Letter XXXVI

Letter XXXVI

EXTERNAL ANATOMY OF INSECTS CONTINUED.

THE ABDOMEN, AND ITS PARTS.

The abdomen of insects, which we are next to consider, is the third great section of the body, and is the seat of the organs of generation, as well as of a principal part of those connected with respiration. My remarks upon it will be under the following heads: Its substance; articulation with the trunk; composition; shape and proportions; its appendages; and its clothing.

i. Substance. Under this head I may observe in general, that where the abdomen is protected by hard elytra or tegmina, as in most Coleoptera, and many Heteropterous Hemiptera, the upper side is generally of a softer and more flexible substance than the under, which from its exposure requires a greater degree of hardness and firmness to prevent its being injured. In some,--as the Dynastidæ and those beetles whose elytra are connate, or as it were soldered together, the former is scarcely more than membrane. In others of the above tribes, nearly the whole of the back of whose abdomen, as in Staphylinus; or only its anal extremity, as in Melolontha; or its sides, as in Lygæus, &c., is not covered by the elytra or tegmina, that part, as was requisite for its protection, is harder than the covered portion.

ii. Articulation with the trunk. Two distinct modes of this articulation take place:--in the first the abdomen is united to the trunk by the whole diameter of its base, without any appearance of incision; in the other only a small part of that diameter, with a very visible incision. All the Orders, except the majority of the Hymenoptera and Diptera, and the Araneidæ, belong to the first of these sections; for in all these the aperture by which the abdomen is suspended to the trunk, occupies the whole of the base; I say suspended, because, though in many cases it inosculates in the posterior cavity of the latter part, it does not in all, and the margins of the orifice are united by ligament to those of that cavity. Indeed, in the Coleoptera and others that have a somewhat prominent metaphragm[2125], the trunk may with more propriety be said to inosculate in the abdomen. With regard to the second section,--those in which the orifice is of less diameter than the base, occupying only a portion of it,--it may be further subdivided into those whose abdomen is sessile, and those in which it is united to the trunk by the intervention of a long or short pedicle or footstalk: to the first of these subdivisions belong all those Diptera that have an incision between the trunk and abdomen--for many tribes of this Order, as the Tipulidæ, Asilidæ, &c., belong rather to the first section--and the Araneidæ; the abdomen, however, in all is merely suspended, without any inosculation. To the second subdivision belong all the Hymenoptera, except the Tenthredinidæ and Siricidæ, the abdomen of which is united to the trunk by the whole diameter of its base; these may be further subdivided into those that have a very short pedicle and those that have a long one; but as the mode of articulation in both these is the same, there will be no necessity to consider them separately. M. Cuvier has included the Diptera and Araneidæ in the same tribe with such Hymenoptera as have a petiolate abdomen[2126]; but as the manner in which the latter articulates with the trunk is widely different from that of the Diptera &c., I thought it best to consider them as distinct; especially as in the Diptera there is no tendency to a pedicle, while only the above two tribes of Hymenoptera are wholly without it. This learned author thus describes the articulation where the abdomen is connected by a pedicle. "They have," says he, "a real solid articulation, a kind of hinge in which the first segment is emarginate above, and receives a saliant portion of the trunk upon which it moves; this articulation is rendered solid by elastic and powerful ligaments; muscles which have their attachment in the interior of the trunk are inserted in this first segment, and determine the extent of its movement[2126]." But this passage by no means conveys an adequate idea of the singular mechanism by which the Divine Artificer has enabled these little creatures to impart the necessary movements to an organ so bulky compared with its very diminutive point of attachment. As no author that has fallen in my way has examined the articulation of the abdomen with the trunk in these Hymenoptera with the attention which it merits[2127], I shall enlarge a little upon it. You would be surprised, and not without reason incredulous, were I seriously to assert that these insects lift their weighty posteriors by means of a rope and pulley; yet something like this really does take place, though not with all in a manner equally striking. The point of articulation in the insects in question, except in Evania, is at the base of the metathorax just above the posterior pair of legs: here you see a small orifice, either insulated or connected by a narrow opening with the larger one, when the abdomen is removed, which in many instances, as in the common wasp, is surmounted by another still smaller, through which, if you examine it attentively, you will find there is transmitted a flat and sometimes broadish ligament or rather tendon, in which the levator muscles of the abdomen, attached by their other end to the metaphragm[2128], terminate: another minute orifice above the base of the pedicle affords a point of attachment to the tendon, so as to give it prize upon the abdomen. Here the upper orifice in the trunk is the pulley (trochlea)[2129], the tendon is the rope (funiculus)[2129], and the abdomen is the weight to be lifted. When the muscles contract, the tendon, running over the edge of the aperture, is pulled in, and the part just named is elevated; and when they are relaxed the tendon is let out, and it falls. Some little variation in the structure takes place in different tribes: thus, in the Formicidæ, Scoliadæ, &c., instead of a separate orifice, the part I call the pulley is merely an upper sinus of the large orifice that receives the pedicle of the abdomen. The shape of these orifices, both of the trunk and abdomen, varies in different genera: thus, in the bee it is triangular, with the vertex reversed; and in the wasp the upper one is circular, and the lower one transversely oblong; but in all, the apertures of the trunk correspond with those of the abdomen. In Evania, in which the minute abdomen is inserted in the upper side of the metathorax, there is scarcely any trace of this structure. With regard to the articulation of the pedicle itself with the lower orifice of the trunk, it appears simply suspended, with little or no inosculation. I may observe under this head, that though the abdomen in almost all insects is wholly clear of the cavity of the trunk, yet in some Phalangidæ (Gonyleptes K.) it appears almost retracted within it[2130].

iii. Composition. I shall next consider the segments into which the abdomen is usually divided, their number, and other circumstances connected with them. In the Hippoboscidæ, Acaridæ, Phalangidæ, and Araneidæ, the part we are considering is not divided into segments, though in some instances, as in Gonyleptes and the cancriform Epeiræ[2131], they are represented by folds; but in the great majority of insects it consists of several dorsal and ventral pieces or segments, forming by their union the annuli or rings into which it appears divided. The number of these abdominal segments varies in different insects; I have noticed more than twenty such variations, and probably there are many more. Before I give you them in detail, I must first observe that the dorsal and ventral segments, though sometimes they correspond in number, yet very often do not, the dorsal most commonly exceeding the ventral by a segment; in a few cases however the reverse takes place. In the sexes also there is frequently a difference in the number of segments, as has been before observed[2132]. I shall express the variations in question by two figures, the first representing the number of dorsal segments, and the second the ventral--they usually only express the apparent segments: perhaps a very general examination and dissection might bring many of them nearer to a common type.

