 0.16, pores 0.01, bars 0.003; inner shell 0.12; length of the spines 0.2, breadth 0.02.

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

7. Hexalonche brevicornis, n. sp.

Cortical shell thin walled, smooth, three times as broad as the medullary shell. Pores of the former regular circular, double-edged, six to eight times as broad as the thin bars, five to six on the radius. Six spines triangular pyramidal, as broad as one pore and only twice as long.

Dimensions.--Diameter of the outer shell 0.14, pores 0.02, bars 0.003; inner shell 0.045; length of the spines 0.05, basal breadth 0.02.

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

{182}8. Hexalonche grandis, n. sp.

Cortical shell thick walled, smooth, four times as broad as the medullary shell. Pores of the outer shell regular circular, four times as broad as the bars; thirteen to fifteen on the radius. Six spines conical, scarcely half as long as the radius, at the base as broad as one pore.

Dimensions.--Diameter of the outer shell 0.2 to 0.32, pores 0.01 to 0.02, bars 0.003 to 0.005; inner shell 0.06 to 0.08; length of the spines 0.06, breadth 0.02.

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

Subgenus 2. Hexalonchetta, 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 by-spines.

9. Hexalonche amphisiphon, n. sp. (Pl. 25, figs. 2, 2_a_, 2_b_).

Cortical shell thin walled, armed with very numerous bristle-shaped, radial by-spines, a quarter to a half as long as the six main spines. Pores regular hexagonal, twelve to fourteen on the radius, with very thin bars, prolonged on the outer as well as the inner surface into a short truncated conical tube (Pl. 25, fig. 2_b_). Medullary shell octahedral, with irregular polygonal meshes and very thin bars between them (fig. 2_a_), connected with the outer (six to eight times larger) shell by six very thin radial beams. These are prolonged outside into six strong pyramidal spines, nearly as long as the diameter of the outer shell, with sharp straight edges, at the base twice as broad as one pore.

Dimensions.--Diameter of the outer shell 0.15, pores 0.01, bars 0.001; inner shell 0.02; length of the spines 0.12, basal breadth 0.02.

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

10. Hexalonche anaximandri, n. sp. (Pl. 22, fig. 5).

Cortical shell thin walled, covered with short conical spines (smaller than the pores), three times as broad as the medullary shell. Pores of the outer shell subregular hexagonal, four times as broad as the bars; five to seven on the radius. Inner shell with regular hexagonal pores of half the size, connected with the outer by six strong, three-sided prismatic beams, which are prolonged outside into six very stout pyramidal spines, with three prominent edges, longer than the radius and twice as broad as one pore.

Dimensions.--Diameter of the outer shell 0.12, pores 0.01, bars 0.0025; inner shell 0.04; length of the spines 0.07, basal breadth 0.02.

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

{183}11. Hexalonche octocolpa, n. sp. (Pl. 22, figs. 6, 6_a_).

Cortical shell thin walled, nearly octahedral, with eight hemispherical or bosom-shaped vaultings, corresponding to the eight faces of a regular octahedron, the three axes of which are indicated by the six spines. Surface covered with short bristle-shaped spines. Pores regular hexagonal, ten to fifteen times as broad as the thin bars; seven to nine on the radius. Medullary shell (fig. 6_a_) spherical, with regular circular pores, one-third as broad as the cortical shell, and connected with it by six strong triangular radial beams, which are prolonged outside into pyramidal spines, one-third as long as the shell diameter.

Dimensions.--Diameter of the outer shell 0.2, pores 0.03, bars 0.002; inner shell 0.06; length of the spines 0.06, breadth 0.02.

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

12. Hexalonche cristata, n. sp.

Cortical shell thick walled, four times as broad as the medullary shell, and covered with short conical spines arising from the nodal points of elevated crests which form regular hexagonal frames around the funnel-shaped circular pores. These are two to three times as broad as the crested bars; eight to ten on the radius. Six spines three-sided pyramidal, with strong prominent edges, about as long as the radius of the shell.

Dimensions.--Diameter of the outer shell 0.16 to 0.2, pores 0.01 to 0.015, bars 0.003 to 0.005; inner shell 0.04 to 0.05; length of the spines 0.08 to 0.12, basal breadth 0.01 to 0.03.

