eat = ; Vial ala NAY" WRAL aT +. AAA MAS Z l SA c4 < | A oO = lhe Clk ee < + 4 aX G FRA + C760 LIdAQOW WALYDAI ~ si ny Ie 3 ee He INTRODUCTION ENTOMOLOGY: OR ; ELEMENTS NATURAL HISTORY OF INSECTS: WITH PLATES. By WILLIAM KIRBY, M. Ay E R. anp L.S. RECTOR OF BARHAM, — AND WILLIAM SPENCE, Esg. F.L.S. a VOL. 11. TE as Py Te es j LONDON; € PRINTED FOR LONGMAN, REES, ORME, BROWN, AND GREEN, PATERNOSTER ROW. 1826. PRINTED BY RICHARD TAYLOR, SHOE LANE, LONDON. ADVERTISEMENT. RCC ARNEL RL ECE SESE TOES THE publication of the concluding volumes of the “ Introduction to Entomology” has been un- avoidably delayed by the continued ill health of one of the Authors, which has devolved upon the other a considerable increase of labour, and de- manded a greater expenditure of time than would otherwise have been required: for though Mr, SPENCE put every facility in Mr. Kirny’s power, and had drawn up a rough copy of every Letter belonging to his department ; yet, as most of them had been written several years ago, many curious facts, and a great variety of interesting information subsequently derived from various Sources, were necessarily to be inserted, and the whole to be prepared for the press. When the thousands of objects that were to be examined, and many of them repeatedly, in com- posing the Letters on the External Anatomy of Insects, are considered, it will not appear sur- a 2 iv ADVERTISEMENT. prising if some errors should have crept in; espe- cially as Mr. Kırgy was deprived of the effectual help formerly derived from the acumen, learning, and judgement of his esteemed coadjutor, by his lamented and protracted indisposition : but it is hoped that these errors will be found of minor importance, and not to affect any general prin- ciples advanced, The same remarks are also in part applicable to the Anatomical and Orismolo- gical Tables (Vox. II. p. 354—393, and Vor. IV. p. 257—354), which were drawn up by the Au- thors jointly many years ago, before any other portion of the work was composed, but which have, especially the former, required considerable alterations and additions in consequence of sub- sequent observations and information. It will not be amiss here to state, in order to obviate any charge of inconsistency in the pos- sible event of Mr. Kirzy’s adverting in any other work to this subject, that though on every material point the authors have agreed in opinion, their views of the theory of instinet do not precisely accord. That given in the second and fourth volumes is from the pen of Mr. Spence. It was originally intended, as mentioned in the Preface, to have given a complete list of Entomo- ADVERTISEMENT. logical works, of which a large portion was drawn up; but the great length to which more important matters have extended, has the intire omission of this rendered necessary list,—an omission in some degree compensated by the catalogue of Authors quoted, which comprises most of the standard Entomological works, ERRATA. Page. Line. 29 27, for Pseudo-cordia read Pseudo-cardia. 33 7, for zs read 1, 35 7 and elsewhere, for Gigas read grandis. 46 16, for number and situation read in some respects. 98 6, for Furtina read Jurtina. 121 note 4, for c read cl. 185 note >, for XXIV. read XXIII. 137 note*, for 17 read 18. 251 4, for ten read nine. 378 10, 21, note >, for a’ read a”. note >, for b” read b’. 1, dele Pelecotoma. 10, for orbicular read subtriangular. 512 antepenult. fter genera insert, except in some Acrida@, as A. viri- dissima. 562 note ®, for rvew read ryvy 606 5, for Heteropterous read Homopterous. ? Jor frænum read frænum. DIRECTIONS TO THE BINDER. The Synoptical Table of the Nomenclature of the Parts of the External Crust of Insects should be placed opposite to page 354. Plates VI--XX, should be placed in this Volume, and the re- mainder in the Fourth. i It is however suggested to Purchasers, that in binding complete Sets of the Work, a separate Volume may be formed of the Synop- tical Table, the Plates and their Explanations, and the Indexes. CONTENTS OF VOL. III. Letter. | XXVIII. Definition of the Term Insect XXIX. States of Insects. Egg state XXX. The same Subject continued. Larva XXXI. The same Subject continued. Pupa 238—290 XXXII. The same Subject continued. Imago 291—347 XXXIII. External Anatomy of Insects. and their Definition Terms 348—393 XXXIV. The same Subject continued. The Head and its Parts 394—528 The same Subject continued. The Trunk and its Parts and Organs’ .. 529—697 The same Subject continued. The Ab- domen and its Parts. . . 698—720 NOTICE RESPECTING VOL. I. ax II. It being judged expedient, since the publication of the last Edition of the first and second Volumes of this Work, to adopt a new plan with respect to the reference letters of the Plates, the Reader is requested to make the following corrections in those Volumes. Vol. I. Page. Note. 125 °, forf, d read a”, 273 °, fora read a. 395 4, for 29, 30 read 13. Vou. II. °, for a read a. b, for 10 read 14, 4, fora read e". *, for 7—. read 16—. b, fora read s”, v”. c, forb read t”. a, for 1.8. aa read 18. ct. >, for bb read q”. e, for bb read C". €, forec read C” C”, which represent the bundles of mus- cles in connexion with the drums. In the above figure the mirror is the part directly under those bundles. AN INTRODUCTION ENTOMOLOGY. See LETTER XXVIII. DEFINITION OF THE TERM INSECT. WHAT is an insect? This may seem a tion after such copious details as have been former Letters of their history and economy, in which it aþpears to have been taken for granted that you can an- swer this question. Yet in the scientific road which you are now about to enter, to be able to define these crea- tures technically is an important first step which calls for attention. You know already that a butterfly is an insect —that a fly, a beetle, a grasshopper, a bug, a bee, a louse, and flea, are imsects—that a spider also and centi- pede go under that name; and this knowledge, which every child likewise possgsses, was sufficient for compre- hending the subjects upon which I have hitherto written. But now that we are about to take a nearer view of them— to Investigate their anatomical and physiological charac- VOL: TH, B . strange ques- given in my 2 DEFINITION OF THE TERM INSECT. ters more closely—these vague and popular ideas are insufficient. In common language, not only the tribes above mentioned, but most small animals—as worms, slugs, leeches, and many similar creatures, are known by the name of insects. Such latitude, however, cannot be admitted in a scientific view of the subject, in which the class of insects is distinguished from these animals just as strictly as beasts from birds, and birds from reptiles and amphibia, and these again from fishes. Not, indeed, that the just limits of the class have always been clearly understood and marked out. Even when our corre- spondence first commenced, animals were regarded as belonging to it, which since their internal organization has been more fully explained, are properly separated from it. But it is now agreed on all hands, that an earthworm, a leech, or a slug, is not an insect; and a Naturalist seems almost as much inclined to smile at those who confound them, as Captain Cook at the island- ers who confessed their entire ignorance of the nature of cows and horses, but gave him to understand that they knew his sheep and goats to be birds. You will better comprehend the subsequent definition of the term Insect, after attending to a slight sketch of the chief classifications of the animal kingdom, more es- pecially of the creatures in question, that have been pro- posed. That of Aristotle stands first. He divides ani- mals into two grand sections, corresponding with the Ver- tebrata and Invertebrata of modern Zoologists: those, namely, that have blood, and those that have it not? :— by this it appears that he only regarded red blood as real blood; and probably did not suspect that there was a Everio, Avare., Hist. Animal. |. i. c. 6. DEFINITION OF THE TERM INSECT. 3 a true circulation in his Mollusca and other white-blooded animals, His Enaima, or animals that have blood, he divides into Quadrupeds, Birds, Fishes, Cetacea, and Apods or reptiles ; though he includes the latter, where they have four legs, amongst the quadrupeds?; and his Anaima, or animals without blood, into Malachia, Ma- lacostraca, Ostracoderma, and Entoma, The first of these, the Malachia, he defines as animals that are ex- ternally fleshy and internally solid, like the Enaima ; and he gives the Sepia as the type of this class, which answers to the Cephalopoda of the moderns. The next, the Ma- lacostraca, synonymous with the Crustacea of Cuvier and Lamarck, are those, he says, which have their solid part without and the fleshy within, and whose shell will not break, but splits, upon collision®, The Ostracoderma, cor- responding with the Testacea of Linné, he also defines as having their fleshy substance within, and the solid with- out; but whose shell, as to its fracture, reverses the cha- racter of the Malacostraca. He defines his last class Entoma, in Latin Insecta, with which we are principally concerned, as animals whose body is distinguished by in- cisures, either on its upper or under side, or on both, and — has no solid or fleshy substance separate, but something intermediate, their body being equally hard both within and without’. This definition would include the Anne- lida and most other Vermes of Linné, except the Testacea, which accordingly were considered as insects by those Zoologists that intervened between Aristotle and the lat- ter author. The Stagyrite, however, in another place, * Hist. Animal. 1. $e, 5,6: compare l. v., ¢. 3 and 83, and De Partibus Animal. l. iv. c. | and 1], b To de S*ANOY eeurTay g Seavroy arg Drnsor. © Hist. Animal, l, iv. c. 1, BQ 4. DEFINITION OF THE TERM INSECT. has expressly excluded all apods*. From other passages in his works, it appears that he regarded the Vermes, &c. either as larvæ, or as produced spontaneously and not ex ovo”. | This definition of an insect, though partly founded on misconception, as well as his primary division of animals ‘in general, is by no means contemptible. If you look at a bee or a fly, you will observe at first sight that its body is insected, being divided as it were into three principal pieces—head, trunk, and abdomen‘; and if you examine it more narrowly, you will find that the two last of these parts, especially the abdomen, are further subdivided. And this character of znsection, or division into segments, more or less present in almost every insect‘, is not to be found (with the exception of the Crustacea, which Ari- 2 Eyrowx rorvroda pey yoo est rayta. De Part. Animal. |, iv. c. 6. d Hist, Animal. 1. iv. ©. 19. c. The insection that distinguishes these parts, the abdomen espe- cially, is most visible in the majority of the Hymenoptera and Diptera orders; next in some Coleoptera, as the Lamellicorn tribes, &c. and the Lepidoptera. Latreille is of opinion, that the two last segments of the thorax in some insects are represented by the first of the abdomen, and that the upper half segment of this part in Coleoptera also represents the same. Latr. De quelques Appendices, &c. An- nales Générales des Sciences Physiques. A Bruxelles, vi. livrais. xviii. 14. In fact,in the Lepidoptera, when the abdomen is separated from the trunk, this segment usually remains attached to the latter. In the Myriapods, the trunk is to be distinguished from the abdomen only by its bearing the three first pair of legs. € There is no general rule without exceptions, and no character is so universal as to be distinctly exhibited by every member of a class or other natural group. Thus, in the majority of the mites (Acarus L.) the body is marked by no segments, and the only articulation or incision is in the legs, palpi, &c. But as the exception does not make void the rule, so neither does the extenuation or absence of some primary character at its points of junction with others, in some indi- viduals, annihilate the class or group. DEFINITION OF THE TERM INSECT. 5 stotle. distinguishes by the nature of their integument and its contents) in any of the other classes into which he divided animals without blood. It was on account of this most obvious of their characters, that these little creatures were in Greek named Lintoma, and in Latin Insecta ; and from the former word, as you know, our favourite science takes the name of Entomology. Pliny adhering to the definition of Aristotle, as far as it relates to the znsection of the animals we are speaking of, expressly includes Apods, as well as Aptera, amongst them*; and in this was followed, without any attempt at improvement, by all the entomological writers that inter- vened between him and the great Aristotle of the mo- derns, Linné. es This illustrious naturalist, aware of the incorrectness of the primary divisions of the animal kingdom founded upon the presence or absence of blood, establishes his system upon the structure of the heart, and upon the temperature and colour of the circulating fluid. He di- vided animals into two great sections or sub-kingdoms, each comprising two classes. His Jirst section included those having a heart with zwo ventricles, ¢wo auricles, and warm and red blood, viz. the Mammalia or beasts, and the Aves or birds. His second, those having a heart with one ventricle, one auricle, and cold and red blocd, namely, the classes Amphibia, which included reptiles, serpents, &c. and Pisces or fish. His third, those haying a heart with one ventricle and na auricle, and cold white sanies in the place of blood, namely, his classes Insecta et Vermes, including the Invertebrate animals of La- © dttst,..¥at, 1, xi, c, | ° 6 DEFINITION OF THE TERM INSECT, marck. ‘Thus the first of Aristotle’s great divisions he increased by the addition of a new and very distinct class, the Amphibia, by which some ground was gained in the science ; but as much was lost by his compressing the four classes of which the last consisted into two, by which the natural classes of Cephalopoda and Crustacea merged under Jnsecta and Vermes. Linné was not aware of the extraordinary fact, that the Cephalopoda have three hearts; and that though the Crustacea and Arachnida have a circulation, ZJnsects have none, or he would never have taken this retrograde step. Indeed Linné’s definition of an Insect is, in many most material points, inapplicable, not only to the Crus- tacea, but to many other animals included under that denomination. This will appear evident from a very slight examination. ‘Thus it runs: Polypod animal- cula, breathing by lateral spiracles, armed every where with an osseous skin, whose head is furnished with mov- able sensitive antenne*.” Now of this definition only the first member can be applied to the whole class which it is meant to designate; for the entire genus Cancer L., which, with some others, forms the class Crustacea of the moderns, does not respire by spzracles at all, but by gills ; and the same in some degree may be said of spiders, scorpions, &c. With the last member of the definition Linné himself must have been aware that a large number of what he conceived to be insects were at variance, as mites, spiders, and many other of his apterous tribes : though from some very recent observations of M. La- a Animalcula polypoda, spiraculis lateralibus respirantia, cute ossea cataphracta; antennis mobilibus sensoriis instruuntur. ‘ Syst. INGE Cd Te i aoe DEFINITION OF THE TERM INSECT. 7 treille*, there seems some ground for thinking, that in these the antennz are represented by the mandibles,’ palpi, &c., and to the soft flexible, coriaceous or mem- branous skin of a vast number of insects, the term cutis ossea is by no means applicable. Evident as these incongruities are, when the Herculean task which Linné imposed upon himself, and the vastness and variety of his labours, are considered, they become very venial. Indeed, unless he had divided his class Jn- secta into two or more; it was impossible to define it in- telligibly to ordinary readers, otherwise than nearly in the terms which he actually employed; and these cha- tacters, restricted and amended by qualifying clauses, are still those to which recurrence must be had in a popular definition of the class, when separated as it ought to be from the Crustacea and Arachnida. Pennant, Brisson, and other zoologists, who, attending to nature rather than system, saw the impropriety of unit- ing a crab or a lobster in the same class with a bee or a beetle, long since assigned the Crustacea their ancient distinct rank. * But these changes,” as Latreille ob- serves*, ‘¢ being only founded’ upon external characters, might be deemed arbitrary; and to fix our opinion, it was necessary to have recourse to a decisive authority— the internal and comparative organization of these ani- * Quoted by Mr. Wm. MacLeay in ‘his very remarkable and learned work Hore Entomelogice, in which he inclines to the same opinion. 383, unt > Treviranus (Ueber den innern Bau der Arachniden, &¢c. 22.) al- ways calls the palpi of spiders * Fiilhirner.? In Scorpio he regards them as palpi (Palpen). e N Dict. d Hist. Nat. xvi, 181. 8 DEFINITION OF THE TERM INSECT: mals. It results from the observations of the most pro- f ound comparative anatomist of our age, M. Cuvier, that the Crustacea and Arachnida differ from insects properly so called, and particularly from those that are furnished with wings, in having a complete system of circulation, a different mode of respiration, and that they have a more perfect organization. Influenced by these motives, both Cuvier and Lamarck have considered them as forming two classes separate from insects. ‘Treviranus, led by considerations founded on the organs of circulation, of respiration, and of generation, is of opinion that spiders and scorpions ought to form one class with the Crustacea : he observes, however, that the nervous system of all three ‘is very dissimilar; and that in an arrangement founded on this circumstance, the organs of motion, and the ex- ternal shape, even spiders and scorpions must be placed in different classes? It is to be observed with regard to the Arachnida of the French school, that the class as laid down by them includes several animals that have no circulation, and breathe by ¢rachee, of which description are the mites (Acarus L.), and the harvest-men (Phalangium L.) &c.; and therefore it has been divided into two orders, Pul- monaria and Tracheana ; but if the definition from the internal organization be adhered to, the latter should either remain with the class Insecta, or form a new one by themselves. Yet the animals that compose the Trachean order of Arachnida, their external form considered, are certainly much more nearly related to the spiders and a Treviranus, ut supra, 48. For the nervous system of scorpions, see £ i. f. 13; and for that of spiders, t. v. f. 45, DEFINITION OF THE TERM INSECT. 9 scorpions than to any members of the class Insecta at present known, This circumstance, perhaps, may seem to throw some doubt upon the modern system of classi- fication. . I must further observe, that the assertion of Treviranus, which appears to intimate that the respiration of the pul- monary Arachnida is the same with that of the Crustacea, is not quite correct, since in the latter the branchige or gills are external, and in the former internal, the air en- tering by spiracles before it acts upon them, It may not be aniiss in this place to lay before you the principal points in which the Crustacea and Arachnida agree with Insecta, and also those in which they differ. _ The Crustacea agree with Jnsecta in having a body divided into segments, furnished with jointed legs, com- pound eyes, and antenna. ‘Their nervous system also is not materially differ ent, and they are both oviparous. ‘They differ from them in having the gr eater insections of the body less strongly marked C ber of legs on the trunk, the ing the office of maxille ; moveable footstalk ; their four antennee ; in the greater num- anterior ones perform- in their eyes usually on a their palpigerous mandibles; and at least in the great majority. But the principal difference consists in the internal organi- zation and the fountains of vitality; for the Crustacea have a double circulation, the fountain of which is a hear t in the middle of their thorax?, They have too a kind of gizzard and liver, at le ast the Decapods*, and their re- spiration is by gills, Genuine insects terminate their _* PLate XXIX. Fre, 2. Treviranus, é inf l. > Cuvier Anat, Comp. iv, 407, © N, Dict. d Hist. Nat. ix. 190, 10 DEFINITION OF THE TERM INSECT. existence after they have laid their eggs*; but the Crus- tacea live longer, and lay more than once. The Arachnida will be found to differ from insects more widely than even the Crustacea. They agree in their jointed legs and palpi; immoveable eyes; and in being covered with a coriaceous or corneous integument: but they differ in having a system of circulation; gills instead of tracheæ; their organs of generation double; and the females lay more than once in their lives. Their head also is not distinct from the trunk as in insects; they have no compound eyes; and their antennze, if we admit the opinion on this head of MM. Latreille and Treviranus, that they have representatives of these or- _ gans, differ totally in structure, situation, and use, from those of the great body of insects. In the Araneide or Spiders, their body seems to have no segments or incisure but that which separates the abdomen from the trunk ; and in the Scorpionide they are observable only in the abdomen. Other particulars might be enumerated in which these two classes differ from insects; but these will be sufficient to convince you that Aristotle and MM. Cu- vier and Lamarck were justified in separating them. The two last-mentioned authors made further improve- ments in Zoology. The latter, from the consideration of the general structure of animals, perceiving that Aristo- tles Enaima were distinguished from his Anaima, by being built as it were upon a vertebral column, very ju- diciously changed the denomination, which was indeed improper, of “ The Philosopher’s” two sub-kingdoms, into 2 The females of Dorthesia, however, a genus related to Coccus, are said to survive laying their eggs. N. Dict. d Hist. Nat, ix, 558, DEFINITION OF THE TERM INSECT. . il that of Vertebrata or animals that have a vertebral co- lumn, and Invertebrata or those that have no vertebral column. These he distributes into three primary divi- sions according to their supposed degrees of intelligence —Thus: EB: * Apathetic Animals. 1. ĪNFUSORIA, 2. Poryrt. . RADIATA. : . VERMES. ** Sensitive Animals. (Epizoaria.) INSECTA. . ARACHNIDA. CRUSTACEA. . ÂNNELIDA. . CIRRHIPEDA. . Morrusca. *** Intelligent Animals. 11. Pisces. 12. REPTILIA. 13. AVES. 14, MAMMALIA. ? Profiting by the light afforded by the Aristotelian sy- stem, this eminent zoologist improved, we see, upon that of Linné, by resolving his Znsecta into three classes, and his Vermes into seven, interposing the Linnean Insecta between the four first and three last, in which he was not so happy, since as to sense insects should certainly occupy the place he has here assigned to the Mollusca. In the work from which I have taken this statement of Lamarck’s system, that acute writer has given a sketch of another method of arrangement, in which he has made the first deviation from the beaten track of an unbroken * Anim. sans Vertebr. i, 881, 12 DEFINITION OF THE TERM INSECT. and unbranching series. In the Supplement to the first volume, he has distributed the Invertebrata in a double subramose series—one consisting of articulate, and the other of inarticulate animals*. Upon Lamarck’s system, most of the modern ones, with some variation, are founded.. There is one, how- ever, by a learned countryman of ours, that is more unique, sui generis, and I may add profound, than any that has yet appeared. I am speaking of that, you will perceive, of which our friend Mr. Wm. MacLeay has given a detailed statement in his Hore Entomologice. In this he goes even far beyond what Lamarck has at- tempted in the above sketch, and substantiates his claim to be considered as one of those original thinkers, rari nantes in gurgite vasto, that do not appear every day. The following are the principal bases of his system. 1. That all natural groups, whether kingdoms or any subdivision of them, return into themselves; a distribu- tion which he expresses by circles. 2. That each of these circles is formed precisely of five groups, each of which is resolvable into five other smaller groups, and so on till you reach the extreme term of such division. s 3. That proximate circles or larger groups are con- nected by the intervention of lesser groups, which he de- nominates osculant. 4. That there are relations of analogy between the corresponding points of contiguous circles. This system he has represented by tables of circles inscribed with the five primary divisions of each group. His first table exhibits a general view of organized matter a Anim. sans Vertebr, i, 457. DEFINITION OF THE TERM INSECT. 13 as distributed. in the animal and vegetable kingdoms— Thus: Pp MOLLUSCA. ~ VERTEPRATA. DICOTY LE- DONES. *xe® | ACRITA. MONOCOTY=- LEDONES,. ANNULOSA. RADIATA. ANIMALIA. Our learned author here divides the animal kingdom into what may be denominated five sub-kingdoms or pro- vinces, in three of which (with the exception of the Crus- tacea and Arachnida belonging to his Annulosa) no cir- culation of blood is visible, but which obtains in the rest. These he names— 1. Acrita, consisting of the Infusory Animals, the Polypi, the Corallines, the Tenia, and the least organized of the Intestinal Worms. 2. Raprara, including the Jellyfish, Star-fish, Echini, and some others. . 3. ANNULOSA, consisting of Insecta, Arachnida, and Crustacea. 4, VERTEBRATA, consisting of Beasts, Birds, Reptiles, Amphibia, and Fishes. . 5. Moxuusca, including the numerous tribes of shell- fish, land-shells, slugs, &c., which, from their mucous or gelatinous substance, from their nervous system and the imperfection of their senses, return again to the Acrita, 14 DEFINITION OF THE TERM INSECT. though connected with the Vertebrata by having a heart and circulation. His next set of circles shows the sub-division of these five sub-kingdoms into classes—Thus : >. t; Ma SrA Y w r S S i MOLLUSCA Brudes Acephata PRraginat erp OT erati lia AQ Seta Q DAZUsM B rachopoda? Agastria ISW ACRITA Amphibia ANIMALIA Mammal VERTEBRATA Pa Ruatantes, Hee 0 A ` ULOPOULST A QUIOGIA I JO- ® 4 k z Fistulida po (Aculephida Mandi-: bulat Echinida Crustacea RADIATA ANNULOSA Aea Haustel- cdusida Stelleridy In this scheme the osculant classes are those placed between the circles. In the Mollusca circle two classes are still wanting to complete the quinary arrangement of that sub-kingdom. I am not sufficiently conversant DEFINITION OF THE TERM INSECT. with the details of the animal kingdom at large to hazard any decided opinion upon Mr. MacLeay’s whole system, or to ascertain whether all these classes are sufficiently distincta. My sentiments with regard to those of the Annulosa I shall state to you hereafter. Upon a future occasion I shall consider more at large the station to which insects seem entitled in a system of invertebrate animals, which will not accord exactly with that assigned by MM. Cuvier and Lamarck. But I am now in a field in which I have no intention to expatiate further, than as it is connected with the subject of the present letter. I shall therefore confine myself in what I have more to say to the definitions of Jnsecta that have been given by modern authors, beginning with that of the zoologist last mentioned. Insects form a part of his second group, which he terms sensitive animals (animaux sensibles), which group he thus defines: “ They are sen- tient, but obtain from their sensations only perceptions of olyects—a kind of simple ideas which they cannot combine to obtain complex ones. Charact. No vertebral . column ; a brain, and most commonly an elongated me- dullary mass ; some distinct senses; the organs of move- ment attached under the skin: form symmetrical, by parts, in pairs®.” This division of animals, from the * The number jive, which Mr. MacLeay assumes for one basis of his system as consecrated in Nature, seems to me to yield to the number seven, which is consecrated both in Nature and Scripture. Metaphysicians reckon seven principal operations of the mind; mu- Sicians seven principal musical tones; and opticians seven primary Colours. In Scripture the abstract idea of this number is—comple- tion—fullness—perfection. I have a notion, but not yet sufficiently matured, that Mr. MacLeay’s quinaries are resolvable into septenaries. b Anim. sans Vertebr. i. 381. 16 DEFINITION OF THE TERM INSECT. kind and degree of sense and intelligence that they pos- sess, seems rather fanciful than founded in nature, since many insects show a greater portion of them than many vertebrate animals. Compare in this respect a dee with a tortoise*. Lamarck divides his group of animaux sen- sibles into two sections, namely, Articulated animals, ex- hibiting segments or articulations in all or some of their parts; and Jnarticulated animals, exhibiting neither seg- ments nor articulations in any of their parts. Jnsecta, Arachnida, and Crustacea, belong to the first of these sections, which he defines as “ those whose body is di- vided into segments, and which are furnished with jointed legs bent at the articulations?” Insrcra he defines— “ Articulate animals, undergoing various metamorphoses, or acquiring new kinds of parts—having, in their perfect state, six feet, two antenne, two compound eyes, and a corneous skin. © The majority acquiring wings. Respira- tion by spiracles (stigmates), and two vascular opposite chords, divided by plexus, and constituting aeriferous tra- chee, which extend every where. A small brain at the anterior extremity of a longitudinal knotty marrow, with nerves. No system of circulation, no conglomerate glands. Generation oviparous: two distinct sexes. A single sex- ual union in the whole course of life’.” = ARACHNIDA he defines—“ Oviparous animals, having at all times jointed legs, undergoing no metamorphosis, and never acquiring new kinds of parts. Respiration tracheal or branchial : the openings for the entrance of the air sptraculiform (stigmatiformes). A heart and circulation beginning in @ See on this point MacLeay, Hor. Entomolog. 209—. b Anim. sans Vertebr. iii. 243. c Ibid. ii. 246 DEFINITION OF THE TERM INSECT. 17 many. The majority couple often in the course of life.” I shall next add his definition of Crustacea: “ Ovipa- rous, articulated, apterous animals, with a crustaceous in- tegument more or less solid, having jointed legs; eyes either pedunculate or sessile, and most commonly four antenne, with a maxilliferous mouth seldom rostriform ; maxille in many pairs placed one over the other ; scarcely any under-lip ; no sptraculiform openings for respiration ; Jive or seven pair of legs; a longitudinal knotty marrow terminated anteriorly by a small brain. A heart and ves- sels for circulation. Respiration branchial with external branchiæ, sometimes hid under the sides of the shell of the thorax, or shut in prominent parts ; sometimes uncovered, and in general adhering to particular legs or to the tail, Each sex usually double?” I have given Lamarck’s definitions of these three classes, all considered as Insecta by Linné, that by comparing them together you may be better enabled to appreciate the system of this author. On looking over the characters of the Arachnida as here given, you will see at once that it consists of heterogeneous ‘animals—for in fact he in- cludes in this class not only the Trachean Arachnida of Latreille, but the Ametabolia of Dr. Leach, or the Hera- pod Aptera, and the Myriapoda. = I shall next copy for you Latreille’s latest definition o Insecta and Arachnida. “ InsEcTA: A single dorsal vessel representing the heart: two trunks of tracheæ running the whole length of the body, and opening externally by numerous spira- cles; two antene ; very often upper appendages for Hight, indicating the metamorphosis to which the animal a Anim. sans Vertebr. iii. 245, » Ibid. POL TtT, c 18 DEFINITION OF THE TERM INSECT. és subject when young ; legs most commonly reduced to. sic. ARACHNIDA: Distinguished from Crustacea by having their respiratory organs always internal, opening on the sides of the abdomen or thorax to receive the re- spirable fluid. Sometimes these organs perform the office of lungs, and then the circulation takes place by means of a dorsal vessel, which sends forth arterial, and receives wenose branches. Sometimes they are trachee or air- wessels, which, as in the class Insecta, replace those of circulation. These have only the vestige of a heart, or a dorsal vessel alternately contracting and sending forth no branch. The absence of antenna, the reunion of the head with the thorax, a simple trachea but ramified and almost radiating, serve to distinguish these last Arachnida, or the most imperfect of insects, which respire only by trachee*”? Under this head he observes—“ Of all these characters, the most easy to seize and the most, certain would doubtless be, if there were no mistake in it, that of the absence of antenneze ; but later and compara- tive researches, confirmed by analogy, have convinced me, that these organs, under particular modifications it is true, and which have misled the attention of naturalists, do exist? :” and he supposes, from the situation and di- rection of the mandibles of the Arachnida, corresponding with that of the intermediate pair of antenne in Crustacea, that they really represent the latter organs. If this sup- position beadmitted, their use is wholly changed; the palpi, in fact, executing the functions of antennze, which proba- bly induced Treviranus to call them Fiihthorner ( Feeling- @ Des Rapports généraux, $c. des Anim. invertebr. artic, Ann. du Mus. i pin b Thid, Hor. Entomolog. 383. DEFINITION OF THE TERM INSECT. - 19 horns). Perhaps these last may be regarded as in some Sort representing the external antenne of the Crustacea ? With regard to Insecta, their antenne seem to disappear in the Pupipar@ Latr., or the genus Hippobosca L. The above definitions of the Arachnida by these two celebrated authors, appear to me the reverse of satisfac- tory. When we are told of animals included in it, that Some breathe by gills and others by tracheæ, that some have a heart and circulation and others not, we are im- mediately struck by the incongruity, and are led to sus- pect that animals differing so widely in the fountains of life ought not to be associated in the same class. A learned zoologist of our own country, Dr. Leach, seems to have made a nearer approach to a classification in ac- cordance with the internal organization, by excluding from Arachnida the Acari and Myriapoda. Sub-kingdom ANNULATA Cuv. * Gills for respiration, Classes. Legs sixteen: .... Antennz two or four .s.ssssssses 1 CRUSTACEA, ** Sacs for respiration. Legs twelve: a. Antenne none ssccccssesseeeee 3 ARACHNOIDEA, | *** Trachese for respiration. a. No Antenne. IPPON Cece eeeeeesscesetsceseesseesscsecatenssrerecesecsss 4 ACARI b. Two Antenne. Six thoracic legs: Abdomen also bearing legs.... 2 MYRIAPODA, Six thoracic legs: No abdominal legs 5 Insecta’. Mr. MacLeay, on whose system I shall now say a few Words, divides his sub-kingdom Annulosa into five classes, namely, Crustacea, Ametabola, Mandibulata, Haustellata, Arachnida. From the Crustacea he goes by the genus * Leach in Entomologist’s Useful Compendium, by Samouelle, 75. € 2 20 DEFINITION OF THE TERM INSECT. Porcellio Latr. to Julus*, which begins his Ametabola : these he connects with the Mandibulata, by Nirmus, which he thinks approaches some of the corticarious Coleoptera”. This class he appears to leave by the Tri- choptera Kirby, and so enters his Haustellata by the Le- pidoptera’, and leaves it again by the Diptera by means of the Pupipare Latr., especially Nycteribia, connecting this class with the Arachnida, which he enters by the Hexapod Acari L.4, and these last he appears to leave by the Araneide, and to enter the Crustacea by the De- capods*: thus making good his circle of classes, or a series of Annulose animals returning into itself. Mr. MacLeay’s whole system upon paper appears very har- monious and consistent, and bears a most seducing aspect of verisimilitude; but it has not yet been so thoroughly weighed, discussed, and sifted, as to justify our adopting it in toto at present: should it, however, upon an impartial and thorough investigation, come forth from the furnace as gold, and be found to correspond with the actual state of things in nature, my objections, which rest only upon some parts of his arrangement of Annulosa, would soon vanish. Some of those objections I will state here, and some will come in better when I treat of the Systems of Entomology. My first objection is, that his Ameta- bola, Mandibulata, and Haustellata, approach much nearer to each other than they do to the other two classes of his circle, or than even these last to each other; so that under this view it should primarily consist of three greater groups, resolvable, it may be, into five smaller ones. My next objection is, that he has also considered a Hor. Entomolog. 348, b Ibid. 354, © Ibid. 373. a Ibid. 381. ~ e Thid. 389. DEFINITION OF THE TERM INSECT. 21 the Trachean and Pulmonary Arachnida as forming one class. Whether an animal breathes by gills or trachez, or has a circulation or not, is surely as strong a reason for considering those so distinguished as belonging to di- ferent classes, as the taking of their food by suction or by manducation is, for separating others to the full as much or more nearly related as to their external structure. But of this more hereafter. I cannot help, as a last ob- jection, lamenting that our learned author has rejected from his system a term consecrated from the most remote antiquity, and which, even admitting his arrangement, might have been substituted for Annulosa, a name bor- rowed by Scaliger from Albertus Magnus, neither of whom, in Entomology, is an authority to weigh against Aristotle, from whom we derive the term Insecta, in Greek Evropa. As Fabricius did not alter Linné’s class Insecta, but merely broke up his orders into new ones, which he named classes, I shall give you a detail of the alterations he introduced into the science in a future letter. Having stated what my predecessors have done in classification, I shall next proceed to lay before you my Own sentiments as to—What is an insect. Since our Correspondence commenced, the Arachnida, principally on account of their internal organization, have been ex- cluded from bearing that name, carrying with them, as we have seen, several tribes, which as yet have not been discovered to differ materially in that respect from the present Insecta: for the sake, therefore, of conve- hience and consistency, that I may, as far as the case will admit, adhere to the Horatian maxim Servetur ad imum Qualis ab incepto processerit et sibi constet, 29 DEFINITION: OF THE TERM INSECT. .I shall regard as Insects all those Annulosa that respire by tracheæ? and have no circulation, considering the Trachean Arachnida and the Myriapoda for the present as sub-classes, the one bordering upon the Arachnida, and the other upon the Crustacea. Some of these I am ready to own seem separated by an interval sufficiently wide from the Hexapods, which may be regarded as more pe- culiarly entitled to the denomination of Insects. The most striking differences will be found in the coalition of the head with the trunk in some (Phalangide), and the disappearance of the annulose form of the body in others (Acarus L.), so that the legs only are jointed’, Yet an è There is some reason for thinking, though the octopod and my- riapod insects breathe by trachez, that there is no small difference in the distribution of these organs. The Trachean Arachnida have only a pair of spiracles, from which the trachee must radiate, if I may so apply the term, in order to convey the necessary supply of air to every part of thebody. Scutigera, as far as I can discover, has only a single series of dorsal spiracles (see Prate XXIX. Fre. 20)—an unusual situ- ation for them: in these also, to attain the above end, each trachea must also radiate, so as to supply each part of the segment it is in. Those of Tulus, according to the observations of Savi (Osservaz. per servire alla Storia di una Specie de Iulus,&c, 15—), consist of bundles of parallel tracheze. Perhaps these circumstances would warrant the considering of these Arachnida and the Myriapoda as primary classes? The genus Galeodes is said to breathe by gills similar to those of the Araneide, which structure, probably, carries with it a system of cir- culation, and exhibits a third type in the Arachnida, with four palpi, six legs, and a distinct thorax. This genus, then, is the corresponding point in the Arachnida to the Hexapod Aptera, as the Scorpions are to the Cheliferide or Pseudo-Scorpions, and the Araneide to the other Octopods; and these analogies furnish a strong proof, that the Tra- cheans belong rather to Insecta than Arachnida. Comp. N. Dict. d Hist. Nat. xxvi. 445; and Description de six Arachnid. nouv. &c. par Leon Dufour, 16. es >’ Mr. MacLeay observes with regard to the Tardigrade, de- scribed by Spallanzani and Dutrochet, that “ it proves that an animal may exist without antennæ or distinct annular segments to the body, but having two eyes and six articulate legs.” (Hor. Entomolog. 350—.) Many Acari prove the same thing. De Geer, vii. t, vii. f. 14, DEFINITION OF THE TERM INSECT. 23 approach to such structure may be traced in some Hexa- pods; for instance, the coalition of the head and trunk in Melophagus, Latr., and that of the trunk and abdomen in Sminthurus, Latr.+ The Myriapoda exhibit other re- markable differences; though their head and trunk are distinct, the former antenniferous, and their body annu- lose, the abdomen as well as the trunk is furnished with legs, sometimes amounting to hundreds; but even to this a tendency has been observed in some Hexapods®. If you examine a specimen of Machilis polypoda, an insect related to the common sugar-louse (Lepisma saccharina)» you will find that the abdomen is furnished with a double series of elastic appendages, which, being instruments of motion, may be regarded as representing legs. It is worthy of notice, that the Myriapoda when first disclosed from the egg have never more than six legs*, and keep acquiring additional pairs of them and additional seg- ments to their abdomen as they change their skins: and it is equally remarkable, that many Hexapods are subject to a law in some degree the very reverse of this, having many abdominal legs in their first state, and losing them all in their last. The union of the head with the trunk in the Trachean Arachnida has been regarded as almost an unanswerable argument, in spite of their different in- ternal organization, for including them in the same class with the Pulmonary Arachnida ; but the case of Galeodes, which, though furnished with gills, (as an eminent Rus- sian Entomologist Dr. G. Fischer is reported to have discovered,) implying also a circulation, and evidently belonging to the last-mentioned class, has nevertheless a -distinct thorax consisting of more than one piece, to which De Geer, vii. ¢. iii. f. 8 > Hor. Entomolog. 351 © De Geer, Ibid. 571, 583. t. xxxvi. f. 20, 21. 24, DEFINITION OF THE TERM INSECT. are affixed only six legs*, proves that even this circum- stance possesses no weight when set against the organi- zation. If it was a difference in this respect, that proved the Crustacea classically distinct from Insecta—that like- wise was the principal reason for the separation also of the drachnida—it seems to follow that it ought also to furnish an argument equally cogent for considering the Trachean Arachnida, as well as the Myriapoda, distinct from the Pulmonary. Another difference between the tribes in question is that of their metamorphosis; and this appears to have had great weight with Lamarck, inducing him to include in his Arachnida, not only the Tracheans and Myriapods, but even the apterous Hexapods, except Pulex, or the Anoplura and Thysanura of modern authors. But the metamorphosis alone, unless supported by the internal organization, will I think scarcely be deemed a sufficient reason for separating from each other tribes agreeing in that respect, and placing them with others with which they disagree. The metamorphosis in some of the Hex- apods (Lepidoptera) consists in the loss of legs, the ac- quisition of wings, a great change in the oral organs and in the general form; in others (some Coleoptera), in the acquisition only of wings and a change of shape, the oral organs remaining much the same; in others again (Cur- culio L.), in the acquisition of six legs and wings and a change of form; in the flea, in the acquisition of six legs and a change of form only; in the Orthoptera, He- miptera, &c. in the mere acquisition of wings; in the Libellulidæ, in the loss of the mask that covers the mouth and the acquisition of wings ; in the Diptera, in the ac- * Dufour ubi supra. Hor. Entomolog. 382. DEFINITION OF THE TERM INSECT. 25 quisition of six legs, wings, a change of the oral organs and of the form; in some of the Octopods (Acarus L.), in the acquisition of a pair of legs; and in others (Pha- langium and Aranea L.), solely in a modification of them as to their proportions; in the Myriapods, the alteration that takes place in this respect is considerable ; a large number of pairs of legs is acquired and many additional abdominal segments, and the proportion which the ab- domen bears to the whole insect is quite altered. In all these cases there is a change more or less, either partial or general, of the original shape or organs of the animal; and with regard to their metamorphosis, there is a greater difference between a young and adult Julus than between a young and adult grasshopper or bug: so that if the meta- morphosis, per se, be assumed as a principal regulator of the class, the grasshopper or bug have as little claim to belong to it as the Tulus. M. Lamarck lays considerable stress upon another character—That Jnsecta engender only once in the course of their lives, and Arachnida more than once. But this, if examined, will be found to be confined chiefly to the Pulmonary Arachnida, the Tr acheans following the law of Insecta in this respect?. You may perhaps object that the bringing of the Tra- chean Arachnida and the Myriapoda into the class In- secta will render the approximation of them to a natural arrangement more difficult, since it will be impossible at the same time to connect the Myriapods with the Crustacea, and the Trachean with the genuine Arachnida. * Male Insecta in some instances engender more than once. Mr. MacLeay sen. has observed this with reord to Chrysomela Polygoni, and I have noticed it in Bombi ya Mori, 26 DEFINITION OF THE TERM INSECT. I admit the validity of your objection, but by no arrange- ment of insects in a simple series can we attain this object : the difficulty, however, may perhaps be obviated in this way. The distribution of organized matter, to adopt Mr. Wm. MacLeay’s metaphor?, begins in a dichotomy, constituting the animal and vegetable branches of the great tree of nature, and from these two great branches, by means of infinite ramifications, the whole system is form- ed, and, what is remarkable, these branches unite again so as to represent a series returning into itself, a disco- very due to the patient investigation and acumen of our learned friend just mentioned. Now, in considering the Aptera order, we find at first setting out from the Hexapods, a dichotomy, where the Anoplura Leach branch off on the one side, and the Thysanura Latr. on the other—the former, by means of the Pediculide, tak- ing their food by suction, particularly Phihirus Leach, or the Morpion (in which the segments of the trunk and abdomen become indistinct) approach the Octopods by the hexapod Acari L.—the latter by Machilis polypoda tending towards the Myriapods. In the Octopod branch a further dichotomy takes place, from which you proceed on one side to the Araneide in the Arachnida, by Pha- langium, &c.; and in the other by Chelifer, &c. to Scorpio. Again, the Myriapod branch also divides, going by the Tulidæ to one branch of the Isopod Crustacea, and by the Scolopendride to another. But there is another view of this subject before alluded to, which may be repeated here, and which seems to * Hor. Entomolog. 134. 200. ma » Zoolog. Miscell. iti. t. 146. In this figure the segments are made much more distinct than they are in my specimen. DEFINITION OF THE TERM INSECT. 27 prove that the types of form in one natural group or class are reproduced in another; this appears to result from the following parallel series : Neuropterous Aptera. Arachnida. Crustacea. Galeodes Larunda. Decapoda bra- ` chyura. Octopoda : ; oF ma-! Phalangium. «. . Aranea .. croura. Tha- lassina Scorpio - especially. Ephemera Myriapoda XEKE Isopoda. Panorpa ? Chelifer series Scorpio... No type representing the Myriapoda has yet been discovered in the Arachnida class; but I have little doubt of its existence. You will observe that the ana- logies between the larvæ of the winged orders and the Aptera were first noticed by Mr. W. MacLeay*. It is probable that these parallel series of representatives of each other might be increased, as well as the numbers in the respective columns. What I have said will, I trust, sufficiently justify me for making at present no more material alterations in the classification I long since proposed to you”; I shall, therefore, now proceed to define the objects I consider as Insecta; but I shall first observe—that as Latreille con- siders the branchiopod Crustacea or Entomostraca of Müller as entitled to the denomination of Crustaceo- _Arachnida‘ ; so his Trachean Arachnida might be called Arachnido-Insecta, and his Myriapoda, Crustaceo-Insecta. 2 Hor. Entomolog. 422—. > See above, Vor. I. 4th Ed. p. 66. Note *. © Surely thedenomination ought to have been Arachnido-Crustacea, since the learned author considers them as belonging to the Crustacea class. DEFINITION OF THE TERM INSECTS Sub-kingdom—ANNULOSA?. Class—InsrEcra. First Definition—From their external Organization. Bopy—divided into Head—Trunk—Abdomen. Hzap.—Principal seat of the organs of sensation. Organs of sight. Immoveable eyes, simple or com- pound, varying in number. Organs of hearing uncertain, probably connected with the antennee. Organ of taste. Ligula or palate within the mouth, accompanied by the organs of manducation—a pair of mandibles and maxillze and an upper and lower lip, or their representatives, Organs of touch. Principally two jointed antennz or their representatives, and four jointed feelers— two maxillary and two labial. Trunk. Principal seat of the organs of motion. Organs of walking, running, or gumping. Six or eight jointed thoracic legs, in pairs. Organs of flight, Four wings or their representa- 2 It may not be without use to give here a short definition of the Annulosa ; I mean excluding the Vermes, which Mr. W. MacLeay has included; and the Annelida, which Latreille has made the fifth of his Annulose classes. Ann. du Mus, 1821. Annulosa. Animal invertebrate, oviparous; external integument of a firmer consistence than the internal substance, serving as a general point of attachment to the muscles; eyes immoveable; degs more than four, jointed, CLASSES. i 1. Crustacea. Gills external; more than eight legs, 2. Arachnida. Gills internal ; spiracles; eight legs. 3. Insecta, Trachew; spiracles; six to eight thoracic legs. DEFINITION OF THE TERM INSECT: 29 tives, mostly with branching nervures containing air-vessels ; found in the majority of the class. Organs (external) of respiration. A double set of lateral spiracles, some for expiration. ABDOMEN. Principal seat of the organs of generation. Organs of motion. In the Myriapods many pairs of acquired legs; in the Thysanura elastic ventral or caudal appendages. l _ Organs of respiration. A double series of lateral spiracles for inspiration in the majority: in some only a single series, and in others only a single pair. ; Organs of generation those common to the Ver- tebrata, but retractile within the body, attended usually by various anal appendages, particularly a forceps in the males, and an ovipositor in the females. . Second Definition—From their internal Organization. SENSATION, Nervous System. A small brain usually subbilobed, crowning a knotty double medullary chord; nerves proceeding from the brain and other ganglions to all parts of the body. CIRCULATION. Heart replaced by a simple alternately contracting dorsal vessel or pseudocordia, without arteries or veins, but filled with a white cold sanies. RESPIRATION. Lungs replaced by tracheæ, which receive the air from the spiracles, and distribute it by bronchia infinitely ramified, 30: DEFINITION OF THE TERM INSECT. DIGESTION. Liver and biliary vessels in most replaced by from 2 to + 150 floating hepatic filaments opening into the space between the two skins of the intestinal canal below the pylorus. GENERATION. _ Internal organs. Males—Vasa deferentia, and vesi- culze seminales, and the other ordinary organs. Fe- males—Ovary usually bipartite, with palmate lobes; genital organs single and mostly anal; one sexual union impregnates the female for her life. Development. In their passage to their adult state, after they have left the egg, insects undergo several si- multaneous changes of their integument or successive moults, and the majority assume three distinct forms, with distinct organs, which appear as rudiments in their second state, and are completely developed in their last. In defining the Arachnida I shall only mention those particulars in which they differ from Insecte in their ex- ternal anatomy. Class—ARACHNIDA. Bopy. Heap and Trunk usually not separated by a suture. Eyes. Two to eight, not lateral. Mandibles cheliform or unguiculate, representing the interior pair of the antennze of the Crustacea. Palpi pediform or cheliform. Trunk. Legs eight or their representatives: tibiae mostly consisting of two joints. _ ABDOMEN with from two to eight spiracles, — DEFINITION OF THE TERM INSECT. 31 SENSATION. Nervous System. A small bilobed brain crowning à double, knotty, medullary chord; nerves proceeding from the brain and other ganglions to all parts of the body. CIRCULATION. Heart unilocular, inaurite, with a system of circulation by arteries and veins; blood a cold white sanies. RESPIRATION. Lungs replaced by internal gills receiving the air by spiracles. À Dicrsrion. Liver, consisting of conglomerate glands, and enve- loping the intestines? ; hepatic ducts. GENERATION. Genital organs double, ventral; more than one sexual union in the course of life. The external characters in this class are the same al- most in every respect as those which distinguish the Phalangide, the whole difference consisting almost in the systems of circulation, respiration, and digestion, Perhaps some future anatomist may discover in the tribe just mentioned, that there is a nearer agreement between them and the Arachnida in these systems than is at pre- sent suspected, which would prove them true Arachnida. I am inclined to think that Phrynus and Gonyleptes, &c. breathe by branchial spiracles; but having no opportu- * What L. Dufour regards as the liver in Scorpio (N. Dict. d’ Hist. Nat. xxx. 42) .) Treviranus looks upon as an Epiploon (Fetthorper) both in Scorpio and Aranea. 6. t.i. f. 6. A A. t ii. f. 24, dd. Hepatic ducts: ¢. i. f. 6. ii, £, ii, f. 24. B. B. Be B 29 DEFINITION OF THE TERM INSECT. tunity of examining living specimens, I dare not speak with any confidence on the subject. Having thus given you a view of the most important diagnostics by which what we have all along called In- sects may scientifically be distinguished from other inver- tebrate animals, it may not be without use, if, under this head, I take a more popular and familiar view of the subject, and say something upon those distinctions which may attract the attention of the more common observer. The notion of diminutive size, particularly as com- pared with vertebrate animals, seems more frequently attached to the idea of an insect than any other; and this notion is generally correct, for one insect that is bigger than the least of the above animals, thousands and thousands are vastly smaller: but there exist some that are considerably larger, whether we take length or bulk into consideration, and this in almost every order. To prove this most effectually, and that you may have a synoptical view of the comparative size of the larger insects of the different orders and tribes, I now lay be- fore you a table of the dimensions of such of the largest as I have had an opportunity of measuring, including particularly those giants that are natives of the British isles. 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(081 ttararaIsy snode AUD, PUD AIPA 38 DEFINITION OF THE -FERM INSECT: From this table you see that several insects included in it exceed some of the smallest Vertebrata in bulk. In the Mammalia, the Sorex Araneus, called by the common people here the Ranny, is not more than two inches long’ excluding the tail; and the Mus messorius, or har- vest-mouse, peculiar to the southern counties of England, is still more diminutive: so that to these little animals, the larger Dynastide, Goliathi, and Prioni, &c., appear giants, and. may compete with the mole in size. Even some of the beetles of our own country, as the great Hydrophi- lus, the stag-beetle, &c., are more bulky than the two first-named quadrupeds. Amongst the birds, many Pica, Passeres, &c., yield to several insects in dimensions, and their wings when expanded do not extend so far as those of not a few Lepidoptera. The great owl-moth of Brazil (Erebus Strix) in this respect is a larger fowl than the quail. Those beautiful little creatures, the humming- birds (Trochilus: L.), the peculiar ornament ‘and life of tropical gardens, which emulate the most splendid but- terflies in the brilliancy of their plumage, are- smaller than: a considerable number of insects in almost every order, and even than some of those that are natives of Britain. Various reptiles also are much inferior in size to many of the insects of the above table. ‘The smallest lizard of this country would be outweighed by the great British beetles lately mentioned, and the mole-cricket (Gryllotalpa vulgaris); and some of the serpent tribe are smaller than the larger Scolopendre and Tuli.. Amongst the fishes also, though some are so enormous in bulk, others in this respect yield the palm to several: insects. The minnow and the stickleback that frequent our own pools and streams are considerably inferior in ‘size to some of our water beetles. DEFINITION OF THE TERM INSECT: 39 In looking over the table, and comparing the different Species that compose it with each other, you will perceive that the largest insects of the two sections of Hemiptera, of the Lepidoptera as to their body merely, of the Hy- menoptera and Diptera, in general size fall considerably short of those of the other orders; and that certain indi- viduals of the Orthoptera and Aptera bear away the Palm in this respect from all the rest. In the Coleoptera the giants, with the exception of the Golzathi, are chiefly to be found amongst the timber devourers in the Lamel- licorn and Capricorn tribes. Of orthopterous insects the Phasmid@ present the most striking examples of magni- tude; and in the Neuroptera, the Agrionide of great length. It is worthy of remark here, that although the tropical Species of a genus usually exceed those of colder climates in size, the Gryllotalpa of Brazil is very considerably smaller than that of Europe: whether this is the case with the rest of the cricket tribe I have not had an op- portunity of ascertaining. The Lepidoptera, though often remarkable for the vast expansion of their “ sail-broad vans,” if you consider only their bodies, never attain to gigantic bulk. Even the hawk-moths (Sphing L.), though usually very robust, make no approach to the size of the great beetles, or the length of some of the spectres (Phasma) and dragon-flies (Agrionid@). With regard to the superficial contents of their wings, a considerable ifference obtains in different species where they expand to the same length—for the secondary wings are some- limes smaller than the primary, and sometimes they equal them in size. In some instances, also, the latter although long are narrow, and in others they are nearly as wide as long: regard, therefore, should be had to their ex- 40 DEFINITION OF THE TERM INSECT. pansion both ways. In the Hymenoptera and Diptera, the principal giants are to be found in the predaceous or blood-sucking tribes, as Scolia, the Sphecide, Pompilida, Vespide, &c., belonging to the former order; and the Asilide and Tabanide to the latter. The true-and false humble bees (Bombus and Xylocopa) and the fly tribe (Muscide), though they sometimes attain to considerable size, scarcely afford an exception to this observation. Amongst the Aptera none of the Hexapods strike us by their magnitude, and few of the Ociopods, though the legs of some of the Phalangide inclose a vast area. That in the table would with them describe a circle of six inches diameter, though its body is little more than a quarter of an inch in length. The Myriapods exceed most insects in the vast elongation of their body, which with their motion gives them no slight resemblance to the serpents. In the class Arachnida, the bird-spiders (Mygale) are amongst the principal giants, nor do the Scorpions fall far short of them—both of them when alive often alarming the beholder as much by their size as by their aspect. | i But as I have before observed, generally speaking, one of the most remarkable characters of the insect world, is the little space they occupy; for though they touch the vertebrate animals and even quadrupeds by their giants, yet more commonly in this feature they go the contrary way, and by their smallest species reach the confines of those microscopic tribes that are at the bottom of the scale of animal life. I possess an undescribed beetle, allied to Stlpha minutissima E. B.