1:1. Chelonus.

3:3. Chrysidæ[2133].

4:2. Leucospis[2134].

5:5. Syrphus.

5:6. Halictus ♀.

6:5. Nepa.

6:6. { Halictus ♂. { Belostoma.

7:5. { Curculio L. { Cerambyx L.

7:6. Dytiscus ♀.

7:7. Ammophila, &c.

8:6. { Dytiscus ♂. { Lucanus, &c.

8:7. Geotrupes Latr.

8:8. Pimpla.

8:10. Euchlora M^cL.[2135]?

8:13. Scutigera.

9:5. Carabus Latr.

9:6. Gymnopleurus Ill.

9:7. Perga Leach ♀.

9:8. Perga ♂.

10:7. Locusta Leach ♀.

10:8. --------------- ♂.

10:10. Æshna.

11:7. Phasma.

11:9. Chelifer.

12:11. Thelyphonus.

Many: Myriapoda.

I shall next explain the articulation of the segments with each other, both that of the rings formed by the union of the dorsal and ventral pieces, and that of those pieces themselves. In general it may be stated with respect to the former, that each ring is suspended by ligament to that which precedes it; but this takes place in three ways--in some the margins of the suspended rings touch each other only, with little or no inosculation; in others the dorsal segments only touch, and the base of each ventral is covered more or less by the apex of the preceding one; and in others again the base of the whole ring, both above and below, is so covered, or inosculates. The first kind here mentioned you will find exemplified in Melolontha, Geotrupes, Musca, &c.; the second in Scorpio; and the third in Staphylinus, the Hymenoptera, and many others. In the Coleoptera, says M. Cuvier, speaking of the movements of the abdomen, the rings only touch each other at the margin, and the movement is very limited; whilst in the Hymenoptera they are so many little hoops, which inosculate in each other as the tubes of a telescope, one third only of their extent often appearing uncovered[2136]. We see the reason of this structure when we consider the calls they have for greater powers of movement in this part in laying their eggs, and annoying their enemies and assailants; and also in the Staphylinidæ to enable them to turn up their abdomen like a scorpion, both as a posture of attack, and to fold their wings: in all cases, however, as far as my observation goes, these animals, when they want to lengthen this part, can disengage the rings from almost all inosculation, so that no impediment remains to any movement.

The articulation of the dorsal and ventral segments with each other is next to be considered. In Iulus and some Centroti the ring appears to be formed of a single piece, with scarcely any trace of the existence of any such division; it is however almost universal, and is of three descriptions; in the first the dorsal segments are united to the ventral at the lateral margin or edge of the abdomen; in the second it is above this margin, and in the third below it. You will find that in Fulgora and many other Homopterous Hemiptera these segments unite at the margin, as they do likewise in Cimex lectularius belonging to the other Hemipterous section; but in the rest of the Heteropterous tribes, the ventral segments turn upwards, and their union with the dorsal is in the back of the abdomen; in these the Hemelytra and wings only cover the dorsal segments, leaving the edge, formed of the ends of the ventral, uncovered. The Lamellicorn beetles also, and many other Coleoptera, exhibit the same structure. To the last description, in which the dorsal segments turn down to meet the ventral, belong the Lepidoptera, Locusta Leach; likewise Sirex, Chrysis, and many other Hymenoptera. The articulation between these segments is by means of an elastic membranous ligament, which usually is not externally visible; but in many instances, in which the connecting ligament is of a firmer substance, as in Scorpio, Thelyphonus, and Phrynus, it is very conspicuous, and in the latter genus exhibits many longitudinal folds, as it does likewise in Gryllotalpa, which must permit a vast extension of the abdomen. In this membrane, in some cases, as in Dynastes M^cL., Melolontha, &c., the two or three first spiracles are fixed[2137]. In the Hymenoptera and many other insects the dorsal segments do not unite by their margin with the ventral, but the end of each dorsal laps over that of the corresponding ventral.

Dorsal segments[2138]. I shall next notice the segments seriatim, in the order of their occurrence, beginning with the dorsal ones. The most remarkable circumstance with respect to these that occurs to my recollection takes place in the Cancroid spiders (Epeira cancriformis, aculeata, &c.), in which the back of the abdomen is formed by a plate, in some extended in a transverse direction (E. cancriformis), in others in a longitudinal one (E. aculeata), of a much harder substance than the under side and quite flat, set with strong sharp spines, in the former species apparently moveable, and terminating behind in a piece resembling in some measure the scutellum of the Stratyomidæ and similarly armed with a pair of spines[2139]: in E. aculeata the sides of the abdomen, under the plate, have a number of longitudinal folds like those of Phrynus. In Cryptocerus, a genus of ants peculiar to South America, the first segment, not reckoning the pedicle, forms almost the whole back of the abdomen, and the three last are so minute as scarcely to be distinguishable. Nothing very remarkable is exhibited by the other segments, except that in Trichius the penultimate is the largest; in some Staphylinidæ (S. splendens) and Brachini (B. melanocephalus) it is emarginate, and in the former tribe also often terminating in a white membrane. The dorsal segment most worthy of notice is the last, which is called the podex; for though in general it is a minute piece, often retracted within the abdomen and invisible, as in many Diptera, yet sometimes it is the most conspicuous of the dorsal segments. It is most commonly triangular, and usually deflexed and forming an angle with a horizontal line; but in Clytra, Chlamys, and Oryctes, it is inflexed; in many Lamellicorns it is nearly vertical. In Tettigonia F., many other Homopterous Hemiptera, and some Hymenoptera (Cimbex), its sides turn down and become ventral; on its lower side it has in these a longitudinal cavity which receives the ovipositor in repose[2140]. In many other insects it unites with the last ventral segment, the hypopygium, to form a tube for that organ, as you will find in Callidium violaceum[2141], many Muscidæ, and Thelyphonus. As to its termination the podex is sometimes bifid, Blatta; bipartite, Ranatra; mucronate, Sirex; acuminate, Melolontha vulgaris, Trichius hemipterus. Generally this part is flat; but the disk is elevated or gibbous in Oryctes and some other Lamellicorns. In the majority of the Coleoptera Order it is quite covered by the wings and elytra; but in many of the last-mentioned tribe, and sometimes the penultimate segment also, it is not covered by them[2142]. In some insects the piece we are considering appears to consist of two segments; in the male of Locusta morbillosa the whole podex is rhomboidal, but it is formed by two triangular pieces which articulate with each other; this structure permits the more easy elevation of the terminal one for the extrusion of the feces.