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

13. Hexalonche serrata, n. sp.

Cortical shell thick walled, four times as broad as the medullary shell, with spiny surface. Pores regular circular, twice as broad as the bars, five to seven on the radius, funnel-shaped, separated by hexagonal frames, the sharp crests of which are serrated; at the nodal-points longer bristle-shaped by-spines. Six main spines triangular prismatic, longer than the diameter of the shell, twice as broad as one pore.

Dimensions.--Diameter of the outer shell 0.15, pores 0.01, bars 0.005; inner shell 0.04; length of the spines 0.2, breadth 0.02.

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

14. Hexalonche anaximenis, n. sp. (Pl. 25, fig. 5).

Cortical shell thin walled, twice as broad as the medullary shell, and covered with short conical by-spines. Pores regular circular, twice as broad as the bars; five to six on the radius. Circular pores of the medullary shell one-third as broad. Radial main spines conical, nearly as long as the radius of the shell.

Dimensions.--Diameter of the outer shell 0.1, pores 0.01, bars 0.005; inner shell 0.05; length of the spines 0.04, basal breadth 0.015.

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

{184}15. Hexalonche aspera, n. sp.

Cortical shell thin walled, three times as broad as the medullary shell, and covered with short conical spines. Pores regular circular, four to six times as broad as the bars; eight to ten on the radius. Radial spines conical, about as long as the diameter of the shell.

Dimensions.--Diameter of the outer shell 0.12, pores 0.08, bars 0.0015; inner shell 0.04; length of the spines 0.1, basal breadth 0.02.

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

16. Hexalonche castanella, n. sp.

Cortical shell thick walled, five times as broad as the medullary shell, and covered with numerous short conical spines. Pores regular circular, twice as broad as the bars; ten to twelve on the radius. Radial spines triangular pyramidal, about as long as the radius of the shell.

Dimensions.--Diameter of the outer shell 0.22, pores 0.01, bars 0.005; inner shell 0.045; length of the spines 0.12, basal breadth 0.02.

Habitat.--North Atlantic, Station 353, depth 3125 fathoms.

Subgenus 3. Hexalonchilla, Haeckel.

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

17. Hexalonche hexacantha, Haeckel.

Haliomma hexacanthum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 35, Taf. iv. fig. 5.

Haliomma hexacanthum, Haeckel, 1862, Monogr. d. Radiol., p. 430.

Cortical shell thin walled, smooth, with irregular polygonal pores (commonly hexagonal or pentagonal), two to three times as broad as the bars; eight to ten on the radius. Medullary shell one quarter as broad, connected with the former by six thin radial beams which are prolonged outside into six triangular pyramidal spines (not quadrangular, as Müller describes), longer than the radius of the shell.

Dimensions.--Diameter of the outer shell 0.2, pores 0.01 to 0.015, bars 0.005; inner shell 0.05; length of the spines 0.15, basal breadth 0.015.

Habitat.--Mediterranean (Messina, Nice, Genoa).

18. Hexalonche geometrica, n. sp.

Cortical shell thick walled, smooth, with very peculiar geometrical formation of its network, the pores of which are of very different size and form, but highly regular disposition. Each of the six {185}triangular spines is surrounded at the base by three small roundish pores (between the three wings of its base), and further by a coronal of six very large pores, three of which are pentagonal, and the other three (alternating) heptagonal. The six basal coronals are separated by irregular smaller pores. Medullary shell thin walled, with regular hexagonal pores (three on the radius) and thin bars, connected with the outer shell by six thin triangular prismatic radial beams, which are prolonged outside into short pyramidal spines (half as long as the radius).

Dimensions.--Diameter of the outer shell 0.2, thirty-six larger pores of the coronals 0.03 to 0.04, smaller pores between them 0.01 to 0.02, bars 0.005; inner shell 0.05 (with pores of 0.008); length of the spines 0.05, basal breadth 0.03.

Habitat.--South Atlantic, off Buenos Ayres, Station 323, depth 1900 fathoms.