*, which, though fur- 2 S. minutissima of Marsham is synonymous with Dermestes ato- marius De Geer, Scaphidium atomarium Gyllenh., and Latridius fascis cularis Herbst., but surely arranging with none of these genera, being DEFINITION OF THE TERM INSECT. 41 nished with elytra, wings, antennee, legs, and every other organ usually found in the order it belongs to, is abso- lutely not bigger than the full stop that closes this period. In several other coleopterous genera there are also very Minute species, as in Cryptophagus, Anisotoma, Agathidi- um, &c. I know no orthopterous insect that can be called extremely minute, except that remarkable one found on — the Continent in the nests of ants, the Blatta Acervorum of Panzer*, but now called, I believe, Myrmecophilus : nor indeed any in the Hemiptera, Neuroptera, and Di- plera, that approach the extreme limits of visibility: but in the Lepidoptera, the pygmy Tinea occultella is almost invisible except in flight, being scarcely thicker than a horse’s hair, and proportionably short; indeed, many others of those lovely Lilliputians, the subcutaneous Tinea, decorated with bands of gold and silver, and studded with gems and pearls, that in larger species would dazzle the beholder’s eye, are in size not much more conspicu- ous. In the Hymenoptera order, Ichneumon Punctum of Dr. Shaw, which forms so striking a contrast to his giant Phasma dilatatum, being placed together in the same plate; and another that I possess, under the trivial name of Atomos, would elude the searching eye of the ento- mologist unless when moving upon glass. Linné named the tribe of parasites to which these belong, Minuti, on account of their generally diminutive size. But these little minims, under the superintendence of Pro- vidence, are amongst the greatest benefactors of the Sufficiently distinguished from them and every other insect by its Singular capillary wings. In my cabinet it stands under the name of Trichopteryx K. ‘ * Panz. Fn. Germ. Init. lxii, 24, Comp. Hor. Entomolog. Addenda, cc, 523, : 42 DEFINITION OF THE TERM INSECT. human race, since they keep within due bounds the va- rious destroyers of our produce, The number of minute species of insects seems greatly to exceed that of large ones, at least in Europe, of which it may be asserted probably with truth, that two-thirds are under a quarter of an inch in length, and one-third not exceeding much a duodecimal of it. It might hold good perhaps in Coleoptera, Hymenoptera, Diptera, and | Aptera : but in Orthoptera, Hemiptera, Neuroptera, and especially Lepidoptera, a large proportion would be found to exceed three lines in length. Neither can it be af- firmed of extra-Kuropean species, of those at least pre- served in cabinets, amongst which it is rare to find an insect less than the fourth of an inch long. This, how- ever, must probably be attributed to the inattention of collectors, who neglect the more minute species, Though sizeforms a pretty accurate distinction between insects and the great bulk of vertebrate animals, it affords less assistance in separating them from the invertebrate classes, which are of every size, from the monstrous bulk of some Cephalopoda (cuttle-fish) and Mollusca (shell- fish, &c.) to the invisible infusory animalcule: but ex- ternal characters, abundantly sufficient for this purpose, may be drawn from the general covering, substance, form, parts, and organs of the body. As I shall enter into pretty full details upon this subject when I come to treat of the external anatomy of insects, I shall here, therefore, only give such a slight and general sketch of the distinctions _ Just mentioned, as will answer the end I have in view. I must here repeat what I have before observed, and what it is necessary that you should always bear in mind, namely, DEFINITION OF THE TERM INSECT; 43 that at the limits of classes and of every other natural group, the characters begin to change, those peculiar to the one group beginning gradually to disappear, and those of the other to show themselves; so that it is im- Possible almost to draw up a set of characters so precise as exactly in every respect to suit all the members of any natural group. Whichever way we turn our eyes on the objects of Creation, above—below—athwart, analogies meet us in every direction, and it appears clear, that the Book of Nature is a Book of Symbols, in which one thing repre- Sents another in endless alternation. And not only does one animal, &c. symbolize another, but even between the parts and organs of one set of animals there is often an analogy as to their situation and use, when there is little or no affinity as to their structure—or again, the analogy is in their situation, without affinity in either structure or use. Thus certain parts in one tribe represent other certain parts of another tribe, though as to their structure there is often a striking disagreement. ‘This is particu- larly observable between the vertebrate and invertebrate animals. I shall therefore, in my remarks on the ge- neral and particular structure of insects, contrast it in its most important points with that of the first-mentioned tribe, r The first thing that strikes us when we look at an Insect is its outside covering, or the case that incloses its muscles and internal organs. If we examine it attentively, Wwe find that it is not like the skin of quadrupeds and Other ye ertebrata, covering the whole external surface of the body ; but that in the large majority it consists of Several pieces or joints, in this respect resembling the 44) DEFINITION OF THE TERM INSECT. skeleton of the animals just named; and that even in those in which the body appears to have no such segments, as in many of the Mites ( Acarus L.), they are to be found in the limbs. ‘This last circumstance, to have externally jointed legs, is the peculiar and most general distinction by which the Insecta of Linné, including the Crustacea, may always be known from the other invertebrate animals*. If we proceed further to examine the substance of this crust or covering, though varying in hardness, we shall find it in most cases, if we exclude from our considera- tion the shells of the Mollusca, &c., better calculated to resist pressure than that of the majority of animals that ` have no spine. In all the invertebrate tribes, indeed, the muscles, there being no internal skeleton, are attached to this skin or its processes, which of course is firmer than the internal substance; but in insects it is very often rigid and horny, and partially difficult to perforate, sel- dom exhibiting that softness and flexibility which is found in the cuticle of birds and most quadrupeds. From this conformation it has been sometimes said, that insects — carry their bones on the outside of their body, or have an external skeleton. This idea, though not correct in all respects, is strictly so in this—that it affords a general point of support to the muscles, and the whole structure is erected upon it, or rather I should say within it. The difference here between Insects and the Vertebrata seems very wide; but some of the latter make an approach to- wards it. I allude to the Chelonian Reptiles ( Testudo L.), a The Annelida have, however, sometimes jointed organs, which facilitate their progressive motion whether vermicular or undulatory ; but they cannot be deemed legs, since they neither support the body nor enable it to walk, &c. Latreille Anim. invertebr, Artic, 126. Ann, du Mus. 1821, DEFINITION OF THE TERM INSECT. 45 in which the vertebral column becomes external or merges in the upper shell. The cyclostomous fishes also are not very wide of insects as to their integument. But on this Subject I shall be more full hereafter. _ The forms of insects are so infinitely diversified that they almost distance our powers of conception: in this re- Spect they seem to exceed the fishes and other inhabitants, of the ocean, so that endless diversity may be regarded as one of their distinctions. But on all their variations of form the Creator has set his seal of symmetry ; so that, if we meet with an animal in the lower orders in which the parts are not symmetrical, we may conclude in general that it is no insect. But it is by their parts and organs that insects may be Most readily distinguished. In the vertebrate animals, the body is usually considered as divided into head, trunk, and limbs, the abdomen forming no part of the skeleton; but in the insect tribes, besides the organs of sense and motion, the body consists of three principal. parts—Head, Trunk, and Abdomen—the first, as was before observed, bearing the principal organs of sense and manducation ; the second most commonly those of motion ; and the third those of generation—the organs of respiration being usually common to both trunk and ab- domen. These three primary parts,—though in some in-- Sects the head is not separated from the trunk by any Suture, as for instance in the Arachnida; and in others, head, trunk, and abdomen form only one piece, as in some Mites,—still exist in all, and in the great majority they are Separated by incisures more or less deeply marked: this is Particularly visible in the Hymenoptera and Diptera, Which, in this respect, are formed upon a common model; 46 DEFINITION OF THE TERM INSECT. and in the rest, with the above exceptions, it may be distinctly traced. — ~The head of insects is clearly analogous to that of vertebrate animals, except in one respect, that they do not breathe by it. It is the seat probably of the same senses as seeing, hearing, smelling, tasting—and more pe- culiarly perhaps of that of touch. The eyes of insects, though allowed on all hands to be organs of sight, are differently circumstanced in many particulars from those of the animals last mentioned; they are fixed, have nei- ther iris nor pupil, are often compound, and are without eyelids to cover them during sleep or repose; there are usually two compound ones composed of hexagonal facets, but in some instances there are four; and from one to three simple in particular orders. The antenne of insects in number and in situation correspond with the ears of the animals we are comparing with them; but whether they convey the vibrations of sound has not been ascertained : that they receive pulses of some kind from the atmosphere I shall prove to you hereafter—so that if insects do not hear with them in one sense, they may, by communicating information, and by aéroscopy, to use Lehman’s term, not directly in his sense*, supply the place of ears, which would render them properly ana- logous to those organs. That in numbers these remark- able organs are factors is generally agreed, but this is not their universal use. That insects smell has been often. proved; but the organ of this sense has not been ascer-. tained. What has improperly been called the clypeus, or the part terminating the face above the upper lip” (labrum), is in the situation of the nose of the Vertebrata, * De Antennis Insect. ii. 65. DEFINITION OF THE TERM INSECT. 47 and therefore so far analogous to it, and in some cases even in form: I therefore call it the nose.. Whether this part represents the nose by being furnished with what — answer the purpose of nostrils, residing somewhere at or above the suture that joins it to the upper lip, I cannot Positively affirm; but from the observations of M. P. Huber, with regard to the hive-bee, it appears that at least these insects have the organ of the sense in question Somewhere in the vicinity of the mouth, and above the tongue*: analogy, therefore, would lead us to look for its site somewhere between the apex of the nose and the upper lip; and in some other cases, which I shall here- after advert to, there is further reason for thinking that it actually resides at the apex of the nose. The organ of taste in insects, though some have advanced their palpi to that honour, is doubtless in some part within the mouth analogous in a degree to the tongue and palate of the higher animals. The organs of manducation, in what may be deemed the most perfect description of mouth, consist of an upper lip closing the mouth above, a pair of mandibles moving horizontally that close its upper sides, and a lower lip with a pair of mazille at- tached to it, which close the mouth below and on the under sides, both labium and maxille being furnished with jointed moveable organs peculiar to annulose pedate animals, called palpi. In some tribes these organs as- Sume a different form, that they may serve for suction ; but though in many cases some receive an increment at * Nouv. Obs. sur les Abeilles, ii. 376—. It appears from M. Huber’s. €Xperiment, that it was only when the hair-pencil, impregnated with the oil of turpentine, was presented “ près de la cavité, au dessus de insertion de la trompe,” that the bee was sensible of the odour. 48 DEFINITION OF THE TERM INSECT. the expense of others, and a variation in form takes place, none, as M. Savigny has elaborately proved, are totally obliterated or without some representative*. The organs now described, except the upper lip, are formed after a quite different type from those of Vertebrata, with which they agree only in their oral situation and use. The second portion of the body is the Trunk, which is interposed between the head and abdomen, and in most insects consists of three principal segments, sub- divided into several pieces, which I shall afterwards ex- plain to you. I shall only observe, that some slight ana- logy may perhaps be traced between these pieces and the vertebree and ribs of vertebrate animals, particularly the Chelonian reptiles. This is most observable in Gryllus L. and Libellula L., in which the lateral pieces of the trunk are parallel to each other®. In the Diptera and many of the Aptera most of these pieces are not separated by sutures. Each of the segments into which the trunk is resolvable bears a pair of jointed Jegs, the first pair point- ing to the head, and the two last to the anus. These legs in their composition bear a considerable analogy to those of quadrupeds, &c., consisting of hip, thigh, leg, and foot ; but the last of these, the foot or Tarsus, is almost universally monodactyle, unless we regard the Calcaria that arm the end of the tibia, as representing fingers or toes, an idea which their use seems to justify. Acheta monstrosa and Tridactylus paradoxus, however’, exhibit ; some appearance of a phalanx of these organs. They differ from them first in number, the thoracic legs being a Anim. sans Vertebr. I. i. Mem. i. b Prare VII. Fic. 10—14; IX. Fic. 6—8, © Coquebert Tust. Ic, tii, t, xxi. f. 3, DEFINITION OF THE TERM INSECT. 49 invariably six in all insects, with the exception of the Octopods or most of the Trachean Arachnida, which have Usually eight. In the Myriapods, though there are hun- dreds of abdominal legs, only six are affixed to the trunk. Next they differ with regard to the situation of their legs; for though the anterior pair or arms are analogous in that respect, the posterior pair are not, since in quadru- Peds these legs are placed behind the abdomen, but in i insects before it—in fact, in the former the legs may be considered as placed at each end of the body, excluding nly the head and tail, but in the latter in the middle. Though they correspond with those of quadrupeds in eing in pairs or opposite to each other, yet their direc- tion with respect to the body is different, the legs of quadrupeds, &c. being nearly straight, whereas in insects they are bent or form an angle, often very obtuse at the principal articulations, which occasions them to extend far beyond the body, and when long to inclose a propor- tionally greater space. The wings are the organs of Motion with which the upper side of the trunk is fur- nished; and these, though they are the instruments of fight, are in no other respect analogous to those -of birds, which replace the anterior legs of quadrupeds, tut *pproach nearer, both in substance and situation, to the fins of some fishes, and perhaps in some respects even to the leaves of plants. M. Latreille is of opinion, That the four wings or their representatives replace the four thoracic legs of the decapod Crustacea. Upon this P inion, which shows great depth of research and prac- tica] acumen, I shall have occasion to express my senti- Ments when I come to treat more at large on the anatomy * Hor. Entomolog. 413—. VOL. III, E 50 DEFINITION OF THE TERM INSECT. of the trunk and its members; at any rate they do not replace the two anterior pair of legs of the hexapod Aptera. When merely used as wings, they commonly consist of a fine transparent double membrane, strength- ened by various longitudinal and transverse nervures, or bones as some regard them, accompanied by air-vessels, of which more hereafter, as well'as of their kind and cha- racters. I shall only observe, that insects are known from all other winged animals, by having four wings, or what represent them, and this even generally in those that are supposed to have only a pair. Another pecu- liarity distinguishes the trunk of insects that you will in vain look for in the vertebrate animals—these are one or two pair of lateral spiracles or breathing pores. Though the respiratory sacs, &c. of birds are almost as widely dispersed as the tracheze and bronchise of insects*, yet their respiration is perfectly pulmonary, and nothing like these pores is to be discovered in them. The principal peculiarity of the third part of the body, the abdomen, is its situation behind the posterior pair of thoracic legs, and its rank as forming a distinct portion of what represents the skeleton. In most insects it is so closely affixed to the posterior part of the trunk as to _ appear like a continuation of it, but in the majority of the Hymenoptera and Diptera, and in the Aranezdan Arachnida, or spiders, it is separated by a deep incisure ; and in the first-mentioned tribe is mostly suspended to the trunk by a footstalk, sometimes of wonderful length and tenuity. In the Mammalia the male genital organs are partly external; but in insects as well as in many 0 the vertebrate animals, except when employed, they are a N. Dict, d Hist, Nat. xxviii.; compare 104 and 110. DEFINITION OF THE TERM INSECT. 51 retracted within the body. This part is the principal Seat of the respiratory pores or spiracles, many having eight in each side, while others have only one. Such are the principal external characters which di- Neuish Insecta and Arachnida, or what we have here- tofore regarded as insects, to which here may be added “nother connected with their internal organization. The Union of the sexes takes place in the same manner as “Mongst larger animals; and the females with very few Xceptions, more apparent than real, are oviparous. They are, however, distinguished by this remarkable pe- Culiarity already alluded to, that, except in the case of the Arachnida, one impreguation fertilizes all the eggs they are destined toproduce. In most cases, after these are laid, the females die immediately, and the males after they have performed their office, though they will some- times.unite themselves to more than one female. One other circumstance may be named here—that no genuine. insect or Arachnidan has yet been found to inhabit the Ocean. sti Before I conclude this letter, it is necessary to apprize you, that every thing which it contains relative to the characters of insects, has reference to them only in their last oy perfect state, not in those preparatory ones through Which you are aware that the majority of them must pass. he peculiar characteristics of them in these states—in the “88 the larva, and the pupa, will be the subjects of my Next letters, which will be devoted to a more detailed hrig of the metamorphosis of insects than I gave you efore when adverting to this subject*. * See above, Vor. I. Ed. 4. p. 63—. nae LETTER XXIX. STATES OF INSECTS. EGG STATE. ON a former occasion I gave you a general idea of what has been called, perhaps not improperly, the metamor- phosis of insects?; but since that time much novel and interesting speculation on the subject has employed the pens of many eminent Physiologists; and besides this, the doctrine then advanced of successive developments has been altogether denied by a very able Anatomist, Dr. Herold, who, with a hand, eye, and pencil, second only to those of Lyonnet, has traced the changes that gradually take place in the structure of the cabbage-but- terfly (Pieris Brassice) on passing through its several states of larva, pupa, and imago. It is necessary, there- fore, that previously to considering separately and in a The word yeramoePow, and its derivative werapoeQwatc, are not extant in any Greek writer before the date of the New Testament. They are used to express any eaternal change of form or colour, and metaphorically an inward change and progressive improvement of the mind. Comp. Matth. xvii. 2. Ælian. Var. Hist. 1.i. c. 1. Rom, xiii. 2+ 2 Cor. iii. 18. They are, therefore, not improperly applied, as some have supposed, to the changes of insects, STATES OF INSECTS. 53 detail the states of insects, I should again call your atten- tion to this subject, and endeavour to ascertain whether Dr. Herold’s hypothesis rests upon a solid foundation ; or whether that adopted from Swammerdam by all the Most eminent Entomologists and Physiologists since his time can be maintained against it. I shall first give you a short abstract of the new hy- pothesis, According to Dr. Herold—The successive skins of the Caterpillar, the pupa-case, the future butterfly, and its Parts and organs, except those of sex which he discovered in the newly excluded larva, do not preexist as germes, but re formed successively from the rete mucosum, which it- self is formed anew upon every change of skin from what he denominates the blood, or the chyle after it has passed through. the pores of the intestinal canal into the general cavity of the body, where, being oxygenated by the air- vessels, it performs the nutritive functions of blood. He attributes these formations to a vis formatrix (Bildende Kraft), i The caul or epiploon (Fett-masse), the corps graisseux of Reaumur, &c., which he supposes to be formed from the Superfluous blood, he allows, with most physiologists, to be Stored up in the larva, that in the pupa state it may serve Jor the development of the imago. But he differs from them in asserting that in this state it is destined to two distinct purposes—first, for the production of the muscles of the butterfly, which he affirms are generated from it in the Shape of slender bundles of fibres ;—and secondly, for - the development and nutrition of the organs formed in the larva, to effect which, he says, iż is dissolved again into the mass of bload, and being oxygenated by the air-vessels, - BA STATES OF INSECTS. becomes fit for nutrition, whence the epiploon appears to be a kind of concrete chyle*. Need I repeat to you the hypothesis to which this stands opposed— That every caterpillar at its first exclu- sion contains within itself the germe of the future butterfly and of all its envelopes, which successively presenting them- selves are thrown off, till it appear in perfection and beauty, with all its parts and organs, when no further de- velopment takes place. ; I believe you will agree with me, when you have read and considered the above abstract of Dr. Herold’s hy- pothesis, that in it he substitutes a name for knowledge, talks of a vis formatrix because his assisted eye cannot penetrate to the primordial essence or state of the germes of being, and denies the existence of what he cannot dis- cover. From ancient ages philosophers have done the same, to conceal their own ignorance of causes under a sounding name, when they have endeavoured to pene- trate within the veil of the sanctum sanctorum, which it is not permitted to vain man to enter. This has occa- sioned the invention, not only of the term in question, but of many others, as little meriting the appellation of Signs of ideas ; such as Plastic Nature, Epigenesis, Pan- spermia, Idea seminalis, Nisus formativus, &c. But upon a Entwichelungsgeschichte der Schmetterlinge 12—27. 105—. > Dr. Virey’s observations under the article Embryo (N. Dict. d Hist. Nat. x. 195.) deserve here to be considered. “Tl y a donc quelque chose au dessus de l’intelligence humaine dans cette forma- tion des êtres; en vain on veut l’approfondir, Cest un abime dans lequel on ne voit que la main de Dieu. A quoi bon s’appesantir sur le mystére de la formation des étres, sans esperance de l’expliquer ? Ne vaut-il pas mieux observer les opérations de la nature autant qv il est permis à lil humain de les appercevoir ?” STATES OF INSECTS. 55 this subject you cannot do better than consult what the learned Dr. Barclay has said in his admirable work On Life and Organization*, in which he has placed the inanity, the vor et preterea nihil, of such high-sounding terms in their true light. The processes of nature in the formation and development. of the fetus in utero, of the chick in the egg, of the butterfly in the caterpillar, we in vain attempt fully to investigate ; yet we can easily comprehend that pre-existent germes, by the constant accretion of new matter in a proper state, may be gra- dually developed, but we find it impossible to conceive how, by the action of second causes, without the inter- vention of the first cause, the butterfly should be formed in the caterpillar, unless it preexists there as a germe or foetus, < Is it not clear,” asks Dr. Virey in his lively manner, ‘ as Blumenbach and other Physiologists main- tain, that there is a formative power, a nisus formativus, which organizes the embryo? Admirable discovery !” says he, ‘ which teaches us that the foetus forms itself because it forms itself! As if you should affirm that the stone falls because it falls?!” Had Dr. Herold considered what Bonnet says with as much good sense as modesty, he would never have imagined that his discovering the organs of the butterfly one after the other at certain pe- riods in the caterpillar, was any sound argument against their preexistence and coexistence as germes. Or- gans,” says that amiable and excellent Physiologist, “that have no existence as to us, exist as they respect the embryo, and perform their essential functions ; the term of their becoming visible is that which has been * § xv. b N, Dict. d Hist. Nat. x. 193. 5G STATES OF INSECTS. erroneously mistaken for the period of their existence*.” This has been Dr, Herold’s grand error ; he mistook the commencement of the appearance of the organs of the butterfly for that of their existence, and yet the early ap- pearance of the sexual organs ought to have led him to a conclusion the reverse of that which he has adopted. — - Dr. Virey has observed with great truth—that “ Every being has a peculiar and unique nature, which would be impossible if the body was composed. of parts made at several intervals, and without a uniform power that acts by concert®:” and every Physiologist acquainted with the history of insects that undergo a complete metamor- phosis will allow, that their developments and acquisition of new parts and organs take place according to a law which regulates the number, kind, and times of them, differing in different species, and which has had an in- variable operation, since the first creation, upon every sound individual that has been produced into the world. In consequence of this law, one species changes its skin only four times, and another five or six ;—in some eases the first skins shall be covered or bristled with hairs or spines, and the last be naked and without arms; —-that which forms the case of the pupæ shall differ in form and substance from the preceding skins, varying in both respects in different species; and finally the butterfly shall invariably follow, when no other change but the a Œw. v. 279, “ Il n’est pas exact de dire que le cœur, la tête, et la moelle épinière, sont formés les premiers dans les Peti des ani- maux à sang rouge et vertébrés,” says Dr. Virey; “ mais il faut dire seulement que tel est Pordre dans lequel ces organes commencent à devenir visibles.” WN. Dict. d Hist. Nat. x. 196, b Ibid, 193, STATES OF INSECTS. oT last‘mortal one shall take place. Can this law, so con- Stantly observed, be the result of a blind power? Or are We to suppose that the Deity himself is always at work to create the necessary organs in their time and place? Is it not much more consonant to reason and the general analogy of nature, to suppose that these parts and organs €xist in embryo in the newly-hatched caterpillar, and _ Stow and are successively developed by the action of the hutritive fluid? In the pupa of many Diptera the in- closed animal, even under the microscope, appears with- Out parts or organs, like a mere pulp; but Bonnet tells us, that if boiled, all the parts of the pupa appear*, which proves the preexistence of these parts even when not to be discerned, and that nothing but the evaporation of the fluids in which they swim is wanted to render them visible. Mr. William MacLeay has with great truth observed: “ The true criterion of animal as well as vegetable per- fection is the ability to continue the species?;” and in their progress to this state certain changes take place in the parts and organs of all animals and vegetables : there is, therefore, an analogy in this respect between them ; and this analogy also furnishes another argument against Dr. Herold’s hypothesis, as we shall fedattty See. These changes are of three kinds: In the vege- table kingdom, at least in the pheenogamous classes, ide is a Succession of developments terminating in the ap- pearance of the generative organs, inclosed in the flower ; in this kind the i integuments, or most of them, are usually Persistent. Tn insects and other annulose and some ver- tebrate animals, there is a succession of spoliations, or * Œuvr, viii, 315, b Hor, Entomolog. 446; 58 STATES OF INSECTS. simultaneous changes of the whole integument, till the animal appears in its perfect form with powers of repro- duction; in this kind the integuments are caducous.—In man and most of the vertebrate animals there isa gradual action of the vital forces in different organs till they are fitted for reproduction ; accompanied, as progess is made to the adult state, by the acquisition of certain organs, &c. as of teeth, horns,’ pubes, feathers, &c.* Let us now consider a little in detail the analogies that appear to exist between the second and the first and third kinds. I shall first consider the latter as the least obvious. That able, judicious, and learned physiologist, Dr. Virey, has pointed out no inconsiderable resemblance between the metamor- phosis of the insect, and the changes, which he denomi- nates a metamorphosis by metastasis, to which most ver- tebrate animals are subject. In them, he observes, a state analogous to the larva state begins at the exclusion of the foetus from the womb; it is deprived of teeth, and its viscera are only accommodated to milk: in the cornute species the horns are in embryo: the digestive system now preponderates, and the great enjoyment is eating. A second state, in a degree analogous to that of pupa, commences at the period of dentition—the teeth now produce another modification in the intestinal canal, which becomes capable of receiving and digesting solid food: during this period the vital forces are all tending to produce the perfect state of the animal; and in this state, in man especially, the individual is educated and fitted to discharge the duties of active life. Again, ana- logous to the ¿mago state is the age of puberty, in which e See on this subject N. Dict. d Hist. Nat. xx. article Metamor- phosis. STATES OF INSECTS. 59 the complete development of the sexual powers takes place in both sexes, and the animal has arrived at its acme, and can continue its kind?: now the digestive powers diminish in their activity, and love reigns para- mount. When this state is fully attained, no further or higher change is to be expected, and the progress is soon towards decay and the termination of the animal’s mortal career. So we see that in fact man and other mammalia, though they do not simultaneously cast their skins like the insect; or pass into a state of intermediate repose, — before they attain the perfection of their nature, like the caterpillar; have their three states, in each of which they acquire new parts, powers, and appetites. i But a more striking analogy has been traced between the insects that undergo a complete metamorphosis and the vegetable kingdom; for though the primary analogy seems to be between the Polypus and the Plant, yet the secondary one with the Insect is not by any means remote. There are circumstances to which I shall have occasion hereafter to call your attention, which afford some ground for supposing, that the substance of the insect and the vegetable partakes of the same nature, at least approxi- mates more nearly, than that of the insect and the verte- brate animal; and every one who has observed these little creatures with any attention, will have observed amongst them forms and organs borrowed as it were from the kingdom of Flora; and vice versé the Botanist, if he makes the comparison, will find amongst his favourite tribes many striking resemblances of certain insects. But the analogy does not stop here; for the butterfly and the plant appear to have been created with a parti- a N, Dict. d@ Hist. Nat. xx. 349—. 60 STATES OF INSECTS. cular reference to each other, both in the epoch of their appearance and the changes that take place in them. Thus, as Dr. Virey has observed, the caterpillar is si- multaneous with the leaf of the tree or plant on which it feeds, and the butterfly with the flowers of which it im- bibes the nectar*. Swammerdam, I believe, was the first who noticed the analogy between the changes of the insect and the vegetable, and has given a table in which he has contrasted their developments, including other animals that undergo a metamorphosis?: an idea which has been generalized by Bonnet*, and adopted and enlarged by Dr. Virey*. A state analogous to that of the larva in the insect begins in the plant when it is disclosed from the seed, or springs from its hybernaculum in the bulb, &c., or is evolved from the gemma; integument after in- tegument, often in various forms, as cotyledon, radical, cauline, or floral leaves, expands as the stem rises, all which envelopes incase the true representative of the plant, the fructification, as the various skins do the future butterfly. When these integuments are all expanded, the fructification appears inclosed by the calyx or corolla as the case may be, in which the generative organs are matured for their office—this is the bud, which is clearly analogous to the pupa state of the insect. Next the calyx and corolla expand, the impregnation of the germen takes ` place, and the seed being ripened, and dispersed by the opening of the seed-vessel or ovary of the plant, the in- dividual dies: thus the ¿mago state of the insect has its representative in the plant. “If we place,” says Dr. Virey, * here the egg of the insect, next. its caterpillar, a little a‘ N. Dict. @ Hist. Nat. xx. 348. b Bibl. Nat. Ed: Hill. ii, 138. © (Eur. v. 283--. STATES’ OF INSECTS. - | further the chrysalis, and lastly the butterfly—what is this but an animal stem—an elongation perfectly similar to that of the plant issuing from the seed to attain its blossoming and propagation ?# There being, therefore, this general analogy in their progress to that state in which they can continue their Species between every part of animated nature, it holds good, I think, that the same analogy should take place in their developments. If the adult man or quadruped, &ce. is evidently an evolution of the foetus, as from mi- Croscopical observations it appears that they are®, if the teeth, horns, ‘and other parts, &c. to be acquired in his progress to that state are already in him in their embryos, we may also conclude that the butterfly and its organs, &c. are all in the newly-hatched caterpillar. Again, if the blossom and its envelopes are contained inthe gemma, the bulb, &c. where they have been discovered*, it follows analogically that the butterfly and its integuments all preexist in its forerunner. Perhaps after this view of the objections to Dr. He- rold’s hypothesis, it will not be necessary to say much with regard to the argument he draws from the change _ of organs—the loss of some and the acquisition of others —since this may readily be conceived to be the natural consequence of the vital forces tending more and more to the formation of the butterfly, and the withdrawing of their action more and more from the caterpillar; I Shall not, therefore, enter further into the question, espe- è N. Dict. d’ Hist. Nat. xx. 355. b Leeuwenhoek discovered in the incipient foetus of a sheep, not larger than the eighth part of a pea, all the principal parts of the future animal. Arc. Nat. I. ii. 165, 173. © Bonnet, Euvr. v. 284, 62 STATES OF INSECTS: cially since the change of organs will come more regu- larly under our notice upon a future occasion. Winged insects, many branchiopod Crustacea, and the Batracian reptiles, have been observed by Dr. Virey to bear some analogy to the mammalia, aves, &c. in another respect. In leaving their egg, they only quit their first integument, answering to the chorion or external envelope of the human foetus; they therefore still continue a kind of foetus, so to speak, more or less enveloped under other tunics, and principally in their amnios, or the covering in which the foetus floats in the liquor amnii*. This the butterfly does in the pupa case; and its birth from this, under this view, will be the true birth of the animal. Tu the human subject, the ova upon impregnation are said to pass from the ovary through the Fallopian tube into the uterus. In the insect world, upon impregnation, the eggs pass first from the ovaries into the oviduct, answer- ing to the Fallopian tube, which in them terminates in the ovipositor, or the instrument by which the parent animal conveys the eggs to their proper station: there is, therefore, nothing properly analogous to the uterus in the insect, and the substance upon which the larva feeds upon exclusion answers the purpose of a placenta. After this general view of the most modern theories with regard to the metamorphosis of insects, I shall in the present and some following letters, treat separately of the different states through oti these little beings suc- cessively pass.’ The first.of these is the Egg state, the whole class of insects being strictly oviparous. Some few tribes indeed 2 N. Dict. d’ Hist. Nat. xx. 302) STATES OF INSECTS. 63 bring into the world living young ones, and have on that account been considered as viviparous, but incorrectly, . for the embryos of none of these are nourished, as in the true viviparous animals, within a uterus by means of a placenta, but receive their development within true eggs Which are hatched in the body of the mother. This is proved by the observations of Leeuwenhoek, who found eges in the abdomen of a female_scorpion?; and of Reaumur, with regard to the flesh-fly (Musca carnaria) and other viviparous flies as they have been called”. A Similar mode of production takes place in vipers and some other reptiles, which have hence been denominated 0v0-viviparous, to distinguish them from the true vivi- parous animals—the class Mammalia. By far the larger ‘portion of insects is oviparous in the ordinary acceptation of the term. The ovo-viviparous tribes at present known are scorpions; the flesh-fly and several other flies; a minute gnat belonging to Latreille’s family of Tipularie<; some species of Coccus; some bugs (Cimicide)4; and most Aphides, which last also exhibit the singular fact of indi- viduals of the same species being some oviparous and others ovo-viviparous, the former being longer in propor- tion than the latter.—Bonnet, however, is of opinion that the eggs of the first are not perfect eggs, but a kind of cocoon, which defends the larva, already formed in some degree, from the cold of winter €. * Select Works by Hoole, i. 132. The fact is confirmed by M.L. . ufour, who, having opened the abdomen of a female scorpion, found in the midst of some eggs nearly mature a little scorpion a quarter of an inch long; it lay without motion, with its tail folded under the body. N. Dict. d? Hist. Nat. xxx. 426. e Reaum. iv. 425—. ` c Ibid. 428—. t. xxix. f. 10, 11. 1 Busch, a German author, affirms that many Cimicidæ are subject 40 this law. Schneid. i, 206. ° Quoted in Huber Fourmis, 208. Some reptiles also are at one 64 STATES OF INSECTS. When excluded from the body of the mother, or from the egg, as has been before observed, some insects appear nearly in the form of their parents, which, with a very slight alteration, they always retain; others, and the greater number, assume an appearance totally different from that of their parents, which they acquire only after passing through various changes. It is to these last, which have chiefly engaged the attention of Entomologists, that the title of metamorphoses has been often restricted. As, however, those insects which undergo the slightest change of form, as spiders do, undergo some change, and almost all insects cast their skins several times? before they attain maturity, Linné and most Entomologists, till very recently, have regarded the whole class as under- going metamorphoses, and as passing through four dif- ferent states, viz. the Egg—the Larva—the Pupa—and the Imago. It is obvious, however, that in ovo-viviparous species three states of their existence only come under our cog- nizance, as these, being hatched in the body of the mother, come forth first under the form of larvae. There is even one tribe of insects which presents the strange anomaly of being born in the pupa state. This: is the Linnean genus Hippobosca (Pupipara fam. Latr.), to which our forest-fly belongs, the females of which lay bodies so much resembling eggs, that they were long considered as such until their true nature.was ascertained by Reaumur (most of whose observations were confirmed ‘by De Geer), who, from their size, which nearly equals time oviparous, and at another ovo-viviparous. N: Dict. d Hist, Nat. xii. 568. ; a I say almost all insects, because the larvæ of Hymenoptera and Diptera are supposed not to undergo this change. N. Dict. d’ Hist. Nat. xx. 365. STATES. OF INSECTS. l 65 that of the parent fly—from their slight motion when first extruded—from spiraculiform points which run down each side of them—and lastly, from their producing not a larva, as all other insects’ eggs do, but perfect flies in the winged state—inferred, and doubtless with reason, that they are not real eggs, but pupæ, or larvæ just ready to assume the pupa state, which, however strange it may Seem, have passed the egg and larva states in the body of the mother?, i Insects, therefore, as to their mode of birth, may be divided into— I Ovo-viviparous, subdivided into— 1. Larviparous, coming forth from the matrix of the mother in the state of larvee, as the Scorpion (Scorpio), the Flesh-fly (Musca), the Plant-louse (Aphis), &c. 2. Pupiparous, continuing in the matrix of the mo- ther during the larva state, and coming forth in that of pupa, as the Forest-fly (Hippobosca equina), the Sheep-louse (Melophagus ovinus), the Bat-louse (Nycteribia Vi espertilionis), &c. H: Oviparous. All other insects. Our business for the remainder of this letter will be th the latter description of these little animals. The unerring foresight with which the female deposits er eggs in the precise place where the larvee, when ex- cluded, are sure to find suitable food; and the singular Wi "struments with which, for this purpose, the extremity °F their abdomen js furnished, have been noticed in a ormer letter®, š and those last mentioned will be adverted 'o in a future o ne. Ishall now, therefore, confine myself * Reaum. vi. Mém. xiv. De Geer, vi. 280. » See Vor. I. Lett. xr. YOu. TIT. F 66 STATES OF INSECTS. to other circumstances connected. with the subject, ar- ranged for the sake of order under several distinct heads, as—their exclusion—situation—substance—number—size —jigure—colour—and period of hatching. i. Exclusion. The exclusion or extrusion of the im- pregnated eggs takes place, when, passing from the ovary into the oviduct, they are conducted by means of the ovipositor, in which it terminates, to their proper situa- tion. By far the greater number of insects extrude them singly, a longer interval elapsing between the passage of each egg in some than in others. In those tribes which place their eggs in groups, such as most butterflies and moths, and many beetles, they pass from the ovaries usually with great rapidity ; while in the Ichneumonidae, Sphegide, Cistri, and other parasitic genera, which usu- ally deposit their eggs singly, an interval of some minutes, hours, or perhaps even days, intervenes between the ex- trusion of each egg. One remarkable instance of the former mode I noticed in my letter on the Perfect Socze- ties of Insects* ; another may be cited, to which you may yourself be a witness—I allude to that common moth, vulgarly called the Ghost (Hepialus Humulz), which lays a large number of minute black eggs, resembling grains of gunpowder, and ejects them so fast that, according to ‘De Geer, they may be said to run from the oviduct, and are sometimes expelled with the force of a popgun”. A. Tetrapterous insect, the genus of which is uncertain, is said, when it is taken, to discharge its eggs like shot from à gun’. And a friend of mine, who had observed with at- tention the proceedings of a common crane-fly (Tipula)s a See Vor. II. p. 36. b De Geer i. 494—. © Called by M. PAbbé Preaux, who observed it near Lisieux in Normandy, Mouche Baliste. N. Dict. d’ Hist. Nat. xxi. 442. STATES OF INSECTS. 67 assured me that several females which he caught pro- jected their eggs to the distance of more than ten inches. A few Diptera extrude them in a sort of chain or necklace, each egg being connected by a glutinous mat- ter with that which precedes and follows it. In a small Species of a genus allied to Psychoda (a kind of midge), Which one season was abundant in a window of my house, this necklace is composed of eggs joined by their sides, Not unlike those strung by children of the seeds of the mallowa, Other Lipulide on the contrary extrude their eggs joined end to end, so as to resemble a necklace of val beads. Beris clavipes and Sciura Thome, two other flies, produce a chain about an inch long, consisting of oval eggs connected, in an oblique position, side by side; an arrangement very similar prevails in the ribband of eggs which drop from some of the Ephemeræ?. These eggs, like those of the insects first mentioned, though connected, are expelled in succession; but other tribes, as the Libellulide, with the exception of Agrion, Many Lphemere, Trichopterous insects, &e. expel the Whole at once, as it were in a mass. In those first men- tioned they are gummed together in an oblong cluster €. In one Ephemera mentioned by Reaumur ‘4, they formed two oblong masses, each containing from three to four hundred eggs, and three and a half or four lines long. These animals as soon as their wings are developed eject these masses by two orifices, and are aided in the process Y two vesicles full of air, wherever they happen to alight °F to fall; in most instances it is the water, their proper element, that receives them, but the animal does not ap- pear to know the difference between a solid and a liquid, * Prare XX, Fic. 20. > Reaum. vi. 509. t. xiv. f. Y1, 12. € eaum. vi, 434. à Töid. vi, 494. F2 68 STATES OF INSECTS. and seems only anxious how to free herself from a bur- then that oppresses her; all has been contrived that an insect so short-lived may finish her different operations with the utmost celerity : the term of her existence would not have admitted the leisurely extrusion of such a num- ber of eggs in succession*. Some Trichoptera, or May- flies, as Phryganea grandis L., exclude their eggs in a double packet, enveloped in a mass of jelly, (a circum- stance often attending the eggs that produce aquatic larvee,) upon the leaves of willows®. A similar double packet in the year 1810 I observed appended to the anus of a black species with long antenna, probably Phry- ganea atrata F.© Upon taking several of the females I was surprised to find in the above situation a seemingly fleshy substance of a dirty yellow. At first, from its an- nular appearance, I conceived it to be some parasitic larva, but was not a little surprised upon pulling it away that it was full of globular transparent dusky eggs: it was about two lines and a quarter in length and nearly one in breadth. Being bent double it was attached to the animal by the intermediate angle, and when un- folded was constricted in the middle‘. Each half, which was roundish, had about ten sharp transverse ridges, the interstices of which appeared as if crenated, an ap- pearance produced by the eggs which it contained. Upon more than gentle pressure it burst and let out the eggs. Though resembling the packet of P. grandis in shape and other circumstances, it was nothing like. a The vesicles, which Reaumur thinks may be pulmonary vesicles, as well as assisting in the extrusion of the masses of egos, he has figured ¢. xliv. f. 10. u u. b De Geer ii. 534. ¢, xiii. f. 13. c Coquebert IHustr. Ic. t. i. f. A. B. a Prare XX. Fra, 25. STATES OF INSECTS. 69 jelly, but had rather a waxy appearance, and seems to have been covered by a membrane: so that the ex- cluded larvae must probably have eaten their way out fit | have still by me, in 1822, specimens of these “88-packets, which, after the lapse of so many years, re- tain their original form and colour. It is not improbable that other species extrude their eggs in a similar case. Scopoli says of P. bicaudata L., that the female carries about under her belly her eggs united into a globe, like Lycosa saccata*. The eggs of Geometra Potamogata F. are also enveloped in a gelatinous substance, and the Mass is covered with leaves?. Insects of the Diptera order also, like frogs and toads, commit their eggs to the water imbedded in masses of jelly. Dr. Derham describes two different kinds of them, in one of which the eggs were laid in parallel rows end to end, and in another in a single row, in which the Sides were parallel*. But the most remarkable and beautiful specinien of this kind that I ever saw was one that, many years ago, I took out of a pond at Wittersham in Kent, from which I requested a young lady to make the drawing I send yout. The mass of jelly, about an inch and a quarter long, and rather widest in the middle, was attached by one end to some aquatic grass, and from one €nd to the other ran a spiral thread of very minute eggs, e turns of the screw being alternately on each side. The mode of exclusion of the eggs of the Blatte, which “re engaged for a whole week in the business of oviposi- tion, is very singular: the female deposits one or two arge suboviform capsules, as large as half their abdomen, rounded on one side, and on the other straight and ser- è Ent. Carniol. 269. n. 705. b Reaum. ii. 401. ° In Raii Hist. Ins. 264. d Prare XX. Fic. 24, “0 STATES OF INSECTS. rated, which at first is white and soft, but soon becomes brown and hard. This ege-case, as it may be called, contains sixteen or eighteen eggs arranged in a double series, and the cock-roaches when hatched make their escape through a cleft in its straight side, which shuts so accurately when they have quitted it, that at first it ap- pears as entire as before*. The insects of the genus Mantis also, or what are called the praying insects, when they deposit their eggs, eject with them a soft substance, which hardens in the air and forms a long kind of enve- lope resembling parchment, in which the eggs are ar- ranged also in a double series. And the Locusts (Gryl- lus Locusta L.) are said by Morier® to deposit-in the ground an oblong substance, of the shape of their abdo- ‘men, which contains a considerable number of eggs ar- ranged neatly in rows. The peristaltic motion observed in the females of some insects during oviposition has been before described °. ii. Situation. Under this head I include the situation in which the female insect places her eggs when extruded, whether she continues her care of them and carries them about till they hatch, or whether she entirely deserts them, placing them either without a covering within reach of their food, or enveloping them in hair or other- wise protecting them from accident or the attack of ene- mies. I shall consider them under two views: frst, as depositing their eggs in groups, whether covered or naked; and secondly, as depositing them singly. _ *Goeze Naturf. xvii. 183—. t. iv. f. 16—19. Comp. N. Dict. @ Hist. Nat. iii. 475. and xix. 239. De Geer iii. 533. b Second Journey through Persia, 100—. e See Vor. II. p. 36. STATES OF INSECTS. 71 1. Those that deposit their eggs in groups are first to be considered. I shall begin with those that protect them With some kind of covering. I have already mentioned in a former letter? the Silken bag with which Lycosa saccata Latr., a kind of Spider, surrounds her eggs, and in which she constantly Carries them about with her, defending them to the last extremity, Many other spiders, indeed nearly the whole tribe, fabricate similar pouches, but of various sizes, forms, texture, and colours. Some are scarcely so big aS a pea, others of the size of a large gooseberry ; some globular, some bell-shaped ;. others, the genus Thomisus Walck, in particular, depressed like a lupine; some of a Close texture like silk; others of a looser fabric resem- bling wool : some consisting of a single pellicle, but most ofa double, of which the interior is finer and softer® ; Some white; others inclining to blue; others again yel- low or reddish; most of them are of a whole colour, but that of Epeira fasciata is gray varied with black*. And while the parent spider of some kinds (the Lupi) always Carries her ege-bag attached to her anus, others hold them by their palpi and maxille; and others ‘suspend them by a long thread, or simply fasten them in different situations, either constantly remaining near them (the Telariæ), or wholly deserting them (the Retiaria). The “888 of one of these last Lister describes as often fixed S a very singular situation—the cavity at the end ofa Tipe cherry; and thus, as he expresses it—‘ Stomachi maxime delicatuli quoties hanc innocuam buccam non minus ‘Snoranter quam avide devorarunt*,” * Vou L p. 359—. À Latr, Hist. Nat. des Fourmis, 334, N. Diet. d Hist. Nat iix284. : Lister De Aran. Tit. 13, 14. N. Dict. d Hist. Nat. ii. 284. Lister Ibid. 56. Tit. 15. 72 STATES OF INSECTS. Herman informs us, that the species of the genus Che- lifer carry their eggs in a mass under their belly. Madam Merian gives an account of two species of Blatta, which she affirms carry an egg-pouch about with them—one species (B. gigantea ?) she describes as car- rying its eggs in a globular pouch of web like certain spiders, and the other in a brown bag, which, when alarmed, it drops and makes off>. But this admirable paintress of natural objects was not always correct in her statements‘: it seems very improbable, from the habits of those species of which we know the history, that any of them should spin a pouch of web for their eggs. The only insects certainly known to spin an egg-pouch like the spiders, are the Hydrophili, a kind of water- beetles. Some of these, as H. lividus, carry them about with them, like Lycosa saccata, attached to the under side of their body, as M. Miger observed‘; and others when they are finished desert them. That of the great water-beetle (Hydrophilus piceus) was long ago described and figured by Lyonnet; and a more detailed account of it has since been given by M. Migerf. In form it somewhat resembles a turnip when reversed, since it consists of a pouch of the shape of an oblate spheroid, the great diameter of which is three quarters of an inch ; and the small, half an inch, from which rises a curved horn, about an inch long and terminating in a pointé. The animal is furnished with a pair of anal spinners, which move from right to left, and up and down, with e N. Dict. d’ Hist. Nat. xxvi. 447. > Ins. Surinam, t. i. ¢ A striking instance of this may be seen in her forty-ninth plate, in which she has clapped the rostrated head of Fulgora laternaria upon the body of a Cicada Latr., affirming it to be the former fly in its previous state! This might be a trick upon her. a N. Dict. d’ Hist. Nat. xv. 489. e Lesser L. i. 300. t Annales du Muséum, xiv. 441, E Lesser L, i, t. tt. f. xvi. STATES OF INSECTS. 73 much quickness and agility : from these spinners a white and glutinous fluid appears to issue, that forms the pouch, Which it takes the animal about three hours to construct. The exterior tissue is produced by a kind of liquid and glutinous paste, which by desiccation becomes a flexible Covering impermeable to water; the second, which en- Velops the eggs, is a kind of light down of great white- Ness, that keeps them from injuring each other. The tissue of the horn is of a silky nature, porous and shining, and greatly resembling the cocoons of Lepidoptera. This Part, contrary to what Lyonnet supposes, appears calcu- lated to admit the air, the water soon penetrating it when Submerged. At its base is the opening prepared for the €gress of the larvae, when hatched, which is closed by Some threads, that, by means of the air confined in the cocoon or pouch, hinder the water from getting in*. This nidus does not float at liberty in the water till after the eggs are hatched, the parent animal always attaching It to some plant. By means of this anomalous process for a beetle, which this insect is instructed by Providence - thus to perfect, the precious contents of its little ark are Secured from the action of the element which is to be the theatre of their first state of existence, from the voracity of fishes, or the more rapacious larvee of its own tribe, Until the included eggs are hatched, and emerge from their curious cradle. I shall next amuse you with a few instances, in which the Allwise Creator instructs the parent insect, instead of defending her eggs with a covering furnished by her internal organs, to provide it from without, either from à * Miger Ann. du Mus. ubi supr. Comp. N. Dict, d’ Hist. Nat. xv. 52 ; ee . >A STATES OF INSECTS. her own body or from some other substance. Most commonly, indeed, the female leaves her cluster of eggs without any other covering than the varnish with which in this case they are usually besmeared. Either they are deposited in summer and will soon be hatched, or they are of a substance calculated to encounter and resist the severities of the season. But many species, whose eggs ‘are more tender or have to resist the cold and wet of winter, defend them in the most ingenious manner with a clothing of different kinds of substance. Cassida viridis, a tortoise beetle, Résel tells us, covers her group of eggs with a partially transparent membrane. ‘Arctia Salicis F., a moth, common on willows, wholly ‘conceals hers with a white frothy substance, which when ‘dry is partly friable and partly cottony, and being insoluble in water effectually protects them from the weather*. The female of Lophyrus Pini (a saw-fly), having by means of her double saw made a suitable longitudinal incision in the leaf of a fir, and placed in it her eggs in a single row end to end, stops it up with a green frothy fluid mixed with the small pieces of leaf detached by her saws, which when dry becomes friable : a necessary precaution, since these eggs are extremely brittle’. Aretie chry- sorhea, Hypogymna dispar, and several other moths, sur- round theirs with an equally impervious and more singular. clothing—azr stripped from their own bodies. With this material, which they pluck by means of their pincer- like ovipositor, they first form a soft couch on the sur- face of some leaf: they then place upon it successively layers of eggs, and surround them with a similar downy coating, and when the whole number is deposited cover a De Geer i. 192. b Thid. ii. 982. STATES OF INSECTS: 75 the surface with a roof of hairs, which cannot be too much admired; for those used for the interior of the nest are placed without order, but those employed ex- ‘ternally are arranged with as much art and skill as the tiles of a roof, and as effectually keep out the water, one layer resting partly on the other, and all having the same direction, so that the whole resembles a well-brushed Plece of shaggy cloth or fur. When the mother has finished this labour, which often occupies her for twenty- four hours, and sometimes even twice that period, her body, which before was extremely hairy, is almost wholly Naked—she has stripped herself to supply clothing to her offspring, and having performed this last duty she expires. The female moths which thus protect their eggs are often furnished with an extraordinary quantity of hair about the nus for this express purpose; and Reaumur conjectures, that the singular anal patch of scales resembling those of the wings, but considerably larger, which is found in the female of Lasiocampa Pityocampa, is destined for the Same purpose’. | Reaumur had once brought to him a nidus of eggs clothed still more curiously: they surrounded a twig in ® spiral direction, like those of Lasiocampa Neustria, but Were much more numerous, and were thickly covered with . fine down, not pressed close, but standing off horizon- tally, which assumed much the ‘same appearance as a {ox’s tail would if twisted spirally round a branch». A procedure nearly similar was observed by De Geer some species of Aphides (4. Alni and A. Pruni), which Covered their eggs with a white cottony down detached * Reaum. ii. 97. 