Ventral Segments[2143]. We are now to turn our attention to the ventral segments of the abdomen. The first of them is what is called the epigastrium[2144] in the table. This part, according to M. Chabrier, is of considerable importance to the animal in flight, as, by its pressure against the trunk, not only regulating the movements of the abdomen, but as, in his opinion, contributing to push forward the trunk[2145] in the descent of the animal. It is remarkable only in the Coleoptera and Heteropterous Hemiptera, to which my observations upon it will be confined. It may be stated as usually consisting of two articulations, that nearest the trunk being narrow, and in the Predaceous beetles[2146], as also in Scutellera, Pentatoma, &c., interrupted in the middle[2147]. In many Lamellicorns this joint is concealed under the posterior coxæ, and with the anterior part of the second forms a hollow cavity for their reception; this last joint is what is properly the Epigastrium, the former, especially when distinct, being called in the table the Hypochondria. In Sagra and Brentus the epigastrium is particularly conspicuous for its size, in the former occupying half, and in the latter nearly two-thirds of the under side of the abdomen; but in general it is distinguished from the remaining segments only by the central mucro or point that terminates it towards the trunk[2148], and which is received by a sinus of the metasternum; this point is generally minute and triangular, but in Sagra it is large and rounded at the extremity, and in Calandra it terminates nearly in a transverse line somewhat waving. It is most remarkable, however, in some species of the Heteropterous genus Edessa F.; for in E. nigripes and affinities it is a sharp sterniform conical horn, which passing between the four posterior legs covers the end of the promuscis. In fact, this part appears a kind of abdominal sternum. In the Cetoniadæ, &c., the Hypochondria unite before this mucro, and form a ridge which articulates with it, and dips towards the abdominal cavity; in Scolytus the epigastrium is much elevated from the rest of the ventral segments, so that the under side of the abdomen appears as if it were suddenly cut off, whence Herbst's awkward though not inexpressive name, Ekkoptogaster; this part in this genus has something of a posterior mucro.

The intermediate ventral segments exhibiting no very remarkable peculiarities, I shall pass them without further notice, and call your attention to the last, which is opposed to the podex, and which I have named the hypopygium[2149]. Though usually a single small piece, in Edessa and many Pentatomæ it consists of several plates; and in Trichius it is very large: it is mostly intire, but in the male Dytisci it is cleft; in Lamia ocellata trilobed; in Edessa tripartite; in Centrotus Taurus it is boat-shaped and hollowed out to receive the stalk of the ovipositor. It is also generally in the same line with the body, but in Xenos it is turned up and bent inwards[2150].

iv. Shape. With regard to shape, in some Orders the abdomen varies considerably; but the most general form is one that approaches to trigonal, so that a transverse section will be a triangle, with the vertex more or less obtuse, and the base more or less convex; some tendency to this form will often be found even in those insects whose abdomen appears almost as flat as a leaf, as in many Aradi. In the hive-bee the transverse section is almost an equilateral triangle; in Belostoma grandis the disk of the under side of the part in question is longitudinally elevated into a trigonal ridge, the section of which is an equilateral triangle, the sides being quite flat. In general, in the vertical section of an abdomen, the vertex of the triangle points downwards, but in Libellula F. it points upwards. In Blatta this section is nearly lanceolate; in Staphylinus olens it is a segment of a circle with the convex side downwards; in Æshna F. with that side upwards; and in Agrion the section is circular. In Copris, Ateuchus, &c., the abdomen is very short and thick; in Staphylinus slender and long; in Aradus, Nepa, &c., depressed and flat; compressed in Ophion and Evania; conical in Cœlyoxis; rhomboidal in many Mantes; boat-shaped in many Lygæi; fusiform in various Papilionidæ; lanceolate in some Ichneumonidæ, falcate in others; nearly round in Diapria pupurascens; ovate in Lyrops; elliptical in Andrena; oblong in many Xylocopæ; heart-shaped in the naked Euglossæ; triangular in Dytiscus; gibbous in Flata; and vaulted in Chrysis. At its base it is truncated in Sirex; retuse in most bees; forming the segment of a circle in Andrena; in general sessile, but in the majority of Hymenoptera, as has been already observed, terminating in a pedicle. The pedicle is very short in the Andrenidæ and Apidæ; long in the Sphecidæ; thick in the Formicidæ; slender in Evania; fusiform in Pelecinus; clavate in Ammophila; campanulate in many Vespidæ; nodose in Myrmica[2151]; squamigerous in Formica[2152]: it sometimes also consists of two joints, as in Ammophila and many Vespidæ. As to margin, some have none, as Centrotus; in others, as Dytiscus, it is very narrow; in others again, wide and flat, as in the Nepidæ; in Staphylinus, &c., it is distinguishable only on the upper side of the abdomen; in Locusta Leach only on the under side, though mostly intire; it is serrated in Blatta, sinuated in Acanthia paradoxa, and crenated in Cerceris.

v. Proportions. These vary greatly in the different tribes; in some the abdomen is long and slender, as in Locusta, and Staphylinus; disproportionably so in a remarkable degree in some Agrionidæ from South America, as A. lineare, &c.[2153]; in others it is extremely short and thick, as in Copris, &c.; a mere appendage in Evania; it is shorter than the elytra in Trox; of the same length in most beetles; longer in Melolontha, Hister, &c.; disproportionably so in Staphylinus: though usually of the same width with the trunk, in many Mantidæ it is much wider[2154]; and more slender in the Libellulina, Myrmeleon, &c.

vi. Arms and Appendages[2155]. These are various; and may be considered under the following heads: processes; organs of respiration, motion and prehension; weapons; and other anal appendages the use of which is unknown.

1. Processes. Under this term I include all prominences of whatever kind, whether tubercles, teeth, spines, or horns, that arm any part of the abdomen. Many of these are sexual characters, and have been sufficiently described in a former letter[2156]; I need not therefore detain you long on this head. Of the first kind is a remarkable elevation that distinguishes the second ventral segment of Scolytus Destructor (Ips Scolytus Marsh.) or of a species allied to it[2157]; in S. pygmæus (I. multistriatus Marsh.) the same segment is armed by a flat horizontal tooth or horn; in an Aradus from Brazil, before alluded to[2158] (A. laminatus K. MS.), the margin of the abdomen is surrounded by eight flat subquadrangular laminæ; in another species figured by Stoll[2159], it is cut out into bays by a number of denticulated teeth; and in Acanthia paradoxa by long spinose lobes[2160]. In Edessa F., another genus of bugs, the abdomen usually terminates in four strong sharp dentiform spines, the intermediate ones being the shortest, and in some the margin is also armed with spines[2161]; occasionally the anal spines are very long[2162]. In addition to the ventral horns before mentioned that distinguish the sexes of some insects[2163]; the males of the genus Conops, a two-winged fly, have, on the antepenultimate ventral segment, a singular process, varying in length and shape in the different species, standing nearly at right angles with the belly, convex towards the trunk, and concave towards the anus. De Geer supposes that with the anal extremity this forms a forceps with which this fly seizes the other sex[2164].