19. Hexalonche pythagoræa, n. sp. (Pl. 22, fig. 1).

Cortical shell thick walled, smooth, three times as broad as the medullary shell. Pores irregular roundish, twice to eight times as broad as the bars, of very different size; usually in the space between every three spines are three or six larger pores, separated by numerous smaller pores (often the disposition of the larger pores is much more regular than in the figured specimen). Medullary shell with regular circular pores, connected with the outer by six very thin radial beams, which are prolonged outside into six short triangular pyramidal spines about as long and broad as the half radius.

Dimensions.--Diameter of the outer shell 0.12, pores 0.008 to 0.03, bars 0.004; inner shell 0.04; length of the spines 0.04, basal breadth 0.03.

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

20. Hexalonche aristarchi, n. sp. (Pl. 22, fig. 3).

Cortical shell thin walled, smooth, four times as broad as the medullary shell. Pores irregular polygonal, of very variable size and form, twice to six times as broad as the bars; six to ten on the radius. Medullary shell with regular hexagonal pores, connected with the outer by six very thin radial beams, which are prolonged outside into six triangular pyramidal spines, nearly as long as the radius.

Dimensions.--Diameter of the outer shell 0.1, pores 0.005 to 0.02, bars 0.003; inner shell 0.025; length of the spines 0.05, basal breadth 0.01.

Habitat.--North Pacific, Station 241, depth 2300 fathoms.

21. Hexalonche ekphantæa, n. sp.

Cortical shell thin walled, smooth, four times as broad as the medullary shell. Pores irregular roundish, of very variable size and form, twice to six times as broad as the bars, ten to fifteen on the radius. Six spines cylindro-conical, longer than the diameter of the shell.

Dimensions.--Diameter of the outer shell 0.2, pores 0.004 to 0.012, bars 0.002; inner shell 0.05; length of the spine 0.3, basal breadth 0.01.

Habitat.--Indian Ocean, Sunda Strait, surface, Rabbe.

{186}Subgenus 4. Hexalonchusa, Haeckel.

Definition.--Pores of the cortical shell irregular, of different size or form; surface covered with numerous conical or bristle-shaped, radial by-spines.

22. Hexalonche philosophica, n. sp. (Pl. 22, fig. 4).

Cortical shell thin walled, covered with short conical spines, three times as broad as the medullary shell. Pores irregular polygonal, or more roundish, twice to six times as broad as the bars; six to eight on the radius. Inner shell of the same structure, pores three times smaller, connected with the outer by six very thin radial beams, which are prolonged outside into six strong, triangular pyramidal spines, as long as the radius. (Similar to Hexalonche anaximandri, Pl. 22, fig. 5, but different in the irregular network and the shorter by-spines.)

Dimensions.--Diameter of the outer shell 0.11, pores 0.005 to 0.015, bars 0.0025; inner shell 0.04; length of the spines 0.06, breadth 0.02.

Habitat.--North Atlantic, Færöe Channel, John Murray; Iceland, Krabbe, surface.

23. Hexalonche seleuci, n. sp.

Cortical shell thick walled, covered with numerous short, bristle-shaped spines. Pores of very different size and form, and of a peculiar, subregular disposition, similar to those of Hexalonche geometrica (though in this case more regular). Each of the six triangular main spines (which reach nearly the length of the radius) is surrounded at the base by three small roundish pores, and these are further supplemented by a coronal of six very large polygonal pores; the six coronals are separated by irregular rows of smaller pores. Inner shell equal to one-third of the outer. Six main spines pyramidal, as long as the radius.

Dimensions.--Diameter of the outer shell 0.16, larger pores 0.03 to 0.04, smaller pores 0.01 to 0.02, bars 0.05 to 0.01; inner shell 0.05; length of the spines 0.08, basal breadth 0.03.

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

24. Hexalonche sexaculeata, Haeckel.

Haliomma sexaculeatum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 87, Taf. i. fig. 8.

Cortical shell thick walled, twice as broad as the medullary shell, and covered with short conical spines. Pores irregular polygonal (mostly hexagonal), twice to three times as broad as the bars; six to eight on the radius. Six spines triangular-pyramidal (not quadrangular), somewhat longer than the radius of the shell.

Dimensions.--Diameter of the outer shell 0.11, pores 0.06 to 0.08, bars 0.03; inner shell 0.06; length of the spines 0.07, basal breadth 0.015.