159, > Ibid, 107—. ¢. iii. y. 15. 76 STATES OF INSECTS. from their belly by means of their hind legs?. . In this case, however, the eggs were separately coated with the down, but there was no general covering to the group. Several insects make the leaves and other parts of plants serve as coverings for their eggs. Tenthredo Rose L., a saw-fly, and other species of the same genus, with their saws make an incision in the green twigs of shrubs and trees, and fill it with a line of eggs placed end to end, taking care that, as the eggs grow after they are laid, they are placed at such distances as to leave room for their expansion’. Rhynchites Bacchus, a brilliant weevil, well known to the vine-dressers for the injury it does‘, rolls with much art the leaves of the vine, so as to form a cavity, in which it places its eggs; other species practise similar manoeuvres; and some probably place their young progeny in the interior of twigs, making an opening for that purpose with their rostrum—at least, I once saw Rhynchites Alliarie L. with its rostrum plunged up to the antennæ in the twig of a crab-tree. Others of this tribe, as we know, place their eggs in the interior of fruits and grain, as the nut, acorn, and common weevils. It is probable that most of the above coverings serve another purpose besides the protection of the eggs from wet and cold—that of sheltering them from the action of too great light, which, as Dr. Michellotti by numerous experiments has ascertained, is fatal to the included germe’. On this account it is perhaps that so many in- sects fasten their eggs to the under side of leaves. Those a De Geer iii. 48. 51. b Reaum. v. 122. © See above, Vor. I. p. 196. 202. 4 Journ. de Phys, Philos. Mag. ix. 244, STATES OF INSECTS. 77 exposed in full day have usually an opaque and horny texture. Some insects are spared all trouble in providing a Covering for their eggs, their own bodies furnishing one i every respect adapted to this purpose. Not to mention the Onisci, or wood-lice, since they rather belong to the Crustacea, which have a four-valved cell under the breast, in which they carry their eggs, as the kangaroo does its Young in its abdominal pouch, the whole body of the fe~ male of those strange animals the Cocci becomes a cover- ‘hg for her eggs, which it incloses on every side. To make this intelligible to you, further explanation is necessary. ou must have noticed those singular immovable tortoise- shaped insects, which are such pests to myrtles and other 8teenhouse plants. These are the young of a species of Coccus (C. Hesperidum L.), and their history is that of the Whole race. Part of them never become much bigger than the size of which you ordinarily see them, and when full- Stown disclose minute two-winged flies, which are the Males, The size of the females, which glue themselves to * twig or leaf as if lifeless, now augments prodigiously, and the whole body, distended with the thousands of eggs Which it includes to the bigness of a large pea, without “ny vestige of head or limb, resembles a vegetable ex- “rescence or gall-apple rather than an insect. If you *e€Move one of them, you will perceive that the under Part of its abdomen is flat and closely applied to the Surface of the branch on which it rests, only a thin ayer of a sort of cotton being interposed between them. ka lay ing her eggs the female Coccus does not, like most Msects, protrude them beyond her body into day-light; Ut as soon as the first egg has passed the orifice of her 78 STATES OF INSECTS. oviduct, she pushes it between her belly and the cottony stratum just mentioned, and the succeeding eggs are de- posited in the same manner until the whole are excluded. You will ask how there can be found space between the insect’s belly and the cotton, to which at first it was close- ly applied, for so large a mass of eggs? Tocomprehend this, you must consider that nearly the whole contents of its abdomen were eggs; that in proportion as these are extruded a void space is left, which allows the skin of the under side of the body to be pushed upwards, or towards that of the back, affording room between it and the cottony web for their convenient stowage. If you examine the insect after its eggs are all laid, you will find that they have merely changed their situation ; instead of being on the upper side of the skin forming the belly, and within the body, they now are placed between it (now become concave and nearly touching the back) and the layer of cotton. As soon as the female Coccus has finished. her singular operation she dies; but her body, retaining its shape, remains glued upon the eggs, to which it forms an arched covering, effectually protecting them, until they are hatched, from every external injury. Some species lay so many eggs, that the abdomen is not sufficiently large to cover the whole mass, but merely one side of it, the remainder being enveloped in cottony web?. I am next to consider the situation of those eggs that are excluded by the mother in groups without any other covering than the varnish with which they are usually besmeared in their passage from the oviduct. -The fe- 3 Reaum. iv. Mem. i. STATES OF INSECTS. 79 males only place them upon or near the food. appropri- ated to the young larvee, to which they adhere by means of the varnish Just mentioned. These groups consist of a greater or less number; and when the eggs are hatched. by the heat of the sun, the larvee begin to disperse and attack with voracity the food that surrounds them. It is thus that most butterflies and moths attach their eggs to the stems, twigs, and leaves of plants; that the lady birds (Coccinelle), the aphidivorous flies (Syrphi &c.), and the lace-winged flies (Hemerobii), deposit them in the midst of plant-lice (Aphides) ; that the eggs of some flesh- flies are gummed upon flesh ; those of crickets and grass- hoppers buried in the earth; those of gnats and other ipulidans set afloat upon, or submerged in, the water. Frequently the whole number of eggs laid by one “male is placed in one large group, more commonly, “OWever, .in several smaller ones, either at a distance from each other on the same plant, or on distinct plants. The object in the latter case seems to be, in some in- Stances, to avoid crowding too many guests at one table, m others to protect the unhatched eggs from the voracity Of the larvee first. excluded, which would often devour “em if in their immediate neighbourhood. In the disposition of the eggs which compose these Stoups much diversity prevails.- Sometimes they are Placed without order in a confused mass: more fre- {ently, however, they are arranged in different, and Often, in very beautiful modes. ‘The common cabbage- butterfly (Pieris Brassice) and many other insects place theirs upon one end, side by side, so as, comparing small things with great, to resemble a close column of soldiers, in consequence of which those larvæ which, on 80 STATES OF INSECTS. hatching, proceed from the upper end, cannot disturb the adjoining eggs. Many indeed have a conformation purposely adapted to this position, as the hemispherical eggs of the puss-moth (Cerura Vinula), which have the base by which they are gummed membranous and trans- parent, while the rest is corneous and opaque. The same ready exit to the larva is provided for in the oblong egos of the emperor moth (Saturnia Pavonia), which are piled on their sides in two or more lines like bottles of wine in a bin?. Where the larva does not emerge exactly from the end of the egg other arrangements take place. The whirlwig-beetle (Gyrinus natator) and the saw-fly of the gooseberry &c. (Tenthredo flava L.) dispose theirs end to end in several rows; the former upon the leaf of some aquatic grass, the rows being parallel”, the latter gummed to the main nerves of gooseberry or currant leaves, the direction of which they follow °. But the lackey-moths (Lasiocampa Neustria, castren- sis, &c.) adopt a different procedure. As their eggs, which are laid in the autumn, are not to be hatched until the spring, the female does not, like most other moths, place them upon a leaf, with which they might be blown by the winter’s storms far from their destined food, but upon the twig of some tree, round which she ranges them in numerous circles. If you examine your fruit-trees, you can scarcely fail to find upon the young twigs col- lections of these eggs, which are disposed with such ad- mirable art, that you would take them rather for pearls, set by the skilful hand of a jeweller, than for the eggs of a Rösel, ix. 157. t. 265? = b Ibid. iii, 197. ¢ See above, Vor. F p. 195. STATES OF INSECTS. ae an insect. Each of these bracelets, as the French gar- deners aptly call them, is composed of from 200 to 300 Pyramidal eggs with flattened tops?, having their axes Perpendicular to the circumference of the twig to which SY are fastened, surrounding it in a series of from ff teen to seventeen close spiral circles, and having their terstices filled up with a tenacious brown gum, which, ile it secures them alike from the wintry blast and the Attack of voracious insects, serves as a foil to the white namel of the eggs that it encompasses. It is not easy ° Conceive how these moths contrive to accomplish so accurately with their tail and hind feet an arrangement Which would require nicety from the hands of an artist ; pia could Reaumur, with all his efforts and by any con- trivance, satisfy himself upon this head. He bred num- ers of the fly from the egg, and supplied the females er impregnation with appropriate twigs; but these, as “ugh resolved that imprisonment should not force from them the secret of their art, laid their egos at random, “nd made no attempt to place them symmetrically >. . _ this illustrious Entomologist was more successful in ‘covering the mode in which another insect, the com- on 8nat, whose group of eggs is, In some respects, as ordinary as that last described, performs its opéra- "S. The egos of this insect, of a long phial-like form, are glued together, side by side, to the number of from 250 to 300, into an oblong mass, pointed and more “levated at each end, so as considerably to resemble a tin shape. You must not here suppose that I term boat by way of illustration merely ; for it as all the essential properties of a boat. In shape it Use the a Phare XX, Fic, 14, > Reaum. i 95— f. 1—13. VOL, rt, ‘ G 82 STATES OF INSECTS. pretty accurately resembles a London wherry, being sharp and higher, to use a nautical phrase, fore and aft; convex below and concave above ; floating, moreover; constantly on the keel or convex part. But this is not all. It is besides a Ujfe-boat, more buoyant than even Mr. Greathead’s: the most violent agitation of the water cannot sink it; and what is more extraordinary, and a property still a desideratum in our life-boats, though hollow it never becomes filled with water, even though exposed to the torrents that often accompany a thunder- storm. To put this to the test, I yesterday (July 25, 1811) placed half a dozen of these boats upon the surface of a tumbler half full of water; I then poured upon them 4 stream of that element from the mouth of a quart bottle held a foot above them. Yet after this treatment, which was so rough as actually to project one out of the glass, I found them floating as before upon their bottoms, and not a drop of water within their cavity. This boat, which floats upon the surface of the wate? until the larvae are disclosed, is placed there by the female gnat. But how? Her eggs, as in other insects, are extruded one by one. They are so small at the base in proportion to their length that it would be difficult to make them stand singly upright on a solid surface, much more on the water. How then does the gnat contrive to support the first egg perpendicularly until she has glued another to it—these two until she has fixed # third, and so on until a sufficient number is fastened to gether to form a base capable of sustaining them in their perpendicular position? This is her process. She fixes her four anterior legs upon a piece of leaf, or a blade of grass, and projects ’her tail over the water. She STATES OF INSECTS. 83 then Crosses her two hind legs, and in the inner angle Which they form, retains and supports the first laid egg, As it Proceeds from the anus. In like manner she also "UPPorts the second, third, &c., all of which adhere to each other by means of their glutinous coating, until she eels that a sufficient number are united to give a stable ase to her little bark; she then uncrosses her legs, and Merely employs them to retain the mass until it is of the “equired size and shape, when she flies away, and leaves t to its fate floating upon the water?. t May not be out of place to mention here a re- markable circumstance which not seldom attends a kind p Water-scorpion (Naucoris F.) occasionally to be met “ith in collections of Chinese insects. Its back is often “vered with a group of rather large eggs, closely ar- aged; but whether these are its own eggs or those of Bites large species of water-mite (Fydrachna Maill.) has Not “en clearly ascertained. On the former supposition, Ovipositor must be remarkably long and flexile to nable the animal to place the eggs onits back. In con- ation of the latter it may be observed, that the spe- Cles of the genus Hydrachna usually attach their egos ‘© the body and legs of aquatic insects, as for instance ` @stergens to the water-scorpion (Nepa cinerea), &e.® 2. After having thus laid before you some of the pro- Ures of t € . . ee hose insects that usually deposit their eggs n F i ; . STOUps, either naked or defended by coverings of va- ri À 3 Ous kinds, I next proceed to a rapid survey of those of e . ; j Species that commonly deposit them singly.: Some _* Reaum; iv. 615—. Z xliv. Sf. 2-7. ” N. Dict. d Hist. Nat. xv. 445. Rös. iii. 156. G2 84 STATES OF INSECTS. of these, as for instance the Admiral Butterfly (Vaness4 Atalanta), glue each egg carefully to its destined leaf by alighting on it for a moment. Another butterfly ( Hip- parchia Hyperanthus) whose caterpillar is polyphagous, drops hers at random on different plants. In general it may be observed, that all those larvee which live in s0- litude, as in the interior of wood, leaves, fruits, grain, animals, &c., proceed from eggs laid singly by the female, which is usually provided with an appropriate instrument for depositing them in their proper situation. Thus the nut-weevil ( Balaninus Nucum Germ.) and also that of the acorn (B, Glandium) pierce a nut or an acorn with theif long beak, and then deposit in the hole an egg, from which proceeds the maggot that destroys those fruits Leeuwenhoeck asserts that the common weevil (Calan dra granaria) adopts the same process, boring a hole # every single grain of corn before it commits an egg to ib and at the same time, by this manœuvre, prepares a small quantity of flour to serve for the food of the tender grub when it is first hatched?. It is probable that the Rhy?” cophorous or weevil tribe in general chiefly use their beak’ for the purpose of depositing their eggs in different veg” table substances, and perhaps principally in fruit or grail The tribe of gall-flies (Cynips) on the contrary, whos? economy, detailed in a former letter>, interested you ® much, bore an opening for the egg with their spiral ow duct, which also conveys it. Another large tribe of insects depositing their ego? singly, are those which feed upon the bodies of othe animals, into the flesh of which they are either insertew or placed so as speedily to find their way into it. Som? a Epist. 1687. b Vor. I. p. 448—. 7 _STATES OF INSECTS. 85 of these introduce them into diving animals, and then “ave them to their fate, as the Ichneumons and gad-flies: Others deposit them along with the dead body of an in- ‘ect interred in a hole, often prepared with great labour, às the different species of sand-wasps (Sphecide), spider- Wasps (E ompilide), &c.: the manners of the latter of these tribes have been already adverted to*, and those of the chneumonide will come more fully under consideration When I treat of the diseases of insects. Similar labour in providing suitable habitations for eir egos is undergone`by various other insects whose arvæ live chiefly on vegetable food, some inserting their “88 Within the substance the larva devours, as those that Prey on timber, twigs, roots, or the like, and others on hs: Surface, One would suppose at first, that the exeeed- ngly Small egg which produces the subcutaneous larvæ Would, by the parent moth, be imbedded in the substance of the leaf which is to exhibit hereafter their serpentine Ballleries but this is not the case, for she merely glues it on the Outside; at least such was the situation of the only “8S of these very minute moths Reaumur had ever an P Portunity to observe. . i Other insects, belonging to the tribe which lay their pa singly, bury them in the ground. l Of this descrip- „œ “re many of the lamellicorn insects, the dung-chafers “arabeide MacLeay) particularly, which, inclosing tings oe ii a pellet of dung, deposit teem in deep cy- as oa Cavities. Concerning the proceedings of some which as well as of the whole race of bees, wasps, ee all lay single eggs, I have before detailed to you a See above, Vor, I. p. 344—, b Reaum, ii, 8—, 86 STATES OF INSECTS. many interesting particulars*. I must not conclude this subject without observing, that the female Pycnogonidds an osculant tribe between Insects and Crustacea, catty their eggs upon two pair of false legs». iii, Substance. From this long dissertation on the situ” ation of the eggs of insects and matters connected with it I pass on to their substance or their external and internal composition, giving at the same time some account of the embryo included in them. The eggs of insects, like those of birds, consist in the first place of an external coat of shell, varying greatly, as to substance, in different gener® Most commonly, particularly in those which deposit the eggs in moist situations, as in dung, earth, and the like it is a mere membrane, often thin and transparent, and showing, as in spiders, all the changes that take place # the inclosed embryo, as the formation of the head, trank and limbs*. This membrane is sometimes so delicat? as to yield to the slightest pressure, and insufficient © protect the included fluids from too rapid an evaporatiol™ if the eggs be exposed to the full action of the atmospher@ In most Lepidoptera, and several other tribes, this int@ gument is considerably stronger, in those moths whos eggs are exposed throughout the winter, as Lasiecamp" Neustria, &¢., so hard as not to yield easily to the knife Even in these, however, its substance is more analogo™ to horn or a stiff membrane than to the shell of the egg? of birds. Nothing calcareous enters into its compositio” and it is not perceptibly acted upon by diluted sulphur a Vor, I. 349—. 371~—. 2 ° N. Dict. d Hist, Nat. xxviii. 2" $ De Geer vii. 194. STATES OF INSECTS. 87 acid. The eggs of birds are lined by a fine membrane: but I have examined several of those of insects, and have been able to discover nothing of the kind in them. I will not, however, affirm that it does not exist, though the shell of the insect egg appears more analogous to the Membrane that lines that of the bird than to the outside shell itself. Within this integument is included a fluid, on the Precise nature of which, except that it is an aqueous Whitish fluid, few or no observations have been made, or Indeed are practicable; but it is reasonable to suppose, that like the white and yolk of the bird’s egg, it serves for the development of the organs of the germe of the future insect, But few observations are recorded that relate, to the embryo included in the egg. It is stated, that it is in- Vested with an extremely fine and delicate pellicle—sup- Posed by some analogous to the Chorion and Amnios of the human foetus, though others think the shell of the °8 to correspond with the Chorion, and the successive ‘Nteguments of the larva with the Amnios*. When the “Sg is first laid, nothing indeed is to be seen in it but the fuid Just mentioned; the first change in this fluid is the “Ppearance of the head of the embryo, more particularly in Coleoptera, of two points, the rudiments of the mandi- es, and of those apertures into the tracheæ which I ave called spiracles>; the little animal we may suppose the Compare N. Diet, d’ Hist, Nat. xvi. 246. with xx. 352— ; but as e Amnios immediately envelops the foetus, the pellicle seems most ogous to it, and the shell to the Chorion. x Swamm. Bibi. Nat. ed. Hill. 1, 133. a. Comp. N. Dict. d’ Hist. “Nal, Xvi, 246, anal t 88 STATES OF INSECTS. then assumes its form and limbs. The embryo is usually so folded in the egg that the head and tail meet?, and the head, annuli, and other parts of the larva are often visible through the shell®. Swammerdam even saw the pulsation of the great dorsal vessel through the shell of the egg of Oryctes nasicornis. Under this head I must notice another singular cir- cumstance peculiar I believe to the eggs of insects, that sometimes, though rarely, they are covered with down or hair. Those of a singular little hemipterous insect, of a genus I believe at present undescribed, the ravages of which upon the larch have been before noticed‘, are co- vered by a downy web, as is the case with the animal itself. De Geer has described the eggs of a bug, not uncommon in this country (Pentatoma juniperina Latr.), which are reticulated with black veins, in which very short bristles are planted’. I possess also a nest of brown eggs, probably of a species of the same genus, found upon furze, which appear to be covered with very short downy hairs. The top of these is flat, and sur- rounded by a coronet of short bristles, each surmounted by a small white ball, so as to wear the appearance of a beautiful little Mucor. But hairy eggs are not confined to the Hemiptera Order, for, according to Sepp, those of the figure-of-eight moth (Bombyx cceruleocephala) are of this description €. iv. Number. The fertility of insects far exceeds that of a Swamm. Ibid. > Sepp. iv. ¢. iii. f.i. e. v. t, iv; fı 2 ¢ See above, Vor. I. p. 208: it is there called an Aphis, but it is 2 distinct genus. d. De Geer iii, 245. t. xii. f. 20—22, © Sepp. iv. 2. xii. f. 2. 3. STATES OF INSECTS. 89 birds, and is surpassed only by that of fishes*. But the \ number of eggs laid by different species, sometimes even Ta of the same natural family, is extremely various. -Thus | the pupiparous insects may be regarded as producing | only a single egg; Musca Meridiana L., a common fly, | lays two», other flies six or eight; the flea twelve; the : burying beetle (Necrophorus Vespillo*) thirty; May-flies | (Trichoptera K.) under a hundred; the silk-worm moth ' about 500; the great goat-moth (Cossus ligniperda) 1,000; Acarus americanus more than 1,0004; the tiger-moth (Cal- limorpha Caja) 1,600; some Cocci 2,000, others 4,000; the female wasp at least 30, 000°; the queen bee varies Considerably in the palais aes eggs that she produces in One season, in some cases it may amount to 40,000 or 50 000 or more f; a small hemipterous insect, resembling a ‘little moth (Aleyrodes proletella Latr.) 200,000. But all these are left far behind by one of the white ants {Termes fatale F. bellicosus Smeath,)—the female of this insect, as was before observed £, extruding from her enor- Mous matrix not less than 60 eggs in a minute, which gives 3,600 in an hour, 86,400 in a day, 2,419,200 in a lunar month, and the enormous number of 211,449,600 ina year: probably she does not always conan laying at this rate; but if the sum be set as low as possible, it Will exceed that produced by any other known animal in the creation. V. Size. The size of the eggs is in proportion to that of è The sturgeon is said to lay 1,500,000 eggs, and the cod-tish 9 nog ,000. ° Reaum} iv. 392, ¢ See above, Vox. I. p. 350. “ De Geer vii. 159. e See above, Vor. I. p. 109. f Ibid. 159. 166. s Ibid. 36—. 90 STATES OF INSECTS. the insect producing them, though in some instances small ones produce larger eggs than those laid by bigger species. Thus the eggs of many Aptera, as those of that singular mite Uropoda vegetans, and of the bird-louse | found in the golden pheasant, are nearly as large, it is probable, as the parent insect; while those of the ghost- moth (Hepialus Humuli) and many other Lepidoptera, &e. are vastly smaller. This circumstance perhaps de- pends principally on the number they produce: the ma- jority of them, however, are small. The largest egg known, if it be not rather an egg-case, is that of a spectre insect (Phasma dilatatum), figured in the Linnean Trans- actions *, being five lines in length and three in width, which ili approaches near the size of that of some humming-birds. The largest egg of any British insect I ever saw was that of the common black rove-beetle (Staphylinus olens) sent me by Mr. Sheppard—this is a line and half long by a line in width. But we do not often meet with insect-eggs exceeding a line in length. A vast number are much smaller: those of Ephemerze are more minute than the smallest grains of sand’, and some almost imperceptible, as those of the subcutaneous moths, to the naked eye. Commonly the eggs laid by one female are all of the same size; but in several tribes, those con- taining the germe of the female are larger than those that are to give birth to a male. This appears to be the case with those of the Rhinoceros beetle (Oryctes nasicornis‘), and according to Gould with those of ants’. As the female in a vast number of instances is much bigger than the male, it is not improbable that this law may hold a iv. £. xviii. f. 4. 5: b De Geer ii, 638. © Bibl, Nat. i. 132... _ * Gould 36. STATES OF INSECTS. 91 very extensively. It is stated, however, by Reaumur®, that the reverse of this takes place in the eggs of the hive-bee, those that are to produce males being larger than the rest. | _ Another peculiarity connected with the present head is the augmentation in bulk which takes place, after exclusion, in the eggs of the great tribe of saw-flies (Tenthredo L.), the gail-flies (Cynzps L.), the ants (Formica L.) and the water- mites (Hydrachna Maill. Atax ¥.). Those of the two for- mer,which are usually deposited in the parenchymous sub- Stance of the leaves, or of the young twigs, of various plants, imbibe nutriment in some unknown manner, through their membranous skins, from the vegetable juices which sur- round them>, and when they have attained their full size are nearly twice as large as when first laid. Except in the egos of fishes, whose volume in like manner is said to augment previously to the extrusion of the young, there is nothing analogous to this singular fact in any other of the oviparous tribes of animals, the eggs of which have always attained their full size when they are laid. It is to M. P. Huber that we are indebted for the knowledge of the fact that the eggs of ants grow after being laid, a circumstance favoured probably by the Moist situation in which the workers are always careful to keep them. By an accurate admeasurement he found that those nearly ready to be hatched were almost twice as big as those just laid*. A similar observation was made on the red eggs of a water-mite (Hydrachna abs- tergens) by Résel, who conjectured that they draw their Means of increase from the body of the water-scorpions = LA * Reaum. v. 477. t Thid, ii, 5796V-4215 © Fourmis, 69-—. a a aa Ses 92 STATES OF INSECTS. (Nepe), of which they form so singular an appendage*, which opinion is confirmed by De Geer, who observes that when the water-scorpions are covered by an unusual number of the eggs of the water-mites, they grow weak and languid, and endeavour to rid themselves of their parasitic appendages®. It is most probable that the mite lately named (Uropoda vegetans), which is often found planted as it were upon the bodies of various beetles, by means of a long pedicle, through which, as the foetus by an umbilical chord and placenta, it derives its nutriment from the above animals, is at first so fixed in the egg state, though before it is disengaged from the pedicle it is hatched, since it is often found with its legs displayed and quite active—this is the more probable, as the eggs of the water-mite are fixed by a pedicle to the animals to which they are attached €. I have met with a remarkable instance, in which pedunculated eggs seem to draw nu- triment from the mother, which brings the pedicle still near to the nature of the umbilical chord. ‘Those of the small hemipterous insect which infests the larch before alluded to, are attached to the anal end of the mother by a short foot-stalk not longer than the ege. Dr. Derham seems to have observed, that the eggs of some Diptera, of the tribe of Tipulidae, also increase in size before the larva is excluded¢. It seems to me likely enough, that in this and many of the above cases in which the egg is supposed to grow, it is rather an extension of the flexile membrane that forms their exterior propor- tioned to the growth of the included embryo from food @ Rosel iii. 152. b De Geer vii. 145, c Ibid. 123—. See above, Vox. I. p. 393, 4 Raii Hist. Ins. 265. STATES OF INSECTS. 93 it finds within the: egg, than from any absorption from without. i. Shape. We are accustomed to see the eggs of dif- Sat species of oviparous animals so nearly resembling each other in form, that the very term egg-shaped has been appropriated to a particular figure. Amongst those of birds, with which we are most familiar, the sole variations are shades of difference between a globular and oval or Ovate figure. The eggs of insects, however, are confined by no such limited model. They differ often as much, both as to their shape, sculpture, and appendages, as one Seed does from another; and it is not improbable that, if duly studied, they would furnish as good indications of generic distinctions as Geertner has discovered in those of plants. Their most usual form indeed is glo- bular, oval, or oblong, with various intermediate modifi- Cations. We meet with them ovate, or of the shape of the common hen’s ego, flat and orbicular, elliptical, co- Nical, cylindrical, hemispherical, lenticular, pyramidal, Square, turban-shaped, pear-shaped, melon-shaped, boat- Shaped, of the shape of an ale-stand, of a drum, &c.?, and sometimes of shapes so strange and peculiar, that we can scarcely credit their claim to the name of eggs. Thus the eggs of the gnat are oblong and narrow, or nearly cylindrical, having at the top a cylindrical knob®, 80 as to give them the precise form of the round-bottomed Phial sometimes used by chemists: those of the common * Eggs of various shapes are given Prate XX. Fic. 3—23. See also Brunnich. Entomologia 4. N. Dict. d Hist. Nat. xvi. 245. Reaum. ii. 4. ill, iv. xiv. xxvi. xxvii. &c. ° Prats XX. Fie. 18, 94 STATES OF INSECTS. water-scorpion (Nepa cinerea) are oblong, and at the upper end are surrounded by a sort of coronet, consisting of seven slender rays or bristles of the length of the egg*, so as to resemble somewhat the seeds of Carduus bene- dictus (Cnicus acarna?) of the old botanists. One would think this spinous circlet a very awkward appendage to bodies which are to be gradually extruded through the fine membranous ovaries and oviduct which inclose them : but they are so admirably packed, the unarmed end of each egg fitting closely into the space inclosed by the spines of the one next below it, or, rather, the spmes which are moveable, embracing it closely, that not only is no room lost, but the ovaries are perfectly secure from injury. The eggs of another species of this tribe (Ra- natra linearis) have only two of these spines or bristles —they are inserted in the stem of a water-rush (Scirpus) or other aquatic plant, so as to be quite concealed, and are only to be detected by the two bristles which stand out from it®. The eggs of the beautiful lace-winged flies (Hemerobius), those golden-eyed insects so serviceable in destroying the plant-lice (Aphides*), are still more sin- gular. Those of H. Perla are oval, and each of them attached to a filiform pedicle not thicker than a hair, and seven or eight times as long as the egg. By this pe- dicle (which is supposed to be formed by a glutinous matter attached to one end, which the female draws out by abstracting her ovipositor with the egg partly in it 2 Prats XX. Fic. 23. Swamm. Bibl. Nat. t. iü. f. 7,8. Ina specimen I opened of this insect the bristles converged so as to form a kind of tail to the egg. b Darwin Phytolog. 512. c Geoffr. Ins. Par. i. 480. £ x. f. 1. bue- a See above, Vor, I. p. 261. STATES OF INSECTS. - 95 from the leaf, to which she has previously applied it, to a proper length, when the gluten becoming sufficiently Solid she wholly quits the egg,) the eggs are planted in 8Toups of ten or twelve on the surface of leaves and twigs, from which they project like so many small fungi, to some of which they have a remarkable resemblance. When the included larva has made its way out of them by forcing Open the top, they look like little vases, and were actually once figured by a Naturalist, as we learn from Reaumur, as singular parasitic flowers growing upon the leaves of the elder, for the origin of which he was extremely puz- led to account*. Eggs similarly furnished with a pedicle are also laid by other insects; but as most of these have een before alluded to, it is not necessary to describe them ered, The cause of these differences of form is for the Most part concealed from us: in many instances it may Perhaps be referred to that will to vary forms, and so to glorify his wisdom® and power, independently of other considerations, which, as Dr. Paley has well remarked 4, Seems often to have guided the Great Author of Nature. ut in some cases the end to be answered is sufficiently evident. The long footstalks of the eggs of the Heme- | Tobin Just mentioned, there can be little doubt, aré meant \ to place them out of the reach of the hosts of predaceous | sects which roam around them, from whose jaws, thus | elevated on their slender shaft, they are as safe as the , Reaum. iii, 386—. 2. xxxii. f. 1. t. xxxiii. f. 5. allude to Ophion luteum F. (Ichneumon L.) Vol. i. Ed. 3. T 269. figured Prare XX. Fic. 22; and the Hydrachne or Trom- idia. See above, and De Geer vii. 145. ° From this circumstance called roavwo:xsrog copia by the Apostle, Phes. iii, 10, . * Nat. Theol. 11th Ed. 375. 96 STATES OF INSECTS. eggs of the tailor bird in its twig-suspended nest from the attack of snakes. Reaumur has described the eggs of a kind of fly, common upon the excrements of the horse and other animals (Scatophaga vulgaris Latr.), or one related to it, that requires to be immersed in the dung to which it is committed, on which the future grubs are to feed. He found that if not thus surrounded with moisture, they infallibly shrivelled up and came to no- thing; but it is equally necessary that they should not be ‘wholly covered: if they were, the young larva would be suffocated at its first exit from the egg. In what way is this nice point secured? In this manner. Each egg is provided at its upper end, at which the animal when ;, hatched comes out, with two diverging horns; these | prevent it from being stuck into the excrement, in which ‘. the female deposits the eggs one by one, more than three- fourths of its length: and when examined they resemble not badly, as Reaumur remarks (except that their colour | is white), a parcel of cloves stuck into a pudding, as they are neatly inserted at due distances in the disgusting mass’, The French Naturalists found these eggs in swine’s dung; I have observed them in cow-dung. La- treille thinks that the bristles above described attached to the eggs of Nepa and Ranatra have a similar use, as the female plunges them all but these bristles into the stems of aquatic plants °: but may not this have some- thing to do with their oxygenation? Reaumur has figured another egg of a dipterous insect which has a longitudinal wing or lateral margin attached to it, giving a Prare XX. Frc. 19. a a. b Reaum. iv. 376—. ¢. xxvii. f. 9, 10. © Hist. Nat. gen. et partic. des Crust. et Ins. xii. 282, STATES OF INSECTS. 97 it the form of an oblong square, the object of which, he Conceives, is to give a greater surface by which it may © more firmly fixed to the substance against which the fly. attaches it, Besides these more striking variations in figure, their Surface, though often smooth, is frequently curiously and most elegantly sculptured, a circumstance that di- Stinguishes the egos. of no other oviparous animals. Some, as the margined egg just mentioned, are only sculptured n one side, the other being plain; or, as those of ‘the usseh silk-worm > ( Attacus Paphia) and other Bombyces, Which have orbicular depressed eggs with a central ca- Vity above and below, have their circumference crossed with wrinkles corresponding with the rings of the inclosed “bryos, Others again are sculptured all over. Of ese, in some, the sculpture of the two sides is not sym- Metr ical, as in those of a fly figured by Reaumur4: but ™ general there is a correspondence in this respect. be- Ween the different parts of the egg. In those elegant MSS before alluded to of some bird-louse attached to the Solden Pheasant, the shell resembles the purest wax, and S scored with longitudinal striæ, each distinguished by Series of impressed points, which give it a beautiful ap- p arance of net-work. In the others, as in a common “tterfly (Hipparchia Ægeria) and moth (Geometra cra- ‘@gata), the whole surface is covered with hexagonal re- ticulations e, Others, as those of another butterfly (Hip- ; Reaum, iy. 381, t, xxvi. f. 19, 20. oxburgh in Linn, Trans. vii. 34. P Tis TE SR Abee hara similar eggs, as N. Lappa. Sepp iv. LA Ra d Reaum. ubi supr. f. 22, 23. Prats XX. Fic. 6. 8, Vo L. I. H 98 STATES OF INSECTS. parchia Hyperanthus), are beset with minute granules of tubercles*. Others again, like those of the cabbage and hawthorn butterflies (Pieris Brassice and Crategt), ave remarkable for beautiful longitudinal ribs, often connected by elevated lines crossing them at right angles? ; and in some, as in another butterfly (Hipparchia Furtina), crown- ed by imbricated scales*. Many other minor differences in this respect might be noticed, but these will suffice to give some idea of the infinite variety exhibited in this respect by these little atoms. If the Creator has wrought them with so much art and skill, can it be beneath his reasonable creatures to examine and admire them, that they may glorify those attributes which they serve to il- lustrate ? Some eggs after exclusion occasionally become slightly corrugated: Malpighi supposed that this occurs only when the eggs are barren, having observed that those of the moth of the silk-worm which preserved their plump- ness always produced caterpillars, while those which lost their original rotundity and became wrinkled were con- stantly unprolific. Bonnet, however, found exactly the reverse take place in another moth 4, so that these ap- pearances are scarcely to be depended upon. Kuhn as- serts, that a virgin female of the puss-moth (Cerura Vinula) having begun to lay eggs, which were yellow above, green below, and depressed, he introduced to het an hour afterwards a male, and some minutes subse- quently to the union, she again deposited eggs, which were whoily of a dark brown and convex *. a Prare XX, Fic. 5. > Ibid. Fie. 3. 4. 7. 9. &e. c Ibid. Fie. 15. d Bonnet Œuvr, ii. 9. e Naturf. xii, 229. STATES OF INSECTS. 99 vii. Colour. The colour of the eggs of insects is as va- "ous as their shape and sculpture. They are very often White, those of some spiders like minute pearls?; some are yellow, as those of the silk-worm; others orange, Such are the egos of the bloody-nosed beetle ( Timarcha tenebr tcosa); others again of a golden hue; sometimes they are of a sanguine red. I remember once being much surprised at seeing the water at one end of a ca- hal in my garden as red as blood: upon examining it farther I found it discoloured by an infinite number of cee ise pray to some pipidond pulidan tribe. There are also eggs of every intermediate shade between red and black ; some “gain are blue and others green. ‘They are not always of whole colours, for some are speckled like those of many birds, of which I can show you specimens, that nee also shaped like birds’ eggs; these I think were ad by a common moth (Odenesis potatoria); others are anded with different colours—thus the blue eggs of the “Ppet-moth (Gastropacha quercifolia) are encircled by = brown zones»; others are brown with a white ne ¢, Many egos assume a very different colour after being aig = z la few days. In general upon their first exclusion ; ue are white. Those of the chameleon-fly (Stratyomis . “meleon) which I once found in great numbers, ar- nd like tiles a a roof one laid partly over ee = i a side of the leaves of the watensplantam, from R ecome green, and then change to olive green. Ose of the hemipterous enemy of the larch, more than R a @ Hist. Nat. xvi. 245. > Reaum: i. 286. — ATE XX, Fig. 11. Sepp £. iv. f. 2. a2 100 STATES OF/ INSECTS, once mentioned in this letter, are first mouse-coloured, then they assume a reddish hue, and lastly a blackish one. Those of the gnat from white in a short time as- sume a shade of green, in a few hours they are entirely green, and at length become gray*. Those of the silk- worm, which at first are of a yellow or sulphur colour, acquire a violet shade. The eggs of that rare moth Ær- dromis versicolor, are at first sulphur-coloured, then green, next rose-coloured, and lastly blackish. The colour of almost all eggs changes when they dre neat hatching; but this change depends more frequently upon the colour of the included larva, which appears through the transparent shell of the egg, than upon any actual alteration in the egg itself viii. Period of hatching. The general rule for the hatching of the eggs of insects is the absorption by the embryo of all the superabundant moisture included in them; but the time varies according to the state of the atmosphere, to the action of which they are subjected. Like those of other animals, they require a certain degree of heat for the due evolution of the included larva. This heat in much the greater number of instances is derived from the temperature of the air, but often also from other sources. The eggs of the gad-fly tribe are hatched principally by the heat of the body of the animal to which they are committed; and doubtless the vital heat of va- rious larvee, small as it may be, must contribute some- thing to the hatching of the eggs deposited in them by various Ichneumons. In the fermenting bark in which the instinct of the rhinoceros beetles (Oryctes nasicornis &c.) a Reaum. iy, 617. l 1 STATES BS INSECTS. 101 impels them to place theirs, the dung which the Scara- beide select for that purpose, and the decaying vegeta- €s chosen by many other insects, a degree of artificial “at must exist: and the eggs, or rather ego-like pupee, Of the Spider-fly of the swallow (Ornithomyia Hirundinis) are hatched by the heat of those birds which sit upon €m along with their own egos. as. Fabricius says, “ Insects never sit upon their eggs? ;” } -t certainly, -as I formerly related to you, the female ` “arwig does this, and one would be induced to suppose, » tom the circumstance of the you’ g ones following their | Nother, as chickens do the hen, that Pentatoma grisea | ‘mex Linn. ), formerly mentioned, may do the same‘. ith these exceptions, the eggs of all insects are ‘atched by atmospheric heat alone, the variations in “hich determine the more speedy or more tardy disclo- ‘Ure of the included insect. The eggs of such species as "Ve several broods in the year, as the nettle butterfly . (Vanessa Urtice), when laid in summer are hatched in a = days; but if not laid till the close of autumn, they emain dormant through the winter, and are only hatched . © return of spring. That this difference is to be at- “buted to the influence of heat has been often proved y Xperiment: the autumnal eggs if brought into a a room may be hatched as soon as those laid in the “ight of summer. Silk-worms’ eggs naturally are not “tched till they have been laid six weeks, but in coun- les where they are reared, the women effect their ex- ; "sion in a much shorter period by carrying them in “It bosoms : yet to retard their hatching with particu- * Philos. Ent. 76. b See above, Vor. I. 358—. ° See above, Vor. I, Ibid. 102 STATES OF INSECTS. lar views is in many circumstances impossible. When the heat of the atmosphere has reached a certain point, the hatching cannot be retarded by cellars ; and M. Faujas has remarked, that in June the silk-worm’s egg§ would hatch in an ice-house*. The period of exclusion does not, however, depend solely upon temperature : the hardness or softness of the shell, and possibly differences in the consistence of the included fluid, intended to serve this very purpose, cause some eggs to be hatched much sooner than others exposed to the same degree of heat. Thus the eggs of many flesh- flies are hatched in twenty-four hours? ; those of bees and some other insects in three days; those of a commo lady-bird (Coccinella bipunctata) in five or six days) those of spiders in about three weeks; those of the mole- cricket in amonth; while those of many Lepidoptera and Coleoptera require a longer period for exclusion. The hard eggs of Laszocampa Neustria and castrensis, noticed above, remain full nine months before being hatched “s as do those of another moth (Hypogymna dispar), which; though laid in the beginning of the warm month of Au gust, do not send forth the included caterpillar till the April following". We know no more of the cause ° a Young’s France, ii. 34. This author asserts, that no art wil hatch the eggs of the common silk-worms the first year, or that a which they are laid; but that there is a sort brought from Pers!” which are hatched three times a year, and which will hatch in gifte” days in the proper heat. In 1765, it is said, the common sort hatcbe in the first year. Ibid, 226—. b In the N. Dict. d Hist. Nat. xii. 564. the eggs of the fesb-fY are said to hatch in two hours. This is true I believe m very walt weather. c Brahm. 310. à Rimrod Naturf. xvi. 131. STATES OF INSECTS. 103 this difference than of that which takes place in the Period of exclusion of the eggs of the different species of birds, Some eggs change considerably both their form and “ohsistence previously to being hatched. M. P. Huber found that those of different species of ants when newly laid are cylindrical, opaque, and of a milky white; but just before hatching their extremities are arched, and they “come transparent with only a single opaque whitish Point, cloud, or zone, in their interior*. An analogous Change takes place in the eggs of many spiders, which Just before hatching exhibit a change of form corre- “Pending with that which the included spider receives When its parts begin to be developed, the thin and flexible ‘kin of the egg moulding itself to the body it incloses”, In proportion as the germe included in the egg is ex- Panded, it becomes visible through the shell when trans- Parent: this ‘is particularly the case with spiders, in Which, as was before observed, every part is very di- Stinctly seen. At length, when all the parts are consoli- ated so as to be capable of motion, which im spiders takes place in four or five days after they begin to be Visible in the egg, the animal breaks the pellicle by the ‘Welling of its body and the movement of its legs, and en quits it, and disengages all its parts one after the CrS. ON general, at least where the shell is harder than that of spiders, insects make their way out by Shawing an opening with their mandibles in the part Nearest their head, which, when the shell is very strong (as in Lasiocampa Neustria, &c.), it is often several Š Fourmis. 69. b De Geer vii. 195. c Thid. 196. 104 STATES OF INSECTS. hours in accomplishing*. In many instances, however, the larva is spared this trouble, one end of the egg being furnished with a little lid or trap-door, which it has but to force up, and it can then emerge at pleasure: such lids are to be found in the eggs of several butterflies and moths, as Satyrus Mera, Saturnia pavonia major, &c. and the common louse’. In those exquisitely elegant eggs, before described, of some kind of bird-louse (Nzr- mus) found adhering to the base of the neck feathers of the golden pheasant, there is a lid or cap of this kind. of a hemispherical form terminating in a tortuous style. Those of a species of bug (Pentatoma Latr.), found by our friend the Rev. R. Sheppard, besides a convex lid are furnished with a very curious machine, as it should seem, for throwing it off. This machine is dark-brown, of acorneous substance, and of the shape ofa cross-bow 4, the bow part being attached to the lid or pushing against it, and the handle, by means of a membrane, to the pla end of the side of the egg. When the included animal has made its way out of the egg, it enters upon a new state of existence, that of Larva, to which I shall direct your attention in the fol- lowing letter. 2 Reaum. ii. 167. » Brahm. 249. Rosel. iv.130. Swamm. Bibl. Nat. t. i. f. 2. ¢ By Mr. White, jun. cordwainer at Ipswich. ¢ Prare XX. Fic. 16. a. LETTER XX STATES OF INSECTS. LARVA STATE. Tur Larva state is that in which insects exist imme- diately after their exclusion from the egg (or from the Mother in oyo-viviparous species), in which they usually fat voraciously, change their skin several times, and have the power of locomotion, but do not propagate. Almost all larvæ, at their birth, are for a time in a very feeble and languid state, the duration of which differs in different species. In most it continues for a very short time, a few minutes or perhaps hours, after which they ~ revive and betake hemselves to their appropriate food. others, as in the generality of spiders, this debility lasts for seven or eight days, and in some species even a Month, during which the young ones remain inactive in the €go-nouch?, and it is not till they have cast their first skin that their active state of existence commences. All larvee may be divided into two great divisions :— I. Those which in general form more or less re- semble the perfect insect. II. Those which are wholly unlike the perfect in- sect, * De Geer vii. 197. 106 STATES OF INSECTS. I shall begin by calling your attention to the charac- ters of the first of these divisions: the second, which is by far the most numerous, will be afterwards considered. I. The frst division includes the larvee of Scorpions, Spiders, Cockroaches, Grasshoppers, Lanthorn-flies, Bugs, &c.; or generally, with the exception of the Flea and Crustacea, the whole of the Linnean Orders Aptera and Hemiptera. All these larvae, however remotely allied in other respects, agree in the general similarity which they bear to the perfect insects which proceed from them. The most acute entomologist, untaught by experience, could not even guess what would be the form of the perfect insects to be produced from larvee of the second division, while they can recognise the form of the spider, the cricket, the cockroach, the bug, and the frog-hopper, in that of the larvee. There are, however, differences in the degrees of this resemblance, according to which we may, perhaps, divide this tribe in their second state as follows :— i. Those that resemble the perfect insect, except in the relative proportions and number of some of their parts. ii. ‘Those which resemble the perfect insect, except 7 that they are apterous, or not yet furnished with organs of flight. i. Spiders, Phalangia, scorpions, lice, Podure, sugar- lice (Lepisma), mites, centipedes, millepedes, &c. come under the frst subdivision. The larvee of the first six tribes here mentioned differ at their birth from the per- fect insect, only in size and the proportions of their parts. STATES OF INSECTS. - 107 Thus the larvæ of spiders have their legs of a different relative length from that which they subsequently ac- quire; and the palpi in the males, which previously to the discoveries of Treviranus were regarded as their Sexual organs, are not yet fully developed *: and a si- milar difference takes place in the legs of Phalangza. The general form too of the body undergoes slight alter- ations, and the colour very considerable ones, with each change of the skin—a change to which all these tribes are subject. The larvæ of the three last-mentioned tribes (the Mites, centipedes, aud millepedes) differ from the per- fect insect not only in the proportion but also in the number of their parts. Leeuwenhoeck states (and De Geer confirms his assertion, extending it to other species of mites»), that the common cheese-mite, which in its Perfect state has eight legs, when first excluded from the egg has but siz, the third pair being wanting*. Some however are born with eight legs, for instance A. eruditus of Schrank, which he saw come from the egg itself with that number‘. Others again have never more than six legs: this is the case with Latreille’s genera—Carvs, Leptus, Atoma, and Ocypetes of Dr. Leach*. In the centipedes (Scolopendridæ) and millepedes (Zuid) dif- erences still more remarkable, as I have stated in a for- mer letter, have been observed by De Geer; these ani- mals, in their progress to the perfect state, not only gain Several additional pairs of legs, but also several additional Segments of the body. This illustrious Entomologist found that Pollyxenus lagurus (Scolopendra L.) was born a hexa- è De Geer vii. 197. è Ibid, 85. © Epist. Ixvii. 1694, 390. l Enum. Ins. Austr. 575. e N, Dict. ? Hist. Nat. i. 74. 108 STATES OF INSECTS. pod, with but three segments and as many pairs of feet, but successively acquired five additional segments with other appendages, and nine more pairs of feet?. A spe- cies of millepede (Iulus terrestris L.), which he also traced from its birth, and which begins the world at first with only eight segments and six feet, by a successive development at length acquires, in its perfect state, 50 segments and not less than 200 feet>. The nature of these very singular accretions, which Latreille and Mr. Wm. MacLeay have also observed in the centipedes‘, seems not well understood. If, as is most probable, though De Geer could not find any exuvite‘, the larvee cast a skin before each change, they do not essentially differ from the metamorphosis of other insects. The legs that these insects thus acquire are affixed to the abdomen, the six that they set out with being attached to the part representing the trunk, so that the former may be regarded as analogous to the prolegs of cater- pillars. These animals therefore, as I have before inti- mated, invert the order of Nature, and from perfect de- generate into zmperfect insects. ii. If you examine the cockroach, cricket, or grasshop- per, in different stages of their growth, you will find that the larva does not vary essentially from the perfect insect, except in wanting wings and elytra. The case is the same in almost all the Linnean genera of the modern order—Hemiptera; and with Raphidia, Termes, and Psocus, in the Neuroptera. Some of these, however, ex- 2 De Geer vii. 576. t b Ibid. 584. © Considerat. Géner. 21. Hore Entomolog. 353. 4 De Geer, Ibid. Mr. W. MacLeay observes of the Chilopoda, or Centipedes, that they moult in the manner of Crustacea. ubi supr, 352. STATES OF INSECTS. 109 hibit slighter discrepancies in the proportion of some of their parts, but without affecting the general resemblance. Thus the larvee of the common ear-wig have at first only eight, and subsequently nine joints to their antenna, whereas the perfect insect has fourteen *; and the forceps 'S quite different, resembling rather two straight styles than what its name implies. In those also of many bugs (Coreus marginatus F. &c.), the joints of the antenne are Of a shape dissimilar to that which obtains in the perfect insect, In that of the common water-scorpion, the anal air-tube, which is so long in the imago, is scarcely visi- ble’, In the Cicada tribe, so celebrated for their song'¢, neither the larva nor the imago have the enormous thigh armed below with strong teeth, the tibiae terminating in à fixed incurved claw, probably for the purpose of dig- ging the holes into which they retire till they disclose the fly, which distinguish the pupze of some species, and is Particularly conspicuous in one commonly brought from China 4. These often exhibit also other minor differences. Il. In treating of the second great division of larve, those that are wholly unlike the parent insect,—which Meludes, with few exceptions €, the whole of the Linnean ` De Geer iii. 549. The figure of the forceps in De Geer (Ibid. » XXy, br J. 21) is not quite correct. The styles do not taper to a point, 't are filiform and acute. : Compare De Geer iii. ¢, xviii. f. 2 and 12. 9. ig above, Vou. II. p. 401. tate XVI. Fic. 4. c. Reaum. v. é.xix. f.16. De Geer ubi supr. of Gee: 26. According to Reaumur, the larva as well as the pupa „Hermes Ficus has wing-cases (iii. 353). S ese are in the female sex of some Coleoptera, as Lampyris, &c. retain in the perfect state nearly the same form which they ae When larvae. The larva: of some Staphylini are not very dissi- arm form to the perfect insect, 110 STATES OF INSECTS. orders, Coleoptera, Lepidoptera, Hymenoptera, Diptera, the majority of the Neuroptera, Coccus and Aleyrodes in Hemiptera, and the genus Pulex in A ptera,—I shall ad- vert to their characters, under several distinct heads; and to avoid unnecessary circumlocution, I shall in what fol- lows wholly leave out of consideration the frst division already explained, and use the term larve with reference only to those of the second. The heads under which I propose to treat of them are: The substance of their body, its parts, shape, oY figure, clothing, colour. Also the Economy or mode of life of these creatures: their food, moultings, growth, age, sex, and their preparations for as- suming the Pupe. i Substance. with the exception of the head and six fore-feet, which are usually corneous, the exterior inte- gument or skin of larvee is commonly of a membranous texture, and the body is of a much softer consistence than in the perfect insect. In those, however, of some Staphylinide and other Coleoptera, the dorsal part of the three first pieces, which represent the trunk of the perfect insect, is hard and horny. Some also have their whole skin coriaceous, as the tortoise-shell butterfly (Vanessa polychloros); and some few, as the wire-worm (Elater segetum), and other Elateres, very hard. I pos- sess a very remarkable larva from Brazil, from the ex- treme flatness of its body, and from its having cavities to receive its legs when unemployed, probably living under bark, the skin of which is still harder than that of the grub of the Elaters. Perhaps it has to resist great pressure ; and on that account is gifted with this quality, so seldom to be met with in other kinds of larva. The STATES OF INSECTS. 111 interior of the body of these animals is generally of a Softer consistence than in the perfect insect. Their in- testines, and other internal organs, are usually wrapped in a voluminous substance of a fatty nature, which is re- garded as analogous to the epiploon, omentum, or caul, which envelops the viscera of quadrupeds, &c., and is called by Reaumur the corps graisseux. The use of this general flexibility of larvæ is obvious; for, their bodies eing mostly long and narrow, a hard rigid covering Would have been very inconyenient, and a considerable pediment to their motions. When a caterpillar is feeding, it has occasion to apply its body to any part of : “margin of a leaf so as to support itself by its prolegs, and when moving it wants to give it all the curves that are hecessary to enable it to avoid obstacles, and thread tts way through the sinuous labyrinths which it must often traverse. On the other hand, the hardness of the Substance of its head affords a strong fulcrum to the Muscles which keep its powerful jaws in constant play. the larvee, indeed, of some Diptera have a membra- Nous head; but their mandibles, which serve also as “88, afe not grinders, but merely claws, the muscles of Which require less powerful support*. Under this head it may be proper to observe, that generally larve are “Paque; but some, as those of ants, and a few Lepido- Perad -are diaphanous. That of Corethra crystallina ‘pula De Geer) is so beautifully transparent as to re- _ * The lary: Imago at b æ described in the first Section, which resemble the > are usually covered with askin not materially different from of the insect in that state. uber Fourmis. 