2. Organs of respiration[2165]. I shall defer my account of the spiracles, and other external respiratory organs, till I come to treat of the system of respiration in insects, when every thing connected with that subject will be most properly discussed; but there are certain appearances in some insects, which at first sight seem to partake of the same character, but which being really independent of that vital function, may here have their place. If you examine the abdomen of the mole-cricket (Gryllotalpa vulgaris), you will easily discover the true spiracles in the folds of the pulmonarium, which separates the back of that part from the belly; if you next inspect the five intermediate segments of the latter, you will discover on each nearer the base a pair of oblique little channels, which precisely resemble closed spiracles. These may be denominated false or blind spiracles. Again, if you examine the pupa of any Scutellera or Pentatoma, in which tribe the true spiracles are ventral, you will discover, placed in a square on the two or three intermediate dorsal segments, four or six elevated points resembling spiracles, but not perforated, connected often by corrugations in the skin or crust[2166]; in the larvæ also of some Reduvii the first minute dorsal segment, at each lateral extremity, has a similar elevation with a central umbilicus precisely resembling a spiracle, but still not perforated: another instance of false spiracles in this section of the Hemiptera, is furnished by Aradus laminatus before mentioned, in the perfect insect; between the spiracle and the margin of each ventral segment is a white round callus, with a dark point resembling a perforation on its exterior side, and terminating internally in a channel covered by membrane leading to the disk of the segment, so that the whole in shape resembles a tobacco-pipe[2167]. A number of similar callosities with a central impression, but without any channel, variously disposed, are also to be found in another bug, Rhinuchus compressipes K.[2168] In the Homopterous section of this Order, a series of impressed points, which may be easily mistaken for spiracles, are to be discovered on both sides of the abdomen, at the margin in Centrotus, in which the real spiracles are quite concealed.

In spiders, as we learn from Treviranus, the open ventral spiracles of the scorpion are replaced by pseudo-spiracles; these in Epeira Diadema are three pair of small black points: on the back of the abdomen also are four pair, but in some species there are only two[2169]: the most remarkable, however, are exhibited by the cancriform spiders before noticed[2170]: in Epeira cancriformis, in the plate which covers the abdomen, they are dark red spots with an elevated rim and centre[2171] exactly resembling spiracles, except that they are not perforated; there are twenty-four of them, twenty arranged round the margin, and four in a square in the disk.

3. Organs of motion. In a former letter you were told that several insects are enabled to leap by means of organs in their abdomen; I shall now describe such of them as require further elucidation. I then said that Podura and Sminthurus, two apterous genera, take their leaps by means of an anal fork[2172]. In the former genus the fork consists of a single piece attached to the under side of the anus, and terminating in a pair of long slender sharp processes which articulate with it and form the fork or saltatorious instrument[2173]. In Sminthurus the tines, as they may be called, of the fork do not articulate with the base, but are of the same piece and consist of two joints, the terminal one being flat and obtuse[2174]. Machilis to the anal fork adds eight pair of ventral linear springs (Elastes), which are covered with hair or scales, and terminate in a bristle or two. I have on a former occasion mentioned the natatorious laminæ with which the anus of the larva of Agrion and of some Diptera is furnished[2175]; the same part in that of Dytiscus ends in a pair of tapering organs, fringed on each side like the hind-legs of the imago[2176], which doubtless assist it in swimming; those respiratory foliaceous laminæ which so singularly distinguish the abdomen of the larvæ of Ephemera, like the legs of the Branchiopod Crustacea, are probably used in some degree as fins, and aid their motions in the water[2177]. Under this head may also be mentioned the many-jointed bristles that form the long tails[2178] of the fly that proceeds from these larvæ, whose interesting history I long since enlarged upon; for when they fly the two lateral ones diverge from the central one, and perhaps perform the same office as the tail feathers (rectrices) of birds. These bristles are also to be found in Machilis[2179], and probably, as its leaps are almost as long as flights, for a similar purpose, to steady their motion. I may here lastly state that I once saw a Cryptophagus (Corticaria Marsh.), but I forgot to note the species, walking upon my window, which when it wanted to turn fixed itself to the glass by an inflated anal vesicle, and so accomplished its purpose.

4. Organs of Prehension[2180]. The abdominal organs of prehension are various; but as the great body of them are connected with the sexual intercourse of insects, I shall not consider them till I come to treat on that subject. The only remarkable one that is common to both sexes is that of the earwig, which is too well known to every child to call for any long description. The external organs of oviposition I shall also describe hereafter, and likewise those of secretion that have not already been noticed.

5. Weapons. As the stings of some Hymenoptera are analogous to the ovipositors of the majority of that Order, I shall consider them both together when I treat of the sexual organs of insects; but there is one, and that a tremendous one, not connected with those organs, which may be noticed here. I mean the sting of the scorpion. There appears to be some analogy between the poisonous fangs of one tribe of the Ophidian reptiles[2181], the mandibulæ of spiders[2182], the second pair of pedipalps, or the fangs of the Scolopendridæ[2183], and the organ in question[2184]; but the last possesses this peculiarity, that it is placed at the opposite extremity of the body, where it is preceded by a long jointed tail, which properly speaking is merely a continuation of the abdomen, since the spinal marrow, the intestinal canal, and the pseudocardia, are extended into it[2185]. Providence might have a double view in thus contracting the dimensions of this part of the abdomen; in the first place, the animal is by this enabled to turn its tail over its back preparatory to its inflicting a wound, and in the second, perhaps, this formation favours the sublimation of the venom, the long tail acting as an alembic for that purpose. This machine consists of six angular joints including the sting, the last but one being the longest, and the last inflated, as it were, at the base, and terminating in a sharp subulato-conical point which curves downwards, and has an orifice in a channel at the end on each side. Treviranus could not discover these orifices in the sting of Scorpio europæus[2186]; they may however be readily seen if viewed with a sufficiently high power, though not under a common pocket microscope. Whether the very slender, many-jointed, real tail of the remarkable genus Thelyphonus is used in any respect as a weapon, has not been ascertained: it is a filiform hairy organ consisting in some specimens of more than twenty joints, the first being very much larger than the rest[2187].