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

{187}25. Hexalonche heracliti, n. sp. (Pl. 22, fig. 7).

Cortical shell thick walled, covered with bunches of small spines, each bunch at the nodule point between every three pores composed of four to eight conical spinules. Pores irregular roundish, twice to four times as broad as the bars; four to six on the radius. Inner shell equal to one-third of the outer, connected with it by six thin radial beams, which are prolonged outside into six strong triangular spines about as long as the radius.

Dimensions.--Diameter of the outer shell 0.15, pores 0.015 to 0.03, bars 0.08; inner shell 0.05; length of the spines 0.06, basal breadth 0.02.

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

26. Hexalonche xenophanis, n. sp.

Cortical shell thin walled, covered with numerous short conical spines, four times as broad as the medullary shell. Pores irregular circular, twice to eight times as broad as the bars; five to seven on the radius. Six spines conical or more cylindrical, as long as the diameter of the shell or longer.

Dimensions.--Diameter of the outer shell 0.16 to 0.24, pores 0.01 to 0.04, bars 0.005; inner shell 0.04 to 0.06; length of the spines 0.2 to 0.3, breadth 0.02.

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

27. Hexalonche setosa, n. sp.

Cortical shell thin walled, covered with numerous bristle-shaped spines, half as long as the six main spines. Pores irregular roundish, twice to five times as broad as the bars; ten to twelve on the radius. Inner shell equal to one-fifth of the outer. Six spines conical, as long as the radius.

Dimensions.--Diameter of the outer shell 0.25, pores 0.008 to 0.02, bars 0.004; inner shell 0.05; length of the spines 0.12, basal breadth 0.03.

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

28. Hexalonche hystricina, n. sp. (Pl. 25, fig. 6).

Cortical shell thick walled, covered with numerous bristle-shaped spines, half as long as the six main spines. Pores irregular roundish, twice to four times as broad as the bars; five to seven on the radius. Medullary shell with very small circular pores, one-fourth of the cortical shell, connected with it by six thin prismatic radial beams, which are prolonged outside into six strong, short, three-sided pyramidal, cuspidated spines, only half as long as the radius of the outer shell.

Dimensions.--Diameter of the outer shell 0.2, pores 0.015 to 0.03, bars 0.008; inner shell 0.05; length of the spines 0.05, basal breadth 0.02.

Habitat.--Indian Ocean, Sunda Strait, surface, Rabbe.

{188}Genus 76. Hexancistra,[106] Haeckel, 1881, Prodromus, p. 451.

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

The genus Hexancistra differs from its ancestral form, Hexalonche, in the ramification of the six radial spines. These are very different in the two subgenera; in Hexancora each spine bears only three simple lateral branches, while in Hexapitys there are three rows of verticillate lateral branches on each spine.

Subgenus 1. Hexancora, Haeckel.

Definition.--Each radial spine with three simple lateral branches only (one branch from each edge of the triangular spine).

1. Hexancistra tricuspis, n. sp. (Pl. 22, fig. 9).

Cortical shell thin walled, covered with short conical by-spines, three times as broad as the medullary shell; its pores regular circular, three times as broad as the bars; ten to twelve on the radius. Pores of the medullary shell half as large, also regular circular. The two shells connected by six thin prismatic radial beams, which are prolonged outside into six very stout main spines, three-sided prismatic, as long as the shell diameter, with three thin wing-like edges. Each edge at the distal end prolonged into a strong curved lateral branch.

Dimensions.--Diameter of the outer shell 0.13, inner 0.4; cortical pores 0.01, bars 0.003; medullary pores 0.005, bars 0.003; length of the six spines 0.13, breadth 0.02.

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

2. Hexancistra ancorata, n. sp.

Cortical shell thick walled, smooth, twice as broad as the medullary shell; its pores regular circular, twice as broad as the bars; six to eight on the radius. Six radial spines, three-sided prismatic, as long as the shell radius, with three recurved lateral branches at the distal end like the three teeth of an anchor.

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

Habitat.--South Pacific, Station 296, depth 1825 fathoms.