73; N. Dict. d’ Hist. Nat. vi. 250. 112 STATES OF INSECTS. semble a piece of crystal, and scarcely to be distinguished from the water in which it lives *. ii. Parts. The body of each larva consists of the head, including its different organs, and of the succeeding seg- ments, of which the three first may usually be denomi- nated the trunk, and have the six anterior feet, when present, attached to their under side: the remainder is the abdomen. The latter includes in some species a vari- able number of membranous feet, as well as various ap- pendages affixed usually to its tail and sides. No larva is ever furnished with wings’. Each of these greater divisions, and the organs which they include, require separate consideration. | 1. Head. This, as was lately observed, is exteriorly of a horny substance, or at least harder than the rest of the body, in most larvee; and on this account, though rarely separated from it by any visible distinct neck °, is, if the a Reaum. v. 40. é. vi. f. 4—15. b Müller, the Danish zoologist, relates, that he once met with a papilio which, with the true wings of the genus, had a head without antenne or tongue, furnished with mandibles; and, in short, that of a true caterpillar, It was a female, which deposited eggs that proved barren. If this solitary instance was not a mistake, is it possible that some parasitic larva had devoured only the inclosed head of the but- terfly, or so injured it that it could not reject the hard skin of the larva, and yet not be destroyed ? ¢ The only larva which havea visible distinct neck are those of some Dytisci, Staphylini, and a few others, in which this part is quite distinct : proving the erroneousness of the opinion of those German entomologists, who consider the thorax as analogous to the neck of other animals, and hence call it Halsschild. In some lepidopterous larvee, however, as in that of Pieris Brassieæ, though no visible neck presents itself, one is very perceptible when the insect stretches the head forward considerably. Reaum. i. 469. STATES OF INSECTS. 113 larva be of a tolerable size, distinguished at the first view. In those of many Dipterous insects, however, the head is “overed with the same flexible membranotis skin with the h of the body, from which it is often scarcely to be di- “Unguished. In these, except that it contains the organs ie Manducation, it wears no more the appearance of a fad than any other segment of the body, and scarcely so much as the last or anal one. The head of theselarvæ 'S also remarkable for another peculiarity,—that it is ca- le of being extended or contracted, and assuming dif- “ent forms at the will of the insect: a property which if head of no superior animal can boast. It is probable se there is a considerable variety in the shape and cir- a, of the heads a larvee; but since, with the èx- og ai those of Lepidoptera, they have had less at- Tay paid to them than they deserve (indeed in a vast er of cases, from the difficulty of meeting with them, “Se Variations, except in afew instances, have not been seribed), I will here mention a few of the most remark- “The head of the young larva at its first exclusion ess egg is usually the most dilated part of the body, oes not often continue so. In that of Cicindela ‘Ca ‘é ‘i u "Pestris, however,—-the beautiful green beetle some- Mes fo . ‘fro und in sandy banks,—and also in several cater- of Lepidoptera, it is much larger than any of the . _ 8 Segments?; which, in conjunction with the imal’, ; ““S formidable jaws, gives it a most ferocious ap- x In some lepidopterous larvæ the head is of Bien diameter with the rest of the bedy, but in in- S In general it may, I think, be stated as less; and a Prate XVII. Fic. 13. I K VOL, ry. 114 STATES OF INSECTS. occasionally it bears no proportion whatever to it. This is the case with the subcortical one from Brasil lately mentioned. It is more commonly longer than broad; but in some, as in the larvæ of carrion beetles (Silphæ)} the reverse of this takes place. Its shape varies from triangular to orbicular, the mouth of the animal forming the vertex of the triangle. In some larvæ of Hemerobils however, the head is narrowest behind. That of the grub of a gnat noticed above (Corethra crystallina) forms ® kind of sharp horn or claw, terminating the body ante riorly è. The contour of the head of larvee is usually intire and unbroken; but in the caterpillars of some Lepr doptera, as the butterfly called the grand admiral (Vi anesst Atalanta), the Glanville fritillary (Melitea Cinzia), KC it is divided into two lobes®. In the Brazil flat larve # is trilobed, each lateral lobe being divided into thre? smaller ones: in which circumstance it somewhat rese bles the head of some subcortical Cimicidæ. Althoug! the part we are treating of is generally without horns yet in some tropical butterflies of the tribe of Nymphal@ it is singularly armed with them. Thus Papilio Anchisé is distinguished, according to Madame Merian €, by two in the occiput, which it has the power of retracting. jo the purple highflier (Apatura Iris), a British species, the a Reaum. v. £ vif. 7. ic. v In fact, in almost all Lepidopterous larvæ the head may be e garded as divided into two lobes or eye-shaped portions, which w clude in the angle formed by their recession anteriorly from Gar other, the nasus (clypeus F.), the labrum, and other instruments `, manducation. Posteriorly these lobes generally come into: contat?! but I have a specimen in which there is a narrow space petwe? them. c Ins. Surinam. t. XV STATES OF INSECTS. 115 two lobes of the head, I am informed, terminate behind in two horns; as they do likewise in the brilliant Morpho enelaus*, the lobes assuming the form of a pear, and the horn representing the stalk. In a caterpillar I found “Mongst Mr, Francillon’s larvee, the head is bilobed, With a very long recurving subcapitate subramose spine. N Satyrus Cassie, the head is armed with three occipital Stout Spines>, The larva of Nymphalis Amphinome Latr, menitis F.) is crowned with a coronet of eight occipi- tal stout acute spines, the intermediate ones being the °ngest c; and that of Morpho Teucer has a similar coro- net, consisting of only seven blunt rays, seemingly, rather than Spines4, With regard to the articulation of the fad with the trunk, it is generally by its whole diame- T; but in some instances, only by a part of it. This is the ĉase with one of a sphinx figured by Mad. Merian €; wdy have another, probably belonging to the nocturnal Pidoptera (Phalena L.)f. In both these, the head is vertica] and triangular: and in the latter (which is a re- Markable creature, the tail itself being more like a head, wt furnished with what resemble two prominent: black “Yes) the vertex of the triangle is considerably higher than € back of the animal. Whatever may be the clothing of à € body, the head is usually naked. Sometimes, however, Tis itself beset with very small simple spines, as in the but- terfly of the mallow (Hesperia Malve); or with longer c mpound ones, such as are found on the rest of the body. | tns. Surinam, t tii. b Tbid. t. xxxii. © Ibid. t. viii. ta. £. xxii. © Tbid. t, xiv. be Purchased this singular caterpillar from the collection of the bs Saas Francillon, with his other exotic larvæ; but without any ton of the fly to which it belonged. P2 116 STATES OF INSECTS. his is the case with one of a butterfly named by Résel Papilio morsa. ‘The most common colour of the head of larvee, where it differs from the rest of the body, is # darker or lighter reddish brown, or piceous. This 18 particularly observable in those of Coleopterous insects but it is very commonly in other tribes of the same hue. Sometimes, amongst the Lepidoptera, the head is of 4 different colour from the rest of the body; especially where a contrast renders it striking. I can show the ca- terpillar of some insect, probably of the hawk-moth tribe (Sphingide), from Georgia, remarkable for the length of its anal spine, in which the body is black, and the head red: another has a white head and a brown body. Jn the larvee of some Lepidoptera, Coleoptera, and Diptera the head can be wholly or nearly withdrawn within the first segment of the body. This may be readily seen in that of the common glow-worm; and that of a small gnat (Tipula replicata De Geer) withdraws it so completely that the anterior margin of that segment closes the ort fice, so that the animal appears to have no head *.—~ The parts of the head which require distinct consider? tion are, the eyes, antenna, and the mouth: consisting of various organs, which will be specified. Some of thes? parts and organs are peculiar to larvæ of one ordet others to those of another, and some are furnished with ‘them all. Eyes. The larvae of many insects have no eyes. Thos with antennse which terminate in a lamellated_ cla? (Scarabeus L.), and capricorn beetles also (Cerambyx Le) a: De Geer vi. 352. \ STATES OF INSECTS. 117 amongst the Coleoptera, are without them, and probably several others; and amongst the Diptera, all those with à membranous or variable head. Those of the remain- ‘Ng orders, with the exception, perhaps, of some Hymen- Plera and Lepidoptera, are furnished with these organs; and in the Coleoptera all the predaceous tribes, as well aS most of those that are herbivorous or granivorous, ‘nd the Gnats and other Tipulidans ( Tipulariæ Latr.) in the Diptera, are also distinguished by them. In the lar- væ of the dragon-flies (Libellula L.), and other Neuro- Plera, they are composed of many facets as in those of the perfect insect, from which they differ chiefly in being maller, But in the other insects of this description they = Simple, and resemble those of the Arachnida, and any aptera. ‘These simple eyes vary in their number, ; different genera and tribes, from one to six on each “ide of the head. Thus the larva of Telephorus, and the “2W-flies, has only one ?; that of Cicindela three, the two Posterior ones being large with a red pupil surrounded y _* paler iris, which adds to the fierce aspect of this “tinal; and the anterior one very minute. Those «. the tortoise-beetles also (Cassida) have three»; of “aphylinus, Jour; of Timarcha (the bloody-nosed beetle) rs of Carabus, and the Lepidoptera in general, siv. ne last they are of different sizes, and generally a ged in a circle: in that of Hemerobius there are five in “Circle, with one central one °, The appearance of these p De Geer iv. 66. ii, 922, ene eer v, 170. larva ory says, he could not make out the number of eyes of the here are = re (Gyrinus): probably, as in that of Dytiscus, » Iv. 362. 385. r 118 STATES OF INSECTS. globules, which are often not visible but under a power- ful lens, is so different from that of the eyes of a butter- fly or moth, or other perfect insect, that it has been doubted whether they actually perform the office of eyes, but without reason. They occupy the usual station of those organs, being situated in many instances upon a protube- rance which appears to incase them; and seem of a con- struction closely analogous to that of the eyes of spiders, and the stemmata or ocelli of Hymenoptera, which have been satisfactorily proved to be organs of vision. In the larva of a moth not yet ascertained to exist in this coun- try, Attacus Tau, and probably other species, the eyes, after the skin has been changed a few times, are no longet to be seen *. Antenne. Most larvæ are provided with organs neat the base of the mandibles, which from their situation and figure may be regarded as antenna. Fabricius has as- serted that the larvee of the saw-flies (Zenthredo L.) have no antennze; but in this he was mistaken, for though very short, they are discoverable in them, as he might have learned by consulting De Geer”. In the majority of Neuropterous larvæ, they almost precisely resemble those of the perfect insect. In all the rest they are very different. The antennæ of Coleopterous larvae are ust” ally either filiform or setaceous, consisting of four or five joints, nearly equal in length. Those of Lepidopterow™ larvee are commonly conical, as are those likewise ° Chrysomela and Coccinella &c. amongst the Coleopter® and very short, composed of two or three joints, of which the last is much thinner than the first, and ends in one 0" a Poz. 188. "ii, 923, £ xxxvi. fi 4, bb: Fabr, Philos, Ent. 6° STATES. QF- INSECTS. 119 two hairs or bristles. These antenne the larva has the Power of protruding or retracting at pleasure. Lyonnet. Informs us, that the caterpillar of the great goat-moth (Cossus ligniperda) can draw the joints of its antennæ one within the other, so as nearly to conceal. the whole2. he larva of the common gnat has two long incurved se- 'aceous antennæ, fringed with hairs at some distance from their apex, which consist only of a single joint”, The Steater number of Dipterous larvae, however, all indeed. except the Tipulidans (Tipularie Latr.), and many be- mging to the Coleoptera and Hymenoptera orders (as %se of Curculio, Apion, Apis, &c.), are wholly deprived. antennse, It is'a general rule, that the antenne of “Ve are shorter than the same organs in the perfect in- sect, the tribe Ephemerina perhaps affording the only “Sample in which the reverse of this takes place $. Mouth. All larvæ have a mouth situated in the head, Y which they receive their food, and furnished with one °F more instruments for the purpose of mastication and ®glutition, These instruments, in all the orders except se ‘doptera, some Neuroptera and Diptera, bear a ge- “Stal resemblance to the same parts in the perfect insect. n larvæ of the Coleopterous, Lepidopterous, and Hy- "a orders, we ies catenin for the ats 0 Per and under lip; two pairs of jaws ans g © mandibulæ and maxillee; and two, four, or six pal- PLS: and some of these instruments may be found in aot Diptera, Fach of these parts require separate no- ice, Upper-tip (Lasrum). The mouth of almost all larver, : Lyonnet SA. daa ta) b De Geer vi. 307. ay bid. ji, lxvi Comp. f. 2 aa with fi 14 aa. nthe larva of Cicindela thereare six palpi, as im the perfect insect. 120 STATES OF INSECTS. except some of the order Diptera, are provided with a distinct upper-lip, for retaining their food during masti- cation. As the construction of this part does not widely differ from that of the perfect insect, which will hereafter be more fully described, it is only necessary to observe, that it is usually a transverse moveable plate, attached posteriorly to the nasus (clypeus F.), and situated just above the mandibles ?. Upper-jaws (Manprsuiz). The most usual figure of these, which are of a hard horny consistence ®, is that of two slightly concave, oblong, or triangular plates, often at their lower extremity of considerable thickness, and of very irregular form, the base of which is filled with powerful muscles, and planted: in the side of the mouth so as to move transversely. The other extremity can be made to meet or diverge like the claws of pincers, and are divided into one or more tooth-like indentations, by means of which the food of the larva is cut®. This i their construction in the larvee of all Lepidoptera, and iN many of those of the other orders. They frequently» however, assume a different form, though their situation is always the same. ‘Thus in the larvee of the capricor? beetles (Cerambyx L.) and of other wood-boring species they are shaped like the half of a cone, the inner sides of which, applying close to each other, form a pair of power- ful grindstones, capable of comminuting the hardest tim- a Lyonnet, t.i,f.7.£. In the larva of Callidium violaceum, how ever, this part is of a singular shape, being orbicular. Kirby Lin Trans. NE t. xi, f. 12. a. > It is affirmed (N, Dict. d’ Hist. Nat, vii. 333) that the larve of those Coleoptera that live in carcases have mandibles almost me!” branous : those, however, of that of Silpha rugosa are horny 2 hard. c Lyonnet, #. i. f. 1. D pv, and f. 2, 3, 4. STATES OF INSECTS. 121 bera, M. Cuvier has observed, with regard to the man- dibule of those of stag-beetles (Lucanus), that besides their teeth at the extremity, they have towards their base a flat striated molary surface; so that they both cut and rind their ligneous food». It seems to have escaped him, that a similar structure takes place in many perfect insects of the lamellicorn tribe, as I shall hereafter show you. In the larvee of the water-beetles (Dytiscus L.), “nt-lions ( Myrmeleon L.), and lace-winged flies ( Hemero- bius L.), they resemble somewhat the forceps at the tail of an ear-wig, being long and incurved; and, what is more remarkable, hollow and perforated at the end, so as’ to Serve as a channel for conveying into the larva’s mouth the juices of the prey which by their aid it has seized. Caumur even asserts, that. the larva of Myrmeleon has Ro other entrance into its throat than through these tu- bular mandibles*. That of the rove-beetles (Staphy- linus L.), and of many other Coleopterous genera, have these organs of this forcipate construction, without being Perforated¢, In the larva of the carnivorous flies, and Many other Diptera, are two black ‘incurved subulate Parts, connected at the base, and capable of being pro- truded out of, and retracted into, the head, through the skin of which they are usually visible. As I informed You in a former letter e these mandibles are used for ®alking as well as feeding: they are parallel to each other, and are neither formed for cutting nor grinding z Kirby in Linn, Trans. v. t. xii. f.7 6. Cuvier Anat. Comp. iii, 322. c Reaum. vi. 340. e larva of Cicindela campestris has mandibles of this descrip- Prats XVII, Fra. 13, c c. ° See above, Vox. II) 275—. tion. 122 STATES OF INSECTS, like the mandibles of other insects, but merely detach particles of food by digging into it and tearing the fibres asunder. In this operation they are probably assisted by an acutely triangular dart-like instrument of a horny sub- stance, which in some species (Musca vomitoria) is placed between the two. In others this part is wanting. Some Dipterous larvee have two similar mandibles, but in- stead of being parallel, they are placed one above the other; others (Musca domestica and meridiana) have but one such mandible, and some have no perceptible mandible of any kind. Themandiblesof thelarva of the crane-flies ( Tipula), which are transverse and unguiform, do not act against each other, but against two other fixed, internally con- cave and externally convex, and dentated pieces *. Under-jaws (Maxim). These are a pair of organs, usually of a softer consistence, placed immediately under the upper-jaws; but as they are usually so formed and si- tuated as not to have any action upon each other, it is probable that in general they rather assist in submitting the food to the action of the mandibulee, than in the com- minution of it. In Lepidopterous larvee they appear to be conical or cylindrical (at least in that of the cossus so admirably figured by Lyonnet >), and to consist of two joints; which may, I imagine, be analogous to the upper and lower portions of which the maxillee of perfect insects usually consist. The last of these joints is surmounted by two smaller jointed palpiform organs. If any part of the maxillee can act upon each other, it is these organs or palpi; but itis evident they are not calculated for mas- tication, although they may assist in the retention of the a Reaum. v.9. tif dce0h P Traité Anatom. t ii; f. len JI STATES OF INSECTS. 123 Substance to be masticated. In a figure given by Reau- mur of the under side of the head of another lepidopte- Tous larva (Hrminea Pomonella), the maxillse consist of a single joint, and appear to be crowned by chelate pal- Pi*: a circumstance which is also observable in that of a ‘Common species of stag-beetle (Lucanus parallelipipedus), the weevil of the water-hemlock (Lizus paraplecticus »), and other insects. In general the maxillee of larve are Without the lobe or lobes discoverable in those of most Perfect insects, this part being usually represented by a kind of nipple, or palpiform jointed process, strictly ana- gous to the-interior maxillary palpi of the predaceous Coleoptera; but in most of the lamellicorn beetles the lobe exists in its proper form $, as it does likewise in that of the capricorn-beetle before noticed (Callidium viola- feum*), Inthe former instance, itis armed with spines or claws; but in the latter it is unarmed, and rounded at the end, In the larva of Cicindela campestris, the base of the Maxilla runs in a transverse direction from the mentum, to which, as is usually the case, it is attached. From this at right angles proceeds the lobe, from the outer side of Which the feeler emerges; and the inner part terminates = an uncuiform joint, ending in two or three bristles. he structure in the larvee of water-beetles (Dytiscus L.) is different, for they appear to be without maxilla °; but the case really seems to be, that these organs are repre- ‘ented by the first joint of what M. Cuvier calls their Palpi® ; from which proceed the real palpi, the interior _ * Ream. iit 40. f. 4, b De Geer v. 229. ° Ibid. iv. z xl. f. 16. pp. € Linn. Trans, vet. xi. f. 10, i Cuvier Anat. Comp. iii. 323. b e Geer iv, £ xv. f. 9. 66. The exterior and interior palpi are oth represented in this figure. 124 STATES OF INSECTS. one being very short, and consisting only of a single joint. These maxillee of larvae were regarded by Reau- mur and other writers. as parts of the under-lip, on each side of which they are situated; and indeed, as well as those in the perfect insect, they form a part of the same machine, being connected by their base with the mentum, which is part of the labium, but they are clearly analo- gous to the maxilla of the imago. They are not to be found in the larve of many Dipterous insects, and per- haps in some species belonging to other orders. In some Neuropterous larvee, as those of the Lzbellulina MacLeay, the maxillæ are of a substance quite as solid and horny as the mandibles, which in every respect they resemble *, Under-lip (Lazium). Between the two maxille in the larvee of most of the insects under consideration is a part termed by Reaumur the middle division of the under-lip, but which is in fact analogous to the whole of that organ in the imago. ‘This organ varies in shape, being some- times quadrangular, often conical, &c. Interiorly it is frequently connected with a more fleshy protuberance, called the tongue by Reaumur >, and supplying the place of the ligula in the perfect insect. On each side of the apex of the under-lip is a minute feeler, and in the mid- dle between these in the Lepidoptera and many others, is a filiform organ, which I shall call the spinneret (Fusulus), through which the larva draws the silken thread em- ployed in fabricating its cocoon, preparatory to assuming the pupa state, and for other purposes*®. This organ is a Reaum. vi. t. xxxvii. f. 5. e e. b Thid.i. 125. c Prats XXI. Fic. 9. The organ with which the larvee of Heme- robius, Myrmeleon, and Hydrophilus, spin their cocoons, is situated in the anus. The spinneret of the Cossus is figured by Lyonnet Ana- tom. t. ii. f. 1.1, and fig. 9. STATES OF INSECTS. 125 found only in those larvee which have the power of spin- hing silk; that is, in all Lepidoptera, most Hymenoptera, Trichoptera, some Neuroptera, and even a Dipterous in- secta, This tube, Lyonnet had reason to believe, is com- Posed of longitudinal slips, alternately corneous and mem- branous, so as to give the insect the power of contracting lts diameter, and thus making the thread thicker or Smaller, There is only a single orifice at the end, which 'S cut obliquely, somewhat like a pen, only with less obli- Wity, and without a point, the opening being below, so aS to be conveniently applicable to the bodies on which the larva is placed. Reaumur conceived that this spin- neret had two orifices; but Lyonnet ascertained this to ĉa mistake, the two silk tubes uniting into one before they reach the orifice. From the contractile nature of the sides and the form of the orifice, combined with the Power the insect has of moving it in every direction, re- sults the great difference which we see in the breadth and orm of the threads, some being seven or eight times as $ dick as others, some cylindrical, others flat, others chan- helled, and others of different thickness in different parts». n the larvee of many Diptera the under-lip is merely a Small tubercle, which can be protruded fromthe insects Mouth by pressure €. ne of the most remarkable prepensile instruments, in Which the art and skill of a Divine MECHANICIAN are singularly conspicuous, and which appears to be without * parallel in the insect world, may be seen in the under- 'P of the various species of dragon-fly (Libellula L.). In a l ha De Geer vi. 370. This species (Tipula Agarici seticornis De Geer) aS ; à two separate spinnerets. £, xx. f. 8. mm, 4yonnet 55—, © Reaum. iv. 166, 126 STATES OF INSECTS, other larvee this part is usually small and inconspicuous, and serves merely for retaining the food and assisting in its deglutition; but in these it is by far the largest organ of the mouth, which when closed it entirely conceals ; and it not only retains but actually seizes the animal’s prey, by means of a very singular pair of jaws with which it is furnished. Conceive your under-lip (to have re- course, as Reaumur on another occasion *, to such com- parison, ) to be horny instead of fleshy, and to be elon- gated perpendicularly downwards, so as to wrap over your chin and extend to its bottom,—that this elongation is there expanded into a triangular convex plate‘, at- tached to it by a joint 4, so as to bend upwards again and fold over the face as high as the nose, concealing not only the chin and the first-mentioned elongation, but the mouth and part of the cheeks *: conceive, moreover, that to the end of this last-mentioned plate are fixed two other convex ones, so broad as to cover the whole nose and temples ‘,—that these can open at pleasure, transversely like a pair of jaws, so as to expose the nose and mouth, and that their inner edges where they meet are cut into numerous sharp teeth or spines, or armed with one oF - more long and sharp claws § :—you will then have as ac- curate an idea as my powers of description can give, of the strange conformation of the under-lip in the larvae of the tribes of Libellulina ; which conceals the mouth and face precisely as I have supposed a similar construction of your lip would do. yours. You will probably admit a Reaum. v. 155. » Ibid, vi. £ xxxvii. f. 7.59. © Ibid. mee. a Thid. f. 6. p. e Ibid. Compare f. 4 with f. 6, 7. f Tbid. £. xxxvi. f. 12. s ue ¢ Ibid. n e, and xxxvii, f. 7, dc,; De Geer ii. t. xix. f. 17. d g. STATES OF INSECTS. 127 that your own visage would present an appearance not very “ngaging while concealed by such a mask; but it would Strike still more awe into the spectators, were they to see You first open the two upper jaw-like plates, which would Project from each temple like the blinders of a horse; ‘nd next, having by means of the joint at your chin let own the whole apparatus and uncovered your face, em- Ploy them in seizing any food that presented itself, and “onveying it to your mouth. Yet this procedure is that adopted by the larvee provided with this strange organ. hile it is at rest, it applies close to and covers the face. hen the insects would make use of it, they unfold it ike an arm, catch the prey at which they aim by means of the mandibuliform plates, and then partly refold it so as to hold the prey to the mouth in a convenient position Or the operation of the two pairs of jaws with which they We provided. Reaumur once found one of them thus olding and devouring alarge tadpole;—a sufficient proof that Swammerdam was greatly deceived in imagining “arth to be the food of animals so tremendously armed. and fitted for carnivorous purposes. Such an under-lip as Ihave described is found in the tribe of dragon-flies (Libellulina); varied, however, considerably in its figure u the different genera. In the larva of Libellula Fab., Such as Libellula depressa, &c. it is of the shape above “scribed ; so exactly resembling a mask, that if Ento- Mologists ever went to masquerades, they could not more effectually relieve the insipidity of such amusements and attract the attention of the demoiselles, than by appearing at the supper table with a mask of this construction, and Serving themselves by its assistance. It would be difficult, to be sure, by mechanism to supply the place of the mus- 128 STATES OF INSECTS. cles with which in the insect it is amply provided; but Merlin, or his successor, has surmounted greater obsta- cles. In the larva of the Fabrician Zishne (Libellula grandis, &c. L.), this apparatus is not convex but flat: so that, though it equally conceals the face, it does not so accurately resemble a mask; and the jaws at its apex are not convex plates, but rather two single conical teeth *. It is, as to its general shape, similarly constructed in Agrion Fab. (L. Virgo, &c. L.); but the first joint is more remarkably elongated, the jaws more precisely re- semble jaws than in any of the rest, and are armed with three long, very sharp teeth: between them also there is a lozenge-shaped opening, through which, when the ap- paratus is closed, is protruded a circular sort of nipple, apparently analogous to the ligula®. Libellula enea, L., which is the type of another tribe (Cordulia Leach), has amask somewhat different from all the above, the jaws be- ing armed with a moveable claw and an internal tooth °. You will admire the wisdom of this admirable contri- vance, when you reflect that these larvee are not fitted to pursue their prey with rapidity, like most predaceous animals; but that they steal upon them, as De Geer ob- serves 4, asa cat does upon a bird, very slowly, and as if they counted their steps; and then, by a sudden evolu- tion of this machine, take them as it were by surprise, when they think themselves safe. De Geer says, it is very difficult for other insects to elude their attacks, and that he has even seen them devour very small fishes e, a Reaum. vi. ¢. xxxvii. f. 4—6. 8. b Ibid. ¢. xxxviii. First joint f. 8. bf p.; jaws f. " c d.; opening 0, Ligula f. 6. l. ¢ De Geer i. f. 17. Jaws gg; claw d; tooth A. 4 Ibid. 674. e Ibid. ii. 674. i STATES OF INSECTS, = As these animals are found in almost every ditch, you Will doubtless lose no time in examining for yourself an instance of so singular a construction. — Feelers (Parri). In the orders Diptera and Hymeno- Plera are many Jarvee in which these organs. have not fen certainly discovered; yet Reaumur in that of a com- Mon fly (M. meridiana L.) found four retractile nipples 3 Which seem analogous to them; and Latreille has ob- | thay below? thie niandibles of those of ants are minute points, two on each side®: but in all other “I've their existence is more clearly ascertained. The "arillary palpi vary in number, many having żwo on “ach maxilla and others only one. In the perfect insect © former is one of the distinguishing characters of the Predaceous beetles (Zintomophagi Latr.), but in the larvae tis More widely extended; since even in the caterpillars Lepidoptera the inner lobe of the maxilla which re- Presents this feeler is jointed, which is precisely the case “ith the beetles just named. Cuvier has cbserved this teumstance in the larva of the stag-beetle °; and it be- longs to many other Coleoptera that have only a pair of Maxillary palpi in the perfect state. The Zabial palpi are always two, emerging usually one on each side from the apex of the under-lip. With regard to the form of the api, those of the Lepidoptera are mostly conical; in tbair Orders they are sometimes setaceous and some- times filiform, Their termination is generally simple, i Sometimes the last joint is divided. They are for the Most part very short, and the labial shorter than the a . Reaum, iv, 376. o N. Dict. d Hist. Nat. xii. 64. z ase nat. Comp, iii, 322, K 130 STATES OF INSECTS. maxillary. The latter never exceed four joints *, which seems the most natural number; and the former are limit- ed to three. Both vary between these numbers, and onl joint. The joints, though commonly simple, are sometimes branched. This is the case with one I met with in con siderable numbers upon the Turnip, in October 1808; the second joint of the palpi of which sends forth nea¥ fhe apex an internal branch. In the larva of the Coss as Lyonnet informs us, the joints of the palpi are re- tractile, so that the whole of the organ may be nearly withdrawn. After thus describing the head of larvæ; and its priv cipal organs, we must next say something upon the re? mainder of the body, or what constitutes the 2, Trunk and Abdomen: which I shall consider unde! one article. These are composed of several segments oF rings, to which the feet and other appendages of the body are fixed. ‘The form of these segments, or that 0 their vertical section, varies considerably: in many Lep? ‘doptera, the wire-worm, &e., it would be nearly circulati in others a greater or less segment of a circle would rë present it; and in some, perhaps, it would consist of tw? such segments applied together. Their lower surface 1 generally nearly plane. Their most natural nambers without the head and including the anal segment, is twelve: this they seldom exceed, and perhaps nev? fourteen, The three first segments are those whieh ye a At first in the Dytisci they appear to have five joints; but, as J before observed, the first jomt must be regarded as representing the maxilla.. : b Lyonnet Anatom. 55, 58. STATES OF INSECTS. es 131 Present the zrunk of the perfect insect, and-to which the ‘IX anterior legs when present are affixed. In general, they differ from the remaining segments only in being Shorter, and in many cases less distinctly characterized; ut in Neuropterous larvæ, those of Dytisci, and some other Coleoptera, they are longer than the succeeding Ones, and pretty nearly resemble the trunk of the animal m its last state. The surface of the trunk and abdomen Will be considered under a subsequent head; I shall not, ‘ Srefore, describe it here. The conformation of the dif. “rent segments varies but little, except of the terminal “he; or tail, which in different larvee takes various figures. a most, this part is obtuse and rounded; in others acute - ®t acuminate; in others truncate; and in others emargi- Nate, or with a wider sinus, and with intermediate modifi- “ations of shape which it would be endless to particularize. S Some, also, it is simple and unarmed; in others be- Set with horns, spines, radii, and tubercles of different Orms, some of which will come under future considera- ‘on. The parts connected with the trunk and abdo- Men which will require separate consideration, are the “88; the spiracles, and various appendages. Legs. It may be stated generally that the larvæ of the orders Coleoptera, Lepidoptera, and Neuroptera, have “883 and that those of the orders Hymenoptera and Di- Plera have none. This must be understood, however, “ith some exceptions. Thus the larvee of some Coleo- Plera, ag the weevil tribes (Curculio L.) have no legs, un- “88 We May call by that name certain fleshy tubercles be- “Meared with gluten, which assist them in their motions? ; * De Geer v. 203: Te 132 STATES OF INSECTS. while those of Tenthredo and Sirex in the order Hymen- optera are furnished with these organs. At present I know no Dipterous larva that may be said to have real legs, unless we are to regard as such certain tentacula formed upon a different model from the legs of other lar- ya, Résel has, I think, figured a Lepidopterous apode- No Neuropterous one has yet been discovered. The legs of larvee are of two kinds; either horny and composed of joints, or fleshy and without joints>. The first of these, as 1 observed in a former letter‘, are the principal instruments of locomotion, and the last are to be regarded chiefly as props and stays by which the ani- mal keeps its long body from trailing, or by which it takes hold of surfaces; while the other legs, or where there are none, the annuli of its body, regulate its mo- tions. The former have been commonly called true legs (pedes veri), because they are persistent, being found in the perfect insect as well as in the larva; and the latter spurious legs (pedes spurit), because they are caducous, being. found in the larva only. Instead of these not very appropriate: names, I shall employ for the former the simple term Jegs, and for the latter prolegs (propedes) 13) The legs, when present, are always in number sis, and attached by pairs to the underside of the three first seg- ments of the trunk. They are of a horny substance, and consist usually of the same parts as those of the perfect a De Geer iv. 5. Legs of this kind are figured PLATE XXII. Fie. 7. » In the larva, however, of Sialis, or some kindred genus, in which» like those of Scolopendra, the prolegs are jointed, a pair distinguishes each abdominal segment. See Reaum. iv. t. xv. f. 1,2. Compare De Geer ii. t. xxiii. f. 11. e See above, Vor. H 286—. l a Ibid, 288, STATES OF INSECTS. 138 Msect; namely, coxa, trochanter, femur, tibia, and tarsus, Suspended to each other by membranous ligaments: these Parts are less distinctly marked in some than in others. Thus in the legs of a caterpillar, or the grub of a capri- “orn-beetle, at first you would think there were only three or four joints besides the claw; but upon a nearer inspec- tion, you would discover at the base of the leg the rudi- ments of two others 2, in the latter represented indeed by the fleshy protuberance from which the legs emerge. n the larvee of the predaceous Coleoptera, the hip and trochanter are as conspicuous nearly as in the perfect "sect; and the tarsus, which still consists of only a sin- gle joint, is armed with two claws’. In those of the “uroptera order, in which all the joints are very con- ‘Picuous, the tarsi are jointed, as well as two-clawed €. he legs of larvee are usually shorter than those of the Perfect insect, and scarcely differ from each other in Shape, for they all gradually decrease in diameter from ih base to the apex. This is the most usual conforma- ‘ON of them in Lepidopterous, Hymenopterous, and Some: Coleopterous larvee, (those of the capricorn-beetles = very short and minute, so as to be scarcely visible,) m which they are so small as to be concealed by the body °F the insect 4, In Neuropterous larvae, however, and so Ly onnet Anatom. t. iii. f. 8. Coxas. Trochanier c., Femur d. Ti- E. Tarsus r, Claw c. : i Geer iv. #, xiii. f. 20; and £. xv. f.16. id, ii. z. xvi. f. 5,6, 7. d e: and t xix. f. 4. e f g h. he larva of a scarce moth (Stauropus Fagi. See Prate XIX. I i i ; S. 4) is an exception to this. The first pair of its legs are of the Otdinam, e Mary Stature, but the two next are remarkably long, and so thin ang A 3 E i Weak as to be unable to bear the body. Pezold. 119. Another ute Caterpillar described by Reaumur has the third pair of the 134: STATES OF INSECTS. several Coleoptera, as those of Dytiscus, Staphylinus; Coc- cinella, &c., they more resemble the legs of the perfect insect, the joints being more elongated, and the femoral one projecting beyond the body +. You will find no other than true legs in most Coleo- pterous, Neuropterous, and Hymenopterous larve. But those of the saw-flies (Tenthredo L.), and all caterpillars, have besides a number of prolegs : a few Dipterous larve also, are provided with some organs nearly analogous to them. These prolegs are fleshy, commonly conical of cylindrical, and sometimes retractile protuberances, usu- ally attached by pairs to the underside of that part of the body that represents the abdomen of the future fly ”- They vary in conformation and in number; some having but one, others as many as eighteen. | With regard to their conformation, they may be di- vided into two principal sections: first, those furnished with terminal claws; and secondly, those deprived of them. Each of which may be divided into smaller sec- tions, founded on the general figure of the prolegs, and arrangement of the claws or hooks. legs apparently fleshy and singularly incrassated at the apex into @ pyriform figure, terminated by a pair of claws. This conformation is for some particular purpose in the economy of the animal, since they are the most busily employed of all in arranging the threads of her web. Reaum. ii. 258. In the larva of a geometer (Geometra lu- naria) the third pair are remarkably long. Illig, Mag. 402. In that of another moth, according to Kuhn (Naturf. xvi. 78. t. iv. f. 3), the third pair of the fore-legs is remarkably incrassated, being twice a thick and long as the other pair, though consisting of the same num- ber of joints, the last of which has claws. a On the legs and prolegs see also what is said above, Vor. I- p. 286—. t In some few instances these legs are dorsal. Ibid, 281. STATES OF INSECTS. 135 i, The prolegs of almost all Lepidopterous larvee are furnished with a set of minute slender horny hooks, crot- chets, or claws, of different lengths, somewhat resem- bling fish-hooks; which either partially or wholly sur- round the apex like a pallisade. By means of these Claws, of which there are from forty to sixty in each Proleg, a short and a long one arranged alternately, the Msect is enabled to cling to smooth surfaces, to grasp the smallest twigs to which the legs could not possibly -@dhere: a circumstance which the flexible nature of the prolegs greatly facilitates*. Claws nearly similar “te found on the prolegs of some Diptcrous larvæ?, but Rot in any of those of the other orders. These last, how- “ver, are seldom either so numerous, or arranged in ‘he same manner, as in caterpillars. When the sole of the foot is open, the claws with which it is more or less Surrounded are turned outwards, and are in a situation j lay hold of any surface; but when the animal wishes to let go its hold, it begins to draw in the skin of the sole, , rhe claws or crotchets, though general, are not universal, in Lepidopterous larvæ. An exception is furnished to the rule by the “gular limaciform ones of Hepialus Testudo and Asellus of Fabricius, © moths forming Haworth’s genus Apoda, which have no distinct Prolegs, but in their stead a number of small transparent shining tu- *tcles without claws. The larva also of one of the subcutaneous Moths first discovered by De Geer in the leaves of the rose (i. 446), °t Whose history is fully given by Goeze, Naturf. xv. 37—48, (who i satisfactorily ascertained that it is the true larva of a Tinea of mé, but of a different habit from that of most subcutaneous ones), ot NO true legs, and eighteen prolegs without any claws. ‘Another Cutaneous larva, for the history of which we are indebted to of Godeheu de Riville, is according to him entirely deprived of legs >. “ay kind (Bonnet ix. 196—.); as is another of the same tribe that eeds ee sage Ese te on the poplar, an account of which is given by Goeze Natuzfe Xv ~ "105. v Prare XXIV. Fic. 7. See also below, p. 137. 136 STATES OF INSECTS. and in proportion as this is retracted, the claws turn their points inwards, so as not to impede its motion *. The prolegs with claws may be further divided into four different kinds. 1. In the larvae of the great majority of butterflies and moths they assume the form of a truncated cones the lower and smaller end of which is expanded into 4 semicircular or subtriangular plate, having the inner half of its circumference beset with the claws above men- tioned; and, from its great power of dilating and con- tracting, admirably adapted for performing the offices of 5 and a foot. Jungius calls these legs pedes elephantini»; the term is not altogether inapplicable, since they exhibit considerable resemblance to the. clumsy but accommo- dating leg and foot of the gigantic animal he alludes to. ' 2. The larve of many minute moths, particularly of the Fabrician genera Tortrix and Tinea—those which. live in convoluted leaves, the interior of fruits, &c., as well as the Cossus, and some other large moths,—haye their prolegs of a form not very unlike those of the preceding class, but shorter, and without any terminal expansion; the apex, moreover, is wholly, instead of half, surround- ed with claws‘®; the additional provision of which, to- gether with a centrical kind of nipple capable of being protruded or retracted, in some measure, though imper- fectly, supplies the place of the more flexible plate-like expansion present in the first class. 3. The third class is composed of a very few Lepido- pterous larvee which have their prolegs very thick and conical at the base, but afterwards remarkably slender; a Lyonnet Anatom, 84. t. ii. f 11, 12. v Hist, Vermium, 130. e Prare XNUL Fie. 1, STATES OF INSECTS. 137 long, and cylindrical, so‘as exactly to assume the shape of a wooden’ leg?. These, as in the first class, are ex- Panded at the end into a flat plate: but this is wholly cir- Cular, is surrounded with claws, and has also in the mid- dle a retractile nipple, as in the preceding class. In Cossus, at least in an American species (Cossus Robinia), described by Professor Peck », the anal prolegs have the Claws -only on their eater ior half 4. The remaining description of unguiferous prelivis if they may not rather be deemed a kind of tentacula, We those of certain Diptera, provided with no true legs; Which differ from the three preceding classes, either in their shape, or the arrangement of their claws. -In ne kind of those remarkable larvae, which from their. mg respiratory anal tubes Reaumur denominates “ raf-. tailed” that of Elophilus pendulus, there are fourteen of these prolegs, affixed by pairs to the ventral segments, the twelve posterior ones of which are subconical, and- ttuncate at the apex, which is surrounded with two cir- c les of very minute claws, those of the inner being much More numerous and shorter than those of the exterior Mle; while the anterior pair terminate in a flat expan-> ‘ion, and in shape almost exactly resemble those of a mole“. he Prolegs of the larvae of a kind of gnat called by © Geer Tipula amphibia, and of Syrphus mystaceus F., Musca plumata De Geer,) are nearly of a similar con- > struction, but in the last are armed with three claws Only d See s lya, Long moveable claws also distinguish the sin- * Prats XXII, Fic. 17. > Account of Locust-tree Insects, 69. © Reaum. iv, 443, (. xxx. f.6. 71 t xxi. f. 6.00, * De Geer yi, 383. and 137. f, viii. /. 8, 9. 138 STATES OF INSECTS. gular prolegs before described * of another gnat (Tany- pus maculatus Meig., Tipula De Geer). ‘The case-worms (Trichoptera K.) and some others, have two prolegs at the anus, each furnished with a single claw >. ii. The prolegs deprived of claws are found in the larva of the Hymenopterous tribe of saw-flies (Tenthredo L.), in those of some Lepidoptera (Hepialus F. &e.), and in some few Coleopterous and Dipterous genera. Those of the former are of the shape of a truncated cone, and resemble the second class of unguiculate prolegs, except in the defect of claws. In the latter they are a mere re- tractile nipple-like protuberance, in some species so small as scarcely to be perceptible. In all they aid in progres- sive motion; but it is by laying hold of surfaces, and se enabling the body more readily to push itself forward by annular contraction and dilatation, and not by taking steps, of which all prolegs are incapable: to assist in this purpose the protuberance sometimes secretes a gluten “s which supplies the place of claws. Some larvee have the power of voluntarily dilating certain portions of the un- derside of their body, so as to assume nearly the shape and to perform the functions of prolegs. In a Coleopte- rous (?) subcortical one from Brazil, before alluded. to, there are four round and nearly flat areas in each ventral segment of the abdomen, but the last very little raised above the surface, and rough, somewhat like a file; and besides these, the base of the anal segment has ten of these little rough spaces, but of a different shape, being nearly linear, placed in a double series, five on each side Doubtless these may be regarded as a kind of prolegs a See above, Vor. II. p. 278. De Geer ubi supr. 376. > Reaum. iv. 184, ż xv. f. 12. € e. c De Geer v. 203. STATES OF INSECTS; 139- Which enable the animal to push itself along between the bark and the wood?. In considering, in the next place, the sunber and si- tuation of the prolegs, it will contribute to distinctness to advert to these circumstances as they occur in the diffe- tent orders furnished with these organs. To begin with the Lepédoptera.—Lepidopterous larvee Nave either ten, eight, six, or two prolegs, seldom more», and never fewer. Of these, with a very few exceptions, two are attached to the last or anal, and the rest, when Present, to one or more of the sixth, seventh, eighth, and ninth segments of the body: none are ever found on the fourth, fifth, tenth, or eleventh segments. l. Where zen prolegs are present, as isthe case in by far the greatest proportion of Lepidopterous larvæ, there x Constantly an anal pair, and a pair on each of the four termediate segments just mentioned. i 2. In caterpillars, which like those of a few species of the genera Sphinx, Pyralis, and of the Bombycida, &c. We eight legs, they are placed in three different ways. In “Ose which have an anal pair, the remaining six are in we fixed to the sixth, seventh, and eighth; in others, to ae seventh, eighth, and ninth segments. In those which, xe Cerura Vinula, and several other species of the same family, have no anal prolegs; the whole eight ne from the sixth, seventh, eighth, and ninth seg-. ents. 3. The Hemigeometers, as Noctua Gamma, &c. have ; See above, p. 110, 114. iad) a few subcutaneous larvae have more, as that, before men- cighteon served by De Geer in the leaves of the rose; which has prolegs, and no true ones. 14.0 STATES OF INSECTS. only six legs: namely, an anal pair, and two ventral ones, situated on the eighth and ninth segments. 4, The larvæ of the Geometers (Geometre F.) have but four prolegs ; of which two are anal, and two spring from the ninth segment. It should be observed, how- ever, that the larvee of Hemigeometers, and even of some of those that haveten prolegs, where the four anterior ones are much shorter than the rest, move in the same way a5 the Geometers. This even prevails in a few where these organs are all of equal length. 5. Many of the larvee of Tinea L. which live in the in- terior of fruits, seeds, &c., have but one pair of prolegs, ves are attached to the anal segment. . The larvæ of Haworth’s genus Apoda (Hepialus hin and Asellus F.), remarkable for their slug-like shape and appearance, move by the aid of two lateral longitudinal pustule-like protuberances, which leave a trace of a gummy slime in their course. Hymenoptera.—The larvæ of the different tribes of Tenthredo L., almost the only Hymenopterous insects in which prolegs are present, have a variable number of these organs; some sixteen, as the saw-fly of the willow (T. lu- tea L), and this is the most numerous tribe of them, in- cluding the modern genera, Cimbex F., Pterophorus, Xe Others have fourteen, as that of the cherry (T. cerasi L.); and many others with only nine joints to their antenne: _ A third class have only twelve, as that of the rose (7. Ro- sæ L.), but this contains but few species. The last class contains those that have no prolegs at all, but only the six horny ones appended to the trunk. Of this tribe, the caterpillars of which have a very different aspect from the preceding, are those of the genus Lyda F. (T. ery- STATES OF INSECTS, 144 hrocephala L.)*. Two of the prolegs are anal, and the’ ead intermediate, and none are furnished with claws. üis circumstance, in conjunction with the greater num- ber of prolegs, except in the case of Lyda, will always Serve as a mark to distinguish these fausses chenilles, as the French call the larvæ of saw-flies, from true caterpil-. “rs. The dorsal prolegs of a species of Cynips described: Y Reaumur have been before noticed. . Coleoptera.—The larvee of insects of this order are so’ itle known or attended to, that no very accurate gene- talization of them in this respect is practicable. Many of “m, in addition to their six horny legs, have a proleg Wike anus; which in many cases appears to be the last Segment of the abdomen, forming an obtuse angle with € remainder of it, so as to support that part of the body, agoan it from trailing; and in some instances, as ‘rysomela Populi, a common beetle, secreting a slimy Matter to fix itself. In the larvæ of Staphylinidæ this Proleg is very long and cylindrical; in that of Cicin- Se it is shorter, and in shape a truncated cone rather Pressed; it is very short, also, in those of the Silphe th : ; i at I have seen. In the wire-worm (Elater Segetum) it 5 a minut : e retractile tubercle, placed in a nearly semi- “cular space, shut in by the last dorsal segment, which e A aie omes also ventral at the anus. This space is in fact a clas we ee ii. #. xl. f. 15, 16. Bergman has added to these four. Which 3 the larvæ of saw-flies, a fifth; the insects belonging to R as i. affirms, though they have sicbech prolegs, are without the With — Ibid. 931. But as neither De Geer nor Reaumur ever met: of this description, it is probable he was mistaken. Reaumur seen one with eighteen prolegs upon Erysimum alli ; but he does not speak positively. € Geer v, 285, 142 STATES OF INSECTS. the last ventral segment. This seems characteristic of the genus*. From the underside of the body of the common meal-worm (Tenebrio Molitor), at the junction of the two last segments, when the animal walks, there issues a fleshy part, furnished below with two rather hard; long, and moveable pediform pieces, which the animal uses in walking>. In the larva of another beetle, whose ravages have been before noticed, under the name of the cadelle* ( Trogosita mauritanica), a pair of prolegs are — said to be found under the anal segment; and in that of the bloody-nose beetle ( Timarcha tenebricosa), that seg- ment is bifid. That of the weevil of the common water- hemlock (Lixus paraplecticus F.) exhibits a singular ano“ maly: prolegs occupy the usual station of the true legs, being attached to the three segments representing the trunk 4. This insect, however, does not appear to use them in moving. A pair in each of the twelve segments of the body are found in the grub of another weevil (Hypera Rumicis Germ.), the nine last pair being the shortest, which all assist the insect in walking *. But the greatest number of prolegs is to be found in the Brazil subcortical larva lately mentioned. Besides the six horny legs of the trunk, this remarkable animal has four pro legs on each of the seven intermediate abdominal seg- ments, and five on each side of the base of the last, making the whole number of prolegs, if so they may be called, amount to forty-four: a far greater numbe! than is to be found in any larva at present known, Whe® I wrote to you upon the motions of insects, I informed * De Geer iv. 157. > Ibid. v. 36, 4. iif 12. ¢ See above, Vor. I. p: 171. 4 De Geer v. 228. e Ibid. 233. STATES OF INSECTS. 143 you that some larvae moved by means of legs upon their backa, but I was not then aware that any were furnished With them both on the back and the belly at the same time, By the kindness of Mr. Joseph Sparshall of Nor- Wich, a very ardent and indefatigable entomologist, I am ™ possession: of the larva of Rhagium fasciatum, a timber- feeding beetle. This animal on the ten intermediate seg- ments of the underside of the body, which in the centre fom a fleshy protuberance, has on it a double series of *asps, as it were, consisting each of two rows of oblique blong prominences; and on the seven intermediate dor- Sal segments there are also in the centre seven rasps of Tee or four rows each, of similar prominences: so that this animal at the same time ean push itself along both by *rsal and ventral prolegs. It is worthy of observation, that a pair of these rasps is between the second and third Pair of true legs. : Diptera.—The larva of a little gnat, Tipula stercora- ria De Geer? (Chironomus Meig.?), drags itself along by © assistance of a single tubercle, placed on the under~ Side of the first segment of the body, which the animal as the power of lengthening or contracting ®. That of Mother beautiful Chironomus (C. plumosus), remarkable r the feathered antennæ of the male‘, has zwo short Prolegs, or pediform but not retractile tentacula in the ‘ame situation €. Others, as that of Tanypus maculatus, * See above, Vor. II. p. 281. > De Geer vi. 388, ° Ibid. 389, è Reaum. v. £ v. f. 10. ° Ibid. 31, This larva has also a pair of pediform processes at the anns, surrounded at the end with claws (¢. v. f. 4, 5, s s), which he : w the animal use in locomotion; but which he suspects to be re- ‘Pitatory organs (Ibid: 33), which Latreille asserts they are. Gen. “tust, et Ing, iv. 249, | | 144 STATES OF INSECTS. &c. have two pairs, one attached to the anal and the other to the first segment*. Tipula amphibia De Geet in this state has ten prolegs, placed by pairs on the fourth, fifth, eighth, ninth, and tenth dorsal segments °; and Sceeva Pyrastri F., one of the aphidivorous flies, has not fewer than forty-two, arranged in a sextuple series, seven in each row °. It may not be useless to close this long description of the legs of larvee with a tabular view of them, founded chiefly upon these organs; which afford very obvious — marks of distinction. I. Larvee without legs. i. With a corneous head of determinate shape (co- leopterous and hymenopterous apods—Culicid@, some Tipulide, &c. amongst the Diptera). ii, With a membranaceous head of indeterminate shape (Muscide, Syrphide, and other Diptera). II. Larvee with legs. | i. With legs only, and with or without an anal pro- leg (Neuroptera, and many Coleoptera). 1. Joints short and conical (Elater, Cerambyci- = da, &c.). 2. Joints long and subfiliform (Staphylinus, Coccinella, Cicindela, &c.). ii. Prolegs only (many Tipulide, and some subcu- taneous Lepidopterous larvae, Xc.). iii. Both legs and prolegs (Lepidoptera, Tenthredi- nidæ, and some Coleoptera). 1. Without claws ( Tenthredinidæe, &c.). 2. With claws (Lepidoptera, &c.). @ De Geer Ibid. ż. xxiv. f. 15—17, b Ibid. 383. € Thid. 111. £ vi. f. 14—16. STATES OF INSECTS. 145 I should next say something upon the spiracles, or breathing-pores, or any other external apparatus for the Purpose of respiration, in larvee; but I think it will be best to reserve the consideration of these for a subsequent etter. We will therefore conclude this detailed de- Scription of their parts in their first state, with some ac- Count of their other > Wyre iii, Appendages. The generality of larvee have no other &Xternal organs than those already described ; but in se- Vera] and of them we observe various kinds of retractile ones others—protuberances—horn-like processes—rays, | “€.3 which, though not properly coming either under aay of the above parts, or under the clothing of these animals, yet require to be noticed. Upon these I shall ow enlarge a little, *0u must have observed upon the back of the last seg- nent but one of the caterpillar of the silk-worm a horn- Ke Process, rising at first nearly perpendicularly, and : a bending forward. A similar horn, though confined 2 the genus Bombyx to the silk-worm and a few others,’ a May believe Madame Merian, who, however, often “SS great mistakes, is found in the beautiful caterpillar one of the largest and finest moths that we know rebus Strix 2), the glory of the Noctuidæ, and in most y those of the hawk-moths (Sphinæ F.) [S. Porcellus, Vi~ S and a few others excepted; in some of which, as se brusce, &c., this anal horn is replaced by a gibbor eae im others, as S. Ginothere, by a callous eye-like ] in the same situation, but much longer °, and : Merian Ins. Sur. t. xx. b Ibid. t. xxxiv. * le a caterpillar, l believe from Georgia, in which this hors 1 inch long, filiform, slender, and tortuous. VOL, ry, i 146 STATES OF INSECTS. commonly curving backwards over the tail*. Some- times, however, as in S. ocellata and S. Stellatarum, itis perfectly straight. These organs towards the apex arè horny, and often end in a sharp point; nearer the base they are fleshy. They are without any true joint, yet the insect can elevate or depress them at pleasure. Un- der alens, they usually appear covered with spinous emi- nences, arranged like scales. The use of these horns is quite unknown: Goedart fancies that they secrete a pO tent poison, and are intended as instruments of defences but both suppositions are ‘altogether unfounded. It has been remarked, that the body of those caterpillars which have these horns, is firmer, and yields less to the touch than that of those which have no such appendages*. The larva of a small timber-devouring beetle (Zymexylon der- mestoides F.) has, like the above caterpillars, a long hor?» and in the same situation: it has also a singular protu- berance on the first segment ‘4. Upon some other cater- pillars, as in Bombyx Stigma ¥., a singular pair of horn-like appendages arises from the back of the second segment of the body, excluding the head. In a tawny-coloured one from Georgia, with a transverse row of short black spine’ on each segment, these horns are half an inch Jong black, covered with spinous eminences, rather thickest at the base, and terminate in a little knob. They appear to articulate with the body at the lower extremity. I have another species, black, with narrow longitudinal yellow a Plate XVIII. Fie. 12. c. b That of Sphinx Iatrophe L. appears to be jointed, at least it # moniliform. Merian Surinam. t. xxxviii. Compare also £. iii. N. Dict. d’ Hist. Nat. vi. 252. a Schellenberg Entomolog. Beytr. t. 1. STATES OF INSECTS. 