6. Appendages[2188]. We are lastly to advert to those appendages of the abdomen of which the use is not at present discovered. These are the styles (styli) of the Staphylinidæ; the leaflets (foliola) of the Libellulina; the floret (flosculus) of the Fulgoræ; the cerci of the Blattidæ and Gryllina; and the threads (fila) of Machilis: but having nothing important to add concerning them, the definitions of those terms will give you a sufficiently clear idea of them[2189]. As they are common to both sexes, if their use is connected with the sexual intercourse, it must be similar to that which Treviranus ascribes to the pectens of scorpions, they must be instruments of excitement.

* * * * *

And now, after this long discourse on the External Anatomy and structure of these little beings, you may think perhaps at first that the subject is exhausted; and that I must have discovered and described every part and every variation of every part of the crust of an insect. But when you go on to reflect what a comparatively small number of these creatures have fallen under my examination, and in those, after all my laborious and painful researches, from my limited faculties and other imperfections of our common nature, how much will probably have eluded my notice, you may conclude that thousands of facts still remain concealed to reward the patient assiduity of future investigators. Such are the immensity and variety of the works of the CREATOR in this department, that it would require a long life, and fill volumes upon volumes, to discover and give a description of all the peculiarities of structure of the insects that are already known; and could all that exist[2190] be so studied and explained in full detail, the library that the Calif Omar ordered to be burned at Alexandria could scarcely have contained more books than would be required to receive the results. But "who is sufficient for these things[2191]?" This is a question that the most able and most experienced physiologist must often feel disposed to put to himself when, lost in the intricate labyrinth of the works of his Maker, he sees all things arranged, "wheel within wheel," in an order that he can only partially unravel, instead of tracing the "regular confusion" through all its windings. But glimpses of light, and points of irradiation, here and there discover to fragments of the truth of things, and such vestiges of the grand system of the DEITY, as enable him in some degree to appreciate, and dispose him humbly to adore that WISDOM, POWER, and GOODNESS, that at first created and now sustains in its full beauty and harmony the WONDROUS WHOLE.

I am, &c.

END OF THE THIRD VOLUME.

Printed by Richard Taylor, Shoe-Lane, London.

FOOTNOTES:

[2125] Anatom. Compar. i. 450.

[2126] Anatom. Compar. i. 451.

[2127] De Geer notices something of the kind in Cimbex femorata. ii. 947.

[2128] It was omitted to be observed, when the supposed pneumatic pouches in the genus Vespa were mentioned (see above, p. 585), that they have also a very conspicuous metaphragm, as probably have most Hymenoptera, to which the muscles that move the wings are attached.

[2129] PLATE IX. FIG. 13. F´ is the tendon, G´ the aperture in the abdomen C, and a, the aperture in the trunk B.

[2130] PLATE XV. FIG. 11. Linn. Trans. xii. t. xxii. f. 16.

[2131] Surely these Epeiræ, of so different a habit from the rest, form a distinct genus?

[2132] See above, p. 339.

[2133] There is reason to suppose that in Chelonus and the Chrysidæ several segments are retracted within the abdomen, and if the cavity of its under side in the latter be examined, it will be discovered that the epigastrium is divided in the middle into two pieces, and that both the sides of this and the following segments are covered by three narrow accessory plates, one to each, the last being the shortest. De Geer (ii. 833.) describes Chrysis ignita as having four abdominal rings; but this is only in appearance, there being really only three. This appearance is produced by the apex of the last dorsal segment being more depressed and marked with several deep little excavations that look like holes. In some species of Stilbum this segment consists as it were of three ridges or steps.

[2134] In this genus the ventral segments are replaced by a long narrow central plate, succeeded by a minute one.

[2135] In this genus the bed of the posterior coxæ appears to consist of two segments, which are beautifully fringed with parallel short bristles.

[2136] Anatom. Compar. i. 451.

[2137] PLATE VIII. FIG. 9. A´´, B´.

[2138] Ibid. FIG. 5. A´´.

[2139] PLATE XV. FIG. 10.

[2140] Reaum. v. t. xvii. f. 14. a. a.

[2141] Linn. Trans. v. t. xii. f. 15.

[2142] Daldorf (Asiatic Society's Trans. vii.) has divided Geotrupes into two families, one with the podex covered (G. vernalis, &c.) which he calls modesti, the other with it uncovered (G. stercorarius, &c.) which he calls obscæni.

[2143] PLATE VIII. E´.

[2144] Ibid. D´.

[2145] Sur le Vol des Ins. c. i. Addend. 299.

[2146] In Dytiscus marginalis the upper side of the margin of the Hypochondria is curiously cut into transverse corrugations.

[2147] PLATE VIII. FIG. 6. C´.

[2148] Ibid. B´´.

[2149] PLATE VIII. L´.

[2150] Linn. Trans. xi. t. ix. f. 15. b.

[2151] PLATE IX. FIG. 18. I´.

[2152] Ibid. FIG. 17. H´.

[2153] Rœmer. Genera, &c. t. xxiv. f. 4.

[2154] Stoll Spectr. t. vii.

[2155] PLATE XV. FIG. 10-23.

[2156] See above, p. 339--.

[2157] This tubercle I find only in a specimen from Sweden, sent to me by Major Gyllenhal, but not in any British one I possess. In this specimen the declivity before mentioned (see above, p. 709.) is observable in the first segment, but in the others it is formed by the second.

[2158] See above, p. 617.

[2159] Punaises, t. xiii. f. 84.

[2160] Stoll Punaises, t. xiii. f. 101.

[2161] Ibid. t. xvii. f. 117.

[2162] Ibid. t. xxxvi. f. 253.

[2163] See above, p. 339--.

[2164] De Geer, vi. 260. t. xv. f. 8. d.

[2165] PLATE XXIX.

[2166] PLATE XXIX. FIG. 22. is part of the back of the abdomen of the pupa of a Pentatoma. a the pseudo-spiracle, b the connecting corrugations.

[2167] Ibid. FIG. 24. a.

[2168] Ibid. FIG. 27. a.

[2169] Treviranus. Arachnid. 23--.

[2170] See above, p. 702, 706.

[2171] PLATE XXIX. FIG. 26. represents one of them.

[2172] VOL. II. p. 319--.

[2173] PLATE XV. FIG. 14. M´´. De Geer, vii. t. ii. f. 5, 10, 21.

[2174] Ibid. t. iii. f. 4, 14.

[2175] See above, p. 154.

[2176] PLATE XVIII. FIG. 5. a.

[2177] PLATE XXIX. FIG. 3, 4. De Geer, ii. t. xvii. f. 12. and t. xviii. f. 2.

[2178] Ibid. t. xvi. f. 8-13.

[2179] PLATE XV. FIG. 16. S´´.

[2180] Ibid. FIG. 12. L´´.

[2181] Philos. Trans. 1818. t. xxii.