3. Hexancistra triserrata, n. sp. (Pl. 22, fig. 10).

Cortical shell thin walled, thorny, twice to three times as broad as the medullary shell; the two shells connected by six strong triangular beams. Inner shell spherical, with very small, regular, circular {189}pores; ten to twelve on the half meridian. Bars as broad as the pores. Outer shell regularly octahedral, with eight triangular perfectly regular even faces, separated by eight prominent edges; the meshes circular, regular, about twelve to fourteen on the half meridian, two to three times as broad as the bars between them. Six strong radial spines, about as long as the diameter of the outer shell, three-sided prismatic, cuspidate; their three edges prominent, serrate, spirally twisted. Each spine bears about its middle three strong flattened lateral branches, nearly perpendicular to it, not serrated, and slightly curved.

Dimensions.--Diameter of the outer shell 0.13, inner 0.045; pores of the former 0.01, of the latter 0.004; length of the spine 0.12, breadth 0.014.

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

4. Hexancistra quadricuspis, n. sp. (Pl. 22, fig. 11).

Cortical shell thin walled, covered with short bristle-shaped by-spines, three and a half times as broad as the medullary shell. Pores of the latter regular circular, small; pores of the former three to six times as large, very irregular, roundish, double-edged. Six radial spines, three-sided prismatic, about as long as the shell diameter, with three wing-like, slightly twisted edges, which are prolonged towards the distal end into three curved horn-shaped branches.

Dimensions.--Diameter of the outer shell 0.17, inner 0.05; cortical pores 0.01 to 0.03, bars 0.005; medullary pores 0.003, bars 0.001; length of the spines 0.15, breadth 0.013.

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

Subgenus 2. Hexapitys, Haeckel, 1881, Prodromus, p. 451.

Definition.--Each radial spine with three rows of verticillate lateral branches (a row arising from each edge of the spine).

5. Hexancistra mirabilis, n. sp. (Pl. 23, fig. 3).

Hexapitys mirabilis, Haeckel, 1881, Prodromus, p. 451.

Cortical shell very thin walled, three times as broad as the medullary shell. Inner shell spherical, with very delicate, subregular hexagonal meshes; seven to eight on the half diameter. Outer shell octahedral, with irregular polygonal meshes of very different size; on the surface numerous thin accessory radial spines, equal in length to its radius. Six main spines, extremely long and stout, many times longer than the diameter of the outer shell, nearly as broad as the radius of the inner shell, three-sided prismatic, with sharp, prominent, spirally twisted edges; on every edge a great number of thin lateral branches, arranged perpendicularly to it, as long as the diameter of the outer shell, and pinnated by ten to twenty pairs of delicate secondary spinules, biserial and perpendicular to the primary branches. (In the figured specimen the spherical central capsule, between both shells, was well preserved; its nucleus nearly filled the medullary shell. The thick jelly-veil around it was radially striped and octahedral.)

{190}Dimensions.--Diameter of the outer shell 0.13, of the inner 0.05; length of the spines 0.5 to 0.8 or more, breadth 0.02.

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

Genus 77. Hexaloncharium,[107] n. gen.

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

The genus Hexaloncharium exhibits the same relation to its ancestral form, Hexalonche, that Hexastylarium bears to Hexastylus. Two opposite spines of one pair are larger than the four others, and correspond to the three axes of a quadratic crystal.

1. Hexaloncharium octahedrum, n. sp.

Cortical shell smooth, three to four times as broad as the spherical medullary shell, each having regular circular pores, twice to three times as broad as the bars. Form of the outer shell not a sphere, but a regular octahedron, with eight congruent, equilateral triangular even faces. Two opposite spines twice as long as the shell diameter, whilst the four others are scarcely equal to it. Basal breadth of all six the same (three times as large as one pore); form, three-sided prismatic, with cuspidate distal end. (Similar to Hexalonche octahedra, Pl. 22, fig. 8, but distinct in the unequal length of the spines.)

Dimensions.--Diameter of the outer shell 0.16, inner 0.045; length of the major spine 0.3, minor 0.12, basal breadth 0.03.

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

2. Hexaloncharium philosophicum, n. sp.

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XI. LITERATURE AND HISTORY (part 1 of 5)

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XI. LITERATURE AND HISTORY (part 1 of 5)