147 Stripes, in which these horns are of equal thickness at àse and apex, but with the same terminal knob. Da- nais Archippus has a pair of tentacula at the head, and Nother pair, but shorter, at the tail; and D.. Gylippus as, besides these, two in the middle of the body +. . € are equally ignorant of the use of the upright horn und upon the back of the fourth segment in the larva of “ome moths (Noctua Psi, and tridens F.) which is of a con- struction quite different from that of those last described. t is cylindrical, slightly thinner at the apex, which is “btuse, fleshy, incapable of motion, of a black colour, and “Sut two lines long. On the same segment, also, in the “88e-worms (Trichoptera K.) are three fleshy conical emi« ences, which the animal can inflate or depress, so that €Y sometimes totally disappear, and then in an instant Swell out again. When retracted, they form a tunnel- aped cavity, varying indepth®. Reaumur conjectured tha t these eminences were connected with respiration, One circumstance seems in favour of this conjecture, this segment has not the respiratory threads observ- © in the subsequent ones. Latreille mentions certain ““Y naked eminences placed upon the ninth and tenth “8Ments of some hairy caterpillars, which, like those just “tioned, the animal can elevate more or less. ‘They 7 © often little cones; but when it would shorten them, € summit is drawn in, and a tunnel appears where be- "Te there was a pyramid ©. | | n a former Letter I gave you a short account of the that * Smith’s Abbotts Insects of Georgia, t: xii. ® De Geer ii. 507. ż xi. Ff. Wem ET xiv. a 7. ° N. Dict. @ Hist. Nat. vi. 256. i : E ae 148 STATES OF INSECTS. remarkable Y-shaped, as it should seem, scent-organs (Osmateria) of the beautiful caterpillar of the swallow- tailed butterfly (Papilio Machaon L.), and others of the Equites* ; I will now speak of them more fully. That found in the former is situated at the anterior margin 4 the back of the first segment, close to the head, from which at first view it seems to proceed. At the botto™ | it is simple, but divides towards the middle, like the let ter Y, into two forks, of a fleshy substance °, which it cat lengthen, as a snail does its horns, to five times their oF” dinary extent, or retract them within the stalk, soas wholly to conceal them. Sometimes it protrudes one fork, keep” ing the other retracted; and often withdraws the whole apparatus for hours together under the skin, and if place is only marked by two tawny-coloured dots, so that an ordinary spectator would not suspect the existence o such an instrument °. Unfortunately this larva is rat? in this country, so that I can scarcely flatter you with the hope of seeing this curious organ in a living specimen ê, unless you choose to import a parcel of its eggs from the south of Europe, where it is common. ‘This you wil think rather a wild proposition; but why should not En- tomologists import the eggs of rare insects, as well as bo tanists the seeds of rare plants? But if you will be satis fied with the dissection of a dead specimen, I have sev a See above, Vor. II. p. 244—. b Prats XIX. Fic. 1. a. í © Reaum. i. t. xxx. f: 2. N. Dict. d Hist. ‘Nat. xxiv. 490, 497— 4 Ray says he found it feeding on common fennel, about Middle ton in Yorkshire: Lett. 69. The indefatigable Mr. Dale recently found many in the neighbourhood of Whittlesea-mere, feeding ° Selinum palustre. It will also eat the wild carrot. STATES OF INSECTS. 149 tal, done by the ingenious Mr. Abbott of Georgia, in Which this part is well exhibited +. Bidia ~ Another small caterpillar, as it should seem, of a geo- Meter, prepared by the same gentleman, exhibits a pair of similar horns on the fifth and sixth segments: in these the)common base from which. the fork proceeds is very Short and wide, and each branch grows gradually more Slender from the base to the apex, where it is involute. Whether these are retractile, or whether they correspond With those of P. Machaon in their nature and use, cannot “ ascertained from a dead specimen: as they belong to a arva of a quite different tribe of Lepidoptera, the proba- bility is, that they essentially differ. Two globose re- actile vesicles issue from the ninth and tenth segments Sa those of Arctia chrysorrhea, &e. ® A great number of Lepidopterous larvee, particularly Se which are smooth and of a moderate size, have be- tween theunder-lip and fore-legs aslender transverse open- wg, containing a teat-like protuberance of the same con- ii uction as the furcate horn of the caterpillar of the beau- tiful mountain-butterfly, Parnassius Apollo ; and, like that, “an either be wholly retracted and concealed, or by pres- Sure be extended to the length of one of the legs. In some “vee this part is of a subhemispherical figure, generally “ingle, but sometimes double. It is commonly, however, More slender and conical; and when of this shape, it is Sometimes quadruple ©. The use of this part is not very “early known: somé have supposed it to be a second “Pineret, and to be of use in fabricating the cocoon; but * Thi Which S gentleman was remarkable for the admirable manner in he prepared caterpillars, so as scarcely to differ from life, “eam, i, 92. © Bonnet ii. 84—. i. 1, 150 STATES OF INSECTS. it is more probable that it secretes some other kind of fluid, and is connected with. defence. . The singular organ in a similar situation, evidently for that purpose, with which the puss-moth endeavours to annoy its assailants, has been described in a former - Letter, to which I refer you?. Bonnet, who was the first that discovered this organ, ascertained that it might be cut off without injury to either larva or imago. He also remarked in a caterpillar found in the wild succory (C chorium Intybus) another short, biack, needle-shaped or- gan between the conical part just described and the un- der-lip >. De Geer mentions a remarkable fleshy horn- like style, which issues from the lower side of the first segment, between the head and the legs of the case-worms (Trichoptera): he does not describe it as retractile, or it might be regarded as analogous to those of Lepidoptera similarly situated, that I have just noticed. In that of the emperor-moth (Saturnia Pavonia), there are perfo- rated tubercles, which when the animal is molested spit! forth a transparent fluid 4. ` The horn-like appendage of the puss-moth (Cerura Vir nula) is situated at the tail of the insect, and is composed of two distinct cylindrical diverging branches, each about four lines long, not united at the base. Each of these i5 hollow, and includes a smaller cylindrical piece, which can be protruded at pleasure,-and withdrawn again, as ® pencil within its case; or, rather, as the horns of a snail. The two outer horns are tolerably firm, moveable at thei ase, and beset with black spines; the interior tentacul4 are fleshy, moveable in every direction, and in full-grow” a Seë above, Vor. II. 251—. b Bonnet ii. 88. © De Geer ii. 507. t. xi. f. 16. c. 4 Rös. iv. 162. STATES OF INSECTS. 151 larvae of a rose colour. The animal seldom protrudes them, unless in some way disturbed; and frequently it *pproximates the two outer cases so closely that they re- Semble a single horn. It appears to use these inner horns, When protruded, as a kind of whip to drive away the nes, especially the Ichneumons, that alight upon its body. +Aen touched in any place, it will unsheath one of them, md sometimes both, and with them strike the place where is incommoded?. A similar organ is found in some other Bombycide, as B. Tau and Furcula F. Reaumur mentions a caterpillar that to this kind of tail added the resemblance of two ears, or two cylindrical bodies, ter- inating in a point, which emerged from the first segment hind the head>. In another observed by the same au- ‘Or, the legs were replaced by a single horn, but which ld not appear to send forth an internal one: from the ack of its fourth segment also emerged a single conical X pyramidal fleshy eminence or cleft, terminating in two Points c, Some of the tropical butterflies also, as may be Seen in the figures of Madame Merian, have two diver- Smg anal horns instead of anal prolegs; but it does not Wpear that they incase tentacula 4. Wherever these “audal horns are found, the above prolegs are wanting $ : De Geer i. 322—. See Prare XIX. Fic. 2. aa. , Maum. ii. 275. t. xxi. f. 3. bid, 276, 4. xxii. f. 4, 5. i vse is ns. Surin am. t. vii. Nymphalis Amphinome xxn. Morpho Teu- = Xxxil. Papilio Cassia. . 1s is not, however, universally the case, for the caterpillar of a eter described by Reaumur (ii. 363. ¢. xxix. f. 8.) (G. amatoria) as a pair of fleshy anal horns, terminating, it should seem from his gure s sina minute hook thatthe animal uses as'a forceps; which has same time the anal legs, of which indeed these horns seem to © appendages, 152 STATES OF INSECTS. Two conical anal horns also distinguish the caterpillar of one of the moths called Prominents, Notodonta ca- melina; but these are not terminal, but on the back of the last segment but one*. In that of another Bri- tish moth, N. ziczac F., there are three dorsal promi- nences, one near the anus, and two more in the middle Some Geometers (G. fuliginosa, &c.) have two erect horns on the eleventh segment, and others (G. syringarias &c.) two recurved ones on the eighth *, I must not here omit to mention the curious hooks emerging from two tu- bercles on the back of the eighth segment of the ferocious larva of that beautiful tiger-beetle, the Cicindela campe- stris L., not uncommon on warm sunny banks. This ani- mal with incessant labour; as we are informed by M. Des- marets, digs a cylindrical burrow, to the enormous depth, the size of the animal considered, of eighteen inches. To effect this, itcarries out small masses of earth upon its larg? concave head; and having often occasion to rest in ascend- ing this height, by means of these hooks @ it fixes itself to the sides of its burrow, and, having finally arrived at its mouth, casts off its burthen. When these insects lie in wait for their prey, their head, probably in conjunctio? with the first segment of the body, accurately stops the ` mouth of the burrow, so as to form an exact level with the surrounding soil; and thus careless insects, walking over it without perceiving the snare, are seized in a m0 ment and devoured °. Another kind of appendage, which is found in somè? Sepp. iv. £. 1... 6—8, Pirate XIX. Fic. 5. ab. Sepp. iv. t. xii. f. 4—7. e Ros. iii. 69. è Prare XVII. Fie. 13. e, + N, Dict. ¢ Hist. Nat. vii. 95, STATES OF INSECTS. 153 larvæ; is the organ employed by them to carry the excre- Ment; with which, instead of letting it fall to the ground, they form a kind of umbrella to shelter and probably con- al them. All the tortoise-beetles (Cassida L.) have in- struments for this purpose, as well as an Indian genus (Imatidium Latr.) very nearly related to them. ‘This in- Strument is a kind of fork, half as long as the body, con- Sisting of two branches, growing gradually smaller from the base to the summit, where they terminate in a very ne point, of a substance rather horny, and attached to ‘he body near the anal orifice. They are armed on the °Uutside with short spines, from the base for about a third of their length. When this fork, as it usually is, is laid Parallel to the back, with its points towards the head, the “nal aperture points the same way. When the animal Walks, the fork points the other way, and is in the same me with the body, and the anus assumes a prone posi- tion a ; The larvæ of a genus of flies (Volucella Geoffr.) re- Markable for inhabiting the nests of humble bees, are di- “tinguished on their upper side by six long, diverging, Pointed, membranous radii; placed in a semicircle round Ae anus>: what the particular use of these organs may æ, has not been conjectured. Another in my collection aS only four upper radii, but below the anus are two fleshy filiform tentacula. One of a Tipulidan described ay ‘Reaumur, has also four upper teeth; but instead of two subanal tentacula, has six®. The singular larva of Another of this tribe (Chironomus plumosus) has on the : De Geer v. +70 3 v. f. 19—23. Compare Reaum. iii. 235—. LaTe XIX. Fie. 11. a. De Geer vi. 137. Reaum. iv. 482, Saum, iv, Z. xiv. f 9, 10... = 154 STATES OF INSECTS. two last segments four long, fleshy, filiform, flexible ten- tacula, often interlaced with each other; which, accord- ing to the same illustrious author, are used by the ani- mal to fix its caudal extremity, like the geometers, that the other end may be at liberty. Besides these organs round the anus, it has also four other oval ones, of uncertain use; not to mention the two prolegs, which M. Latreille thinks are air-tubes*. Jointed anal organs are observ- able in other larvee: those in that of a saw-fly described by De Geer (Lyda F.) consist of three joints>; in that of Hister cadaverinus, a carnivorous beetle, of two °%- The larva as well as the pupa and imago of Ephemera is furnished with three long diverging multiarticulate tails, which are probably useful as a kind of rudder to assist and direct their motions. That of the smaller dragon flies (Agrion F.) is furnished with three long ver- tical laminæ, by moving which, as fish do their tails, from side to side, the animal makes its way in the water® That singular one, also, with a hooked head, figured by Reaumur, has a single swimming lamina, or fin, shaped like a fan, and placed in a vertical position under the tail £. The whole circumference of the body in some colegpte- rous larvæ,— for instance, in that of the tortoise-beetle lately mentioned,—is surrounded with appendages like rays. These are sometimes simple, rough with very short spinous points‘; but I have a dipterous larva, in a Reaum. v. 32. ¢. v. f.3—5. Latr. Gen. Crust. et Ins. iv. 249. b: De Geer ii. 1031. ż. xl. f; 13, 14. k k. ce N. Dict. d Hist. Nat. x. 430. 4 De Geer ii. 697. ¢. xxi. f. 4, 5. bbb, e Reaum. ysti vi. f. 7. 2 f Prate XVIII. Fic. 2, STATES OF INSECTS. 155 which these radii themselves are beautifully pinmated by afringe of longish spines on each side. Reaumur has de- ge ibed the grub of a beetle, the genus of which is uncer- tain, and which feeds upon the larva of Aleyrodes Prole- . tella, whose body is margined on each side by eight tri- Mgular fleshy mammular processes, terminating each in a bristle, which give it a remarkable aspect*. The cu- rious scent-organs with which the larva of Chrysomela Populi is fringed have been before fully described; and therefore I shall only mention them here>. In the larvee of the lace-winged flies (Hemerobius), and ant-lions (Myrmeleon), the anus is furnished with a small fleshy retractile cylinder, from which proceeds the silken Wead that forms the cocoon inclosing the pupa ®. Pro- Vidence has many different ways of performing the same Peration. From the structure of the oral organs of these animals, the silk could not conveniently be fur- nished by the mouth; the Allwise Creator has therefore Mstructed and fitted them to render it by a spinneret at the other extremity of the body. e respiratory anal appendages of many Dipterous arvæ will be fully described in a subsequent Letter: I “hall therefore now only further observe upon this subject, at although there is seldom any alteration in the form of “se appendages &c. in the same species, the caterpil- ars of two moths (Cerura Vinula and Attacus Tau), how- e , Yer, are exceptions. The former, when young, has two “ry projecting ear-like protuberances, which it entirely ses, as I have myself observed, before it assumes the Pupa; and the latter, in like manner, after its third * Reaum. ii. £ xxv. f. 20. » See above, Vou. IT. p. 245—. e Reaum. iii, 384. vi. 366. £. xxxii. f. 7, 8. 156 STATES OF INSECTS. change of skin, is deprived of its bent thorn-like points which attend it when young*. It is remarkable that these last larvee, when just excluded from the egg, are also entirely destitute of these appendages; they soon, however, appear, from slight elevations which mark their situation, and rapidly acquire their usual form?. Changes of a similar kind, hitherto unobserved, may probably take place in other species. iii. Figure. I am next to consider the general figure oF shape of larvae. All of them, with but few exceptions °» agree in having a body more or less constricted at inter- vals into a series of rmgs or segments ; usually in num- ber, twelve ; often nearly equal in length, but sometimes in this respect very dissimilar*. The general outline oF shape of the body is extremely various: most frequently it approaches to cylindrical, as in most of the caterpillars of Lepidoptera, and of the Hymenopterous tribe of saw- flies (Tenthredo L.). The next most common figure is that more or less oblong or oval one, sometimes ap- proaching to conical, found in many of the larvæ usually called grubs; such as those of the weevil (Curculio L.) and a Ros. iii. t. lxviii. f. 1. Meinecken Naturf. vi. 120. b Ibid. xiii. 175. c In the larva of Tenthredo Cerasi L., and some others, no traces of segments are to be seen ; and in many coleopterous and dipterous ones the folds of the skin prevent the segments from being distinctly perceptible. a Reaum. ii. 361. In the larva of a small common moth often met with in houses ( Aglossa pinguinalis), every segment is divided into tw? parts,and underneath has two deep folds, by means of which these tw? parts can separate to a certain point, or approach again, according t° circumstances. Thus Providence has enabled them to prevent their spiracles from being stopped by the greasy substances on which they often feed. N. Dict. d Hist. Nat. i, 208. s STATES OF INSECTS: 157 of the capricorn (Cerambyx L.), and other coleopterous tribes; of bees, and all Hymenopterous insects but the Saw-flies; and also of a large number of flies (Diptera). In some the figure approaches to fusiform, as in most of the moths of the Fabrician genus Lithosia. In others, as in those of the water-beetles (Dytiscus, &c.), it ap- Proaches to an obovate shape, being widest towards the lead, and terminating in a point at the anus. In others, ‘gain, it is linear; an example of which is that of Staphy- “hus, Some are convex, and others gibbous, above, and flat underneath ; as those of Silpha, Chrysomela and many Other beetles. Others are flat, both above and below, and depressed like a leaf; a remarkable instance of which as been before noticed *. ome are very long, as those of most Lepidoptera; others very short, as that of the ant-lion (Myrmeleon). Many other peculiarities of form N individuals might be instanced; but a dry enumera- tion of these would be of no great use to you. They can ®nly be advantageously learned by the study of good sures, and by watching the actual metamorphosis of the “ngularly-formed larvee that you meet with. ; Instead, therefore, of any further specification of indi- vidual forms, I shall now endeavour to give you, as far as my own knowledge of them and the information I can Collect from other sources will enable me, a larger and More general view of the kinds of larvae; for analytical Mquiries lose half their value and importance unless we sA to apply them synthetically, by forming, if pos- ® mto groups the objects with which we are indivi- dually acquainted. Partial attempts at a synthetical arrangement with re- * See above, p. 110. 158 STATES OF INSECTS. gard to the larvae of Lepidoptera and the saw-flies ( Ten- thredo L.) have been made both by Reaumur and De Geer. M. Latreille also has recently given a Tableau méthodique et général of articulated animals furnished with jointed legs, considered in their first states. The former of these is chiefly founded. upon the number of the prolegs, and the latter upon the metamorphosis, pro- legs, habits, head, and parts of the mouth, without any other notice of the configuration. Mr. Wm. MacLeay, who, though young in years, is old in science and critical acumen, has started a perfectly new hypothesis upon this subject. In the progress of his inquiries into the natural arrangement of animals, particularly of insects in the Linnean sense, he has been the first to observe, that the relation which organized objects bear to each other is of two kinds; one of real affinity, and the other only of ana- logy, or resemblance. ‘This important distinction, upo? which I shall enlarge in a future Letter, when I come to treat of Systems of Entomology, he has applied, in a way quite original, to larvee in general, but more particularly to those of the Coleoptera order. For the basis of his system he assumes a relation of analogy between the larve of Insects that in the progress of their metamor- phosis assume wings, and those that do not, which form his class Ametabola, so that the prototypes of the forme! shall be found amongst the latter>. But though Mr. MacLeay appears to consider the analogy between these two as primary, he extends it in a secondary sense to the Crustacea, at least in several instances °. Upon this oc- 2 N. Dict, d’ Hist. Nat. xvii, 329, b Hor, Entomolog. 285. 397—. 422. 462—. &c. © Ibid. 399—401. STATES OF INSECTS. 159 fasion he very judiciously remarks, that “ in terming larvae Chilognathiformes or Chilopodiformes, it is not Meant that they are Scolopendre or Tuli, or even near to em in affinity; but only that they are so constructed that certain analogical circumstances attending them Strongly remind us of these Ametabola*.” This remark Jou will bear in mind while I am treating of this subject. t should seem from another part of the same paragraph, that the comparison which our learned Physiologist re- commends, is between the young of the Ametabola and the larvæ of the corresponding groups of Coleoptera., his must be understood to refer chiefly to the young of © Chilopoda and Chilognatha, since they approach Nearer to them in that state, having then only six legs; ut the rest of the Ametabola should certainly be brought © this comparison in their adult state: and even the two Ymer orders in that state more strongly resemble nume- rous coleopterous larvæ, than when they are young and much Shorter. I before called your attention to the re- markable circumstance that contrasts very many larvae Hexapod insects that become winged in their perfect “late with adult Myriapoda : namely, that in one the pro- Stess to this state is by losing their prolegs and shorten- Ng their body; while in the other, the reverse of this re place, numerous prolegs and additional segments ing gained before they arrive at maturity’, As the multiplication of organs is a sign of imperfection, it may © affirmed of the former of these tribes, that their pro- Stress js towards greater perfection; while that of the È “t may be called a degradation. As larvæ may be Sarded as a stepping-stone by which approach is made * Hor. Entomolog. 423, - b. See above, p. 23. ° 160 STATES OF INSECTS. from the apterous to the winged tribes of Insects, it seems most consistent with general analogy that each should connect with the other in that state in which the resem- blance is greatest. Now the Myriapoda resemble larv® as we have just seen, most when in their adult states therefore the comparison should be between larvee and adult Myriapoda. Mr. MacLeay divides coleopterous larvæ into five tribes thus characterized :— 1. A carnivorous hexapod larva, with an elongate linear flattened body, having a large head armed with two sharp faleiform mandibles, and furnished with six granular eye on each side. This kind he denominates Chilopodiforms as having for its type in the Ametabola, Scolopendra L. The examples he gives are Carabus and Dytiscus. 9. A herbivorous hexapod larva, with a long and al- most cylindrical body, so fashioned that the posterior ex tremity being curved under the breast, the animal when at rest necessarily lies like an TULUS on its side. This tribe he denominates Chilognathiform, from Tulus L. His eX; amples are, the larvee of Petalocerous insects, as Scara- beus L., Lucanus L. &c. 3. An apod larva, having scarcely the rudiments of an- tenn, but which is furnished instead of “feet with fat fleshy tubercles; which, when continued along the back and belly give the animal a facility of moving in whatever way 1 may be placed. "These he denominates Vermiform, frow certain of the Vermes intestina and Mollusca of Linné which he has associated with his Annulosa*, His exam ples are, Curculio L. and Cerambyx L. r 4. A hexapod and distinctly antenniferous larva, with 4 a The Intestinaux cavitaires of Cuvier, and the Epizoaria of La- marck. See Hor. Entomolog. 286—. STATES OF INSECTS. 161 Subovate rather conical body, of which the second segment ts longer and of a different form from the others, so as to Sve the appearance of a thorax. His denomination for ese is Anopluriform, from Pediculus L., forming Dr: ach’s Anoplura. His examples are, Coccinella and Chrysomela L. 5. A hexapod antenniferous larva of an oblong form, ing like the former vestiges of a thorax, besides two or More articulated or enarticulated setaceous or corneous ap= Pendages to the last segment of the abdomen. This tribe © calls Thysanuriform, from Lepisma and Podura L., tning M. Latreille’s order Thysanura. His example 'S Meloe with a note of interrogation °. The system here stated, of naming and characterizing “vee from the resemblance and analogy, in many cases Very Striking, that they bear to the apterous tribes, is a very happy and original one, and does its author great Credit ; yet I think in some instances, as I shall soon: ave occasion to point out to you, the application of it is NOt so happy as the first idea. But this is always the. c ed ase when a new law of nature is discovered ; the proper aPplicss: = ‘ Pplication of it is gradually developed, and it does not a af : : tall detract from the merit of the first discoverer, that ~ the bearings of such law do not strike him as it were ‘Ntuitively, N Hor, Entomolog. 422. comp- 463. Mr. MacLeay’s idea of the D 20 Meloe is taken from the animal which Frisch, Goedart, and me == imagined to be such; but upon this opinion there rest great g His), (See Kirby Mon. Ap. Angl. ii. 168, and Latreille N. Dict. a at. xx. 109.) At p. 464 he gives also Mordella and many y Dore as having Thysanuriform larvæ. He thinks, that proba- that s of Clerus is of the same description; to which he suspects any of Latreille’s Malacodermi likewise belong. YOu. TiL. M 162 STATES OF INSECTS. Having, however, got the vantage-ground afforded by this discovery of my friend, let us see if by standing upo” it we cannot get a tolerable generalization of the larv® _of all orders of insects that undergo a metamorphosis But first I must observe, that as in the perfect animals, so in their larvee, the different groups are connected by certain transition species, exhibiting characters. commo”? to two or more of them; and likewise that in many cases, which you will see as we proceed, the analogy is as strong or stronger between them and the Crustacea (and in 4 few instances Arachnida, and even Mollusca) than the Ametabola, My denominations, therefore, will be take? from those tribes where the analogy appears to me the most striking, and not from the Ametabola alone. I shall begin by drawing up for you a list of the Pri- mary forms that I seem to have observed, and their cha- racters; and then going through the orders, shall give you the examples of each, with such observations upo” them as the case may require. Primary Forms of Larve. APTERA. ARACHNIDA. CRUSTACEA. MOLLUSC” ANOPLURIFORM. ARANEIDIFORM. IsoPoDIFORM. Liy air o8” THYSANURIFORM. ONISCIFORM. CHILOPODIFORM. IpoTEIFORM.- Ae CHILOGNATHIFORM. AMPHIPODIFORM. ANN ELD a STOMAPODIFORM. Vermiro® DeEcAPODIFORM. BrRaNCHIOPODIFORM. Characters. 1. Anopluriform. Carnivorous; hexapod; antenniferous* with a shortish oblong depressed body, and distinct STATES OF INSECTS. 163 thoracic shield. Example: Psocus, Coccinella, most Hemiptera*. | wars 2. Thysanuriform. Polyphagous; hexapod; antenniferous: body with segments of trunk distinctly marked; anus often furnished with setæ or mucro. Ex.. Meloe”? Thrips, Aphis. g 3. Chilopodiform. Carnivorous; subhexapod; antennife- rous: body depressed, elongate, linear, with falcate acute mandibles, a distinct thoracic shield, and an anal proleg. Ex. Cicindela ©? Carabus L. k Chilognathiform. Herbivorous: body subcylindrical, elongate, linear; no thoracic shield; often many pro- legs, sometimes a retractile one, and sometimes none. —Ex. Elater, Petalocera, most Lepidoptera, Ten- ‘thredo 1.4 pag wk, ermiform. Polyphagous; apod or hexapod: with very short legs; antennz nearly obsolete; body fleshy, plicate, with sides often plicato-papillose ; : Prare XVIII. Fre. 1. as to the thoracic shield. a Lo 27, 1822. This day, T. Allen, Esq. F.L.S. brought mein Phial a vast number of the little insect which Goedart, Frisch, and a RA took for the larva of Meloe Proscarabæus, which he found € leaves. of Achillea Millefolium. These little animals were To each other with wonderful velocity over the sides of the of k To assist them in their motions, they applied to the surface 0, € glass the end of their abdomen, using it, like many larve of R naas as a seventh leg. This circumstance excited a suspicion self key of both Mr. MacLeay.sen., then visiting me, and my- = at after all they might be coleopterous larvee. - One, amongst this ons cumstances, however, seemed to militate strongly against PA Sea, namely, that in this infinite number none appeared to . li size, , Pare XVIL Fre. 13. bid. Fic, 12,; Prare XVIII Fre. 4, 11,13, &e. M 2 164 STATES OF INSECTS. no distiact thoracic shield. Ex. Curculio Le, ©” rambyx L., Musca L., and many other Diptera *: 6. Araneidiform. Carnivorous; hexapod: body very short; mandibles long, suctorious; animal lying in wait for its prey in a pitfall it has prepared; motio” retrogressive. Ex. Myrmeleon L.® Cicindela ? 7. Isopodiform. Saprophagous; hexapod; antenniferot’ with longer antennæ : body oblong ; thoracic shield distinct; anus styliferous or laminiferous. Ex Blatta L. Silpha L.? 8. Onisciform. Herbivorous; polypod ; antenniferous: body short, oblong, depressed, margined. Ex. Ery" cina, Lycena, in the Lepidoptera, and some specie? of Tenthredo L.e | ) 9. Idoteiform. Subcortical; hexapod; antennæ obso” lete: body much depressed, with the last segment elongate, terminating in three or more mucros. E* Larva from Brazil. Perfect insect at present w known. I have placed this larva, which was described abové ’, amongst crustaceous forms, because of the remarkable resemblance which the last segment of the body bears ii that of the Idoteide ; but I do it with considerable he” tation, since in other respects its type seems to be in the Ametabola. In its want of antennze, very short legs, 2” ventral asperities, it resembles some of the Ve ermifor™ larvee; in its small head, distinct thoracic shield, and ob long shape, it approaches the Anopluriform ; and in 6 a Prate XVIII. Fic. 3, 9. b Prave XIX. Fie. 8 c Ibid. Fic.3. Reaum. v. 97. t. xii. f. 17, 18.; De Geer i, 100” t. xxviii f. 12. å See above, p. 110, 114, 138, 142. STATES OF INSECTS. 165 very depressed body, but not at all in other respects, > Chilopodiform. At any rate, it appears of a primary Ype. 10, Lemodipodiform. Herbivorous; hexapod ; antenni- = ferous, with long antennae: body elongate, subcylin- drical; second segment of the trunk the longest ; anterior pair of legs distant from the other two. Ex. Phasma. Amphipodiform. Herbivorous; hexapod; antenni- ferous, with long antennee: body shortish, com- Pressed, saltatorious. Ex. Gryllus L. a t2, Stomapodiform. Carnivorous or saprophagous; hex- pod; antenniferous, with long antemæ: body elon- Sate, subdepressed, with raptorious hands, and ab- domen wider than the trunk; in aquatic species fur- nished with lateral gills. Ex. Mantis, Ephemera ? Sialis 2 18, Decapodiform. Carnivorous; hexapod; antenniferous: body elongate, narrow, convex, compressed, taper- Me towards the tail; tail with natatorious lamine. Ex, Dytiscus L., Agrion F.» Branchiopodiform. Carnivorous ?; aquatic; apod; antenniferous: head distinct: body transparent, flex- ile, furnished with a respiratory tube just above the tail, Ex. Culewr®. *tmaciform. Herbivorous; apod, or with very short “88: body ovate or obovate, slimy. Ex. Apoda aw., Tenthredo Cerasi L. lj, 14, * Prare XVIIL Fie. 7. b Prare XVIII, Fie. 5, * Pratz XIX. Fre, 9. 166 STATES OF INSECTS. The above are the principal forms that appear to me Primary (though some doubt may rest upon the ninth and tenth); and probably others will hereafter be disco- vered, since at present our knowledge of the larve ° most of the Orders is very limited. And now having give? you this generalization of them, as far as they are know” to me, I shall next, in a slight survey of those of the dif- ferent orders, lay before you what I have further to ob serve upon this subject. Coleoptera. The Anopluriform coleopterous larvae, 20° cording to Mr. W. MacLeay’s view of them, include both those of Coccinella L., Chrysomela L., and Cas sida L.; but this appears to me to admit of further co” sideration. With regard to the two former—those ° Coccinella are carnivorous, those of Chrysomela herbi vorous; the first is also usually more flat and depressed As to the latter, Cassida °, it seems to me to belong tO # peculiar type, distinguished not only by its radiated ma“ gin, but by the remar. cable deflected anal fork on which it 3 carries its excrement. At present I know no analogo" form amongst the apterous tribes; I must therefore Jeav? this without a denomination. Perhaps the larva of AM or Alurnus, when known, will throw light upon this sub” ject. The larva of Endomychus agrees with that of Com cinella. az There are very few known larvæ that approach to a tru? Thysanuriform type in this order: that most celebrated is the one supposed to belong to Meloe; but the claim of this to be so considered, is, as we have seen, rather dubiow* Should this point at last be satisfactorily ascertained i a Pirate XVIII. Fic. 2. STATES OF INSECTS. 167 will probably carry with it the whole tribe of vesicatory etles. But even this animal in its general structure is “Nopluriform : the only circumstance that gives it any ana- logy to the Thysanura being its anal sete. Mr. William acLeay is inclined to regard some of the larvæ of the dacodermi Latr., but which of them he does not state, 38 probably belonging to the tribe in question *. Those of Lampyris and of Telephorus, as described and figured by © Geer >, appear to me intermediate between the Ano- Pluriform and Chilopodiform Types: they have no anal “ttiform or styliform appendages, their mandibule are fllcate, and their habits seem carnivorous. Examples of Chilopodiform coleopterous larvæ are More numerous. Of this description are those of Gy- rinus, Cicindela, Carabus, and Staphylinus. That of the "st, indeed, appears to be the most perfectly Scolopeng diform of any yet known; yet the gills or respiratory aminæ, a pair of which issues from each abdominal seg- “ent, and two pair from the last‘, prove that there is "0 slight analogy between it, and indeed many other *quatic larvee, and the Stomapoda amongst the Crustacea. remarkable instance of analogy with the Decapoda of the Same Class is presented by the larva of Dytiscus, &c. Which My, MacLeay considers as Chilopodiform, but Which exhibits no other resemblance to Scolopendræ than à Hor, Entomolog. 465. b De Geer iv. 66. ż. ii, f. 5—8. that bid. #. xiii. f- 16—19. A very singular larva, which preys upon ot Aleyrodes proletella Latr., if Reaumur’s figure be correct (ii. Tga 18—20), is of a perfect Chilopodiform type, the abdomi- PS5 being represented by a tubercle crowned by a bristle: yet e this, which turns to a minute beetle (Ibid. f. 21), has some tens. Y to the Anopluriform type. EEE STATES OF INSECTS. in its predaceous habits and threatening aspect. Its convex, compressed, tapering body, terminating in sete or laminæ, is certainly much more like that of a shrimp or a prawn; to which the older Entomologists thought it was akin °, and after which they named it. As Mr. Mac- Leay’s object was, to take all his forms from the Amel bola, perhaps these larvee will best fall in with his Chilo- podiform type; though in the general form of their body they most represent a section (Lepisma L.) of the Thy- sanura. Chilognathiform forms are equally numerous in the Coleoptera with the preceding. ‘The wire-worm, or larv@ of Elater Segetis, as to shape best represents the full- grown Tulus”, and those of the Petalocera (Scarabæus Ly Lucanus L.) the young one. _ The most abundant of all forms in this order, is, I think, the Vermiform, upon which I have nothing furthe” to remark. i With regard to Crustaceous forms in Coleoptera, be sides the Decapodiform just noticed, I possess two spe” mens of larvee of Stlphide which seem to exhibit a co? siderable analogy with the Zsopodous Crustacea, one rath® è & Squilla insectum a squilla pisce parum differt? Mouffet, 319. b A remarkable difference obtains between the larva of the wit worm and that of Elater undulatus. In the former, the last segne” is longer than the preceding one, terminating in a small acute mu! q at the apex, with a deep cavity, perhaps a spiracle, on each side; # the base. In the latter, this segment is shorter than the preceding one, forming above a nearly circular plate; the margin of which is 4 little elevated, and armed on each side with three teeth, and at the apex with a pair of furcate recurved horns, and without any b2%@ spiracle. De Geer iv, 156. ż, v.f. 25. I have a similar larva, but pot the same species, STATES OF INSECTS. 169 “ohvex and the other flatter, so as to give the idea of an Armadillo and of an Oniscus. Strepsiptera. Larva Vermiform. Dermaptera. Larva Thysanuriform. Type Podura or Sminthurus. Orthoptera. Mr. MacLeay considers the larvæ of this der as primarily Thysanuriform*, though he allows the resemblance between them and Amphipoda to be par- ticularly striking’. For my own part, their prototypes ap- Pear to me to be in the Crustacea, and their analogical re- ations to the Thysanura much more distant. I trust this will appear to you the reverse of dubious in a progress Tough the Crustaceous Orders. I begin with the Zso- Poda, Take the larva of a Blatta, and place it between ; Lepisma, or Machilis, and an Oniscus, or Porcellio ; You will find that in shape and width, and the form of its “Nal styles, it resembles the latter much more than it does the former, with which it possesses scarcely any character in common, except its multiarticulate antenne. It is re- markable, that amongst the Blattide we meet with spe- “les that represent both the Onzscide and Armadillo or Glomeris c, the latter being more convex than the former. n their habits the Blattæ certainly agree with Lepisma ; and Dumeril, who thought the latter and Podura sub- Ìect to a metamorphosis, imagined they were related 4. The Spectres of Stoll (Phasma F.) are so strikingly analogous to another crustaceous tribe, the Lemodipoda, Particularly the genus Caprella, that Montagu gave one *Pecies the Trivial name of Phasma*. The jumping Am- "Hor. Entomolog. 397. > Ibid. 399 © Ibid. 438, Note *. Traité Element. ii. 35. n. 577. e 5 eas ne - Trans, Linn. Soc. vii. 66. t vi. Jek 170 STATES OF INSECTS. phipodiform Crustacea are represented extremely well by Gryllus L., and the Stomapodiform, particularly Squilla Mantis, by Mantis. The resemblance in this last instance is so very striking, that it cannot escape the eye of the least intelligent observer. Orthopterous insects may pel haps one day be discovered analogous to the two othet crustaceous orders, the Decapods and Branchiopods ; but at present I know of none of that description. Hemiptera. The larvee of this order, which in general resemble the perfect insect, except that they have no wings, seem most commonly to belong to the Anoplut- Jorm type*; but the Aphides, Chermes, and Thrips mays I think, be regarded as more analogous to the genera Podura and Sminthurus in the Thysanura>. I have some suspicion that the Nepide, Naucoris, and the remipedes Notonecta, Sigara, &e. may find their prototypes amongst the Crustacea ; but my confined knowledge of the latte! does not enable me to point to any individual genera o" tribes that they may be presumed to represent. Neuroptera. As the kinds of larvee of the different tribes composing this order, as it now stands, are very various, it is to be expected that the analogical forms they repre- sent are equally so. The Libellulina MacLeay (whose metamorphosis that gentleman has denominated 5v- semicomplete, a term warranted by their losing in their perfect state the mask before described‘) in their oral organs, particularly by their galeate maxilla and distinct ligula ĉ, have some relation to the Orthoptera, the proto- types of whose larvae we have found amongst the Crus- a Compare De Geer iii. z. xi. f. 3. and ż. xvii. f. 14. &c. b Ibid. A p fh 9, tdi. f. 15, t f 4. ° See above, p. 125—: 4 Compare Prare VI. Fic. 6. with Fie. 12 e, d, d. STATES OF INSECTS. (171 tacea : probably, therefore, those of the tribe in question lurk in that class; a suspicion that receives strong con- firmation from the larva of Agrion*, which in its taper- ing body and anal natatorious laminæ represents a shrimp. Thelarvee of that very peculiar and distinct tribe, the Ephe- merina, appear to be intermediate between the Stomapo- diform and Thysanuriform types. Their natatory respira- tory abdominal laminæ seem copied from the former, and their anal diverging setæ from the latter’. The Myrme- leonina, as well in their general form as in their motions and habits, present a most singular analogy with the tribe of spiders, as does also in some respect that of Cicindela. With regard to Panorpa, which Mr. MacLeay remarks 'S related to Myrmeleon®, and is a most ferocious insect 4, as its larva has not yet been discovered, nothing certain "especting its analogical form can be asserted; but should 1t, like the male fly, represent the scorpion, both orders of Arachnida will have their representatives in the class We are considering. The Corydalina, as far as the larva x Hemerobius instructs us, is Chilopodiform, but with a tendency to the Araneidiform Type. The Ametabola also furnish the prototype of the next tribe, the Termi- tina, which, as is evident both from Psocus and Termes, "E perfectly Anopluriform. The Sialina, or Plicipennes Latreille, excluding Trichoptera Kirby, appear to me to be intermediate between the Chilopodiform and Stoma- Podiform Types, and not without some relation to the: Yysanuriform. Their pediform, jointed, respiratory ab- dominal appendages, their head and faleate mandibles, Seem copied from the first tribe. ‘The same appendages _ De Geeta Haxi 7.4, 5. © ° Swamm: Bibl: Nat, t xiii. f. L Hor. Entomolog. 438. a See above, Vou. ÍI. p. 256. 172 STATES OF INSECTS. considered as organs of respiration, and their taper forks; are moulded upon the plan of the Stomapodiform Crus- tacea, and the long seta which terminates the abdomen is upon the Thysanuriform plan *. Trichoptera. The larvee of this order appear also to be constructed upon a double plan. The respiratory threads observable in both the upper and under sides of the abdomen connect it with the Stomapoda, and its- cy- lindrical elongate body with Chilognathiform types in the Lepidoptera”. Lepidoptera. The great majority of larvæ in this or- der are Chilognathiform, but there are exceptions to this remark. Those of the Geometre recede from this types both in their motions and the distance and number of their legs. In both these respects they represent the Læ- modipoda in the Crustacea ©. Other caterpillars are Onis- ciform; and a third sort seem to leave the Annalose types and imitate that of the Mollusca, and one is figured by Madame Merian which appears to tend even to the Chilopodiform type. i Hymenoptera. In this order the larvee of the saw-fliess Lenthredo L., are in general Chilognathiform, though some are Onisciform, others Limaciform, and those of Lyda F. (Cephaleia Jur.) and Sirex? have a Vermiform tendency: * De Geer ii. ¢. xxiii. f. 9—14. Comp. Reaum. iv. ¿£ xV f.l, 2. b De Geer ii. t. xiv. f. 7. &c. The caterpillar of P. G. Scratiotaté L. like those of Phryganee, has these respiratory threads. bid. i _ Ł xxxvii. f. 2—6. De Geer has described the larva of a Phryganea L. which is without any respiratory threads, ii. 569. ¢. xy, f. 10. e Hor. Entomolog. 401. Montagu in Linn. Trans. vii. 67. 4 Ins, Surinam. te xxvii. Compare Ibid. t. xix. right-hand figure. e PrLare XVIII, Fre. 10. STATES OF INSECTS. 173 and are a stepping-stone to those of the rest of the order, Which are all Vermiform and apods. Diptera. The majority of this order may be set down as Vermiform, though it is not improbable that some of them bear an analogy to animals that appear far removed from the Annulosa. Thus, the larva of Stratyomis Cha- ®eleon seems to exhibit no small resemblance to some of the Polypi vaginati in the Acrita subkingdom of Mr. W. acLeay*. That of Culex and some others is con- structed on a quite different type from the rest, and seems to possess some analogy tothe Branchiopod. Crustacea. Though some of these analogies are more striking than others, yet in almost all that I have stated there is that d of resemblance that could not be the result of what is Called mere chance; and Mr. MacLeay, by first pointing ut this plan of the All-wise Creator, and by laying down the doctrine of analogies in general, as distinguished from Ginities in the animal kingdom, has furnished the be- ‘ever with a new argument against those attacks of the infidel, that would render null those proofs of the wisdom 8nd goodness of the Author of nature with which the ani- Mal and vegetable creation furnish us; by affirming most absurdly, and under the most stultifying blindness of mind, that the creatures were ina manner their own cre- “tors, their wants under local circumstances stimulating em to efforts that in a long course of years produced all the different forms and organizations that are now to found in our globe. The affinities and close connexion 3 , beings with each other, so that the ascent from low to igh is usually by the most gentle gradations, is the cira * Swamm. Bibl. Nat. te xxxix. Prats XIX. Fre. 13. 174 STATES OF INSECTS. cumstance on which they build this strange and impious theory. But the fact, that certain animals of one tribe were created with a view to certain animals of another! so as to present a striking aspect of correspondence, pa rallel almost with that of type and antitype, without any real affinity or approximation;—this triumphantly prov e5 a Power above and without them, who has associate them not only in a complex chain of affinities, but has caused them to represent and figure each other, eve? when evidently far removed, so as to give a mutual cot respondence and harmony to the whole, which could be produced only by a Being infinite in power and wisdom who made all things after a general preconceived plan and system. iv. We are now to consider the clothing with which larvee are furnished. Many are quite naked, and smooth or rough only with granular elevations or tubercles OF derly arranged; but a very considerable number, esp& cially of the Lepidoptera order, are clothed with hair 0 bristles of different kinds, in greater or less abundanc® and arranged in different modes ; and a proportion still smaller have their skin beset with spines or a mixture 0 spines and hairs. Lyonnet found that the hairs of the caterpillar of the great goat-moth (Cossus ligniperda) wet? hollow, though not to- the apex: probably this is the cas? with those of other larvae, as well as with their spines In this instance they were set, he observes, in a corneous ring, or very short cylinder, elevated a little above the skin. The hair passes through this ring, and appears to be rooted in a soft integument, which clothes the skit within, and upon which the nerves form a reticular tissue STATES OF INSECTS. > a Ae which he thinks he has even seen enter the root e hairs, which perhaps are organs of touch è. ie pilose larvae, some, like most of those of the | ota (Geometra, Ti oriris, Pyralis, &c.), have OR s a tew scattered short hairs, seargely perceptible ex- y rough a lens: others (Odenesis potatoria, Lasiocam- age ane covered Mee down more or less thick: in * S (Eriogaster lanestriss Lasiocampa Neustria) the oi Is ir and more like wool; the body of two spe- c “4 uch I purchased from the collection of Mr. Fran- a covered with woolly hairs, so long as to give i e appearance ofa shock-dog; and Madam Merian hay e p similar one which she could not bring to the o state?. The hairs a many Bag known Ñ only by ine name of hairy caterpillars, as Arctia er- . 4, &ce. are stiffer, resembling bristles; sometimes, as ae chrysorhea, mixed with shorter ones. The either spring immediately from the skin (Noctua ay leporina), or, as is more general, proceed only. = m= tuberomlar elevations, uspally subhemisphe- N $ s ut sometimes conical; of which a number varying “a anne to twelve are found on each segment of diffe- Species. They seem to issue from these tubercles, tttle diverging streams from the rose of a watering-pot. : oth Cases, they form a coating usually so dense as “onceal the body, but sometimes more thinly set, and. Mitting the skin to be seen more or less between them... pelle of the beautiful Arctia ocularia, the hairs, _ tubercles alternately nearer the anterior and Margin of each segment, so as to form a dense Tok yonnet 69—. b Surinam, t. lvii. right-hand figure. 176 STATES OF INSECTS. band, the rest being naked; and in the lovely green and black one of Saturnia Pavonia, cach tubercle bears put six hairs, diverging like a star, the central one being the longest and capitate, so that the chief part of the body appears naked. This diverging position of the hairs S most common in the thick-clothed larvæ also, but many have them placed differently: thus, in those of Callimot” pha Caja and Arctia villica? they are all directed towards the tail, like the quills of a porcupine: in some other’ the anterior ones point towards the head: in that a Eriogaster Quercus half of the tuft of hairs of each tt bercle is directed downwards, the other half upwards’ in that of Arctia Salicis all the hairs point downwards so that the belly is thickly covered, while the back is bare. Another variation is, that the hairs of half the tubercle are sometimes very long, while those of the other half are very short, and even of a different colour ™ In the larva of Tussuck moths (Laria pudibunda, fase lina, &c.) the hairs are collected into tufts of a singul?” appearance, those on the intermediate segments of the back being quite level at the top, so as to resemble 50 many brushes; while those on the first and last segment are longer, and composed of feathered hairs convergi¥S to a point at their extremity, like a common camel-bai” pencil®. This last mode of arrangement prevails als© m the larva of Noctua Aceris; but in this the pencils ae shorter, exactly wedge-shaped, and distinguished by at. other particularity, that of springing directly from the 3 Sepp Vak foes NL Jae b N. Dict. d Hist. Nat. vi. 254. c Prare XIX. Fre. 6. One of these larvæ was taken at mek ville Island. See Parry’s Voyage, Appendix No. x. 37. STATES OF INSECTS. 177 Skin, and not from a tubercle. This is also the case with the large caterpillars of Odenesis potatoria, which has a double row of short bundles of black hairs on the back, Mtermixed with larger ones: at each end of the body is * pencil of converging hairs, and the sides are spotted With bundles of white ones, which with longer tawny Nes are bent downwards, so as to cover the sides of the “Teature a, Some have the anterior aigrettes disposed like the arms of a cross, of which the body of the caterpillar x the stem», But not only is there considerable variety = the general arrangement of the hairs that clothe our little larvae, the hairs themselves differ much in their kind “nd Structure, of which I will now, before I proceed to “sider spines, give you some account. Several of them te feathered like the plumes of a bird: this is the case Mth those of Morpho Idomeneus, on each segment. of the AY of which are three blue tubercles, like so many little “"quois beads, from each of which proceeds a long black umet, Other hairs terminate in a club; those of the Va of Noctua Alni, a specimen of which I possess taken _ Ugland, are flat and incrassated at the. apex, some- "6 like the antennee of some Sphingide. Mad. Merian hae the pesar of another ren En apaw-tree (Carica Papaya) with similar hairs¢. ut the most remarkable larva for the shape of its hairs at of Anthrenus Muscorum, the little pest of our ca- ; ; and Sepp. iv, é. viii. f. 4. Some species have three, others four, 55 Others even five of these brushes. N. Dict. d Hist. Nat. vi, Bas, $ tóig, Merian Erue. xxxiv. upper left hand figure. a p Van Ins, Surinam. t lx. td. tx). Vor, ily, 178 . STATES OF INSECTS. pinets, which I noticed in a former letter *. All the hairs of its body are rough with minute points; but those © six diverging long tufts or aigrettes, laid obliquely 0 the anal extremity of the body, which the animal whe? alarmed erects as a porcupine does its quills, are of # most singular structure: every hair is composed of a 8@ ries of little conical pieces, placed end to end, the point of which is directed towards the origin of each hair, which is terminated at the other extremity by a long and larg? conical mass, resembling somewhat the head of a pike” Besides the one lately mentioned, other caterpilla!® are rendered striking by the brilliant colour of the tuber cles from which their hairs emerge. A remarkable ine stance of this is the thick large caterpillar of a Bomby* which feeds upon the Psidium pyriferum, or white Guav figured by Madame Merian. This caterpillar, which white, with transverse black stripes, and which has (W° singular long converging curved bunches of hairs ned the tail, is splendidly adorned on each side with fifty *© tubercles, shining like coral, from which proceed si% a seven long diverging hairs. Leeuwenhoeck took the tubereles for eyes °. Another figured by the same Jad} who mistakes it, with her usual inaccuracy, for the Jary? of a- Lygæus F., and which seems by her descriptio” d be between the onisciform and limaciform types, has f apparently fleshy mamillæ that project from its sides at back crowned with little hairy red globes, which give ibe animal a most singular and unique appearance ĉ. He ing thus described some of the principal modes in whic? a See above, Vol. I. p. 238. b De Geer iv. 207. t. viii. f. 4—6. c Ings, Sur. t. xix. right hand caterpillar, d Ibid. xli. STATES OF INSECTS. 9 the All-wise Creator has decked and defended these “features with hairs, I shall next give you a short ac- count of the spines with which he has armed others. the spinous larvee are principally lepidopterous, and more Particularly conspicuous in some tribes of the genus.Pa- Pilio L., though some saw-flies and Diptera are also di- Stnguished by them. Vanessa Io*, Atalanta and Urtica, *8ynnis Paphia, Urania Leilus, and many other But- terflies, &c. are clothed with long sharp points, which K aim the denomination of spines, rather than that of ‘ts or bristles; being horny and hard, and so stiff at © point as readily to pierce the skin. Those of the last- Mentioned species, Madame Merian says, are as stiff as tOn-Wwire b, They are sometimes entirely simple, and 00k like spikes rather than spines, as in the caterpillar i Nymphalis Amphinome and Morpho Menelaus €; but tdinarily they are beset with hairs, or more commonly “ith Shorter spines, which often give them the appearance s Plumes, as in Urania Leilus just mentioned: sometimes ese lateral spines are so long as to have the appear- . Nee of a branch of a tree; this is strikingly the case with + Small caterpillar which Captain Hancock brought from razil; its body is so thickly planted with spines of this “Scription, that it absolutely wears the appearance of west or thicket in miniature. A singular circum- “tance attends the spines of this species: in many cases ‘Maller and very slender hair-like spine issues from em ‘ay resembling a sting; and this accounts for an ob- ery A ation of Abbott’s, that many American caterpillars Ng like a nettle, raising little white blisters on the skin * Prate XVUIFic. 13. > Ins, Sur. t XXix, © Ibid. t. vii. liti, N 2 180 STATES OF INSECTS. when accidentally or slightly touched *. Lewin has de- scribed the caterpillar of a moth found in New Holland, which he names Bombyx vulnerans, that, like these Ame ricans, has also the power of wounding, but in a different way. It darts out, he says, when alarmed by the ap proach of any thing, from as many knobs or protube- rances in its back eight bunches of little stings, with which it inflicts a very painful and venomous wound ”. The caterpillar of Papilio Protesilaus F., if Madame Me rian’s account and figure of it are correct, has its body armed with hairy spines, the extreme point of which is surmounted by a star-shaped appendage °. Those of 4 few saw-flies (Tenthredo Prunt L.), and another figured by Reaumur 4, are covered with a little forest of spines without lateral branches, but divided into a fork at tbe apex. Some spines are merely rough, with very short points, as those round the head, which give so terrific ap appearance to the caterpillar of the Bombyx regalis, of some proceedings of which I gave you an account in one of my former letters °, I must now say something upon the arrangement of these spines. Though in a few instances so thickly set as entirely to ċonceal the body of the animal, as in the case of the Brazil one lately mentioned, yet generally speaking, even when they are most numerous, they per mit the skin to be distinctly seen. Their arrangeme? is various, though always orderly: in the majority they a Smith’s Abbotts Ins. of Georg. Pref. vi. b Prodromus Entomology. c Ins, Sur, t. xliii. The figure represents only the two spines ne the head as thus circumstanced. è d Reaum. v. £. xii. f. 8, 14. Prare XVIII. Fre. 11. e See above, Vox. H. p. 238. This, with B, imperatoria, &e. in the modern system, should form a genus. STATES OF INSECTS. 181 ‘re planted singly, but in some caterpillars in bundles. a that of Saturnia Jo, on each segment there are six bun- les of longish, quill-shaped, sharp, slender, diverging “Pines, which also appear to sheath aculei. Madame erian has figured this larva, or one very near it, as the Stub of a Zuglossa*, with which, though she affirms she traced it to the fly, it can have no connection. With re- Sard to number, some larvæ have only four spines on “ach Segment; others five, others again six, and others “even, or even eight: they are planted on the sides and “ack only, never on the belly. They are often more nu- Merous on the intermediate than on the anterior and Posterior segments; but sometimes the reverse of this kes place; in that of Attacus Hrythrine only the head “Ad tail are armed with spines, the rest of the body being Wi ; : _ any>; and in that of Morpho Teucer there is on Th € ; ases those of the head and tail are much longer than ya single spine on the four intermediate segments ©. Y are usually all nearly of equal length; but in some : e Test, and remarkably so in the caterpillar of Urania erlus, also beautifully plumose, and gracefully waved ¢. . _ in the second and third segments are mgh longer Sis any of the pen in that of Bombyx regalis; which mstance gives it the terrific appearance lately al- Med to, In the family to which Argynnis Paphia be- E larva.ds adorned. with two on the back.of-the “st Segment twice as long as the rest, and resembling _tst sight two antenna. 1e spines, as well as the hairs of the new skin, are Con c ‘ et % ealed under the old one, and not incased in its spines; a e 8 Sur. t. xlvili, right hand fieure. bdbid. £2 x4. bid mie oO o a$. XXN, : € Thid. 4, xxix, 182 STATES OF INSECTS. biit Bonnet ascertained, that if cut off very closely, the larva sometimes died in consequence, whilst no such re* sult followed a similar operation on hairy larvæ. We learn from Reaumur*, that some spinous larvæ of saw- flies ( Tenthredo L.) lose their spines at the last change ° their skin; and from Madame Merian, that that of Atta- cus Erythrinæ before mentioned loses also at the same period the six tremendous black spikes that arm its black and yellow larve. The grubs of ants that are destined to pass the winter in the larva state are hairy, but are not so in summer”. ‘The spines found in the grubs of som? gad-flies (Œstrus L.) are of a different kind from thos? above described, being very minute triangular flat plates arranged in different and contrary directions ¢, and serv" ing the insect merely to change its place and fix itself. Two other kinds of clothing, if so they may be called, neither coming under the description of hazrs nor spines are found in some other larvee, not only amongst the Lt pidoptera, but also in some of the other orders. Ny" phalis Populi and others of the same family have Jarvæ furnished on the back of each segment with cylindric” conical processes of a fleshy substance, obtuse at the ape” and surrounded with capitate hairs.. In that of N. Sy billa, which has on each segment two fleshy protube rances, they are bifurcate or trifurcate, and also encit” cled at the base with a hairy tuft®. Others, as those ğ Melitea Artemis, Cynthia, &c. have each segment peset on the back with from seven to nine fleshy, pubescent wedge-shaped protuberances ; two larger ones projectiné 2 Reaum. v. 95. > Huber Mæurs des Fourmis, 79: e See above, Vor. II. p. 276—. è Reaum. v. 72. t. ix. f. 2—* e Ros. t. 211. STATES OF INSECTS. 