[2182] N. Dict. d'Hist. Nat. ii. 275--. Hoole's Leeuwenh. i. t. ii. f. 19. I.

[2183] Leeuwenh. Epist. 17. Octobr. 1687. f. 10. C.

[2184] Hoole's Leeuwenh. i. t. v. f. 12, 13.

[2185] Treviranus, Arach. 4.

[2186] Treviranus, ubi supr. 14.

[2187] In my specimen including the first joint there are twenty, and some seem to have been broken off. In Rœmer's figure (Genera, t. xxix. f. 11.) there are only ten. Perhaps they vary in number according to the age of the animal.

[2188] PLATE XV. FIG. 13, 16, 17.

[2189] See above, p. 391--.

[2190] I have heard it stated upon good authority that 40,000 species of insects are already known, as preserved in collections. How great, then, must be the number existing in this whole globe!

[2191] 2 Cor. ii. 16.

EXPLANATION OF THE PLATES[2192].

PLATE VI.[2193]

FIG.

1. Head of Mylabris. Upper side, or face.

2. ------------------- Under side, or subface.

3. Trophi of Dytiscus. Six pieces.

4. Head of Locusta. Face.

5. ------------------ Front view, to exhibit the mouth.

6. Trophi of ditto. Seven pieces.

7. Head of Cicada. Face.

8. ------- Scutellera. Subface.

9. Trophi, or promuscis of Hemiptera. Three pieces.

10. Head of Æshna. Face.

11. ---------------- Front view.

12. Trophi of ditto. Seven pieces.

13. ------ or antlia of Lepidoptera. Four pieces.

14. ------ of Panorpa. Three pieces.

PLATE VII.[2194]

FIG.

1. Head and trophi of Phryganea L. Face.

2. ------------------ Vespa Crabro. Ditto.

3. Trophi of Bombus.

4. Head of Tabanus L. Face.

5. Trophi or proboscis of ditto. (Reaum.)

6. ------------------------ Bombylius[2195].

7. Head of Oxypterum. Face.

8. Head of Pulex, with its antennæ and trophi, or rostrulum. Side view.

9. ------- Araneidæ, with the trunk.

10. Trophi of ditto.

11. Head of Scolopendra morsitans. Subface.

12. ---------------- --------------- Front view, to show the mouth.

13. Trophi of ditto.

14. Pharynx of Pentatoma. (Savigny.)

PLATE VIII.[2196]

FIG.

1. Prothorax of Lucanus. a. Apex. b. Base. c d. Sides. a. Disk.

2. Antepectus of ditto.

3. Alitrunk of ditto. Upper side. a. A piece between the metathorax and metaphragm.

4. ------------------ Under side.

5. Abdomen. Upper side, or tergum.

6. -------- Under side, or venter.

7. Antepectus of Hydrophilus piceus.

8. Alitrunk of ditto. Under side, to show the metasternum.

9. Abdomen of Dynastes Aloeus, to show the dorsal and ventral spiracles.

10. Prothorax of Locusta. a. Apex. b. Base, c c. Sides.

11. Antepectus of ditto, to show the prosternum.

12. Alitrunk of ditto. Upper side.

13. ------------------ Under side.

14. ------------------ Lateral view. VOL. III. p. 48.

15. Abdomen of ditto. Lateral view.

16. Alitrunk of Cicada Latr. Upper side.

17. -------------------------- Under side. a. The piece in the ♀ corresponding to the drum-covers of the ♂.

18. Abdomen, and part of postpectus of ♂ ditto. Under side, to show the drums. VOL. II. p. 405--.

19. Abdomen, and part of postpectus of ♂. Lateral view, with the covers removed to show the machinery.

20. Alitrunk. Upper side. Pentatoma.

PLATE IX.[2197]

FIG.

1. Alitrunk of Cossus ligniperda. Upper side.

2. Part of ditto, to show the mesophragm.

3. ------------- Under side.

4. Patagia of Lepidoptera. Upper and under sides. VOL. III. p. 368, 539.

5. Tegulæ of ditto. Two species. VOL. III. p. 378.

6. Prothorax of Æshna. a. The base elevated and forming an obtuse angle with the rest.

7. Alitrunk of ditto. Upper side. a. Two elevated areas of the posterior parts of the collar, strengthened by a marginal ridge and denticles, internally connected by an elastic ligament, apparently to aid and sustain the powerful action of the wing-muscles.

8. ------------------ Lateral view. a. A piece by which the mid-leg is connected with the scapular. VOL. III. p. 48, 565.

9. Part of the abdomen of Libellula.

10. Trunk of Semblis F. Upper side.

11. Alitrunk of Vespa Crabro. Upper side. a. Aperture in the trunk for the passage of the ligament that elevates the abdomen.

12. Lateral view of ditto.

13. --------------- posterior part of ditto, and of the base of the abdomen, to show the above apparatus. a. The aperture. VOL. III. p. 701.

14. Head and part of the manitrunk of Tenthredo L. to show the membrane a. representing the prothorax. VOL. III. p. 550--.

15. Alitrunk of Xiphydria. Upper side.

16. ------------------------ Lateral view.

17. Part of trunk and abdomen of Formica, to show the squama. VOL. III. p. 389. 3.

18. ------------------------- of Myrmica, to show the nodus. VOL. III. p. 389. 4.

19. Alitrunk of Musca. Upper side. a. Alula or winglet.

20. Metathorax of ditto.

21. Alitrunk of ditto. Lateral view.

22. Abdomen of ditto. Venter.

PLATE. X.[2198]

N.B. In this plate the red points out the costal, and the yellow the anal areas, the intermediate being uncoloured.

FIG.

1. Elytra, a. Base. b. Shoulder. c. Lateral margin. d. Apex.

2. Tegmina. Blatta.

3. Hemelytra. Pentatoma.

4. Wing. Coleoptera. a. An insulated nervure. VOL. III. p. 625.

5. ----- Dermaptera.

6. ----- Lepidoptera.

7. ----- Neuroptera.

8. ----- Hymenoptera. Tenthredo L.

9. ------------------- Bombus.

10. Under wing. Hymenoptera.

11. --------------------------- Proctotrupes.

12. ----------- Diptera. Tipula.

13. --------------------- Psychoda. VOL. III. p. 645.

14. --------------------- Musca. a b. Two areolets between the costal and mediastinal nervures. c. Areolet between the mediastinal and postcostal nervures. d. Areolet between the postcostal and subcostal nervures, e. Open areolet. VOL. III. p. 634.

15. Under wing. Diptera. Stratyomis. a b. The two areolets between the costal and postcostal nervures; the mediastinal being nearly obsolete. c. Middle areolets crowned by a small one, d.

PLATE XI.[2199] Antennæ.