183 Over the head. Under this head, too, may be noticed, the glutinous secretion which clothes the grub of Cionus Scrophularic, a little weevil; and of Tenthredo Cerasi L. * saw-fly, and that waxy or powdery substance which transpires through the skin of the larvæ of several Aphi- des, Chermes, Cocci, Hylotoma ovata F., &c. The Aphis, Whose extensive ravages of our apple-trees (4. lanata) Were before described to you °, is covered and quite con- Cealed by this kind of substance, so that the crevices in the bark which they inhabit look as if they were filled, Not with animals, but with cotton. The insect, also, that forms those curious galls produced upon the spruce fir, and which imitate its cones (Chermes Abietis L., Aphis e Geer) secretes a similar substance. In these and ther cases of the same kind, this matter seems to be, if May so speak, wire-drawn through numerous pores in ertain oval plates in the skin, more depressed than the test of the back, arranged regularly upon the segments, nd exhibiting minute tuberosities. When young, these “Qimals have more of this secretion than when more ad- Yanced: it then hangs from their anal extremity in Oks b But the insects most remarkable for a covering of this ature are those Coccide of which Bosc has made a ge- Us under the name of Dorthesia. De Geer is the first thor that notices them, and has given a description ‘nd figure of one species mder the name of Coccus floc- à See above, Vor. I. p. 29, 198—. s e Geer iii. 111. Comp.121. It would be as well to adopt the jae word flocon, instead of locks or flocks, which strictly mean Y different things. 184 STATES OF INSECTS. cosis*. It was discovered by Modeer upon some sete fir-leaves in a thick bed of moss. Panzer has figured # second found upon Geranium sanguineum, which from the figure appears distinct from De Geer’s, under the name of Coccus dubius®. Fabricius regards this as syno- nymous with the Dorthesia characias of Bose, inhabiting Euphorbia characias in South Europe *. Olivier found a species upon the bramble*. I once took one, which appears to differ in some respects from the preceding spe- cies, upon Melampyrum cristatum, and our indefatigable friend Mr. Sheppard has sent me another, on what plant found I do not remember, which does not agree with any that I have mentioned. The body of the animals of this ‘genus is covered by a number of cottony or waxy lamin® which partly cover each other, and are arranged usually in a triple series: in De Geers figure the series appears quadruple, the lateral ones being placed obliquely. “The anterior one in my specimen covered the head, and they are all canaliculate. Above the anus are four diverging ones: the whole are of the most dazzling whiteness: When these laminæ are removed, the body appears di- vided into segments. With respect to those larvae which imitate slugs by the viscid covering that besmears them and issues from the” pores, we learn from Professor Peck that this exudatio® takes place as soon as they are hatched; that the animal retains its humidity although exposed to the fiercest heat of the sun, and that at the last moult the skin becomes a vii. 604. £. xliv. f. 26. » Fn. Germ. Init. xxxvi, 2]. £ Syst. Rhyng. 311. 29, è N. Dict, d’ Hist, Nat, ix. 554- STATES OF INSECTS. 185 {Mite clean, and free from all viscidity? It is probable that the other limaciform larvee are similarly circum- Stanced. Madame Merian has figured an onisciform one, the legs of which, she says, are covered with a viscid skin: this produced'a Noctua. Those of Papilio Anchises also re slimy, and adhere to each other °. | V. Amongst other qualities which attach to larvæ, we Must not omit to say something concerning their Colour. “or though those which live in darkness, in the earth, Wood, in fruits, &c. are, with few exceptions‘, of an Uniform whitish colour, yet such as are exposed to the nluence of the light are usually adorned with a vast va- "ety of tints, sometimes the most vivid that can be ima- Sined. That the white colour of the former may be at- tributed to the absence of light is proved by an experi- Ment of M. Dorthes, who having forced some to live un- “er classes, exposed to the light, found that they gradu- aY became brown’. To attempt any classification of “loured larvae would be in vain, since they are tinged With almost every possible shade that can be conceived, of Many of which it would be difficult to find examples “lsewhere; and infinitely diversified as to the arrangement uid figure of their multiform markings and spots. A few Sehera] remarks, therefore, are all that you will expect On this head. Many are of one uniform colour; while a Variety of tints, very different, and very vivid and distinct, “™amentothers, > Sometimes they are distributed in :* Natural History of the Slug-worm, 7. Ins. Surinam, t. xy, xvii. * The larvæ of Carabus L. form one, being generally black. Annales de Chimie ii. 186 STATES OF INSECTS. longitudinal rays or bands, at others in transverse ones Sometimes they are waved or spotted, regularly or yrre- gularly; at others they are sprinkled in dots, or minut? streaks, in every possible way. Various larvæ are of the colour of the plant on which they feed, whence they 4% with difficulty discovered by their enemies. ‘Thus, a Jarg? proportion of Lepidoptera are green of different shades sometimes beautifully contrasted with black bands; a cir- cumstance which renders the caterpillars of two of out finest insects of this order as lovely as the fly: I meal that of Papilio Machaon and Saturnia Pavonia. Very frequently the larvæ of quite different species resemble each other so exactly, in colour as well as shape, * of the same tribe, which includes N. Absinthii, Vi erbasts Chamomille, Abrotani, are so extremely alike, that the most practised eye can scarcely discover a shade of dit- ference between them, though their larvee in colour aP markings are constantly distinct*. The markings o 2 Wien. Verz. 219, STATES OF INSECTS. 187 Species belonging to the same family are usually diffe- rent; but in some cases the latter may be prejudged from the former. The larvee of many of the genus Sphinz L., for example, have their sides marked by oblique streaks running from the back in a direction towards the head ; ‘nd by this last circumstance they are distinguished from those of Bombyx versicolor, Attacus Tau, and others of the same tribe, which have also lateral oblique striæ, but tunning from the back towards the tail*. The colours ofi individual larvee of the same species are usually alike, buti in Sphinx Elpenor and some others they vary exceed- ugly, Many, like those of Lasiocampa Rubi, Saturnia minor, &c., are of one colour when first disclosed, and *ssume others quite different in riper age. Just previ- °usly to changing their skin, the tints of most larvee be- “ome as dull and obscure, asthey are fresh and vivid when the change has fully taken place; and in some instances © the new skin is quite differently marked from the old one. his is remarkably the case with the last skin of some of the larvae of the genus Tenthredo L., which is entirely different from all the preceding ones. As people when they advance far in years usually become more simple in their dress than when they were young, so the larvee in Westion change an agreeably variegated skin for ope of ® uniform and less brilliant colour’. Madame Merian as observed with respect to Attacus Erythrine, that its “aterpillar is at first yellowish, with nine black strize n each side: when arrived at one third of its size, they become | orange; the striae are obliterated, and in their place a round black spot appears on each of the 3 Wien. Verg, 4, b Reaum. v. 92. 188 STATES OF INSECTS. -eight intermediate segments è. “Mr. Sheppard has Te marked to me, that the skin of that of Sphinx LigusiT h after being under ground four days, was changed from # vivid green to a dull red. Very rarely, however, it be- comes of a more brilliant hue just before entering the pupa state: thus, that of another hawk-moth (Smerinthus Tilie) changes to a bright violet; and the yellow hairs of that of Laria pudibunda then become of a lovely rose colour. And here I may observe, that the hairs and spines also, of larvæ, vary greatly in colour. They are t° be met with brown, black, red, yellow, violet, white, &¢ De Geer found, that in the larva of Cimbex nitens the two sides of the body were of a different colour, the left being of a deep green, whilst the right side and the rest of the body were paler >; but as he saw only a single individual, this was probably an accidental circumstante ‘Though the caterpillars, as I lately said, of one of the most beautiful butterflies and moths that inhabit Britai! contend with the perfect insect in loveliness, yet in gene ral no judgement can be formed of the beauty of the fur ture fly from the colour of the larva; and the young AU relian must not flatter himself always with the hope, be cause the caterpillar excites admiration by its colours and their arrangement, that the butterfly or moth it is to pro” duce will do the same; nor ought he to despise and ove!” ook a sombre or plain-coloured individual of the forme under the idea that it will produce one equally plain of the latter, for it often happens that the splendid cate!” pillar gives a plain butterfly or moth, and vice versa ‘De Geer, however, gives us two instances of conformity a Ins. Surinami t. xi. b ii 1017. STATES OF INSECTS. 189 between the colours of the caterpillar and those of the ture moth; the one is that of the common currant- moth (Phalena G. grossulariata L.), the caterpillar of Which is white, ornamented, with several black spots va- ty mg in size. At the two extremities it is yellowish, with ‘longitudinal ray of the same colour on each side, the fad and legs being black. . These colours are all to be und in the fly, the ground of its wings being white or- namented with many black spots of different sizes. Its Upper wings are traversed by a yellowish band; and towards their base is a spot of the same colour. Its body. ' yellowish, with black spots; but the head and legs are lack a The other is that of a green caterpillar, which _ sph moth, figures by Reaumur Leni piai ab.) Sometimes, also, the sex of the future per- “ct insect may be predicted from the colour it exhibits in Us first state: thus, the brown caterpillars of Noctua Pro- uba produce males, and the green ones females °. The Sexes, also, of N. exoleta and Persicarie differ in that State . Vi, To the full account of the Food of insects given in à former letter t, which had reference chiefly to their arva state, it is only necessary in this place to add a few Particulars not there noticed. Many larvae when first . “Xcluded, as those of Pieris Crategi, &c. devour the Shells of the eggs from which they have proceeded °; and * De Geer i, 57. > Ibid. 58, Reaum. i. t. xxxix. f. 13, 14. . © Geer ii. 400. 4 See above, Vor. I. Letters xii. xiii, ee (ii. 18) mentions, that the young larvee of a butterfly $ ratægi), after devouring the exuviæ of the eggs from which Y were hatched, gnawed those which were not so : not, however, 190 STATES OF INSECTS. others (Cerura Vinula, Sphinx Euphorbia, Noctua yer- basci), though their usual food is of a vegetable natur® eat with great apparent satisfaction the skins which they cast from time to time, not leaving even the horny legs This strange repast seems even a stimulating dainty which speedily restores them to vigour, after the painful operation by which they are supplied with it. Under this head it will not be out of place to mention, that some larvee of insects, which feed only on the juices of animals or the nectar and ambrosia of flowers, have no anal pas- sage, and of course no feces. This is said to be the cas? with the grubs of bees, wasps, the larvee of Myrmeleon, &e." vii. You will require no stimulus to induce you to at- tend to the subject I am next going to enter upon,—the Moulting, namely, of Larve; or their changes of ski” This, indeed, is a subject so replete with interest, a? which so fully displays the power, wisdom, and goodnes of the Creator, affording at the same time such large 0“ casion for nice investigation, that a pious and inquisitiv® mind like yours cannot but be taken with it. In th? higher orders of animals, though the hairs of quadrupeds and the feathers of birds are in many cases annually renewed, the change, or scaling and increment of the skin, is gradual and imperceptible; no simultaneous 1% so as to destroy the included animal, but rather to facilitate its eg"e* Those also of Coccinella bipunctata which I lately bred from the €88 as soon as hatched began to devour the unhatched ones around the™ which they seemed to relish highly. I am inclined to believe, OW” ever, that this unnatural procedure was to be attributed to the cir- cumstance of the female not having had it in her power to plac? er eggs in the midst of Aphides, their proper food. aN, Dict. @ Hist. Nat. xx. 309. STATES OF INSECTS. 191 J€ction of it, in which it is stripped off by the animal it- Self like a worn shirt, being observable, till you descend in- the Scale to the Serpent tribe ?, which at certain periods 'Sengage themselves from their old integument, and start forth with that new and deadly beauty so finely described _ by the Mantuan bard :— “So from his den, the winter slept away, Shoots forth the burnished snake in open day; Who, fed with every poison of the plain, Sheds his old spoils and shines in youth again: Proud of his golden scales rolls tow’ring on, And darts his forky tongue», and glitters in the sun.” Prit ln these the new skin, I imagine, is formed under the old from the rete mucosum ; but in insects, as I formerly Stated c, since the time of Swammerdam it has generally “en believed by entomologists, that the larva includes a Series of cases or envelopes, one within the other, con- taining in the centre the germe of the future perfect insect, - Whose development and final exclusion take place only When these cases have been successively cast off. This Ypothesis, as was explained to you on a former occasion‘, as been controverted by a late writer, Dr. Herold; who firms that the skins of caterpillars are also successively Produced out of the rete mucosum. I have however, I Ope, satisfied you that the old system is most consonant eja the human species, after certain fevers a simultaneous and ei moult, if the term may be so applied, takes place. I experi- ced this myself in my boyhood; when convalescent from Scarlatina, € skin of my whole body, or nearly so, peeled off. it he translator, more ignorant of natural history than his author, urned the “ Zinguis micat ore trisulcis” of Virgil, into “ darts his Orky sting.” 4 © = 4 ~ Vor. I, p. 70. 4 Sec above, p. 52—. 192 | STATES. OF INSECTS. to nature and probability : but as we are now to entet, at large upon the Moults of insects, it will not be without use if I add a few additional reasons which seem to 1° ‘still further to prove the correctness of Swammerdam’s system, as far as it relates to that subject. With regard to the mere formation of the skin from the rete mucosuns, were this the whole question few would hesitate to adopt the sentiments of M. Herold ; but when we come to con- sider further—that the number of moults of individuals of the same species is always the same, and that it varies in different species, and takes place at certain periods: ~ we begin to suspect that something more than the mere formation of a new skin upon an old one being cast is t° be accounted for; and that the law which prescribes i own definite number of skins to each species, must begi! to act in the primordial formation of the larva. Agaits the hairs observable in the higher animals do not take their origin from the epidermis solely, but are planted below it in the rete mucosum, or deeper*; so that the change of skin does not affect them; but in the larvee O insects they are a continuation of that integument, sinc® when the moult takes place, they always remain on the rejected skin®: this is the case, also, even with spines If you shave a caterpillar ready to change its skin, eithe! partially or generally, you will find that the parts in the new skin that correspond with those that are denuded» are equally hairy with those that were nott; and j you. pay attention to the new-clad animal, you will find farther, that the hairs never grow after a moult. Fro™ a Cuvier Anat. Comp. ii, 596. N. Dict. d Hist. Nat. xxvi. 165: b Cuvier Ibid. 624. © Reaum. i. 182. . STATES. OF INSECTS. 193 pe it follows, that the hairs have their place and take E whole growth between the new skin and the old ?. ‘Whether the spines, simple or compound, lately described ‘to you, that arm some larve are similarly circumstanced, _ not as yet to have been ascertained; but as the Pinous ones of certain Tenthredines L. and Lepidoptera at their last moult have no spines, the presumption is, “hat, whether incased or not, they are mere appendages : “te skin on which they appear. A new set of hairs, efore, and probably of spines in spinous larvae, ac- a Panying each skin, and these varying very much in > Composition, &c. though a new membrane may be “mitted to be formed from an action in the rete mucosum sa a pre-existent, germe of it, it seems not easy to -Ceive how these hairs and spines can spring up and there, each according to a certain law, without ex- ú Ea y as a kind of corculum oi pozoi akai ; im $ at the germes of the tubercles, in which the hairs 50 generally planted, according to a certain arrange- Mis and in a given number, should also pre-exist, seems , *stconsonant toreason. ‘Theseand the several skins may — in their primordial germes, and romain be- sion s discovery of site highest powers of assisted vi- Yan a Ronin period waon they may first enter the follor, ia njeromopesided oye j does not therefore ba ecause these primordia semina eor are not E that therefore: they may not exist. Our Bar and organs are too limited and of too little power € us to see the essences of being. ; Pon the supposition that the hypothesis of Swam- è N. Dict. X Hist. Nut. vi. 290. Yor áa t Ti o 194 STATES OF INSECTS. merdam is the true one, we may imagine that the enve lope that lies within all the rest is that which covers the insect in its pupa state. Above this are placed sever? others, which successively become external integumen* These changes or casting of the skin in larvee, analogo™ as before observed, to that of serpents, are familiar © every breeder of silk-worms, in which four such chang” occur: the first at the end of about fwelve days from its birth, and the three next cach at the end of kalf that tim? from the moulting which preceded it. With some €% ceptions *, similar changes of the skin take piace in # larvae, not however in the same number and at the sam” periods. Most indeed undergo this operation only thre? or four times; but there are some that moult often” from five up to eight (Arctia villica), nine (Callimorph@ Dominula), or even ten times; for so often, M. Cuvie’ informs us, the caterpillar of the tiger-moth (Caltimor ph" Caja) casts its exuviæ. It has been observed that the caterpillars of the day-fiying Lepidoptera (Papilio L usually change only three times, while those of the night flying ones (Phatena L.) change four®. The perio : that intervene between each change depend upor. the length of the insect’s existence in the larva state. those which live only a few weeks or months, they att from eight to twenty days; while in those that live M” than a year, as the cockchafer, &c. they are proba proportionably longer : though we know very little wit 67) (ag a Those Diptera whose metamorphosis is coarctate (Vol.I. P bees, the female,Cocci, &c. do not cast their skin in the larva °” Reaum. iv. 364. N. Dict. d’ Hist. Nat. xx. 365. i o N. Dict. d Hist. Nat, vi. 289. xx. 372. Cuvier Anat. Comp k 548. M. Cuvier (Ibid. 547.) asserts, that most Papiliones and Bom byces moult seven times. STATES OF INSECTS. 195 "egard to the moult of any insects besides the Lepido- bterg, l A day or two previously to each change of its skin, the larva ceases eating altogether; it becomes languid ‘nd feeble, its beautiful colours fade, and it seeks for a *etreat in which it can undergo this important and some- Mes dangerous and even fatal operation in. security, “re, either fixing itself by its legs to the surface on uch it rests, or, as is the case with many caterpillars, 7 its Prolegs, to a slight web spun for this purpose, it =e and twists its body in various directions, and alter- tely swells and contracts its different segments. ‘The vice of these motions and contortions seems to be, to Patate the exterior skin, now become dry and rigid, bas the new one Just below it. After continuing these Perations for some hours, resting at intervals without “Hon, as if exhausted by their violence, the critical mo- Mt arrives: the skin splits in the back, in conse- a of the still more violent swelling of the second or Oe Segment: the opening thus made is speedily in- get by a succession of swellings and contractions of ., maining segments: even the head itself often di- Vi . : des nto three triangular pieces, and the inclosed larva Al paes withdraws itself wholly; from its old skin. sh: V8, however, do not force their way through this is Precisely the same place. Thus, those of the haw- ioa butterfly (Pieris Cratægi), according to Bonnet t sky their way out by forcing off what may be called their Skin Dii the horny part of their head, without splitting the to — remains entire; others have been observed © their way out at the side and the belly. Reau- * Œuvr, ii, 71. o 2 196 STATES OF INSECTS. mur noticed the larva of 2ygena Filipendula, previously to its last moult, actually biting off and detaching sever portions of its old skin; and before this, drops of a fw resembling water were seen to exude from it *. . The skin when cast is often so entire, that it might be mistaken for the larva itself; comprising not only the covering of the main trunk with the hairs which clothe it, but of the very skull, eyes, antenne, palpi, jaws, an legs; which, if examined from within, are now foun be hollow, and to have incased, like so many sheaths similar parts in the new skin. That the feet of the new” coated larva were actually sheathed, as fingers in a glove in the same parts of the exuviæ, may be proved by? very simple experiment: if a leg of one just ready © cast its skin be cut off, the same limb will be found M tilated when that change has ensued. The anal hoi also, of the larvee of the hawk-moth (Sphinz L.) and othe similar protuberances, are incased in each other in b manner; but hairs are laid flat between the two ski and contribute considerably towards their more easy j paration. Thus, if you saved the skins cast by the Jat" -of Callimorpha Caja, for instance, you would appe? 1 have ten different specimens of caterpillars, furnis yf with every external necessary part, and differing oP fe ‘size, and the colour perhaps of the hairs, and all sep! ‘senting the same individual. 2 ae at” But further changes than this take place. Swan i ‘dam says, speaking of the moult of the grub of Or. nasicornis, a beetle common in Holland, but not jj al factorily ascertained to inhabit Britain, « Nothing » pe nature is in my opinion a more wonderful sight thaP 2 Reaum, tt. 75. STATES OF INSECTS, 197 change of skin in these and other. the like worms. - This Matter, therefore, deserves the greatest consideration, wid is worthy to be called a specimen of natures mira-. cles; for it is not the external skin only that these worms “st, like serpents, but the throat and a part of the sto- Mach, and even the inward surface of the great gut, “hange their skin at the same time. But this is not the Whole of these wonders; for at the same time some hun- Teds of pulmonary pipes within the body of the worm “st also each its delicate and tender skin. These seve- *al skins are afterwards collected into eighteen thicker, "Nd, as it were, compounded ropes, nine on each side of the body, which, when the skin is cast; slip gently and 7 degrees from within the body through the eighteen “Pertures or orifices of the pulmonary tubes before de- “tibed, having their tops or ends directed upwards towards the head. Two other branches of the pulmo- UY pipes that are smaller, and have no points of respi- ation, cast a skin likewise.” . . . “ If any one separates i ast little ropes or congeries of the pulmonary pipes th a fine needle, he will very distinctly see the branches ramifications of these several pipes, and also their War composition a” — Bonnet makes a similar obser- Vati ; Mion with regard to caterpillars; but he appears to have “Served it more particularly, at least the change of the lestines, previously to the metamorphosis of the insect, E he says with the excrements it casts the inner skin 0 the Stomach and viscera. Both these great men ap- * to have recorded the result of their own actual ob- Yations with regard to the proceedings of two very dif- Sep * Bibl. Nat. E. Trans. i. 135. col. 3. t. xxvii. Sf. 6. b Œuvres, viii. 303. 198 STATES OF INSECTS. ferent kinds of insects; the one the grub of a beetle, and the other the caterpillars of Lepidoptera. The account © -the former is given quite in detail, as that of a person who is describing what he has actually seen : yet by a later aw very able physiologist, Dr. Herold, it is affirmed that th? inner skin of the intestinal canal is never cast, that ca”? constantly retaining its two skins. He further affirms, the they are only the large trunks of the Tracheze that cast their skins, none being detached from their smaller rao” fications?. When men so eminent for their anatone skill and nicety, and for their depth and acumen, dis agree, the question must be regarded as undecided # further observations throw sufficient weight into one scat? or the other. The larva which has undergone this painful proc at first extremely weak: all its parts are soft and tender even the corneous ones, as the head and the legs, are the” d wit ess 8 scarcely more than membranous, and are all bathe a fluid, which, before the moult, intervenes between © two skins, and facilitates their separation ®: and it only after some hours, or in some cases even days dv ring which it lies without motion, that this humidity at ‘porates, all its parts become consolidated, and it rr vers its strength sufficiently to betake itself to its wont? food. Its colour, too, is usually at first much paler the before, and its markings indistinct, until their tints hav a Entwickelungsgeschichte, &c. 34, 88. Swammerdam on the H trary affirms, that “ on the hinder part of the cast skin where g twisted and complicated, whoever accurately examines the sK” A self may still observe the coat that was cast by the intestinum recht! Ubi supr. 136. col. a. b N. Dict, d’ Hist. Nat. vi. 290. STATES OF INSECTS. 199 been enlivened by exposure to the air, when they become Nore fresh, vivid, and beautiful to appearance than ever. When a few meals have invigorated its languid powers, the renovated animal makes up for its long abstinence Y eating with double voracity. A similar preparatory fast, and succeeding state, of ebility, accompany every change of the larva’s skin. ach time except the iast, the old skin is succeeded by 3 new one, with few exceptions, similar to the one it has _Scarded, Previously to the final change, which discloses © pupa, it quits the plant or tree on which it had lived, my appears to be quite unsettled, wandering about and “Ossing the paths and roads, as if in quest of some new Welling, It now abstains from food for a longer time an before a common moult, empties itself copiously, “Nd as I have just said, if Swammerdam and Bonnet are ‘0 be depended upon, casts the skin that lines the sto- Mach and intestines, as well as that of the Tracheæ. Thave observed above, that all larvae, with few excep- “lons, change their skins in the manner that. I have de- “cribeq, These exceptions are principally found in the | a der Diptera, of which those of the Linnean genera “scar (Estrus, and probably all that, like the maggot the common flesh-fly, have membranous contractile “ads, never change their skin at all, not even prepara- a to their becoming pupa. ‘The skin of the pupa, ugh often differing greatly in shape from that of the \. va, is the same which has covered this last from its "th, only modified in figure by the internal changes that co place, and to which its membranous. tettre fone y accommodates itself. The larvee of the Dipte- Senera Tipula, Culex, and those which have corne- 200 - STATES OF INSECTS. ous heads, like other larvee change their skins sever al times previously to becoming pupæ*. The grubs, alse of bees, wasps, ants? and probably many other Hymeno ptera, do not change their skin till they assume the pup® nor the larva of the female Coccus”. i If you feel disposed to investigate the reasons of that law of the Creator which has ordained that the skins of the higher animals shall be daily, and imperceptibly, and as it were piece by piece renewed, while those of insects are cast periodically and simultaneously,—the proximate cause must be sought for in the nature of the two kinds of skin, the one being more pliable and admitting j greater degree of tension than the other, and being 5° constructed as to scale off more readily. If, ascending higher, you wish to know why the skins of insects are a differently circumstanced from our own, the most app” rent reason is, to accommodate the skin to the very rap" growth of these animals, which a gradual and slowet change would have impeded too much, or the skin hav? suffered constant dilapidation and injury ; therefore the Beneficent Creator has furnished them with one whic will stretch to a- certain point, and during a certain perio and then yield to the efforts of the inclosed animal, 2” be thrown aside as a garment that no longer fits the wearer. vii, And this leads me to a subject to which I am 4° a Reaum. iv. 604. “6 > Ibid. 364. N. Dict, d Hist. Nat. xx. 365. Huber Fourmis ! M. Huber does not say expressly that the grubs of ants do not cha? iy their skin; but his account seems to imply that they change ne previously to their metamorphosis, STATES. OF INSECTS. 201 sirous now to bespeak your attention,—the Growth, I Mean, and size of Insects in this state. As to size, larvee differ as much as insects in their perfect state: these last, Owever, never grow after their exclusion from the pupa, While larvae increase in bulk in aproportion, and often with à rapidity, almost without a parallel in the other tribes of animals. Thus Lyonnet found, that the caterpillar of the great goat-moth (Cossus ligniperda F.) after having -attained its full growth is at least 72,000 times heavier than when it was first excluded from the ego *; and of “ourse had increased in size in the same proportion. Mnected with the size of larvae, is the mode in which their accretion takes place. -This, with respect to the More solid parts, as the head, legs, &c., is not, as in other animals, by gradual and imperceptible degrees, but sud- €nly and at stated intervals. Between the assumption of a new skin and the deposition of an old one, no in- Tease of size takes place in these parts, while the rest of the body grows and extends itself, till, becoming too big Y these solid parts, nature restores the equilibrium ber Ween them by a fresh moult®, in which the augmenta- tion of bulk, especially in these parts, is so great, that we = scarcely credit the possibility of its being cased in so Small an envelope. Malpighi declares, that the head of. è silk-worm that has recently cast its skin is four times arget than before the change‘. It is very probable, aiso, that when the outer skin becomes rigid, it confines the body of the larva within a smaller compass than it Would expand to if unconfined, so that, when this com- Pression is removed, the soft and elastic new integu- * Lyonnet 11. b N. Dict. d’ Hist. Nat. vi. 290. © De Bombycibus, 68. 202 STATES OF INSECTS. iment immediately swells out, and the animal appears all at once much larger than it was before the moult, 1 fact, the proximate cause of the rupture and rejection ° the old skin is the expansion of the included body, which at length becomes so distended as to split its envelop® aided, indeed, as before described, by the contortions ° the creature itself. The larvee most notorious for the rapidity of theit .growth are those of Musca carnaria and other flesh-flie** A | some of which Redi found to become from 140 to more -| than 200 times heavier in twenty-four hours *: an increase \ of weight and size in so short a time truly prodigious | but essential for the end of their creation—the rapid re ‘moval of dead and putrescent animal matter. As the ‘skins of these larvee are never changed, we may concludes if the cause of the change of skin in other larvae above surmised be accurate, that their skins are more contra tile and capable of a greater degree of tension than thos? of larvæ that are subject to moulting. And two peculi- arities observable in them confirm this idea: in the first place, their head is not hard and corneous, as that © the others, but capable of being shortened or lengthened; and in the next, their breathing-pores are not in the sides but at the extremities of the body, while in the moulti"™ larvee there are two in almost every segment, which must form so many callous points that impede the stretching of the skin to the utmost. The hairs, spines, and tube” cles, that are so often found on caterpillars, must als? form so many points of resistance that prevent that full extension of the integument which it might otherwis? admit. ® Opuse. 1. 27. STATES OF INSECYS. 208 There is not always that proportion between the size of larvæ and of the insects that proceed from them that Might have been supposed, some small larvee often pro- ducing perfect insects larger than some of those proceed- Ng from such as are of greater size. ix, As insects often live longest in the state we are treating of, I shall say something next upon the age of ave, or the period intervening between their exclusion from the egg and their becoming pups. This is exceed- mgly various, but in every case nicely adapted to their Several functions and modes of life. The grubs of the flesh-fiy have attained their full growth, and are ready to come pupa, in six or seven days; the caterpillar of Ar- Synnis Paphia, a butterfly, in fourteen days; the larvee of ĉes in ¢wenty days; while those of the great goat-moth (Cossus ligniperda) and of the cockchafer ( Melolontha wul- Saris) live three years, or at least survive three winters, be- fore the same change. That of another lamellicorn beetle (Oryctes nasicornis F.) is said to be extended to four or , Jive; that of the wire-worm (Elater segetum) to five. That of the stag-beetle (Lucanus Cervus) is affirmed by Ösel to be extended to six years; but the most remark- ble instance of insect longevity is recorded by Mr. Mar- Sham in the Linnean Transactions *. A specimen of Bu- ? restis splendida, a beautiful beetle never before found in f 'S country, made its way out of a deal desk in an office m London in the beginning of the year 1810, which had “en fixed there in the year 1788 or 1789; so that ac- Cord; f : ne rding to every appearance it had existed in this desk à Linn. Trans. x. 399. 204: STATES OF INSECTS. more than twenty years. Ample allowance being made for its life as a pupa, we may conclude that it had existed as a larva at least half the above period. The grubs of the species of the genus Cynips L. attain their full size ina short time; but they afterwards remain five or six months in the gall before they become pupz *. With few exceptions it may be laid down, that thos¢ larvæ which live on dead animals, in fungi, in dung, and in similar substances, are of the shortest duration in this state; and that those which live under the earth, on the roots of grass, &c. and in wood, the longest: the forme! becoming pupze in a few days or weeks, the latter requi" ing several months, or even years, to bring them to ma- turity. The larvæ which live on the leaves of plant seem to attain a middle term between the one and thé other,—seldom shorter than a few weeks, and rarely longer than seven or eight months. Aquatic larve ap- pear to be subject to no general rule: some, as the larv® of Gnats, becoming pupæ in two or three weeks; and others, as those of the ‘Ephemera, which are thus col pensated for their short life as flies, in as many year® ý; "The cause of all these differences is obviously dependent on the nature of the food, and the purposes in the eco" nomy of creation to which the larvee are destined. x. The last part of the history of larve relates to thet! Preparations for assuming the pupa state. When they -have acquired their full size, after having ceased to take 2 N. Dict. d Hist. Nat. vii. 129. b As the larve of Ephemera usually live in the submerged pa the banks of rivers, perhaps they may be regarded as following economy of subterranean terrestrial larve. tof the STATES OF INSECTS. 205 food, by a copious evacuation they empty the intestinal Canal, even rejecting the membrane that lines it and the Stomach; their colours either change totally, or fade; ad they make themselves ready for entering upon a new stage of their existence.. Some merely rest in a State of inactivity in the midst of the substances in which they feed, as if conscious of their inability to select any Safer abode. Of this description are most Coleopterous, Hy menopterous, and Dipterous larve, that feed under Stound, or in the interior. of trees, fruits, and seeds. But a still larger,tribe, those which feed on leaves, ani- mals, &c. act as if more sensible of the insecurity of this to them important epoch. They are about to exchange their state of vigour and activity for a long period of death- ike sleep. The vigilant caution which was wont to guard them from the attack of their enemies will be hencefor- Ward of no avail. Destitute of all the means of active defence, their only chance of safety during their often Protracted night of torpor must arise from the privacy of their place of repose. About this, therefore, they exhibit the greatest anxiety. Many, after wandering about as if * A caterpillar nearly answering to the description of that of °mbyx camelina, which I found upon the hazel, after a few days Produced sixteen grubs of some Ichneumon. At first these grubs were Steen, but they became gradually paler; and after a day or two be- fame pupz. But I mention this circumstance here for another rea- Son ; upon examining them after this last occurrence, I observed that ‘Ney adhered to the lid of the box in which I kept the larva, arranged Somewhat circularly ; and at alittle distance from the anus of each ie pea-green mass, consisting of about eight oval granules, which *ppeared like so many minute eggs. These were the excrement eva- “uated by each grub previously to its becoming a pupa. The appear- Mce of this little group, with their verdant appendage, formed a cu- "lous spectacle: they are still pupæ, July 30, 1822. 206 STATES OF INSECTS, bewildered, retire to any small hole on the surface of the earth, covering themselves with dead leaves, moss, or the like, or to the chinks of trees, or niches in walls and othet buildings, or similar hiding-places. Many penetrate to the depth of several inches under ground, and there for™ an appropriate cavern by pushing away the surrounding earth; to which they often give consistence by wetting it with a viscid fluid poured from the mouth. The larv® of other insects undertake long and arduous journeys in search of appropriate places of shelter. Those of flesh- flies, now satiated with the mass of putridity in which they have wallowed, leave it, and conceal themselves 1” any adjoining heap of dust. .The grubs of the gad-fly (Gistrus) creep some of them out of the backs of cattle, in tumours of which they have resided, and suffer them selves to fall to the earth; while others, which have fed in the stomach of horses, quit their hold, and by a still more extraordinary and perilous route are carried throug! the intestines the whole length of their numerous circum? volutions, and are discharged at the anus. And without enumerating other instances, various aquatic larvee, 3° - that of a common fly (Zlophilus pendulus), &c. leave thé water, now no longer their proper element, and betak? themselves to the shore, there to undergo their metamo™ phosis. Most of these, having reached their selected retreat, require no other precaution; but another large tribe ol larvæ have recourse to further manœuvres for their de- fence before they assume the pupa. Thosé of the aphi- divorous flies (Syrphus F. &c.), of the various lady-birds (Coccinella L.), and tortoise-beetles (Cassida L.), &e, fis themselves by the anus with a gummy substance to thé STATES OF INSECTS. 207 leaves or twigs under which they propose to conceal them- Selves during their existence in that state. Others previ- Siy suspend themselves by a silken thread fixed to the tail, orpassinground the body; by which also, when become Pupæ, they are afterwards pendent in a similar position; and lastly, a very great number of larvee wholly inclose themselves in cases or cocoons, composed of silk and va- “lous other materials, by which during their state of re- Bose they are protected both from their enemies and the action of the atmosphere. As these two last-mentioned Processes are extremely curious and interesting, I shall Not fear tiring you by entering into some further detail "especting them: explaining frst the mode by which lar- Vee Suspend themselves, both before and after they are “come pupæ, by silken threads; and next, the various ases or cocoons in which others inclose themselves, and cir manner of operating in the formation of them. L The larvae which suspend themselves and their pu- Pæ, With the exception of the tribe of Alucita, and some “ometre of the family of G. pendularia, punctaria, &c. "te almost all butterflies*. No others follow this mode. “ag may be divided into two great classes—those which Pend themselves perpendicularly by the tail, and those Whi > ich suspend themselves horizontally by means of a a p Except some species of Polyommatus Latr. (Thecla, Argynnis ¥.), of "Stolus, Corydon, &c., and Hesperia Rubi, Betule F., &c. Some Be larvæ of the former become pup within the stalk of some to ote partly under the earth: those of the latter usually in a leaf ich the abdomen is fastened by various threads. These last © rouleuses of the butterfly-tribe, living, like some moths, in €a ves that they have rolled up. N. Dict. d’ Hist. Nat. xxiv. 499. 208 STATES OF INSECTS. thread girthed round their middle. In both cases it should be observed, that the suspension of the pupa is the object in view; but as the process is the work of thé Jarva, this seems the proper place for explaining it. To begin with the frst case. You are aware that all lepidopterous larvee have thé faculty of spinning silk threads from their mouths, 2% it will readily occur to you that it is by means of thes? threads that they suspend themselves. But how? How is d caterpillar to hang itself by the tail to threads spU? from the mouth? Even suppose this difficulty overcom’ others still greater remain. Suppose the caterpillar be suspended by its tail,—this is but a preparatory op ation,—what is required is, that the pupa shall hang ip the same position: now when you take into consideratio” that it is incased within the skin of the larva, and without feet or other external organs; that it has to extricate I self from this skin; to hang itself in its place, and to 4% tach the skin from the threads which hold it—this wi appear no trifling task. Indeed at first view it see™ impossible. Country-fellows for a prize sometimes amus? the assembled inhabitants of a village by running rac? in sacks: take one of the most active and adroit of thes bind him hand and foot, suspend him by the botto™ ¢ his sack with his head downwards, to the branch off lofty tree; make an opening in one side of the sack, 3” ‘set him to extricate himself from it, to detach it frof its Hold, and suspend himself by his feet in its place Though endowed with the suppleness of an Indiar jus’ gler, and promised his sack full of gold for a reward, pig would set him an absolute impossibility: yet this is whe Y a STATES OF INSECTS.. 209 ur cater Perform, Xplain. When the l pillars, instructed by a beneficent Creator, easily Their manœuvres I shall now endeavour to the caterpillar has selected the under-side of eaf or other object to which it purposes suspending lts first process is to spin upon it a little hillock of „Consisting of numerous loosely interwoven threads; t then Pro erti ‘elf à bends its body so as to insinuate the anal pair of egs amongst these threads, in which, by a slight ex- a k the little crochets which surround them + become ~ongly entangled as to support its weight with ease. Sy suffers the anterior part of the body to fall down, its it hangs perpendicularly from its silken support with ®ad'‘downwards. In this position it remains often for lan “four hours, at intervals altern ately ORDE and i itself. At length the — is seen to split on the Whie Rear the head, erie poets oe the pupa appears, id by repeated swellings acts like a wedge, a ra- a : extends the slit towards the tail. By me continu- ‘ ic these alternate contractions and dilatations of the ing u Pupa, the skin of the caterpillar is at last collected the an Near the tal, like a stocking which we roll upon Omes cle before withdrawing it from the foot. But now on the Important TN: The pupa, being much fro i than the caterpillar, is as yet at some paces is ii e silken hillock on which it is to be fastened; it th PPorted merely by the unsplit terminal portion of aay skin. How shall it disengage itself from this cli nt of its case, and be suspended in the air while it 5 Up to take ‘its place? Without arms or legs to H Prare XXIII: Fre. 1. a. Yo Ta TY, P 210 STATES OF INSECTS. support itself, the anxious spectator expects to see it fall to the earth, His fears, however, are vain; the supp? segments of the pupa’s abdomen serve in the place of arms. Between two of these, as with a pair of pincers, $ seizes on a portion of the skin; and bending its body one? more, entirely extricates its tail from it. It is now wholly out of the skin, against one side of which it is supporte a i but yet at some distance from the leaf. The next step must take is to climb up to the required height, For the purpose it repeats the same ingenious manœuvre, making its cast-off skin serve as a sort of ladder, it successive with different segments seizes a higher and a high portion, until in the end it reaches the summit, whet? with its tail it feels for the silken threads that are to sup” port it. But how can the tail be fastened to them? J” ask. This difficulty has been provided against by Cre tive Wisdom. The tail of the pupa is furnished with BY merous little hooks pointing in different directions *s well adapted to the end in view as the crochets of á larva’s prolegs, and some of these hooks are.sure to fast en themselves upon the silk the moment the tail is th” l amongst it. Our pupa has now nearly completed its ý bours; it has withdrawn its tail from the slough, climb i up it, and suspended itself to the silken hillock—mand vres so delicate and perilous, that we cannot but ad™ that an insect which executes them but once in its Bi should execute them so well: nor could it, as Reau® has well and piously observed, had it not been instru by a Great Master. One more exertion remains*! seems to have as great an antipathy to its cast-off s 2 Prate XXIII. Fie, 8. a. STATES OF INSECTS. 211 8 one of us should, when newly clothed after a long ims Ptlsonment, to the filthy prison garments we had put off. will not suffer this memento of its former state to re- “I near it, and is no sooner suspended in security than | endeavours to make it fall. For this end—it seizes, asit were with its tail, the threads to which the skin is ‘Stened, and then very rapidly whirls itself round, often ~°t fewer than twenty times. By this manoeuvre it ge- ay succeeds in breaking them, and the skin falls Wn, Sometimes, however, the first attempt fails: in ' t case, after a moment’s rest, it makes a second, twirl- te ttself in an opposite direction; and this is rarely un- cessful, Yet now and then it is forced to repeat its ting, not less than four or five times: and Reaumur “een instances where the feet of the skin were so firmly a teg, that after many fruitless efforts the pupa, as if “spair, gave up the task and suffered it to remain 2. ‘t these exertions, it hangs the remainder of its exist- * in this state until the butterfly is disclosed. Š € are now to consider the second mode of suspen- i wach’ i th > In which larve by means of a silken girth round " middle, fix themselves horizontally under leaves, &c. Di follow the same process with that of those last de- ed, in spinning a small hillock of silk to which they z their hind legs; and if the operation concerned the t "a State alone, this would be sufficient, as by means of taj Sa and of their prolegs, they could easily re- “mselves in a horizontal position. But these lar- i Wey, ponet is of opinion that this twirling process is not with any asione 88t rid of the exuviæ, but is caused only by the irritation oc- that of by the spines of the skin of the caterpillar when they touch the pupa. uv, 11.109. P 2 Q12 STATES OF INSECTS. væ act as if they foresaw the assumption of a state m which they will be deprived of legs. It is the suspensio” of the forthcoming pupa that is the object in view; an though this can be hung by the tail in the same way with those of the first class, yet it is plain that it cannot be re tained in a horizontal position, which for some unknow” \ reason is essential to it, without some support to its a ‘terior extremity. It is necessary for the larva, therefor not only to fix its posterior legs amongst a collection ° silken fibres, but to spin a girth of the same mater round its body. ‘This girth, though spparently of a si ‘gle thread, will be found on examination to be compo% of several, often as many as fifty or sixty; and is fasten? on each side of the body of the larva about the middle to the surface under which it is placed. ‘Three differen modes of fixing these girths are adopted by the caterpik lars of different butterflies. Some, as those of the com mon cabbage-butterfly (Pieris Brassicæ), which have * markably pliable bodies, bend them almost double % one side, then fix the thread and carry it over to tH? other in the same position, repeating this operation often as is necessary. Others, as that of Lycena Arg and many more of the Papiliones Rurales and Urbi” le L., which have a short and more rigid body, u : : 0 having bent the head on one side so as to fix one end ands nit” the thread, bring themselves into a straight position, by a manceuvre not easily described, contrive tol duce the head under the thread, which they then pa themselves to fasten on the other side, pushing it t°! proper situation by the successive tension and contra tion of their segments. But the most curious mod” though indeed that which seems most natural, is adopt? STATES OF INSECTS. 213 by the caterpillar of the beautiful swallow-tail butterfly (Papilio Machaon) and others of the same family. This tst forms the loop which is to serve for its girth, and a “n creeps under it. But the difficulty it has to surmount s to keep itself from being entangled in the fifty or sixty Ne distinct threads of which the girth is composed, and to Preserve them all extended so as to be able to intro- Ace its body beneath them. For this purpose it makes "Se of the two first pair of its fore-legs, employing them “8 a Woman does her hands in winding a skein of cotton, a Collect and keep all the threads of its card unentangled ead Properly stretched; and it is often with great diffi- “ulty, towards the end of the process, that it prevents m from slipping off. When a sufficient number of threads is completed, the animal bends its head between “gs, and insinuates it under the collected loop, which Yits annular contraction it easily pushes to the middle Ë the body. ù about thirty hours after the larva: which girth them- $ ves have finished their operations, the skin splits, and be Pupa disengages itself from it by those contractions dilatations of its segments which have been before n neribed, pushing the exuviæ in folds to the tail, by dif- Motions of which it generally succeeds in detach- 3 them. One would have thought diets would eeann ù erable difficulty in slipping the skin past the girth ; ‘ this, according to Reaumur, seems to be easily ef- Cted a > If ee s ; . i You are desirous of witnessing for yourself the manceu- ae : ; ; ; 3 by which ‘these curious modes of suspension are a . . For the above account see Reaum. i Mem. x. xi. 214 STATES OF INSECTS, effected, you may be readily gratified. It is only neces” sary to collect and feed until their metamorphosis the black spinous caterpillars of the common peacock-but terfly (Vanessa To), which in most places may be foun upon nettles, or those of the Pieris Brassica, which swart in cabbages or brocoli in every garden. The former ¥” exhibit to you a specimen of vertical, the latter of hor zontal suspension. It should be observed, however; that to hit the precise moment when these processes are go ing on, it is necessary to feed a considerable number © the larvee of each kind; some one of which, if you wate them narrowly when they have attained their full growths you will scarcely fail to surprise in the act. I must observe here, that although the vertical and horizontal are the two principal positions in which cater pillars suspend themselves, yet that others are inclined ™ various angles; and some are attached with less art, 2 pearing only to be fastened by some part of their abdo” men to the body upon which they are fixed *. 2, The larvee whose procedures Iam in the next plac to describe, are those which, previously to assuming the pupa state, inclose themselves in cases or cocoons of dife rent materials. For the sake of method, I shall divi Š ; g y these into two great classes: First, those which form the? cocoons entirely or principally of silk; and secondly) y those which form them chiefly of other substances. To begin with the frst. The larve which inclos? themselves in silken cocoons are chiefly of the Lepi pterous tribes of Bombycide and Noctuidæ; but & 2 N, Dict. @ Hist, Nat. vi. 21—. STATES OF INSECTS. 215 Geometre (G. papilioniaria, lactearia, &c.); most of the Ymenoptera; some Coleoptera, as certain of the weevil tribe (Hypera Arator, Rumicis Germ.), and those bril- liant beetles frequenting aquatic plants constituting the Snus Donacia F.; the Neuropterous genera Hemerobius md Myrmeleon ; Mycetophila and a few others in the ~ tptera ; and Pulex in the Aphaniptera fabricate cover- Mgs of the same material. In all, with the exception of Myrmeleon and Hemerobius (and perhaps Hypera Rumi- “8, &e.?) which have their spinning apparatus at the “xtremity of the abdomen, the silken thread employed in ‘Ming these coverings proceeds from the middle part of © under-lip, as hefore explained; and is in fact com- Posed of two threads gummed together as they issue from © two adjoining orifices of the spinner. Of the larvae which inclose themselves in silk, the most “Mhiliarly known is the silk-worm: the cocoon of this Consists exteriorly of a thin, transparent, gauze-like coat- hg, through the interstices of which can be seen an in- t, smaller, oval ball of a more close and compact tex- We. The whole is in fact composed of one single tead, but arranged in two distinct modes. To form € exterior envelope, which is merely the scaffolding by “ans of which the inner and more solid covering is con- : “ucted, the caterpillar, after fixing upon a space between Wo leaves or twigs or angles suitable for its purpose, ` Sins by glueing one end of its thread to one of the ad- Vining surfaces. This thread it next eonducts to another Part and then fastens, repeating this process and inter- aay itin various directions, until it has surrounded it- With a slight and loosely spun netting. In the cen- © of this, when contracted into a space sufficiently small, O16 STATES OF INSECTS. it lays the foundation of the interior cocoon. Fixing it self by its prolegs to some of the surrounding threads it bends its body, and by successive motions of its hea from side to side spins a layer of silk on the side opp” site to it: when this is of the requisite thickness, the larv? shifts its position, and repeats the same process in anoth quarter, covering each layer in turn with a new 0? until the interior cavity is reduced to the size desiret Thus, the silken thread which forms this new cocoon is not, as might have been supposed, wound circularly ® we wind the thread of a ball of cotton; -but backwards and forwards in a series of zigzags, so as to compose a nU™ ber of distinct layers. Malpighi could distinguish six © these layers*, and Reaumur suspects there is often ® greater number’, The former found the length of th thread of silk composing them when wound off, w ithout including the exterior case, to be not less than 930 feet? but others have computed it at more than a thousand consequently the threads of five cocoons united would be a mile in length. Estimating by the weight,—the thread of a pound of cocoons, each of which weighs about tw? grains and a half, would extend more than 600 miles i, and sueh is its tenuity, that the threads of five or six €% coons require to be joined to form one of the thickne® requisite in the silk manufacture. It is the continuo” thread of the inner cocoon which is most valuable; the outer loose coating from its irregularity cannot a De Bombyc. 24. b i, 498. © De Bombyc. 43. à N. Dict. d’ Hist. Nat. vi..294- e Lesser. L. ii. 156, note 22. Boyle says an English lady found that the silk of a single cogoon nbi extend 300 English leagues OF miles. But this must be a mistake. STATES OF INSECTS. oa Wound off, and is known in commerce by the name of floss Silk, Manceuvres in their general principle similar to those of the silk-worm are followed by most of those larvae Which inclose themselves in silken cocoons. Many spe- cies, however, adopt variations in the mode of procedure all of which it would be tedious to particularize, but some of them are worth mentioning. The larve of Tortrix Prasinana, and other species of moths which form co- “Sons resembling a reversed boat, arrange their threads oa layers, so as to construct two parallel walls gradually Acining towards the top and ends, where they finally Orce them to approach each other by means of an appa- tatus of silken cables ^. And the larva of Saturnia Pavo- Ma, though it forms the base of its flask-shaped cocoon by ‘Pinning like the silk-worm a number of interwoven zig- Zags, places the threads which compose the interior fan- nellike opening of the apex nearly straight, parallel to “ach other, and converging towards the same point in € centre », | ; These last, as well as almost all larvæ, constantly re- Main in the inside of the cocoon during its construction. ut De Geer has given us the history of a minute cater- Pillar of a species of moth (Tinea L.) which feeds on the Under side of the leaves of the Rhamnus Frangula, or “ack Alder, that actually weaves half of its cocoon on the Utsig e g This cocoon, which is very small, is beautifully “Uted » Consisting of several longitudinal cords, with the Mtervals filled by fine net-work, and shaped like a re- y p "etsed boat °“. ‘The animal begins by laying the founda- ““Reaumid. 5o5—<,- b Prats XVII. Fre. 5. b. ° De Geer i. z. xxxii. f. 3—6. 218 STATES OF INSECTS. tions of one of the ends of her cocoon, she adds new threads to this small beginning, and so proceeds. As the work advances she retreats backwards, and her body is situated nearly in the same line with the cocoon she has begun, and quite oud of it; she only touches with he head and legs its anterior margin. When half the ee coon, or rather of its exterior layer, is finished, she su pends her operations for some moments. She then fo! the first time introduces her head into this demi-cocoo™ ‘and turns herself in it by doubling her supple body, 3” passing one part over, the other, so that at last she M% nages to bring her tail into the pointed end of the cocoo™ the head and the anterior half of her body remaining without. Thus situated, she commences her operation’ afresh. At a distance from the margin of the demi-©™” coon, equal to its length, she begins to spin the pointe end of the other moiety, the length of her body serving her as a measure that enables her to begin at the prope distance from it. This new portion she spins in the sam? manner as the other ; but as she is prevented by the de®” cocoon in which the posterior part of her body is lodg® from retreating backwards, she contracts her body mores which answers the same purpose. When the new wor is so advanced that she can no longer contract her bodys she bends the anterior part of it considerably, and 1 verses her head. When the distance between the ma“ gin of the two halves of the cocoon is very small, so as” longer to admit the head between them, in order to unit? them she is obliged to have recourse to another mane’ vre. Withdrawing her head, she extends silken longi” dinal threads between the two margins, and thus unit? them. This part is more clumsy, and not so regular A STATES OF INSECTS. -219 the rest of the cocoon, so that the point of union is always 'Scoverable. These caterpillars do not always divide ' “cocoon into two equal portions, for often they will ish three quarters of the cocoon before they enter it, and begin at the other end 2. | The general rule is,—that each larva spins for itself a “parate cocoon ; but amongst those of Arctia chrysorhea “nd others which live in society, two or three sometimes egin their operations so close together that they. are Under the necessity of forming one common cocoon, which aves for a covering to the whole number. The same A mg happens to silk-worms, the double or treble cocoons “Which are called Dupions by the breeders. The larvee °t some Ichneumons, besides forming each its separate “coon, spin a joint cottony covering for the whole», Which is effected thus:— After they leave the caterpillar “SY have devoured, they fix themselves side by side ata itle distance from it, and begin to spin each a cocoon; “td in order to defend its end and side that is not covered Y others, they spin further an envelope of loose silk, . "Nd thus this exterior covering is formed. i The size, figure, colour, substance, and texture of à ke cocoons are extremely various. Their size indeed Sually proportioned to that of the included larva or Pupa ; yet it is by no means always so. Some large ca- t . “tpillars spin cocoons so small, that the observer can ay conceive how they can be contained in so narrow Na pass: Eriogaster Cataz is a moth of this descrip- lo ree ; . n°. And others smaller in size lodge themselves in ; De Geer i. 463—, : aa li, Mem. xi. Comp. De Geer ii. 162, Reaum, ii. 424. - Catax—Pupa arcte folliculata, Fab. 220 STATES OF INSECTS. apartments apparently much more spacious than neces sary. ‘The transparent hammock-like cocoons of Hep alus Humuli and Arctia villica, two other moths, would contain seyeral of their pupæ. I possess one in which the pupa is suspended in the centre, that is ten times its size, and-not very short in dimensions of that of Attacus Paphia, a giant silk-moth. The largest cocoon I evel read or heard of, is that thus described by Mr. Hobhous? in his Travels: “Depending,” says he, “from the boughs of the pines, near the Attic mountain Parnes, and stretch ing across from tree to tree so as to obstruct our passag’s were the pods, thrice as big as a turkey’s egg! and the thick webs of a chrysalis, whose moth must be far larg® than any of those in our country.” è — If this statement is correct, and I am not aware that there is any reaso! for doubting it, the cocoon must be vastly larger than the pupa, or the moth it produced would far exceed in siZ? any yet known. Perhaps, however, as this gentleman 15 probably no entomologist, what he took for a cocoo? might be a nidus, in which many larvee were associated» of the nature of those formerly described ’. With regard to figure, the majority are like those of the silk-worm, of a shape more or less oval or elliptic? some, however, vary from this. That of Lasiocamp" Rubi is oblong. I have one from New Holland some what resembling an acorn, fixed to the twigs of some tree or shrub, of a very close silk, and covered by a circulat operculum, which the animal pushes off when it assumes the imago; this is ovate or conico-ovate; others again 4° globose °; others are conical*, as that of Gastropach@ 2: Travels in Greece, 285. b See above, Vor. I. p. 476 e Merian Surinam. t. xv. à Reaum. ii, é, xxiii. f. 5. STATES OF INSECTS. 221 Quercifolia ; others almost fusiform? (Odenesis potatoria). faumur received one from Arabia which was nearly ‘ylindrical®. Those of T. prasinana before noticed, and many other Tortrices, are shaped like a reversed boat €; that of Saturnia Pavonia and others of the same tribe, like a Florence flask with a wide and short neck. . The Cocoon of Lygena Filipendule resembles a grain of bar- SY. Another cocoon in my cabinet, of very slight net- Work, is shaped something like an air-balloon. But the Most remarkable one for its form and characters, is one hat I received from the rich cabinet above quoted. This, Which is of an unusually close texture, is suspended by à thread more than two inches long from the'point of a “af; it then swells into a perfect cone, at the base about °ur-fifths of an inch in diameter and half an inch in “Agth, and covered with scattered setiform appendages : Om the centre of the base projects a large hemispherical Protuberance, which terminates in a long stalk, much “ticker than the thread that suspends the cocoon. There ™ > Commonly no difference between the shape of cocoons ‘Pun by larvee which are to give birth to different sexes of ' -S same species. The silk-worm cocoons, however, Which will produce male moths, have more silk at the “ds, and consequently are more round than those which oto produce females: but the difference is not strik- g. = The most usual colour of silken cocoons is white, yel- OW, or brown, or the intermediate shades. The whites ` very pure in the general envelope of some species Ichneumonide, and yellows often very brilliant. But * Sepp. iv. z. viii. f. 5. b Reaum, i. £. xliv. f. 2. © Plate XVIL Fre. 7. ae a 222 STATES OF INSECTS. besides these more general colours, some cocoons ar black #, some few blue or green, and others red? Some times the same cocoon is of two different colours. Thos¢ of certain parasites of the tribe of Ichneumones minuti L the motions of one of which I noticed on a former occa- sion °, are alternately banded with black or brown and white, or have only a pale or white belt in the middles which gives them a singular appearance. In both cases the difference in colour depends upon the different tints with which the silky gum is imbued in the reservoirs’ the first portion of it is white, and with this the larv# first sketches the outline of its cocoon, and then thickens the layers of silk considerably in those parts where th? white bands appear: when these are finished, its stock of white silk is exhausted, and the remainder of the inte rior of the cocoon is composed of brown silk 4. The cir- cular operculum above mentioned as covering an acor” shaped cocoon, is paler than the latter, and also orn mented by a zone within the margin of deep brow? The pale cocoon also of Attacus Paphia is veined with silk of a deep red. I have very little to say on the substance of the silk of cocoons. Though that of the silk-worm is composed ° such a slender thread, that of many others is still fine” scarcely yielding in tenuity to the spider’s web. On the other hand, the silk of the cocoons of Saturnia Pavonia and of several foreign species is as thick as a hair. With regard to the texture of their cocoons—-in som as in that of the silk-worm, the threads are sO slightly 2 I have a black one from Mr. Francillon’s cabinet. b N. Dict. d Hist. Nat. vi. 294. e See above, Vor. I. p. 298—. 4 Reaum. ii. 436. STATES OF INSECTS. 223 glued to each other, as to separate with facility; but in that of the emperor-moth just mentioned they are inti- Mately connected by a gummy matter, furnished, as faumur conjectures, from the anus*, with which the Whole interior of the cocoon is often plastered. Some, 4S that of the silk-worm, are composed of an exterior Ose enyelope, and an inner compact ball; others have Ro exterior covering, the whole cocoon being of an uni- form and thick texture. The larva of Cossus Robinia eck, in spinning its cocoon, makes the end next the pening to the air, by which the imago is to emerge, of a ‘lighter texture than the rest of it®. The exterior case 'S Sometimes, as in Laria pudibunda, very closely woven, 0 as to resemble a real cocoon®: its form is usually adapted to that of the inner one; but in some which fix them under flat surfaces (Laria fascelina, Callimorpha Caja,) it resembles a hammock. Cocoons of a close texture have generally no orifice in any part; but that of “ogaster lanestris is spun with openings, as if bored m without, the use of which, however, does not seem to have been ascertained’. Many silken cocoons are of so close a fabric, as, when ished, entirely to conceal the included insect; but a Very considerable number are of a more open texture, Composed of a much smaller quantity of silk, and that Woven so loosely, that the larva or pupa may always be 'SCovered through it. Of this description are the co- as of Hypogymna dispar, Arctia Salicis, &c., which “ist only of a few slight meshes. Those of some others . Reaum. i. 503. b Peck on Locust-tree Insects, 69. : Bonnet ii. 260, 4 Sepp. iv. £ii f 4. Brahm, Ins, Kal. 289. 224 STATES OF INSECTS. resemble gauze or lace*. Of the first description is one in my cabinet before alluded te, shaped somewhat like an air-balloon; the meshes are large and perfectly squat® The pupa hangs in the centre, fixed by some few slight threads which diverge from it to all parts of the cocoon— so that it looks as if it was suspended in the air, like Mahomet’s coffin, without support. Of the second de- scription is a black one with very fine and nearly circula meshes: the threads that form these are thick, and see™ to be agglutinated. In our own country, the cocoons of some beetles, as of Hypera Arator, Galeruca Tanaceti, and of some little Tine, also resemble gauze. Many of the larvee, however, which spin these. cocoons, whose thin- ness is probably attributable to the smallness of thei stock of silk, seem anxious for a more complete conceal- ment; and therefore commonly either hide them betwee” leaves tied together, in some with a certain regularity’ in others without art’; or thicken their texture, a” render it opaque, by the addition of grains of earth Z: or of other materials with which their „bodies sup“ ` ply them. ‘These are principally of two kinds. The larvee of Lastocampa Neustria, Arctia Salicis, &e. afte! spinning their cocoons, cast from their anus three or fow" masses of a soft and paste-like matter, which they apply with their head all round the inside of thé cavity; 2 which, drying in a short time, becomes a powder that effectually renders it opake. This is not, as might. be conjectured, an excrement, but a true secretion, evidently a Prate XVII. Fie. 8. b The thick cocoons of Attacus Paphia, Polyphemus, &e. are also thus fastened between leaves. ¢ Merian Europ. ii. t. ix. STATES OF INSECTS. 295 Atended for this very purpose: and, according to Reau- Dur, a similar powder, but white, derived from the vari- “Ose intestines, is used by the caterpillars of Gastropacha Wer cifolia, &e.* The other material, which is still more "equently employed, and which is occasionally mixed Mith the former, is the hair which every one has observed to Cover so thickly the bodies of some caterpillars. This, atter Spinning a sufficient envelope, they tear, or in some aces cut off with their mandibles, and distribute all Nd them, pushing it with their head amongst the in- “stices of the silk, so as to make the whole of a regular k texture. After this process, which leaves the body Co; : > "pletely denuded, and often seems to give them great am : ] Silk Sup » they conclude by spinning another tissue of slight > in order to protect the forthcoming pupa from the ping prickly points. It should be observed, how- > that though many hairy larvee, as those of Noctua ris, Arctia Caja, and others, employ their hairs in the “Dosition of their cocoons, the rule is not general, Vera] never making any such use of them. Nor do all do so employ them distribute them in the same man- as those above described, which rarely attempt to Ta: 3 er = se them in an regular position. Reaumur has no- t y reg p € 5 3 : í is a small hairy caterpillar that feeds on lichens, which „„ re methodical : this actually places its hairs upright, Sid 3 : i * by Side, as regularly as the pales in a alisade, in oo } p ORR : > ig rme around its body, connecting them by a slight tor ` silk, which forces thein to bend into a sort of at the top; and under this curiously-formed cocoon Suy š Nes its state of pupa’. Some larvae make so much * Reaum, ii, 284. b Thid. i, 524, Vor, try. 296 STATES OF INSECTS. hair and so little silk enter into the composition of thei! cocoons, that on the first inspection they would be pr nounced wholly composed of it*; others, thickening t»? interior of their cocoon with hair, line the whole with # viscid matter like varnish ». The larvee of some saw-flies (Zenthredo L.) are ee markable for inclosing themselves in a double cocoon, ™ which the inner is not, as in the silk-worm &c., connect® with the outer, but perfectly distinct from it. Some sp” cies, as T. Rose (Cryptus Jur.), which have but a s™# stock of silk, compose the outer cocoon of thick silke” cords crossing at right angles, and forming an oval nêt which atthe same time that it protects them effectu from the ants, which are always ready to attack them, de mands much less silk than a covering of a closer textur" But the tender nymph itself requires to be inclosed 1? ý case of a softer and more delicate substance; and accot® ingly the inner cocoon is composed of fine silk, W we so closely that the threads are scarcely perceptible unde a microscope °. Reaumur mentions a hymenoptet™ larva belonging to Latreille’s Fossores (Sphex L.) wh thickened its cocoon with the legs, wings, and other rel! of the flies which it had devoured ¢: mophics W drinking- cups of some savages, made of the skulls of thet enemies, or the skull-pyramid near Ispahan—of yi powers of devastation. - It is a general rule, that these larvee which spin 5 coons, never in ordinary circumstances become pep without having thus inclosed themselves. An except!” however, is met with in the larva of a species of ant ” a Bonnet ii. 297. ò Ibid. ix. 181. c Reaum, v. 102. á Thid; iv. 269. STATES OF INSECTS. UST "eed by De Geer (Formica fusca L), some of the indi “duals of which inclose themselves’ in cocoons; while thers neglect this precaution, and undergo their meta- Morphosis- uncovered. Rösel also made nearly the, ‘ame observation on the larva of the flea. . must say something with regard to the situation, Piten very remote from their place of feeding, in which atvæ fabricate their cocoons. A very considerable num- as probably the majority, form them either partially Arctia lubricipeda) or wholly under ground; others “neath dead leaves, moss, or in the chinks of the trees; “ts within the wood in substances on which they ome fed; the larya of Cossus leaves in these a communi- “ton with the open air by which the imago emerges; ' a large number attach them to the leaves and ranches of trees and plants; the cocoon of Donacia fas- sata (?) is fastened by one side to the roots or surculi of Hha latifolia. There is usually nothing very remark- ~ Cin the mode of fixing them, the exterior threads me merely cummed irregularly to different portions of objects which support them. But some effect this with “ater art. I have one from New Holland, very long, ch is suspended from a twig by a long riband, as it re, Which entirely girths the twig. The larva of the Shificent silk-moth, Attacus Paphia, actually forms a Silken stalk to its cocoon, an inch and half in length De tion of Geer ii. 1084. Comp. Ray Hist. Ins. Preef. xi. It is the opi- of the: M.P. Huber, that in this case the naked pupæ are deprived Seen cocoons by the neuters: he states, indeed, that he has often and h em pulled off by them, and also by those of F; cunicularia ; des * Seems to think-that these larva: are never developed. Meurs b rurmis, 84. note 1. > vu, 16, 228 STATES OF INSECTS. and a line in diameter, fastened by the other extremity to a twig, which it closely surrounds as if with a ring at first sight resembling a fruit. of a very singular ap- pearance*. I have specimens of this cocoon with bot stalk and ring. A bell-shaped cocoon fastened by a foot stalk, but of softer consistence, to a blade of grass, foun by Mr. Sheppard, I can also show you; and my frien Mr. Wilkin had a similar one out of the late Mr. Hud son’s collection. Most larvae spin their cocoons in solr tude: some of those, however, which live in society dost close together under their common tent. There are other cocoons that should be noticed he! such as those formed by the larva of Zygena Filipendul@ and some Bombyces, saw-flies (Tenthredo L.), and bee tles (Curculio, Donacia F.), &c. These are formed ° a substance which seems more analogous to gum that silk, yet furnished from the silk reservoirs, and usuallý present the appearance externally of parchment or me” brane. That of the insect first mentioned is coat” however, with a slight interior silken lining; as indeé are almost all cocoons, of whatever substance. The ‘second class, into which I have divided larvæ that inclose themselves in cocoons, includes those which for their coverings not solely or principally of silk, but? j which other materials are mixed more or less. The 0%” coons of some of these larvee are merely composed of § few leaves slightly tied together, either irregularly, °" a ranged, particularly when they are of a linear figure, w! considerable symmetry. The grubs of many beetles, #° : * Linn, Trans, vii. t, iif. 5, 6. STATES OF INSECTS. 229 the rose-beetle, Cetonia aurata, &c., prepare themselves a ©0coon, composed of earth, pieces of rotten wood, and any Substances within their reach; which they fasten together Witha glutinous secretion. The same material is employed Y Others in forming a cocoon wholly of earth; which he Sometimes, as that of the stag-beetle, Lucanus Cer- vus, exceedingly hard; at others, as that of some moths, Octua ambigua, &c., so slight as to fall to pieces as soon 3S touched a; Other cocoons are formed of grains of “arth, Reaumur has given avery interesting account of € Procedures of a larva in repairing one of these co- ag from which he had broken off the top when just Mpleted. Without quitting the interior of the walls at remained, it put out its head from the breach, and % more than an hour employed itself in selecting one Y one grains of earth, which it conveyed with its mandi- ês and deposited within its case: it next spun all round ‘ pening threads of silk, to which it attached grains n earth taken from the previously-stored heap, uniting ss Compactly by means of other silken threads. After Ploying three hours in this laborious process, the in- "Sttious little mason had reduced the diameter of the yp to a few lines. Reaumur was very curious to bis how it would fill up this orifice, which would no r: ¥ admit the protrusion of its head outside the sia Its previous operations. He concluded, that while e Test of the cocoon was exteriorly formed of earth, | Ete would be merely closed with suk. He was en, however: the artist knew how to vary its a Wie ii, f l E Verz. I possess a cocoon of this kind from New Hol- v : : ee : ee en now quite solid, and retaining its form. No silk appears © been used in its composition. ; 80 STATES OF INSECTS. manoeuvres, and make its vault of one uniform textwr® It spun across the opening a little net of silk, between the meshes of which it thrust grains of earth so dexterousl that they projected as far as the outer surface, retained there probably by silken lines previously attached and fastened within. It then finished its habitation by forti- fying the inside of the orifice with another layer of earth" The ant-lion (Myrmeleon) spins a globular cocoon with its anus, which it covers with grains of sand». One that } took in the forest of Fontainebleau, in the quarry that pr” duces the crystallized sandstone called the Fontaineblea” fossil, was covered with large and shining grains. Instead of the grains of earth or sand employed by these larv% those of another tribe substitute grains of stone detached from the softer walls, upon whose lichens they previously feed, which they unite into solid oval cocoons*. Tho® of a fourth form their cocoons of patches of short mo% arranged with the roots downwards, and forming a vault as it were, of verdant turf, admirably adapted for con" cealment 4.. The larvæ of some moths form their coco” of irregular pieces of bark tied together with silk, 2” resembling when completed a knotty protuberance of the twig on which they are fixed. That of Pyralis tuber lana constructs a pannier-shaped one of the parenchy™ of the leaves of plants ¢. All these cocoons, however, must yield in point of singularity of construction, materials, and ingenuity» j one formed by a small caterpillar, described by the illus trious naturalist lately quoted, which feeds upon the 9” This cocoon is wholly composed of small rectangulé * Reaum. i. 579. b Thid. vi. 368. © Ibid. i. 542 a Ibid. 543. e Linn. Trans. i. 196. STATES OF INSECTS. 22) Strap-shaped pieces of the fine upper skin, or epidermis of the twig upon which it rests, regularly fastened to each Other in a longitudinal direction with very slender silken ords. But the mode of its construction is even more "emarkable than the substance of which it is fabricated. he caterpillar’s first process is to form its slips of bark into two flat triangular wing-like pieces, projecting oppo- Site to each other from each side of the twig, somewhat ike the feathers of an arrow. It does not, perhaps, re- Wire any great degree of intelligence in a larva to give its Cocoon the usual oval form, when it begins to arrange its Materials in that shape from the very first, and round 50 good a mould as its own bent body; but we surely must admit that it is a task to which no stupid artist would be “oMpetent, to form first a multitude of strap-shaped la- Ming into two triangular plates, and then to bend these Plates into a case resembling the longitudinal section of a “one, with an elliptical and protuberant base,—the figure Which the cocoon of this insect assumes. All the minu- Œ of the manœuvres which it employs in this nice ope- "ation could not be comprehended without a more diffuse , Xplanation than I have here room to give: suffice it to “AY, that the caterpillar fastens silken lines to each exterior *PPosite and longer side of the laminee, and by applying all the weight of its body forces them to bend and ap- Proach each other, in which position it secures them by ter shorter lines. It next repeats the same process "ith the upper and shorter sides of the plates; which When joined form the base of the cocoon. Both these a sks are e accomplished in less than an hour, and the seams ar © 80 nicely joined as to be imperceptible. A fine inner p estry of silk, covering all the asperities of the exterior 239 STATES OF INSECTS. walls, concludes its labours *. It is to be lamented that Reaumur was unacquainted with the moth that proceeds from the pupæ inclosed in these ingenious cocoons: which being small, and precisely of the same colour as the bark of the twig that supports them, are not to -be discovered but by a very narrow inspection. It would seem, however, to be Noctua Strigula of Berkhause” Pyralis strigulalis of Hubner. The larva, he inform us, is found in May: its body is flatter than common, ° a yellowish flesh-colour, clothed with tufts of red hair 0” each segment, and furnished with fourteen feet. Should this description enable you to detect it upon your oak a view of its ingenious procedures would amply repay you for the trouble of seeking for it. The larve of Ce rura vinula, Stauropus agi, and several other moths form their cocoons of grains of wood gnawed from the trees on which they feed. These grains they masticat® mixed with a glutinous fluid secreted from the mouth, into a paste, which forms a covering of an uniform smoot texture, and so hard as not readily to yield to a knife- Of a substance apparently nearly similar is composé the cocoon of a weevil related to Liparus Pini ; which with its inhabitant was given me by the ingenious Mr Bullock. A little moth, whose ravages have been before noticed °, lines the interior of the grain of barley, : which it has devoured the contents, with silk; divides it into two apartments, into one of which it pushes the e% crement ithad voided, and in the other assumes the pupa” These, and the other larva mentioned above, com * Reaum, i. 545—. b Pyral, 8.3. t. iti, f. 16. ®* See above, Vor. T. p. 172—. * Reaum, ii. 491, STATES OF INSECTS. 233 monly form their cocoons of the substances I have indi- “ated ; but when by any cause they are prevented from i to them, they often substitute such other materials at hand. Reaumur fed a larva that formed its oon of minute fragments of paper, which with its piles it had cut from the piece that covered the glass Sel that contained it?: and the same circumstance *ppened to Bonnet. of y mu a former occasion I described to you the cases rious kinds formed and inhabited by the insects of i Trichoptera Order (Phryganea L.) commonly called “worms>, As these serve for the pupa as well as : a they may be regarded as a kind of cocoon. I k not repeat here what I then said; but having por y ed from the collection of the late Mr. Francillon te that seem to belong to this or some cognate tribe, “ag are of a curious i ia I niihi give you some : of two or three of them in this place. The first Ot quite three inches long, of a sublanceolate shape, aah widest tondre one end. It consists of an in- _ #1 tough and thick bag or cocoon, of a silk resem- . - fine wool of a dirty white colour, which is closely 3 ed transversely by pieces of the stalk of a plant, E three-fourths of an inch in length, and crossing other at an obtuse angle. ‘The next is thicker and =$ 0 : See ; s "ter: the internal bag is just covered with small frag- e : nts of wood like sawdust; over these are fastened ir- re 5 : . Sularly, short stout pieces of a pithy stick or stalk, and Eo : : Whole is clothed with a very close-woven ash-co- Cured web. x It seems difficult to conceive how the in- Ose ‘ ‘ eae ; d animal could contrive to cover her habitation with Reaum, i, 540. b See above, Vor. I. 467-—. II. 264. 234 STATES OF INSECTS. this web without going wholly out of it. The third i$ the most curious and remarkable of all. It is nearly six inches long, and about four-fifths of an inch in diamet™ It. consists of a bag of thick cinereous silk web, to which are fastened, in a sextuple series, pieces of stick about 4” inch long, the end of one mostly resting upon the base ° another: between each series a space of about three-tenth® of an inch intervenes, but at the apex they all converg® This probably imitates the branch or stem of some tre or plant, in which the leaves are linear, and diverge but little from the stem. A label upon it states its country t° be New Holland. I suspect the inhabitants of the tW? last cocoons to be terrestrial animals: the first is proba bly a true aquatic case-worm. The same purpose for which the cocoons above de scribed serve, is answered in the case of numerous D” pterous insects, by a humble and less artificial contri” ance—the skin, namely, of the larva; which, as was b% fore observed *, is never cast, but, when the insect is about to enter into the pupa state, assumes a different form and colour; becomes of a thicker and more rigid texture: and defends the included pupa, which is separate from it till its exclusion. In this case the mouth of the larva ® constantly different from that of the perfect insect, of at least has not with it those relations as to number 3” kind of organs, which have been observed in the mouth of other larvae compared with the insects that they p” duce. The animal, immediately after it is clothed W this skin, if it is opened, exhibits only a soft gelatine” * See above, VoL. I. p. 67. STATES OF INSECTS. 235 k in the surface of which the exterior organs of the insect cannot yet be detected. Nature requires | More time for their elaboration, or at least for the ap- Pearance of their outline, and to consolidate them.: This H first takes an oblong form (Boule allongée Reaum.), id afterwards that of the insect it is destined to give rth to2, The skin of the larva also serves for a cocoon tothe pupæ of male Cocci®. The grub of the genus Án- it so destructive to our cabinets of natural objects £, iis. s assumes tho pupa does not quit its skin, but only S it open longitudinally on the back, and when it “comes an imago makes its exit through the orifice *. Ome Lepidopterous larvae even (Alucita pentadactyla, a imorpha rosea, &c.) assume the pupa state within. er last skin €. When a larva has finished its cocoon,—which with ` N. Dict. d Hist. Nat. xvi. 269—. xxii. 76. = eaum. iv. 32, The author here quoted asserts that the grub of wee Larvarum L, retains its skin, which, he says, is so trans- 44 that the form of the nymph can be seen through it. Ibid. ii... whic De Geer, however, found that this really did cast its skin, ally a so transparent as to be scareely visible, by pushing it gradu- Meet the anus, where it soon dries up and cannot then be dis- ao e Geer ii. 893—. According to Rosel the same circum- attends the transformation of Coccinella renipustulata Mig. had Ent. Brit.), which at first perplexed him not a little. It is n o that in this case the retention of the skin was accidental ; SRRI “i the grubs of a Mycetophila, the transformation of which ienga pe became pupæ within their last skin, while others wholly lecture A themselves from it. The cause of this variation, I con- selves ee arose from the former being too weak to extricate them- m the skin. c o above, Vox. I. p. 238. Byrrhus Musæorum belongs to this a f s N. Dict. d’ Hist, Nat. ii. 161. € Pezold. 102. 236 STATES OF INSECTS. some species, that proceed so earnestly as though they had not a moment to lose, is the work of a few hours; ° others about two or three days,—after a certain inter val it casts its last skin, which is usually suffered to remait in the cocoon (but which one moth, Geometra lacertinar™ ejects through an opening purposely left in its bottom) and the pupa makes its appearance *. This interval is exceedingly various. Most larvae assume the pupa state within a few days after they have formed their cocoons? but some not for several weeks, or even months. The caterpillar of Bombyx cer uleocephala, according to Rosel, lies three weeks in the cocoon before this change is ef- fected; those of many Pupivora and Diploleparie Latt according to Reaumur, six months®; that of Phalen4 urticata nine months*; and that of Cimbex lutea, accord- ing to De Geer, sometimes eighteen monthsè. Brah™ observes, that such larvee of the double-brooded moth, Hepialus Testudo, as form their cocoons in autumn, do not become pupæ until the following spring; while thos? which form them in summer undergo this change in ® few days®. From this fact it might be conjectured, tha! the degree of heat prevailing at the time the insect iD” closes itself determines the period of the pupa’s appeal ance; but this supposition seems contradicted by wha! Reaumur observed of a brood of the larvae of Phalam urlicata, just mentioned, which, though they formed themselves cocoons in September, did not become pup” till the June following f. I am unable, therefore, to 45 sign any plausible cause for these extraordinary varia- a De Geer i. 339—. > Reaum. ii, 423, and iii. 497. e Jbid. i. 605. 1 De Geer ii, 941. 8 Brahm Insek. 72. f Reaum. ubi supra, STATES OF INSECTS. 237 tions, The difficulty of comprehending how animals be- ore so voracious can live so long without food may be Partly surmounted, by adverting to the circumstance of Its having attained its full growth, and laid up a store of hutriment for the development of the perfect insect. It 5 consequently no more wonderful that it should not ®ve need of any further supply without casting off its *pper integument, than that it should not eat after hav- ™g doné so and become a pupa. LETTER XXXI. STATES OF INSECTS. PUPA STATE. WE have now traced our little animals through the egg and larva states, and have arrived at the third stag? of their existence, the Pupa State. This, to include ally can only be defined, —that state intervening between the larva and imago, in which the parts and organs of the perfect insect, particularly those of sex, though in fow cases fully developed, are prepared and fitted for the final and complete development in the last-mentior® state; and in which the majority of these animals # incapable of locomotion, or of taking food. Pupe, like larvee, may be separated into two great dr visions :— I. Those which, in general form, more or less rese™ ble the larvze from which they have proceeded: II. Those which are wholly unlike the larvae fro” which they have proceeded. I. To the first division belong, with some exceptions j 2 In the Hemiptera the male Cocci (Reaum. iv. 32.) and Aleyrodes (Ibid. ii. 311.) belong to the second division. i STATES OF INSECTS. 239 the Dermaptera, Orthoptera, Hemiptera, and most Aptera, With the neuropterous tribes of Libellulina, Ephemerina, and the genus Termes, in the class Insecta ; and the majo- “ty of the Arachnida. This, like the first division of “vee, may be subdivided into two corresponding smaller *€ctions; the first including those pupee which resemble the larvae, except in the relative proportion and number of some of their parts; and the second those that resem- le them, éxcept in having the rudiments of wings, or of Togs and elytra. l The first subdivision will include the pupæ, if they may be so called, of insects of the Aptera order, and of € class Arachnida : as, lice, Podure, Lepismide, centi- Pedes, millipedes, mites, harvest-men, spiders, scorpions, ® These mostly differ from their larvee only in that © relative length or number of their legs, the number of € segments of the body in some, or the development of eir palpi, more nearly approach the characters of the Perfect insect ; and in that while in their larva state they - =e two or more skins to cast, previously to their assump- ‘on of the imago, in their pupa state they have but one. - a fact, this last circumstance is the only one which, ‘rictly speaking, characterizes the pupæ of this subdivi- “dh; as the changes which take place in the number and Proportion of the organs are partly produced with each ä ange of the larva’s skin. And hence, as it is not easy ascertain what number of skins a spider, for example, 48 yet to cast, and as both the larva and pupa differ so x from the perfect insect, it is very difficult to deter- "ine in what state insects of this division are. From ‘ . . . . sic The terms Zarva and pupa, applied to the insects of this subdivi- n ate perhaps not strictly proper. 240 STATES OF INSECTS. this difficulty has probably arisen the too great multipli- cation of species in some of these tribes, particularly the Arachnida, the larva and pupa having been mistaken for perfect insects. The pupæ of this subdivision we! named by Linné complete, from the near resemblan@ which they bear to the imago. ii. The second subdivision will include the pup# of the Dermaptera, Orthoptera and Hemiptera orders, with few exceptions ; as likewise the Libellulina, Ephemerim and Termitina? amongst the Neuroptera : including the well-known tribes of earwigs, cockroaches, cricke! grasshoppers, locusts, lanthorn-flies, froghoppers (Ce cada L.), bugs, plant-lice, dragon-flies, day-flies, white ants, &c. Of these, as in the former subdivision, th? pupæ are equally capable of eating and moving with the larvee, which they resemble, except in having the rudi- ments of wings, or of wings and elytra. The pupæ ° the three orders first enumerated differ from those of thé Neuroptera in resembling the perfect insect in most 1™ stances, both as to shape and the organs for taking theif food ; and in all other respects, except in not having thet! wings and elytra fully developed?. The resemblance the pupæ of the Libellulina and Ephemerina to the p% fect insects is more distant, and the above organs in the two states are very dissimilar ; for the pupæ of the form® are furnished with a prehensory mask similar to that ° the larvee before described *, which the perfect insect h35 * The larvae and pupa of many of the homopterous section of Hem” ptera differ often from the imago, not only in their fore-legs (Prat XVI. Fic. 4.), but also in other respects. Ihave the larva of a Cen » trotus from Canada, given me by Dr. Bigsby, which has a long 4” process or tail, b See above, p. 125—. STATES OF INSECTS. » 24d Not: a. ie ®t; and those of the latter with the usual oral organs of Masticating insects, of which the imago has scarcely the tüdiments, ‘ Thave applied the term rudiments to the wings and Jtra in this state, not in a strict sense, but merely ‘to a their appearance; for in fact the wings, &c. are “sia but only folded up longitudinally and trans- ely, and inclosed in membranous cases, which when S change takes place = attached. to the pupa- state or pupa-case. The tegmina or hemelytra in this „S Usually cover the wings, and the upper wings the ‘der; but in the Libellulina both are usually visible. “ugh commonly very small compared with the instru- “ats of flight in the perfect insect, some of these rudi- “hts, contrasted with the majority, are of considerable ` agnitude, This is the case with those of some ‘species hermes, as we learn from De Geer ?. Tl. The second grand division comprises by far the ar ; “oe number of pupæ: those of all coleopterous, strepsi- rous >» lepidopterous, hymenopterous, dipterous, and wig Bterous, and by far the majority of newropterous in- X i well as the hemipterous genus Aleyrodes, and one th Coccus of the same order. These pupee, however; Ugh agreeing in the circumstance of being unlike the = -= which they proceed, differ si a other in z respects, and require to be divided into three : sections, as under :— ` those pupz in which the parts of the future insect, folded up under a membranous skin closely apply- each, are distinctly visible. To this head belong lary being i üg to è ii. 135. VOL III. R QAZ ; STATES OF INSECTS. generally, the pupæ of coleopterous* and hymenoptero insects; those of the neuropterous genera Myrmeleon an Hemerobius, &c.; the Trichoptera; amongst the Dipte" ay Culex, Tipula L., Tabanus, Bombylius, &c.; and that of i flea (Pulex). These were the incomplete pupee of Linn™ ii, Those pupæ in which the parts of the future insech being folded up under a harder skin, are /ess distinct discoverable. To this subdivision belong the pup of Lepidoptera, and of them alone. These are what Lint’ termed obtected pupæ. iii. Those pup which are inclosed in the thick and opaque skin of the larva, through which no ¢race of the perfect insect can be discovered. ‘These, which Lin? termed coarctate pupæ, include a large proportion of th? dipterous genera; as Cistrus L., Musca L., Empis Ja Conops L., &c. &c.® 2 The pupæ of Cassida, Imatidium, &c. seem to vary somewhat from this type, the upper part being neither membranous nor exhibit? distinctly the form of the inclosed imago. ts b The following arrangement of pupe is perhaps in some resp? e better than that above given, But it is scarcely possible to prop® one free from objections. ~ I. Capable of eating and walking. of i. Like the perfect insect, except in proportion and nus? of parts, he 1. Except in proportion (Lice, Podure, Mites, spid” Scorpions, &e.). je 2. Except in proportion and number (Centipedes, Mi pedes). ii. With rudiments of the organs of flight. ; w 1. With oral organs resembling those of the perfect sect (Hemiptera). fot! 2. With oral organs differing from those of the pe insect (Libellula L., Ephemera L.). II. Ineapable of eating and walking. i, Incomplete pupæ. li. Obtected. jii, Coarctate. STATES OF INSECTS. 243 I shall next advert, chiefly to the pupæ of the grand Wis} z sae à ‘ton last described, under the distinct heads of sub- an A i aes Figure, and parts ; colour, age, sex, motions, and Ur icg+; . cation of the perfect insect. As to their substance—at first interiorly all pupæ d MSist of a milky fluid, in which the unformed members ~ the fature perfect insect may be said to float, and in Lamarck a: 5 > marek divides the pupæ of insects that undergo a metamorphosis y Wee kinds, which he names—Chrysalis, Mumia, and Nympha. 7 Chrysalis, Under this denomination he includes all inactive Tis, Closed in an opaque puparium which entirely conceals them. € further subdivides into two kinds. tery, aati signata. This term is synonymous with the Pupa of Linné, or the Chrysalis of Lepidoptera and some Diptera. Pees hrysalis dolioloides. Equivalent to the Pupa coarctata Linn. larva, àt to those Diptera that assume this state in the skin of the akin Munia, All inactive pupæ which are covered by a transparent subdi tough which all the parts of the inclosed imago may be seen, ed also into two. Lin, “mia coarctata. Corresponding with the Pupa incompleta Q” Which includes the Coleoptera and most of the Hymenoptera. Ome SNS pseudonympha, confined to the Pupa of Phryganea and iii, y ers, This might be named Pupa subincompleta. | pha. Under this denomination are included all insects “ergo only a partial metamorphosis, and are active in their eo Corresponding with the Pupa semicompleta Linn. and also “mpleta MacLeay. See Anim. sans Vertebr. ii. 285—. Bard Tate has started an ingenious idea on this subject with re- se kj ae ; ‘ ; and ates a metamorphosis, which cony eyen both larva : stinct denomination : as thus etan Cmilarve and Deminymph, synonymous with the Semicomplete Q rphosis, 3. 3 ve and Nymph, answering to Incomplete Metamorphosis. , y Pillar and Chrysalis, answering to Obtected Metamorphosis. y. AA larve and Pupa, answering to Coarctate Metamorphosis, CR. Naz. xvi, 272. Rg DA. As STATES OF INSECTS. which they. may be discerned, and separated with m point of a pin*. In proportion as these acquire consist ency, and are more and more developed by the absorp” tion of the surrounding fluid, they occupy its place, e fill up the cavity of the puparium. The rest of this fiu passes off by transpiration ®. Reaumur is of opinion tha it is from the epiploon, or corps graisseux, that this matte is prepared, which he regards as analogous to the whit of an egg*. In coarctate pupe the included animal, d the pulp that contains its germes (in which the limbs 5 body at first are not discernible), fills at this period : whole skin-cocoon; but in proportion as the above eva poration takes place, and the consolidation of the bo’ and parts proceeds, it shrinks at each end, so that whe near assuming the imago, a considerable cavity app” both at the head and tail of the cocoon‘. At this paw of its existence, from the quantity of fluid included inf puparium, the animal weighs usually considerably mo than it does when become a perfect insect °. : The exterior integument or skin of pupæ, which is ust ally lined with a very thin white pellicle, is of differ” consistence in different orders. In the Coleoptera * j j Hymenoptera it is, with a few exceptions, of a soft } membranous texture; in the Lepidoptera (especially 7 that are not defended by cocoons), and Diptera, it is 0 rigid and harder, being either coriaceous or corne™ q fron Lepidopterous pupze, however, are not exclude à N. Dict. d Hist. Nat. vii. 57. b De Geer ii. 105. © Reaum. ii. 428—. Z r os 2 ; peat” Swamm. Bibl. Nat. Engl. Tr. ii. 32. t. xli. f. 2. Comp. IVe Eo RRVO PEs e Thid,i. 144, STATES. OF INSECTS. 245 the Jast skin of the larvae with this hard covering. At © Moment of this change the envelope is nearly as soft w membranous as in the order first mentioned. But *Y are besides covered with a viscous fluid, which ap- Pears to ooze out, chiefly from under the wings, and ah very soon drying, forms the exterior hard shell *. $ ust the antennee, wings, and legs, like those-of Colco- Ši and Hymenoptera, can be each separated from the "ty; and it is only after these parts have been glued to- e by the fluid just mentioned, which takes place in S then twenty-four hours>, that they are immoveably “tached to the body of the pupa, as we usually see them. 2 act, the essential difference between incomplete and tecteq pupæ seems to be, that in the former the limbs a Ody are only covered each with a single membranous ‘’gument, whereas in the latter they are besides glued ether by a substance which forms an additional and der envelope. It is not easy to explain the alteration at takes place in the texture of the skin of such dipte- Mi Pupæ as retain the skin of the larva. In the latter Sas generally a transparent and very fine membrane : “ € very same integument becomes to the pupa an Paque and rigid case. hs! i : he surface of the skin of the greater number of pupæ Mooth; but in those of many Papilionide it is rugose E ` Warty: this you may see, particularly in that of Pa- “= ° Machaon. In many of the hawkmoths (Sphinx L.) 'S Covered with impressed puncta. In Attacus Jo the Pher side of the channels that separate the intermediate “Stents of the abdomen are curiously striated with trans- , a + i Reaum, i, 355. b N. Dict. d Hist. Nat. ubi sup. 59. 246 ž STATES OF INSECTS. verse strize, formed of very minute granula, the lower side being transversely sulcated. In some few instances n in Arctia Salicis, Laria pudibunda and _fascelina, the sion of the pupa is clothed with hair: as is also that of " speria Bixe, according to Madame Merian®. De Get! has described a little beetle under the name of Teneh™ lardarius (Latridius Latr., Corticaria Marsh.), the pap of which is beset with very fine hairs, terminating j a spherical or oval button €. ii. I shall include under the same head both the fig or shape, and parts of pupee, as the latter in most kind are either the same or nearly the same as those of w larva, or merely incasing those of the imago, so as not ; require that detailed notice that I judged necessary whet treating of the parts of larvee. : : ; ah With regard to incomplete pupæ, nothing further a be said of their extremely various figure, than that ith a general resemblance to that of the perfect insecte * head, trunk, abdomen, and their respective external e gans, are alike visible in both; but in the pupee, the jatte” instead of occupying their natural situation, are all close! folded under the breast and abdomen: or, as in the™ of the long ovipositors of some Ichneumons, laid along! back. In a specimen of some coleopterous insect va before me, the following is the order of the arrange” of the parts:—The head is inflexed; the mandibul# a” open ; between them are seen the labium and labial palp : these appear to cover and conceal the maxilla, and ” maxillary palpi extend on each side beyond thew * Prate XVI. Fic. 14. N. Dict. d’ Hist. Nat. vii. 59. i o Ins. Surinam. t. xliv. ¢ De Geer v. 47. t. ii. f 99-3? STATES OF INSECTS. 247 tenna pass above the thighs of the two anterior pair” “gs, and then turning down over the breast between m and the posterior legs, repose upon the base of the Ving ; which also are turned down between the inter- iate and posterior pair of legs, and rest upon the lat- "3 the tibia are bent in and folded upon the thigh, a the tarsi turn outwards*. In another coleopterous ‘Decies, the wings and elytra are placed under the hind- Bs. I all n ETymenopterous pupz the antennze appear usu- y to lie between the legs®. In many Tipule the long Bs are bent into three folds in the pupze; but the tarsi a and lie close to each other, the anterior eing the shortest®. In a specimen belonging to R $ pn: in my cabinet, which I think contained Cteno- is ” Pectinicornis, the six leg-cases are of the same la “eth, exactly par: allel and adjacent, and being annu- Wear the appearance of trachee*. ‘These parts ve each their separate case, so that a pin may be intro- Need between them and the body: which cases, as well © general envelope, are usually formed of a fine soft i Parent membrane; but sometimes, as in the lady- "4 (Coccinella), the tortoise-beetle (Cassida), the.crane-, thon îpula); &c. it is harder and more opaque, so that 8h it is usually easy for a practised Entomologist om an examination of the pupa, particularly in the Hy- 'Optera, to predict to what genus thë insect to be dis- “lt the pupa of Hydvophilus piceus (Lesser L: t. ii. f. 18, 14), the fer p aan of the parts is nearly the same, but the tarsi are not re- ae e mos? 10. De Geer ii. ¢. xxxii. f. 5. Reaum. v. ¢. xxxvi.f. 14, “There Ibid. t. iif. 9. eer € legs of Tipula replicata L. are placed ina similar way. De VER xx. FNLI 248 STATES OF INSECTS. closed from them will belong, yet in these cases the organs : i ; ‘nel being not so conspicuous, a less experienced examine ons arts j might be perplexed, and unable to come to a conclusi Although hymenopterous pupe have usually no P*, but what are afterwards seen in the perfect insect, this! not the case with several coleopterous and dipterous ones, which are furnished with various temporary appendag® indispensable to them to bring about their final chang? or for other purposes. Thus, the pupa of the male ° Lucanus Cervus has two short, jointed anal processes , That of Hydrophilus caraboides hasa pedunculated Junat late one; and moreover, the sides of the abdominal seg ments, and the top of the thorax, are beset with hail which are not seen in the perfect insect. The abdome? of many, also, is armed with spines. That, the arrange ment of whose organs I lately described, has a quadrup! series in the back of this part; viz. on each of the first ÉY segments, 3, 2, 2, 3. The five first ventral segments als? have on each side three spines; the inner are incurved, # intermediate nearly upright, and the outer one recurve” These spines, except those of the innermost ventral serie? terminate in a bristle. In another coleopterous species the back part of the head is armed with a pair of lateral spine and that of the thorax with three processes, the extern? ones armed with a single spine, and the intermediate on? with a pair. De Geer has figured the pupa of an Asih the head of which is armed with eight spines—tw? p bust ones in front, and three smaller ones, conned the base on each side. The abdominal segments, also are fringed with spines*. The abdomen of the pup?’ j a Ris £81. b Toit 95. ° De Geer vi 287-4 xiv STATES OF INSECTS. 249 Ctenocera pectinicornis is armed with several strong co- nical spines, pointing mostly towards the tail, which is likewise the case with that of Tipula: lunata*. As the above pupze are usually subterranean or subcortical, the Spines assist in pushing them out of the ground, &c. he respiratory horns that proceed from the thorax of © pupæ of many of the aquatic gnats will be noticed ù another place. Those of Corethra culiciformis and of ‘ome other aquatic gnat-like Diptera, have their anus "nished with a pair of oars, or natatory laminæ, by Which they rise to the surface”. The figure of obtected pupze, or chrysalises, is more uniform, They are commonly obtuse at the anterior ex- tremity, and gradually contracted to a point at the poste- “br, or tail. The outline usually inclines to a long oval ot an ellipse; but in some, as Attacus To and Luna, the Pupa is shorter and more spherical. In Geometra sam- “aria it represents an elongated cone, and in Hepialus itis Nearly cylindrical. In the butterfly tribe (Papilio L.) © outline is frequently rendered angular by various pro- tuberances, In all these pupæ may be distinguished the following Parts :—first, the Head-case (Cephalo-theca), or anterior “xtremity ; secondly, the Trunk-case (Cyto-theca), or inter- Mediate part; and ¢hzrdly, the Abdomen-case ( Gastro- t lec a) _ l. The Head-case covers and protects the head of the Nelosed imago. From its sides behind proceed the an- ry Reaum. v. t. ii. f. 7. The anal and ventral spines of Tipula re- Beata are also remarkable. De Geer vi. t. Xx. f. 14. e Geer Ibid. 377. t. xxiii. f. 8, 9.n. Reaum. v.42. t. vi. f. 9. mn. 250 STATES OF INSECTS. .tennse-cases (Cera-theca); and before from the middles the tongue-case (Glosso-theca). Just below the base of the antennze-case you may discern the eye-cases (Ophthalmo theca), surrounded on their inner side by a crescent- shaped levigated piece, which may perhaps transmit some light to the inclosed prisoner. 2. The Trunk-case, divided into the thorax, or upper surface, extending from the head to the dorsal segments 0 the abdomen, and consisting of three pieces, answering t° the prothorax, mesothorax, and metathorax of the perfect insect: the first answering to the prothorax small, thé second covering the mesothorax very large, and the tw? next representing the metathorax, at first appearing t° belong to the abdomen, but having no spiracle; and the breast (pectus) or under-surface reaching from the head to the ventral abdominal segments, from. which proceed the wing-cases (Ptero-theca) and leg-cases (Podo-thect) which organs, with the antenna-cases and tongue-cas® entirely cover, or rather form, the breast. The arrang® ment of the whole is as follows :—The wing-cases, which are more or less triangular, and exhibit the larger ner vures of the wings, are a lateral continuation of the me- sothorax, which turn downwards from the sides of t#¢ breast, and cover, or replace, the three first ventral seg” ments of the abdomen. The antenna-cases, united to the anterior portion of the head just behind the eye-case® repose immediately next to those of the wings running _ parallel with their inner margin. Then follow the leg* the tibize forming an angle with the thigh, and the cas? of the anterior pair being innermost, and representing the breast-bone in the pupa. The tongue lies over the for® STATES OF INSECTS. 261 legs, except in the case of some sphinxes, which I shall- Notice afterwards: so that the glosso-theca covers both them and it. | ps The abdomen-case consists of zen segments when “Viewed on the back, and of only siz when viewed below; 80 that it might be said to have ten dorsal and six ven- tral segments: but the fact is, that the place of the three anterior ventral segments, or rather ventral portions of the Segments, (for they form complete rings without any feral suture,) are replaced by the wings and other or- Sans: in consequence of this, the fourth segment, which = less covered than the three first, at its posterior margin forms an annulus or ring. In counting the abdominal Segments of a pupa, you must be careful not to include the piece that represents the metathorax, which looks as Wit belonged to the abdomen?. In the pupæ of butter- es you will discover evident traces of ten dorsal seg- Rents ; but in many moths, and some hawk-moths, you Will perceive at first only eight, or even seven, but a closer *Xamination will enable you to discover the line that Marks out the others; and if you divide the puparium “hgitudinally, and inspect its internal surface, you will ae very visible sutures between them. The intermediate “egments are sometimes separated from each other and preceding and subsequent ones by deep channels. A the pupa of Papilio Machaon there is one such chan- Yel between the third and fourth segments. In Bombyx * The ¢ excluds aterpillar consists of twelve segments (Lyonnet t. if. 4,9), i the head ; on each of which, except the 2d, 3d, and 12th, Re A a pair of spiracles. The chrysalis usually exhibits an analogy are = structure, though the first, second, and last pair of spiracles re or less obsolete in most. 252 STATES OF INSECTS. regalis the channel is between the sixth and seventh, and in B. imperatoria there are three, namely, a channel be- tween the third and fourth, and fourth and fifth, and fifth and sixth segments. The way in which insects with aP exserted sting fold it in the pupa seems not to have bee? noticed; but from an observation of De Geer upon o8? species of Ichneumon, it appears to be turned up over the back of the abdomen °. These little animals, thus swathed and banded, exhibit no unapt representation of an Egyptian mummy ; though Lamarck applies the term Mumia to incomplete pup® 5 to which it seems less happily applicable. Chrysalises, as to the modifications of their general figure, may be conveniently divided into two great classes: first, those that have no angular projections, the anal mucro of some excepted, on different parts of their body’ and secondly, those which have such projections. Each of these classes affords variations in its peculiar chara® ters which require to be noticed. 1. The first of these are called angular pupee °, and are confined to the Butterfly or diurnal tribes. In sow? the head projects into one short conical protuberance’ this you may see in the chrysalis of the common cabbag? butterfly (Pieris Brassice), and others of the same 8° nust; in the brimstone-butterfly (Colias Rhamni°), and in the beautiful purple emperor or high-flier (Apatié”® _ Tris ¥.*): though in this last it is not conspicuous. But a De Geer i. 847. te XOX: f.d: ob b Animaux sans Vertebres, iii. 287. © N. Dict. d Hist. Nat. vii. 57. a Sepp t. £. i f. 4. tii f 4. t iv. f 5. e Prare XVI. Fic. 12, f Prate XVI. Fic. 10. STATES OF INSECTS. 253 the most remarkable instance of a single eminence from the head is exhibited by the pupa of a tropical butterfly (Morpho Idomeneus Latr.), figured by Madame Merian. In this the head projects into a long incurved obtuse horn a, In others the head is armed with two mucros, r conical eminences. This is the case with the common butterfly of the nettle (Vanessa Urtice ¥.°), and with that of the beautiful Papilio Machaon*. In these the promi- nences are trigonal. These processes, which in some, as m the peacock-butterfly (Vanessa Io), stand upright ¢, and in others diverge (Papilio Machaon), form the eye- “ases of the included imago; and in their outer base is planted the crescent-shaped piece I lately mentioned, Which seems intended to convey light into it. In many the prothorax, besides a lateral angular projection, has n the middle another triangular or trigonal one, some- What resembling a Roman nose; on each side of which Is a smaller elevated black point: so that it requires no Steat stretch of imagination to find out in it a sort of re- Semblance to the human face, which, though not quite S striking as honest Goedart figures it®, is however very Considerable. In the pupa of Morpho Menelaus, figured Y Madame Merian f, this nasiform prominence of the Prothorax is extended into a long arched horn, reaching to the middle of the abdomen. The pupa of the silver- Washed fritillary (Argynnis Paphia F.), and others of the ‘ame genus, exhibit beneath this nasiform prominence ns. Surinam. t. 1x. Itis singular that the chrysalis of its congener, he ln Teucer, which she figures ¢. xxiii., exhibits no such process. arvee also widely differ. b Prats XVI. Fre. 11. _ Sepp i LY, AFD, a Sepp i. é. viL f. 5. ° De I; nsectis, ed. Lister, ż. 1. f Ins. Surinam. t. lii. 254 STATES OF INSECTS. a very deep depression, itself beset with one or more 5°- ries of smaller angular elevations. The back of the ab- domen is often furnished with two rows of protuberance» in some species larger, in others smaller*; sometimes sharp and conical, and sometimes flat, and in some in- stances resembling the fins of fishes”. These bosses usually decrease in size towards the tail. 2. The second kind of chrysalises are denominated conical ©. These, which include the crepuscular and noc turnal Lepidoptera, and the butterflies with oniscifor™ larvæ, have no protuberances, and are less variable 1" their form—their anterior extremity being almost cot” stantly oval and rounded, and their posterior conical and acute. An exception to this form is met with in the pup? of a moth long celebrated (Lasiocampa Pithyocamp4) *, which has the head acute and the taii obtuse, and armè with two points‘. Another occurs in that of the Cossus, which has two points on the head, by which it makes an opening in its cocoon: when it assumes the imag one of these is placed below the other‘. And som few have the anterior end nearly flat instead of rounded: The pupa of the orange-tip butterfly (Pieris Cardamines) seems intermediate between the angular and conical kinds: it is somewhat boat-shaped, and distinguished by a fusiform process from the head and tail £. Other modificatious of the usual figure are met with, but are for the most part so slight as not to require notice. One 2 Seppi. t. ü. f. 6. > N. Dict. d Hist. Nat. vii. 60. c Ibid. 57. 4 See above, Vox. I. p. 131. e Reaum. ii, 158. ¢, viii. f. 4, 5. f Lesser L. i. 160. note. ż. i. f. 19. d g N. Dict. d Hist. Nat. xxvi. 165. Reaum, i. 347. Rösel says this is present only in some individuals, I. ii. 47. STATES OF INSECTS. 