FIG.

1. Setaceous. 2. Capillary. 3. Filiform. 4. Incrassate. 5. Fusiform. 6. Prismatic. 7. Ensiform. 8. Falciform. 9. Moniliform. 10. Dentate. 11. Serrate. 12. Imbricate. 13. Distichous. 14. Pectinate. 15. Duplicato-pectinate. 16. Ciliate. 17. Flabellate. 18. Ramose. 19. Furcate. 20. Auriculate. a. The auricle. 21. Palmate. 22. Irregular. 23. Perfoliate.

PLATE XII. Antennæ.

FIG.

1. Capillaceous. 2. Mucronate. 3. Uncinate. 4. Clavate. 5. Nodose, or Biclavate. 6. Convolute. 7. Geniculate. 8. Capitate with a tunicate knob. 9. Capitate with a solid knob. 10. Capitate with a perfoliate knob. 11. Filiform. 12. Globiferous. 13. Connate. 14. } 15. } Setigerous. 16. Subulate. 17. } 18. } Filate, simple. 19. Filate, compound. a. Joints. 20. Filate. 21. Aristate. Setarious a. Bristle. 22. Aristate. Plumate a. Bristle. 23. Stupeous. VOL. III. p. 646. 24. Plumose. 25. Scopiferous. a. Brush. 26. Barbate. 27. Verticillate. 28. Inflated. 29. Auriculate. a. Auricle.

PLATE XIII.[2200]

1. Unguiculate feeler. Gonyleptes. a. Claw.

2. Securiform ditto. Cychrus. a. Terminal joint.

3. Inflated ditto. Araneidæ ♂. a. ditto.

4. Lunulate ditto. Oxyporus. a. ditto.

5. Dentate mandible. Megachile.

6. Suctorious ditto. Larva of Dytiscus. a. Aperture.

7. Prosthecate ditto. Staphylinus. VOL. III. pp. 356, 439.

8. Trophi of Curculio L.

9. Pedunculate eyes. Diopsis. a. Footstalk.

10. Compound ditto. Muscidæ. VOL. III. p. 494. 3.

11. Conglomerate ditto. Iulus. Ibid. p. 494. 2.

12. Rostrate head. Balaninus.

13. Capistrate ditto. Nitidula.

14. Clypeate ditto. Copris.

15. Lychnidiate ditto. Fulgora.

16. Buccate ditto. Myops. a. The inflated part.

17. Cruciate prothorax. Locusta.

18. Cucullate and alate ditto. Tingis.

19. Subulate elytra. Sitaris.

20. Ampliate ditto. Lycus. #/

PLATE XIV.[2201]

FIG.

1. Ideal wing, to exemplify painting. VOL. IV. p. 286--. a. Anterior or exterior margin. b. Interior ditto. c. Posterior ditto. d. Humeral angle. e. Scutellar ditto. f. Posterior ditto. g. Anal ditto. a. Articulate fascia, or band. b. Macular ditto. c d. Sesquialterous ditto. d e. Sesquitertious ditto. f. Dimidiate ditto. g. Abbreviate ditto. h. Pyramidate ditto. i. Supercilium. k. Hastate pupil. l. Compound eyelet or ocellus. m. Nictitant ditto. n. Simple ditto. o. Annulet. p. Bipupillate eyelet. q. Sesquialterous ditto. r. Double ditto. s. Caudate wing. t. Pupil. u. Iris. v. Atmosphere.

2. Reversed wings. Gastrophaca.

3. Digitate ditto. Pterodactylus.

4. Falcate ditto. Attacus.

5. Saltatorious leg, with loricate thigh. Locusta.

6. Natatorious ditto. Dytiscus.

7. Ambulatorious ditto. Lucanus.

8. Prehensorious ditto. Gonyleptes.

PLATE XV.[2202]

FIG.

1. Laminate coxa. Haliplus.

2. Alate tibia. Lygæus phyllopus, a. The appendage.

3. Clypeate ditto. Crabro ♂. a. The clypeus. VOL. III. p. 334.

4. Dolabriform ditto. Curculio maritimus E.B.

5. Fossorious leg, with palmate tibia. Clivina. VOL. II. p. 365.

6. --------------- with digitate ditto. Gryllotalpa. Ibid. p. 366.

7. Chelate feeler. Scorpio.

8. Scutate tarsus. Hydrophilus piceus ♂. VOL. III. p. 336.

9. Patellate ditto. Dytiscus marginalis ♂. a. Cups. Ibid. p. 336, 694--.

10. Obumbrate abdomen. Epeira cancriformis.

11. Retracted ditto. Gonyleptes.

12. Cheliferous tail. Panorpa ♂.

13. Flosculiferous ditto. Fulgora.

14. Saltatorious ditto. Podura.

15. Folioliferous ditto. Æshna.

16. Cauduliferous, and filiferous ditto. Machilis.

17. Styliferous ditto. Staphylinus.

18. Unciferous ovipositor. Locusta.

19. Ensate ditto. Acrida.

20. Navicular ditto. Cicada.

21. Serrulate ditto. Tenthredo L.

22. Telescopiform ditto. Chrysis.

23. Anal apparatus of Blatta.

PLATE XVI.[2203]

FIG.

1. Extricated ovipositor. Pimpla. Two pieces.

2. Telescopiform ditto. Stomoxys calcitrans? (Reaum.)

3. -------------------- Œstrus. (Ibid.) VOL. I. p. 150.

4. Semicomplete pupa. Cicada.

5. Subsemicomplete ditto. Libellula. a. Mask. VOL. III. p. 125--.

6. Incomplete ditto. Hydrophilus. (Lyonnet.)

7. ----------------- Myrmeleon emerging from its cocoon. (Reaum.)

8. ----------------- Vespa vulgaris.

9. ----------------- Chironomus plumosus. (Reaum.) a b. Respiratory plumes.

10. Obtected pupa. Apatura Iris.

11. -------------- Vanessa Urticæ. a. Head-case with two points.

12. -------------- Gonepteryx Rhamni. a. Head-case with one point.

13. Obtected pupa. Sphinx Ligustri. a. The tongue-case. b. The eye-case. c. The trunk-case. d. First segment of the abdomen. e. The adminicula. f. The mucro, or point of the tail. VOL. III. p. 249--.

14. Hairy obtected pupa of Laria fascelina.

PLATE XVII.[2204]

FIG.

1. Coarctate pupa. Œstrus hæmorrhoidalis. (Reaum.)

2. --------------- Stratyomis chamæleon. (Ibid.) a. The pupa as formed within the skin of the larva.

4. Oviform body which many pupæ of Diptera at first assume under the skin of the larva. (Ibid.). VOL. III. p. 235.

3. The same when the parts begin to show themselves. (Ibid.)

5. Cocoon of Saturnia pavonia. a. Pupa. b. Threads that close the orifice. VOL. III. p. 217, 279.

6. Loose and irregular ditto, of Arctia villica. Ibid. p. 220.

7. Boatshaped ditto, of Tortrix prasinana. Ibid. p. 221.

8. Network ditto, attached to the stalk of a plant.

9. Ditto, imitating the scales of fish. (Reaum.) VOL. I. p. 462.

10. Spiral case of Trichopterous larva, formed of pieces of leaf. (De Geer.)

11. Grate spun by these larvæ to prevent ingress. (Ibid.) VOL. II. p. 264.

12. Chilopodimorphous larva of Melolontha vulgaris. VOL. III. p. 163.

13. Araneidiform? ditto of Cicindela campestris. Ibid. 152, 163.

PLATE XVIII.[2205]

FIG.

1. Anoplurimorphous larva. Chrysomela Populi. a. Osmateria, or scent organs. VOL. II. p. 245. III. p. 163, 166.

2. Anoplurimorphous larva. Cassida. a. The fecifork covered with excrement. VOL. IV. p. 353. 5.

3. Helminthimorphous or vermiform ditto of Balaninus Nucum. VOL. III. p. 163.

4. Chilognathimorphous ditto of Elater Segetum. a. a. Spiracles.

5. Decapodimorphous ditto of Dytiscus marginalis. VOL. III. p. 165.

6. Chilopodimorphous ditto of Staphylinus? a. Anal proleg.

7. Amphipodimorphous ditto of Acrida. VOL. III. p. 165.

8. Larva of Zelus.

9. Helminthimorphous ditto. Apis mellifica. (Reaum.)

10. Larva of Sirex.

11. -------- Tenthredo L. (Reaum.) a. 6 legs. b. 16 prolegs.

12. -------- Sphinx. a. 6 legs. b. 10 prolegs. c. Anal horn.

13. Spinose ditto of Vanessa Io.

PLATE XIX.[2206]

FIG.

1. Larva of Papilio Machaon, a. Its retractile osmaterium emerging from its neck. VOL. II. p. 244--. III. p. 148.

2. Larva of Cerura Vinula. a. Its anal mastigia. VOL. III. p. 151.

3. Onisciform ditto of Thecla Rubi.

4. Larva of Stauropus Fagi. (Rösel.) VOL. III. p. 133. note^d.

5. -------- Notodonta ziczac. (Reaum.)

6. -------- Laria fascelina. a. Pencil of hairs, b. Verricules of ditto. c. Fascicule of ditto. VOL. IV. p. 277. 3, 5, 7.

7. -------- of one of the Geometers in their attitude of surveying.

8. Araneidiform larva of Myrmeleon. (Reaum.)

9. Larva of Culex pipiens. (Reaum.) a. Tail. b. Respiratory apparatus.

10. ----- of Chironomus plumosus. (Reaum.) a. Respiratory organs.

11. ----- of a Volucella inhabiting the nests of humble-bees. (Reaum.) a. Anal radii.

12. ----- of Elophilus pendulus. (Reaum.) a. Respiratory tubes.

13. ----- of Stratyomis Chamæleon. (Swamm.) a. Plumes of respiratory orifice.

PLATE XX.[2207]

FIG.

1. Larva of a Musca.

2. -------- an Œstrus.

3. Egg of Vanessa Urticæ. (Sepp.)

4. ------ Hipparchia Pilosellæ. (Ibid.)

5. ------------------ Hyperanthus. (Ibid.)

6. ------ Geometra Cratægata. (Ibid.)

7. ------ Pieris Brassicæ. (Ibid.)

8. ------ Hipparchia Ægeria. (Ibid.)

9. ------ Ourapteryx Sambucaria. (Ibid.)

10. ------ Noctua nupta. (Ibid.)

11. -------------- Fraxini. (Ibid.)

12. ------ Geometra prunaria. (Ibid.)

13. ---------------- armillata. (Ibid.)

14. ------ Lasiocampa neustria. (Reaum.)

15. ------ Hipparchia Jurtina. (Sepp.)

16. ------ Pentatoma. a. Bow-shaped spring, by which the operculum is thrown off. VOL. III. p. 104.

17. ------ Apis mellifica. (Reaum.)

18. ------ Culex pipiens. (Ibid.) a. Summit.

19. ------ Scatophaga. (Ibid.) a a. Auricles.

20. Necklace of eggs. VOL. III. p. 67.

21. Egg of Tipula oleracea. (Reaum.)

22. ------ Ophion luteum. (De Geer.) VOL. IV. p. 213--.

23. ------ Nepa cinerea. (Swamm.)

24. Jelly, with a necklace of eggs running in a spiral direction from end to end, taken out of the water.

25. Jelly of more consistence, enveloping the eggs of Phryganea atrata. VOL. III. p. 68.

Printed by Richard Taylor, Shoe-Lane, London.

FOOTNOTES:

[2192] Recourse must be had to the synoptical table of the nomenclature of the parts of the external crust of Insects (VOL. III. p. 354) for the explanation of the reference letters not here given.

[2193] VOL. I. p. 394--. III. p. 355--, 394--. IV. p. 305--.

[2194] Ibid.

[2195] Probably e´ is resolvable into two pieces.

[2196] VOL. III. p. 367--, 529--. IV. p. 326--.

[2197] VOL. III. p. 367--, 529--. IV. p. 326--.

[2198] VOL. II. p. 347--. III. p. 372--, 595--.

[2199] VOL. III. p. 366, 510--. IV. p. 316--.

[2200] VOL. IV. p. 307. iii, iv. 309. b. 310. d. 313. viii. 328, 334.

[2201] VOL. IV. p. 286--, 338, 345--.

[2202] Ibid. p. 345--, 350--.

[2203] VOL. IV. p. 351. ii. III. LETTER XXXII. VOL. I. p. 65--.

[2204] Ubi supr.

[2205] VOL. III. LETTER XXXI.

[2206] VOL. III. LETTER XXXI.

[2207] Ubi supr. and LETTER XXX.

Tanscriber's Notes:

Obvious punctuation and spelling errors have been fixed throughout.

Inconsistent hyphenation is as in the original.

The Errata mentioned on Page vi for this volume and Page viii for Volumes I and II have been made to the appropriate volumes.

Elements in the Figures that have an asterisk above them are referred in the text as a superscipt asterisk, since most fonts won't display the asterisk above.

Footnote 953: There is no anchor for this in the original, left as is.

Footnote 1553: There is no anchor for this in the original, left as is.