255 ®t two, however, should not be passed over. The pupe of Many hawk-moths (Sphinx L.) have the anterior piece of the head-case elongated into a sort of cylindrical pro- Scis, which is incurved beneath the breast: you will and this formation in S. Convolouli and Ligustri*. In “ome, as ina species figured by Madame Merian, that Seds upon the Annona squamosa, it is rolled up like a “rent in many folds®. In Noctua Linarie the tongue- Case turns upwards, and is prominent laterally beyond i bodys, This singular appendage is one of those “Autiful instances of compensating contrivances, as Dr. aley calls them, which perpetually occur in the insect Mbes, The tongue of these hawk-moths is of very great “sth, often three inches, while the pupa itself is scarcely 9; it could not possibly, therefore, have been extended _“fngth, as it is in common cases, but is coiled up “Within the above protuberance. When the tongue is but à little longer than the breast, the ordinary plan is ad- “ted to, but the apex of the breast projects a little over € abdomen into a sort of nose, in which the end of the tongue is contained. This conformation may be seen in ' the Pupa of Noctua Gamma, Verbasci, and many other Pecies, Sometimes, as in N. Linarie F., this projection “ecurved into a short horn. have before adverted to the adminicula or short spines king towards the anus, with which the dorsal segments 9 the abdomen of some pupz are armed; and by which, : en the time for their exclusion is arrived, they are “abled to push themselves upwards or outwards from : PLATE XVI. Fie. 13. a. b Ins. Surinam. t. iii. De Geer ii, 433. £ viii. f. 4. £. 256 STATES- OF INSECTS. their several. places of confinement *: you will find thes? in the pupa of the great goat-moth (Cossus ligniperda)s and in the cylindrical pupa of the moth called the ghost (Hepialus Humuli F.) there are two rows of sharp triat- gular spines on the back of each segment. These are not laid flat, but, as they do also in the Cossus, form an acute angle with the body; which gives them greater powe? G resistance. Those that constitute the row nearest the base of the segment are longer than the anterior ro”? the middle spines than the lateral ones. The first and last segment are without them, and the last segment but one has a sharp ventral transverse ridge, armed with many sharp teeth, The abdominal spines lately me?” tioned, of semicomplete pupæ, are also adminicula. The tail of this description of pupæ is in many ine stances armed with a mucro, or sharp point, emerging from its upper side. You will see this in most hawk- moths. In the pupa of Hesperia Proteus the mucro is truncate at the apex; in that of Bombyx imperatoria it is long, and terminates in two diverging points. In the | majority of chrysalises of both descriptions the tail © l acute, and usually furnished with hooks of different kinds These are so various in shape and number, &c. that they ` would probably afford good characters for discriminating _ many allied species. In some there are but two or thre’ “in others five or six, in others they are more numerous ? Sometimes they are quite straight 4, but most commo” J recurved, so as to form a hook. The hawk-moths, and 4 a See above, Vot. II. p. 300. b This description was taken from a puparium in my own cabi it is similarly described by De Geer i. 490. t. vii. f. 2. c Plate XXIII. Fic. 8, 9. 4 Kliemann Beitrage, 304. nets STATES OF INSECTS. 257 pectin, as Bombyx Pini, Cerura Vinula, &c., have no ooks whatever. Under this head I shall observe, at m many conical pupæ below the anal angle or mu- 9 1s the appearance of a vertical foramen or passage : is Is is particularly conspicuous in Hepialus, in which it “trmounted by a bifid ridge, and has under it a pair of ute black tubercles. Y pretty accurate judgement of the division to wh Perfect insect when disclosed will belong, may usually è *rmed trom the figure of its chrysalis. All the angu- "Ones, with scarcely any exception, inclose butterflies. C Converse, however, does not hold; for some that are gular, as those of Parnassius Apollo and Mne- Yne, and most of the Linnean Plebeii urbicole, also “lose flies of that description. With these exceptions, . chrysalises give birth to moths or hawkmoths. \ ea even of the family or genus under which the | Meet insect will arrange, may be generally formed from t ‘ figure of the chrysalis; less distinctly, however, in i moe or rounded, than in the angular kinds, in > the prominenċes of the head and trunk, as before bey ak usually vary po daioncas families. Even the | Fen some moths may be judged from the pupz: those ` ales being thicker; and those also of the females that ex h ave : ; 7 no wings, or only the rudiments of them, will of “Our ; w © vary somewhat from the ordinary form: but there a È 1 . . . . » . Vesy still more striking difference in that of Callimorpha ? a P . b tien » and others of the singular tribe before no- a — called by the Germans Sacktrager (sack-bearers), t . . : $ e sack-like cases in which the larva resides. The * See above, Vor. I. 464. Vor, . fer S 958 STATES OF INSECTS.’ females of these having not only no wings, but no anten- næ, and legs not longer than those of the larva, the! pupa more resembles that of a dipterous than of a Lepr dopterous insect, it being not easy to determine which ¥ the head and which the tail?. In these too we can often learn from the outline of the wing-cases, whether the inhabitant of the chrysalis he these organs indented or intire. If the former, the mat“ gins of these cases are sinuate, as in that of Vanes C. album; if the latter, they are intire, as in Pieris Bras sice. Even in conical pupse,—the size, the shape of the antenn, which may be distinguished through the sk that covers them, and slight modifications of the ordi nary form,—give indications of the genus of the include insect sufficiently conclusive to a practised eye. . The true figure of coarctate pupæ when they are u ture, the parts of the future fly being very visible, ae? each being included in a separate case b, is that of thom that belong to the incomplete division; but as this £ 7 character not cognizable without dissection, itis custom} in. speaking of pupæ of this description, to refer solely © the shape of the exterior covering, which is in fact a coco” formed of the dried skin of the larva moulded into 4 p ferent form. In this sense the figure of coarctate pup® extremely various. The majority of them are more 0” j oval or elliptical, without any distinct parts, were it gf that they usually retain traces of the segments which ©? i posed the larva’s body*. Of this figure are the pup® oft d common cheese-maggot 4, and many other flies. othe l _* Von Scheven in Naturf stk. xx. 64. t. ii. f. 4. P Prate XVII. Fie. 2. Lesser L. t. ii. f. 26. © Prate XVII Fie. 1. Lesser L. ż ii. f. 24, 25. p a W š i ically r à Whether M, Meigen has separated this fly generic!) STATES OF INSECTS. 259 al Latr.) have the pupa shaped likea boat. That ag Pyrastri F. assumes the figure of a flask ; or, ne to Reaumur’s more accurate e a of a a The tail;ofi many of these pupæ, partionlanly of S 3 species, is elongated inte a sort of beak, either n e or forked, or is beset with spines variously ar- ged. The pupa of Stratyomis Chameleon, and other ad Species, differs from all the rest of this subdivision *etaining the exact form of the larva; and hence con- tutes an exception to the general character of our se- Con i q 8reat Division. sti ts There is much less variety in the colour of pupæ nin that of larve. The majority of coleopterous and Menopterous pupæ are white, or whitish; of lepido- D and dipterous, brown of various shades, often Sme on black in the former and on red in the latter. angular lepidopterous ones, however, are more decorated. Some, Pieris Brassica, are of a greenish = W, marked with spots of black; others are of a uni- dig Steen, Apatura Iris, Pieris Cardamines ; others, red- 3 Vanessa C. album; others again red with black Ob nia Leilus*. A still greater miymaber shine as bartin gilded with burnished gold—either applied in S y Streaks, Vanessa Cardui; or covering the entire €, Vanessa Urtice. It was from this gilded appear- Ce ; ha M some obtected pupæ that the terms Chrysalis and g Baily Othe ts é . Tiram am not aware: in my catalogue it stands under the name of Sa. ea eee inf > = b Th; um, iii. 376. z, XXXİ. f. 7: Ji . e “ly. 3 ake Ja 318. ¢. xxiii. f I4 xxv. fib *urinam, t, xxix, : sQ as 260 STATES OF INSECTS. Aurelia were applied to the whole. The alchemists wea took this for real gold; and referred to the case aS ap ° i te it argument In favour of the transmutation of metals. Be Reaumur has satisfactorily shown, that in this instant? the old proverb is strictly applicable—* All is woti that glitters.” He found that this appearance is owing to the shining white membrane immediately below th? outer skin, which being of a transparent yellow gives ® golden tinge to the former ; in the same way that tinfo™ when covered with a yellow varnish, assumes the metal? appearance which we see in gilt leather. He mentio™ too, that for the production of this effect—it is essent? that the inner membrane be moist: whence may be ex plained the disappearance of the gilding as soon as the butterfly is ready to escape from the pupa. The shal? of colour in these gilded chrysalises is various: some m of a rich yellow, like pure gold; others much paler; y some nearly as white as silver. That of Hipparel" Cassie F. is red with silver spots °. Though by far the greater number of the chrysalis” of moths are of an uniform chestnut, brown, or black” a few are of other colours; as that of Geometra alnia™ which is of a glaucous blue; of Noctua sponsa, lilacs ap of Noctua pacta, of a lovely blue, caused by a kind ° bloom, like that of a plum, spread upon a brown grou” i A similar bloom is found on that of Parnassius AP? f and on the anterior part of that of Platypteria cult” y and sicula; in which last, Kliemann observed it tO a T S Y; oe . >. o m i . dli ns. Surinam. t. xxxii. Lister imitated the gilding of Ch7Y . a by putting a small piece of a black gall in a strong decoction ° r tles: this produced a scum, which when left on cup-paper, P? will exquisitely gild it—Ray’s Letters, 87. 90. say STATES OF INSECTS. 261 be renewed when rubbed off?. Many pupæ have the iets of the wings of a different colour from that of the ` he the body; a few are variegated with paler streaks ands, as Clostera Anastomosis, which has two red op Situdina] stripes down its dark-brown back; and that the common gooseberry and currant moth, which may € found in every garden, has alternate rings of black ad yellow b, a A few pupe vary in their colour, as the painted lady- . ld (Vanessa Cardui), some of which are light-brown gray streaks and golden dots, others wholly of a Solden yellow or brown, others of a light green €. ; lmost all at their first assumption of the pupa state Ve a different colour from that which they take a few YS afterwards. This last they retain until the disclo- p te of the perfect insect; except some that have trans- ment skins, which a few days previously to this period bit the colours of the included animal. w. There is as great variety in the length of the age sects in their pupa as in their larva state. Some “les Continue in it only ¢wo or three days (Aleyrodes Haworth Lepidopt. Britann. i. 125, An instance is recorded y Scriba’s Journal, in which a pupa was not disclosed until the fo” th year. B.i. st. iii. 222, Pezold. 170. > Marsham in Linn. Trans. x. 402. ; © Meinecken found, that of several pupz of Saturnia pavomh some kept all winter in a room heated daily by a stove, and other in a cold chamber, some of both parcels appeared in March (no® earlier), and some of both had not appeared in July, though evident healthy, Naturf. viii, 143, ae K STATES OF INSECTS. 267 Son unknown to us*, to be disclosed from the pupa in the cold and stormy months of February and March, almost every day of which in certain years is so ungenial that few insects could then survive exposure, much less “posit their eggs and ensure the succession of a progeny. — OW, were all these to make their appearance in the per- fect state in the same year, it might happen that the Whole race in a particular district would be destroyed. Ut this possibility is effectually guarded against by the Sautiful provision under consideration, it being veryim- Probable that three successive seasons should be through- ut unfavourable ; and without such occurrence, it is clear that some of the race of this moth will be preserved. In € case of other moths, whose pupæ though disclosed in € summer are governed by the same rule, the prevention Ë the extinction of the species, by any extraordinary in- ease ina particular year of their natural enemies, seems € object in view”. But though the intention be thus vious, the means by which it is effected are impene- "ably concealed. What physiologist would not be puz- “led with the eggs of a bird, of which one-third should - *equire for their hatching to be sat upon only a fortnight, Nother third a month, and the remainder six weeks? Yet is would be an anomaly exactly analogous to that ob- erved by Mr. Jones with respect to the pupæ of A. men- “ca. Reaumur found that when the skin of pupæ was Yatnished, so as to prevent absorption, the appearance of a i : Te The exclusion of certain moths, &c. from the pupa 1s probably i culated by the time.their eggs require to be hatched, and the ap- arance of the leaves that constitute their appropriate food. i Mr. Marsham makes a similar observation in Linn. Trans., ubi “upr, 268 STATES OF INSECTS, the fly happened nearly two months later than in ordi- nary circumstances. Are we to conjecture that those ° the moth just mentioned, or of E. lanestris, that are Jat- est matured, from a greater degree of viscidity in the fluid that forms them è, have thicker and more imp” vious skins than those disclosed at an earlier period! Or are we to refer the difference to some unknown P% culiarity of organization? On any supposition, the fact remains equally wonderful; and I know of none the illus tration of which is more worthy of the patient investig®” tion of the physiologist. As the period of maturity of the perfect insect is thus in some cases not fixed even to years, and as in maby it seems dependent upon such variable causes; nothing appears more improbable than that it should ever be so strictly determined, that even the week in which the fly will leave its pupa-case can be pretty accurately p!” dicted. Such, however, is the fact with regard to the Ephemera so interestingly described by Reaumur, the myriads of which that issue from the banks of the Se? all appear in two or three days, somewhere between the 10th and 18th of the month of August” in every year at which time the fishermen regularly expect them. like regularity attends the appearance of those describ? by Swammerdam, which every year, for three days about the feast of St. John, issue in clouds from the Rhine*~ Not only is the week fixed, but in several instances ev? @ See above, p. 245. b The appearance of them sometimes continues to near the end of the month: it began on the 19th, when Reaumur observed tHe” vi, 480. 488. c Bibl. Nat. E. Transl. i, 103—. STATES OF INSECTS. 269 the hour, The Ephemerze observed by Reaumur appear at no other time than between eight and ten o’clock in € evening ; and so unalterably is their exclusion fixed, that neither cold nor rain can retard it. Between these ours, in the evenings on which they appear, you may See them fill the air, but an hour before or after, you will n vain look for one?. So also the silkworm-moth and the hawkmoth of the evening primrose (Sphinx Cino- there) constantly break forth from the pupa at sunrise : "nd the hawkmoth of the lime (Smerinthus Tilia) as cer- inly at noon». Schroeter states, that of sixteen speci- ens of the death’s-head-hawkmoth (S. Atropos) which € bred, every one was disclosed between four and seven clock in the afternoon °. efore I conclude this head, I must observe, that after ? Caterpillar or gnat has spun its cocoon, it sometimes "mains for a considerable period before it incloses itself ™ the pupa-case, and casts off the form ofa larva. Thus € little parasite (Jchneumon glomeratus L.) that destroys © caterpillar of the common cabbage-butterfly, remains arva in its cocoon for many months, but it becomes a Perfect insect a few days after it has put on its pupa- ' “tim; and the caterpillars of the great goat-moth (Cos- Sus Ligniperda), if they spin their cocoon in the autumn, “Main in it through the winter in the larva state; ereas, if they inclose themselves in the month of June, €y assume the pupa, so as to appear as flies in three or Ur weekse, It is not therefore easy to state precisely ‘ Reaum, vi. 486. b Brahm. 423. 421. aturf, xxi, 75. a Reaum. ii. 423. Not. : z Geer ii. 370. It is not certain, however, that De Geer did >M this instance, mistake the winter habitation of a larva fora 270 STATES OF INSECTS. the age of those pupze which are produced from Jarv® that spin cocoons. v. I have not much to say with regard to the sex Ob pupe. The male is probably to be distinguished from the female by being smaller; but in the first great div! sion of pups, those which resemble the larvae, and a° locomotive, the female in numerous cases may be know? by the Ovipositor, or instrument for depositing her egg? in their proper station: and the male also has his anal instruments. Sometimes in this state the animal is 5? matured, as to be capable of continuing its kind. I hav® found the pupæ both of a Gryllus L. and of a Cimer & an coil. vi. Though the pups of the second great division a4 usually not locomotive, yet I must not omit some notic? of their motions. As the legs of insects in this state al® folded within a common or partial integument, of cours? none of the pupze now under consideration, with the €% ception of those of the Trichoptera order, can walk: 6% arctate ones are even incapable of the slightest motio™ and exhibit no symptom whatever of animation. Som of those that are termed incomplete, however, and most chrysalises, have the power of communicating to thei! bodies a slight movement, extending more or less in dif ferent species, which is effected by the abdominal seg ments solely. The latter, during the first twelve hou" of being pups, when their skin is soft, frequently tur” cocoon intended to shelter the future chrysalis; since Lyonnet # : ee : : é forms us that they spin a habitation to pass the winter in. Trait Anatomique, &c. 9, STATES OF INSECTS. 271 themselves, that the side on which they lie may not be attened; afterwards by far the majority merely wriggle X twist their abdomen when touched, or in any way in- “ommoded or disturbed. We learn from De Geer, that € Pupa of the ghost-moth (Hepialus Humuli), the co- “Son of which is more than twice the length of the chry- Salis, Moves in it from one end to the other?. Bonnet “served one of a moth (perhaps Lasiocampa Quercus), Which alternately fixed itself at the top and bottom of its Spacious and obliquely-fixed cocoon; descending slowly, ut ascending as quickly, and almost in the same manner, Sa chimney-sweeper in a chimney °. The pupa of the Weevil of the water-hemlock (Lixus paraplecticus) will ~ Ve from one end of the interior of a branch to another `y Means of its adminicula, aided by the motion of its dominal segments °. But the most locomotive of pu- Dee of the second division are those of gnats, and many 'ulidans, which pass this state im the water. eos : lmoye from the bottom to the surface, and back again, th great facility and velocity. I have before mentioned “Yeral other motions of pupæ 4, which I shall not repeat te, by which they extricate themselves from their seve- Ss Places of intermediate repose, before they leave the parium ; if the imago were to be disclosed in the in- “tior of a tree, or in the earth, its wings would be ma- “tally injured in forcing its way out. The object of “eral of the above motions may be to alarm insects that ht attack these defenceless beings. The twirling mo- loh j a 3 . = “Lin Particular, formerly noticed °, in some species, by * De Geer i. 490. z. vii. f. 3, 4. b Œw.. 1. * De Geer yv. 229. ` áa Vol. II. 300—. * Vor. IT, 298. 272 STATES OF INSECTS. causing a rustling against the sides of the cocoon, makes a considerable noise—so singular in that of a red under- wing-moth (Noctua pacta), that Rösel tells us, (who by the by was more timid than becomes a philosopher;) the the first time he heard it, he had nearly thrown away the box that contained it, in his fright *. vii. We are next to consider The extrication of the p? Jeet insect from the puparium, or pupa-case, and from the cocoon. ‘The period when the pupa has attained mat rity, and the inclosed insect is ready to burst the walls % | its prison, may be often ascertained. Just at this time the colour frequently undergoes an alteration, the golde” or silver tint of the gilded chrysalises vanishes; and tho? which are transparent, usually permit the form and e lours of the insect within and the motions of their li P to be distinctly seen through them. In the ae the eyes become more brilliant®. The mature pup# ° the moth lately mentioned (Hriogaster lanestris) have ? particular swell of the abdominal segments, not apparel of in those that are to continue till another season, longer. ‘Those of the case-worms (Tr ichoptera) pus? off the grates from the cases which they have hither! inhabited, and swim aboutt. Other signs and motion’ doubtless predict the approach of this great changè in other species, which have not been recorded. The mode in which insects make their way out © puparium differs in different orders. In obdtected pup™ : the struggles of the included butterfly or moth first effet a longitudinal slit down the middle of the thorax, wher f the gi I. iv. 101. ` b Reaum..vi. 407. e Haworth Lepidopt. Britann.i.127. ® De Geer ii. 566. 4 G STATES OF INSECTS. 273 there is usually a suture for the purpose. The slit ra- vay extends along the head, and down the parts which Mose the breast, and the insect gradually withdraws Self fron its‘case. It is not, however, from the outer : in Merely that it has to disengage itself, but also from Bees Of inner membranous cases, which separately in- “Ose the antenne, proboscis, feet, &c., as a glove does Ne fingers; and similar cases inclose the parts of the Perfect insect in pupæ of all the other orders. This is times a work of difficulty, but ordinarily it is effected ease r "Complete and semicomplete pupse undergo hearly the S Process, save that in them the body is not swathed è M a common case; and therefore they have only to erate themselves from the partial cases that envelop the "al parts of their body. | Carctate pupæ, as those of Muscide, Syrphide, i ide, &c., the process is different. Their outer-case whi "dinarily more rigid and destitute of the sutures, Ye ` in the former tribes so easily yield oi slight effort. the M these, at the anterior end under which the head of to y lies, and from which it always issues, there is n Sép $ to only a sort of lid, joined by a very indistinct suture op. test, which can be pushed off, leaving a sufficient ie Ne for the egress of the insect. In the oe ot tul y a this tribe this lid is composed of two semicir- peci Pleces, which can be separately pee rol Many iiy T Seem to be able to force off the lid of their pupas but A Y merely pushing against it with ier heads ; ate € common flesh-fly and many other Muscide, which are “thaps too feeble to effect this, or whose puparia y tonger than ordinary, are furnished with a very T@s K EEG T 2TA: STATES OF INSECTS. markable apparatus for this express and apparently sole purpose. They are gifted with the power of introdđuci”é air under the middle part of the head, to which the ™ tennze are fixed, and of inflating that part into a sort ° membranous vesicle as big as the head itself; by the action of which against the end of the pupa-case, the lid is 9° forced off. So powerful is this singular lever, that i? even sufficient to rupture the fibrous galls in which the pupee of the gay-winged Tephritis Cardut* are inclos" That it is designed by Creative Wisdom to answet th? sole purpose seems proved, from its disappearing 00 after the disclosure of the fly, whose head shortly peco? all alike hard. Reaumur suspects that it may also © intended to promote the circulation of the insect’s quid but to me his reasons appear not conclusive >. In a instance a mode still more unexpected obtains. The” lustrious naturalist just named found that the fly wh? pilt proceeded from one of the rat-tailed grubs (Zop Latr.) had actually the power of completely reversing! / situation in its narrow case; and that it then employ? tail in pushing off the lid, which other species remove means of their heads ©. ° . $ yê The extrication of insects whose pupæ are ab? ground, like those of butterflies, many beetles, flies» © is comparatively a simple operation. But what, you ied ask, becomes of those species whose pupze are conte? h ae ; j deep in the earth, or in the heart of the trees on © ; their larvee have fed? Of this you shall be informe” Coleopterous insects disclosed from pupa thus cit a Reaum. iii. t. xlv. f. 12—14. b For this whole account, see Reaum. iy. Mem. viii. © Thid. 472. STATES OF INSECTS. 275 Stance i à : i ~“Oced, wait until their organs have acquired strength, ad their elytra are sufficiently hardened to protect their M wings from damage ‘in forcing their way through abe pe wood which covers them. Thus Kpa aee ` Ai a rhinoceros beetle common on the Continent, is „=a _ Month before it reaches the surface of the earth, ter quitting its puparium. But it is evident that no : Y would enable lepidopterous or dipterous insects, 5 a are without elytra, to make their way out of such „alons, without irreparable inju to their delicate "gs. Many of these, therefore, while still within the X ĉase of the pupa, have the precaution, a few days ‘usly to their exclusion, to force themselves up to ` Surface of the earth, or, when they reside in the in- B of trees, to the entranċe of their hole. = is ef by a successive wriggling of the abdominal seg- ats, Which in several species, of the Coleoptera, Lepi- be i and Diptera orders, for this i as = shap Soe than once observed "s are furnished with No p Points (adminicula), admitting a progresive, but toth retrograde motion. The puparia of the great goat- fg (Cossus ligniperda) may be often seen projecting tane < in willow-trees; and those of the common Y (Tipula oleracea) from the surface of the earth, Lo wp: S Which they have thus made their way from a depth of Veral inches. na the preceding instances the exons of the per- thy eK Is complete, as soon as it has withdrawn itself Mie: s Puparium. But to a very large nimer even us is effected, the arduous task still remains of a Q P; See above, p. 255—. and Vor. II p. 301—. T 2 276 STATES OF INSECTS. piercing the cocoons of leaves, of thick silk, of tough ge” or even of wood, in which the pupee are incased. can readily conceive how the strong jaws of coleopter and hymenopterous species may be employed to releas? them from their confinement. But what instruments cai be used for this purpose by moths in a state of great de- bility, whose mouth has nothing like jaws—merely 25° membranous proboscis? How shall the silkworm-mol# (B. Mor7) force its way through the close texture of asilke® ball, through which the finger could not be easily pushed! Or the puss-moth (Cerura Vinula) pierce the walls ° its house of glue and wood, which scarcely yield to the knife? You will not doubt that these difficulties have pee” foreseen by Ixnrıxıre Wiıspom, and provided against by Inrinite Power. The egress of moths from their a coons is secured in two ways;—either by some peculiant in the first construction of the cocoon by the caterpil# ; or by some process which the pupa or perfect insect É instructed to perform. As examples of each, several 0™ rious instances may be cited. The larva of the moth which about 1760 made such havoc in the province of Angoumois in France, becow? a pupa in the interior of the grain of wheat which it he excavated; but the opening by which it first entered g not bigger than a pin’s point, and is quite insufficient the egress of the moth. How, then, is the latter to for? its way through the tough skin which surrounds it? í Jarva, previously to assuming the pupa state, gnaws out ~ little circular piece at that end of the grain where the hem of the future moth would lie, taking care not to detach f entirely. At this little door, which is sufficient tO pre ; tect it from intruders, the moth has but to push, when? STATES OF INSECTS. oT Tr falls i ; S down, and leaves a free passage for its exit, A ONtrive atts r j : trivance almost similar is adopted by a caterpillar W 1 e . . e > "hich feeds in the interior of the heads of a species of teaze| ( of Dipsacus L.), for a minute and interesting history Which we are indebted to Bonnet. This caterpillar eg to its metamorphosis actually cuts a circular hing in the head, sufficiently large for the egress of the Ee moth; but to secure this sally-port during its long Sy it artfully closes it with fibres of the teazel, closely tilara strongly glued together ?. Another small cater- escribed by the same author, resides in the leaf of ash Curiously rolled up into a cone, and then assumes : Pupa, which is inclosed in a silken cocoon, ingeni- SY Suspended by two threads like a hammock in the i le of its habitation, and of so slight a texture that Presents no obstacle to the extrication of the moth. ‘Sthe closely-joined sides of its leafy dwelling that form dart é . a l arrier, which, were it not for the precaution of the ty 5 3 > would be impenetrable to so small and weak an i “al. The little provident creature, before its change. à Pupa, gnaws in the leaf a round opening, taking k. < to cut through tie externar epidermis. This i N to serve the moth for its exit, like that formed: by $ €at-caterpillar. But in proportion to its bulk its at apartment is of considerable size. How then à = mothk now the exact place where n ouie has S Sa How, without a. clue, shall it discover in “abode the precise circle which requires only a Push vid to throw it down? Even this is foreseen and pro~ sha] Qd aga: Ha ; PA against. Out of twenty positions in which its hams a Bonnet, Œuv. i, 169. 278 STATES OF INSECTS. mock might have been slung, the caterpillar has been di- rected so to place it, that the silken cord that suspend the head is fastened close to the side of the door which 9 has previously constructed ; and the moth, guided by this filum ariadneum, at once makes its way out of an apa j ment which, but for this contrivance, might have bee? g it a labyrinth as inextricable as that of Minos*, The mode in which other caterpillars provide for the! extrication, when become moths, from their silken a coons, is not less ingenious. Those of Hrzogaster lanesti® (of which I have lately said so much,) and others, for oblong cocoons, which, viewed externally, you would # the first glance assert were of one solid piece: but om examining them more narrowly, you perceive one end them to be a distinct lid, of a size large enough to por mit the moth to issue out; and that it is kept in its plac by a few slight threads, easily broken by pressure from within>. A few pages back* I mentioned a cocoon forme by the larva of Tortrix prasinana, of the shape © boat reversed, composed of two inclined walls fastet” together at the top and ends, In constructing this coco?” it firmly glues to each other the top and one end, se as form an impermeable suture; but the other end, at whit the moth is to issue, though externally it seems as stro” 4 as the rest, is merely drawn close by a slender thread a two fastened on the inside, and easily broken from W ich And, what is particularly singular in the constructio” i this ingenious habitation, the sides forming the end ie Nt mentioned, though originally requiring force to dr @ Bonnet, Afuve. ii. 207. b Ros. I. iv. 209. z. lxii. cen c See above, p. 217. : STATES OF INSECTS. 9 them into their required position, become so elastic as to Close again when the moth has passed between them and Made her escape; the cocoon preserving its usual shape, Sven when deprived of its inhabitant *. A similar cocoon 8 Constructed by another leaf-rolling caterpillar, that of “trie chlorana”. Many similar proofs of contrivance M the construction of silken cocoons might be adduced, ut I shall confine myself to one more only—I mean that Whished by the flask-shaped brown one of Saturnia Pa- “nia, and some other moths. If you examine one of ĉse cocoons, which are common enough in some places A the pear-tree or the willow, you will perceive that it à Senerally of a solid tissue of layers of silk almost of © texture of parchment; but at the narrow end, or lat which may be compared to the neck of the flask, that it is composed of a series of loosely-attached longi- dina] threads, converging, like so many bristles, to a “nt point, in the middle of which is a circular opening“. tis through this opening that the moth escapes. The “ik of its cocoon is of so strong a texture and so closely Summed, that had both ends been similarly closed, its - Sress would have been impracticable; it finds, however, % difficulty in forcing its way through the aperture of a “rt of reversed funnel, formed of converging threads ki readily yield to pressure from within. But an ob- ection will here probably strike you. You will ask, Is Not this facility of egress purchased at too déar a rate? ust not a chrysalis in an open cocoon be exposed to © attacks of those ichneumons of which you have said F Much, and of numerous other enemies, which will find * Bonnet, Œwvr. ii. 229. P De Geer ii, 477. * Sepp. iv. £ xi. f. 8. i 80 STATES OF INSECTS. admittance through this vaunted door? Our caterpillat would seem to have foreseen your dilemma; at least, U® der heavenly guidance, she has guarded against the dan- ger as effectually as if she had. If you cut open the €07 coon longitudinally, you will see that within the exter! funnel-shaped end, at some distance she has framed # second funnel, composed of a similar circular series ° stiff threads, which, proceeding from the sides of the ©” coon, converge also to a point, and form a sort of con? exactly like the closed peristome of a moss; or, to use? more humble though not less apt illustration, like the wires of certain mousetraps*. In this dome not the slightest opening is left, and from its arched structure it is impenetrable to the most violent efforts of any M% rauders from without; whilst it yields to the slightest pressure from within, and allows the egress of the moth with the utmost facility. When she has passed throug! it, the elastic threads resume their former position, #4 the empty cocoon presents just the same appearance g one still inhabited. Rösel relates with amusing naïvéť? how this circumstance puzzled him the first time he wit nessed it; he could scarcely help thinking that there W as something supernatural in the appearance of one of thes? fme moths in a box in which he had put a cocoon ° this kind, but in which he could not discover the slight est appearance of any insect having escaped from it, until he slit it longitudinally. But from an observation © Meinecken, it appears that these converging threads serve: 9 Aan a Prate XVIL Frc. 5. N.B. Sepp’s figure represents the exteri? funnel; and this, which exhibits the cocoon divisled longitudin®? the interior one; or dome. b Ros, Liv. 31, STATES OF INSECTS. 281 à double purpose; being necessary to compress the ab- domen of the moth as it emerges from the cocoon, which ces the fluids to enter the nervures of the wings, and S've them their proper expansion. For he found, that When the pupa is taken out of the cocoon, the moth is "'Sclosed at the proper time, but remains always crippled M its Wings; which never expand properly, unless thé domen be compressed with the finger and thumb, so 3S to imitate the natural operation *. am next to give you some account of the second Mode in which the release of the perfect insect from 5 cocoon is effected—that, namely, wherein its own “Xertions chiefly accomplish the work. I shall from a age number select only a few instances. The texture ™ the cocoon of the silkworm-moth is uniform in every Dart, and the layers of silk are equally thick at both “uds, The moth makes its way out by cutting or "taking these threads at the end opposite to its head: M Operation which, as it destroys the continuity of € silk, those. who breed these insects are particularly careful to guard against, by exposing the cocoon to. “at Sufficient to destroy the included pupa. ‘The ques- ‘On is—What instruments does the moth employ to €ct this? And this we are not able to answer satis- “ctorily, Malpighi asserts that the animal first wets the “lk With a liquid calculated to dissolve the gum that “nhects the threads, and then employs its lengthened “ad to push them aside and make an opening”. But, as aumur has observed, besides that so obtuse a part as the fad of a moth is but ill fitted to act as a wedge, we find * Naturf. viii, 133. t De Bombyc. 29. 282 STATES OF INSECTS. the threads not merely pushed to each side, but actually cut asunder. He therefore infers that the eyes, which are the only hard organs of the head, are the instruments bY which the threads are divided—their numerous minut? facets serving the purpose of a fine file. It should be observed, however, that Mr. Swayne confirms Malpights assertion, that the silkworm does not cut, but merely pushes aside, the threads of its cocoon; and he infor®* us that he has proved the fact, by unwinding a piere cocoon, the thread of which was entire’, Yet Reat mur’s correctness cannot be suspected: and he affirm that from observation there can scarcely be a doubt that most of the threads are broken €; which is further co!” firmed in an account of the breeding of silk-worms pub- lished in the American Philosophical Transactions: jh which it is expressly stated, that cocoons out of which the fly has escaped, cannot be wounds. Analogy, i must be confessed, is against Reaumut’s opinion; sin? other kinds of silkworms make their escape by means ° a fluid. ‘Thus we are informed by Dr. Roxburgh, that Attacus Paphia, when prepared to assume the imag” | discharges from its mouth a large quantity of liquid, with which the upper end of the case is so perfectly soften’ as to enable the moth to work its way out in a very sho" space of time,—an operation which, he says, is alway ? performed in the night *. Perhaps the two opinions ™ be reconciled, by supposing the silkworm first to moist?” and then break the threads of its cocoon. In thos? that are of a slighter texture, a mere push against the * Reaum. 1.624. - b Trans. of the Society of Arts, vii. 131. © Reaum. ubi supr. 4 ji, 359. e Linn. Trans. vii. 35. STATES OF INSECTS. 83 Neistened end is probably sufficient: and hence we find IR so many newly disclosed moths the hair in that part wet, and closely pressed down*. If it be apparently ficult for the silkworm-moth to effect an opening in its “coon, how much harder must seem the task of the PUss-moth (Cerura Vinula) to pierce the solid walls of its Wood-thickened case? Here the eyes are clearly incom- betent; nor could any ordinary fluid assist their opera- “on, for the gum which unites the ligneous particles is 'ndissoluble in aqueous menstrua. You begin to tremble r the fate of the moth incarcerated in such an imper- “ious dungeon—but without cause: what an aqueous sol- "ent cannot effect, an acid is competent to; and with a "§ of such acid our moth is furnished. ‘The contents of 18 she pours out as soon as she has forced her head tough the skin of the chrysalis, and upon the opposite d of the cocoon. ‘The acid instantly acts upon the ` Sum, loosens the cohesion of the grains of wood, and a Yety gentle effort suffices to push down what was a mi- Nute ago so strong a barrier. How admirable and effec- tual a provision! But there is yet another marvel con~ 7 "ected with it. Ask a chemist, of what materials a vessel Nght to be to contain so potent an acid: he will reply, >of glass, Yet our moth has no glass recipient: her ttle is a membranous bag; but of so wonderful a fabric not to be acted upon by a menstruum which a gum, “Pbarently of a resinous nature, is unable to resist! This act can only be explained by the analogous insensibi-~ ny of the stomach to the gastric juice, which in some "Mmals can dissolve bone,—and it is equally worthy of 2 Pezold, 171. 284 STATES OF INSECTS. admiration. In both cases, the vitality of the membra- nous or fleshy receptacle secures it from the action ° the included fluid; but how—who shall explain ? Ordinarily it is the moth that breaks the cocoon; bu” in the goat-moth and many Yortrices it is the pupa it- self that performs the work, either wholly or partially The pupa of the former is for this purpose furnished with sharp points upon the head, capable of effecting this object*. The locust-moth, another species of Coss (C. Robinie Peck), whose history has been admirably detailed by Professor Peck, has a different process. “ In the silk-moth,” says he, “and all others which I have had opportunity to observe, the chrysalis. bursts in the cocoon, and the fluid which surrounded the new insect i? it escaping at the same time, so weakens or dissolves thé fibre and texture of the silk, that the moth is able to e%“ tricate itself, leaving the chrysalis behind it; but this is not the manner in the locust-moth. After remaining till all its parts are fully grown and it is ready to quit i prison, a certain quantity of exercise is necessary, t° break the ligaments which attach the moth to the shel! of the chrysalis, and to loosen the folds of the abdome” In taking this exercise, it can only move the abdomen 1’ various directions : as one side of the rings is moved fof- ward, the hooks in the serrated lines above mentioned (the adminicula) take hold of the silk, and prevent thei” sliding back; the next flexure brings forward the oppo” site side of the rings, which are prevented by the points on that side from slipping back in the same manner, an the chrysalis is forced out of the slightly woven extremity * Lyonnet 16, STATES OF INSECTS. 285 “the cocoon, and through the silk-lined cavity, till it is Potruded for about one-third of its length out of the *Pening in the bark, and into the air ?.” n exception to the general rule—that the rupturing of the cocoon is the business of the inclosed insect itself S met with amongst ants; the workers of which not R y feed the young, but actually make an aperture in = cocoons, cutting the threads with their mandibles With admirable dexterity and patience, one by one, at time they are ready to emerge, the precise period for Which these indefatigable nurses are well aware of, that Ry may meet with no obstacle. Without this aid, the “ng ant would be unable to force its way through the tong and dense coating of silk that infolds it”. And a Proceeding somewhat akin to this was observed by the n, Captain Percy, R.N., who himself related it to me. 5 s a of thie study of — = in ie Se a g to their motions; and in the beginning of Sep “mber 1891 noticed those of a number of female Tipule, Probably T. oleracea L., busily engaged in depositing their eggs amongst the roots of grass. While observing . a Proceedings, he at the same time saw one quitting is Pupa-case, which had already by its own efforts got , ead, thorax, and anterior legs out of it. It was then ted by two male flies; which, with their anal forceps _ Posterior legs taking hold of the pupa-case, appeared #2 their mouths and anterior legs to push the little pri- Sher upwards, moving her backwards and forwards ; ad as they kept raising her, shifting their hold of the a Thi Some Notice of the Insect which destroys the Locust-trees, 70. Da €moir is in some American periodical work, of which I have the title, b Huber Fourmis $2. 286 ; STATES OF INSECTS. skin till she was entirely extricated, when they left hef to recover her strength by herself. Probably the extrem? length of the two pair of hind-legs of these animals may render such assistance necessary she their extrication. _ There remains yet to be explained under this head th? manner in which the perfect insect is excluded from ce" tain aquatic pupæ; such as those of Phryganee, gn% and one of those Tipulidæ that resemble gnats. The pupe (perhaps that they may be safe from the attack ° birds) are destined to remain during the greater part ° their existence in this state at the bottom of the wate But it is obvious that if the perfect insects were there © be disclosed, their wings would be wetted, and they woul be drowned. It is the provision by which this result is obviated that now calls for your attention. You have already been told that the larvæ of PHY gane@ inclose themselves in cases of different material’ open at each end?. You have also learned, that in be coming pups, they secure each end of their cases with ? grating of silk®, When that change has occurred, they remain motionless at the bottom of the water. Now ho” are these pupee, encased in tubes of a greater specifi? gravity than the surrounding fluid, to make their way © the surface when the time has arrived for their becomi?8 denizens of the air? This they accomplish in the follow” ing manner :—The pupa is furnished with two strong exterior moveable mandibuliform processes, and has the power of moving its four anterior legs and antenre while in the pupa-case. With these temporary jaws it make? an opening in one of the silken doors of its case, forces its a Vor, I. p. 467. b. Vol. II. p. 264. STATES OF INSECTS. 287 Way out at that end, and then by moving its legs, the “ses of which in some species are ciliated for this very Purpose, swims to the surface, where its skin splits, and iscloses the included insect. That these jaws are given or the express and exclusive purpose of being thus ap- P lied, seems undeniable. The pupa eats nothing—they | {re therefore in every other point of view superfluous. | €y are given to it alone of all other similar pupæ, be- , Cause unnecessary to all others; and they are cast off f “ong with the rest of the puparium, the perfect insect aving no vestige of jaws *. he gnat has to undergo its change on the surface of © water—How is it to accomplish this without being Vetted ? In the pupa state they usually remain suspended “ith the posterior end of the body turned downwards: -at when the period for its change is arrived, it stretches tout upon the surface, above which its thorax is elevat- on Scarcely has it been a moment in this position, than, Welling out the interior and anterior parts of the thorax, it causes it to split between the two respiratory horns. tough this opening the anterior part of the gnat then, “Merges, As soon as the head and trunk are disengaged, a; Proceeds with its labour, and gets out more and more; . *Vating itself so as to appear in the puparium like a Mast in a boat. As it proceeds, the mast is more and Nore elevated and lengthened, till it becomes nearly per- Pendicular—just as the mast of a boat is gradually raised. tom a nearly horizontal to a vertical position: at this Period a very small portion of the abdomen remains in ©puparium. Neither its legs nor wings are of any use 3 De Geer ii. 519, IgG STATES OF INSECTS. in maintaining it in this position. The latter are too soft, and, as it were, folded; and the former are stretched 0U* along the abdomen—the segments of this last part are the only agents. The observer who sees how the little bo? gradually sinks, and how its margin approaches the w% ter, forgets the mischievous insect it contains, which % another time he would crush without remorse, and i comes interested for its fate; especially should wind ag” tate the water. A very little is sufficient to drive abou rapidly the little voyager, since it catches the wind ™ some degree as a sail. If it should be upset, it would b° all over with it;—and numbers do thus perish. The gnats after having fixed itself thus perpendicularly, draws first its two anterior legs out of their case, and moves the™ forward, and next the two intermediate ones; then i clining itself towards the water, it rests its legs upon it for water is to them a soil sufficiently firm and solid 1 support them, although surcharged with the weight of the insect’s body. As soon as it is thus upon the wate" it is in safety; its wings unfold themselves and are dried, and it flies away. All this is the work of an instant °. The pupze of Chironomus plumosus proceed from thos? red worm-like larvae so common throughout the summe” in tubs of rain-water, &c., described by Reaumur ý They are not inclosed in cases, but are of a greater sp cific gravity than the water at the bottom of which they reside, until within a few hours of the exclusion of thè fly. They have the power of swimming, however; and by moving the tail alternately backwards and forward® can slowly raise themselves to the top of the water. But 2 Reaum. iv. 610—. b Ibid. v. 30—. 4. v. f. 1—10. See above, p. 153—. STATES OF INSECTS. 289 here Occurs a difficulty. For the extrication of the imago Ts necessary that they should remain quietly suspended “tthe surface; and moreover that the thorax, in which * Opening for its exit is to be made, should be at least sy With it: and this is precisely what takes place. If 00 w le atch one of these pupse when it ascends from the „Ottom, you will see that as soon as it has reached the top remains suspended there motionless; and that its tho- z 1s the highest part of the body, and level with the Mace. Now the question is, in what way this is accom- Boe? How can a pupa of greater specific gravity than “T, remain suspended without motion at its surface? how can its thorax, which is at its heaviest end, be ti, Uppermost ?—By a most singular and beautiful con- ' nce, which I shall explain; the more particularly ‘hs it has escaped Reaumur, and, as far as I know, other entomological observers. The middle of the ick Of the thorax has the property of repelling water— p "rently from being covered with some oily secretion. as soon as the pupa has once forced this part of fr JÅ above the surface, the water is seen to retreat Whi it on all sides, leaving an oval space in the disk, the Is quite dry. Now though the specific gravity of igh, = 1s greater than that of water, it is but so very d Y greater, that the mere attraction of the air to the Cie Part of the thorax, when once exposed to it, is suffi- Sy: to retain it at the surface ; just as a small dry needle tition similar circumstances. That this is a true sult of the phænomenon, I am convinced by the re- Several experiments, If, when the pupa is sus- at the surface, a drop of water be let fall upon r . eae ; 3 Y portion of the thorax, it instantly sinks to the L n : : U 0 Pendeg t 290 STATES OF INSECTS. bottom,—the thorax, which belongs to the heaviest hall being the lowest; and if the pupa be again brought tot : surface, so that the fluid is repelled from its disk, mains suspended there without effort, as before. previously to the exclusion of the fly, the dry part 0 thorax is seen to split in the middle. The air enters, forms a brilliant stratum resembling quicksilver, betwee? it 16° Just f the a the body of the insect and its puparium ; and the forme pushing forth its head and forelegs, like the gnat, res the latter upon the water, and in a few seconds extricat itself wholly from its envelope. Before I close this letter, I must state a fact connected with the subject of it that deserves to be recorded. Jt y a general rule, that one pupa-case incloses only one inset” but Kleesius, a German entomologist, asserts that had once two specimens of Gastropacha quercifolia pe duced from one pupa; which was large, being full W inches long, and one thick. LETTER XXXII. STATES OF INSECTS. IMAGO STATE. EN the insect has quitted the exuviae of the pupa, it attained the last stage of its existence. It is now med an Imago, or perfect insect; and is capable of “*Pagation, lit ust after its exclusion, it is weak, soft, and languid: i tS parts are covered with moisture; and, if a winged sha et, its wings have so little the appearance, either in es $ Size, or colour, which they are about to assume, t might be taken for a mutilated abortion, rather an animal in the most vigorous stage of life. If it s its elytra, instead of covering the back of the en, are folded over the breast: their substance is ap Sale leathery, and their ‘white colour exhibits no of the several tints which are to adorn them. If of ia be a butterfly or a moth, the wings, instead an Ng of their subsequent amplitude, and variegated large Painted with a variety of hues and markings, are in fallin * Species scarcely bigger than the little finger nail, Co ~ the sides of the trunk, and of a dull muddy n which no distinct characters can be traced. U 2 be ah s tta 992 STATES OF INSECTS. If the excluded insect be a bee or a fly, its whole skin ® white and looks fleshy, and quite unlike the colour? hairy crust which it will turn to in an hour or two; 4™ the wings, instead of being a thin, transparent, expa™™ ed film, are contracted into a thick, opaque, wrinkle mass, These symptoms of debility and imperfection, how" ever, in most cases speedily vanish. ‘The insect, fixie itself on the spoils of the pupa, or some other convenie™ neighbouring support, first stretches out one organ, ap then another: the moisture of its skin evaporates, the texture becomes firm, the colours come forth in all the beauty; the hairs and scales assume their natural por tion; and the wings expanding, extend often to five ; six times their former size—exhibiting, as if by mag’ either the thin transparent membranes of the bee oF fý or the painted and scaly films of the butterfly or mo or the coloured shells of the beetle. The proceedin® here described I witnessed ver y recently with regard a very interesting and beautiful butterfly, the only one? its description that Britain has yet been ascertainé produce—I mean Papilio Machaon. The pupa of af being brought to me by a friend ear ly in May this a (1822), on the sixteenth of that month I had the pleas”, to see it leave its puparium. With great care I place upon my arm, where it kept pacing about for the space a more than an hour; when all its parts appearing cons lidated and developed, and the animal perfect in , peau I secured it, though not without great reluctance, for F ` cabinet—it being the only living specimen of this fine oW I had ever seen. To observe hae gradual, and ye ee = a rapid, was the dey elopment of the parts and orgat®» {0 STATES OF INSECTS. 293 Particular i ly of the wings, and the perfect coming forth of © colours and spots, as the sun gave vigour to it, was a = interesting Spe At ara it was caei to ele- aria. even sens its wings; but in eee as the k ae other fluid was forced by the Sana of its trunk | eir nervures, their numerous corrugations and folds S'adually yielded to the action, till they had gained their STeatest extent, and the film between all the nervures be- “ame tense. The ocelli, and spots and bars, which ap- Peared at first as but germes or rudiments of what they Te to be, grew with the growing wing, and shone forth u $ z i Pon its complete expansion in full magnitude and “uty, | the understand more clearly the cause of this rapid 2 Pansion and development of the wings, I have before Sig amed to you that these organs, though often exceed- Sly thin, are always composed of two membranes, hav- 7 a commonly a number of hollow vessels, mişcalleg m running between them. These tubes, which, the French Entomologists, I would name nervures, “tribute as well to the development of the wings, as to te, sequent tension. In the pupa, and commonly “Sieg the two membranes composing the organs in on do not touch each other’s inner surface, as they te l “wards do: there is consequently a space between E and being moist, and corrugated into a vast num- longs folds like those of a fan, but transverse as well as r -a and so minute as to be imperceptible to the eye, the wings appear much thicker than in the “nq -OW as soon as the insect is disclosed, a fluid enters * See above, Vou. II, p. 346. 294 STATES OF INSECTS. the tubes, and being impelled into their minutest ramifi cations, necessarily expands their folds ; for the nervure? themselves are folded, and as they gradually extend r length with them, the moist membranes attached to thew -are also unfolded and extended. In proportion as ths takes place, the expanding membranes approach eat other, and at last, being dried by the action of the atmo sphere, become one. To promote this motion of the flu seems the object of the agitations which the animal from time to time gives to its unexpanded wings. ‘That @ kin of circulation, or rather an injection of an aqueous flu into these organs, actually takes place, may be ascertain by a very simple experiment. If you clip the wings ° butterfly during the process of expansion, you will s that the nervures are not only hollow, but that, how dry and empty they may subsequently be found, they * that time actually contain such a fluid °. Swammerda™ evel who appears to have been the first physiologist that pe attention to this subject, was of opinion that an aerifo™ as well as an aquiform fluid contributes to produce , effect we are considering. He had observed thats ? small portion be cut off from the wing of a bee, a flui the latter kind exuded from its vessels in the for™ pellucid globules, becoming insensibly drops—which concluded proved the action of the latter; and he no” ticed, also, that the wings were furnished with trache™ which were at that time distended by the injected p. whence he justly surmised, that the action of the 4” y also of great importance to produce the expansion?” | 4 wing>. And Jurine found that every nervure conta” 2 - 194 2 Reaum. i. Mem. ult, De Geer i. 73. Swamm. Bibl. Nat. + 18 b Swamm. Ibid. STATES OF INSECTS. 295 * trachea, which, proceeding from the interior of the trunk in a serpentine direction, follows all the ramifica- tion of the nervure, though it does not fill it?. Though “aumur attributes the expansion of the wings chiefly to aqueous fluid, yet he suspects that the air on some *casions contributed to it. The wings of the other tribes of insects probably differ m the Lepidoptera in the manner in which they are Oded, Ie should seem from Reaumur’s description, that Mose of some flies, instead of the straight transverse folds Of the former, have angular or zigzag folds; which “qually shorten the wing. Many Hymenoptera have mgs without any nervures except the marginal. We Y conjecture that these are more simply folded, so as * Tender their expansion more easy; but even in these gs there are often tracheæ, which appear as spurious nervures, and help to effect the purpose we are consi- tine, he operation of expanding their wings, in by far the ger number of insects, takes place gradually as de- “hed above; and, according to their size, is ended in ve, ten, or fifteen minutes; in some butterflies half an a b Jurine Hymenopt. 16. 1v. 342, Herold also attributes the rapid expansion of the wing flow of an aqueous fluid, which he calls &Zood, into the ner- dep S, the orifiees of which open into the breast. Entwickelungs. Sup hmettert. 101. sect. 106.-—-M. Chabrier, in his admirable Essai Serve, Pot des Insectes ( Mém. du Mus. 4ieme, ann, 325), having ob- thinks 4 fluid in the interior of the nervures of the wings of insects, i It probable that they can introduce it into them and withdraw ttrengsy pleasure : the object of whieh, he conjectures, is either to era a them and facilitate their unfolding, or to vary the centre > ty in flight, and increase the intensity of the centrifugal force. Thid. 340, : tot ' 296 STATES OF INSECTS. : z as hour, in some even an hour. A few species, such £ Sphinx Ginothere F., require several hours, or eve? . day, for this operation; and, from the distance to which they creep before it has taken place, a considerable 4 gree of motion seems requisite for causing the necessvy impulse of the expanding fluids*. In a few genera, how- ever, as the gnat, the gnat-like Tipulidæ, and the phe meræ, this process is so rapid and instantaneous, that the wings are scarcely disengaged from the wing-cases befor? they are fully expanded and fit for flying. ‘These genet? quit the. pupa at the surface of the water, from which after resting upon it for a few moments, they take flight but this would evidently be impracticable, and immersi@® in the fluid, and consequent death, would result, were pol the general rule in their case deviated from. Some species of the last of these genera, Ephemer™ are distinguished by another peculiarity, unparalleled, as far as is known, in the rest of the insect world. After bes ing released from the puparium, and making use of ther expanded wings for flight, often to a considerable di- stance, they have yet to undergo another metamorphos They fix themselves by their claws in a vertical positio” upon some object, and withdraw every part of the pod} even the legs and wings, from a thin pellicle which a inclosed them, as a glove does the fingers; and so exactly do the exuviæ, which remain attached to the spot whet? the Ephemera disrobed itself, retain their former fig! that I have more than once at first sight mistaken the for the perfect insect. You can conceive without E” culty how the body, and even legs, can be withdraw” a Brahm, Insek. ii. 423. STATES OF INSECTS. 297 from their cases; but you must be puzzled to conjecture W the wings, which seem as thin, as much expanded, And as rigid as those of a fly, can admit of having any Sheath stripped from them; much less how they can be Withdrawn, as they are, through a small opening at the ase of the sheath. The fact seems to be, that though © outer covering is rigid, the wing inclosed in it, not- Mthstanding it is sometimes more than twenty-four hours Clore the change ensues, is kept moist and pliable. In Proportion, therefore, as the insect disengages itself from “anterior part of the skin, the interior or real wings “ome contracted by a number of plaits into a form Nearly cylindrical, which readily admits of their being Pulled through the opening lately mentioned; and as *on as the insect is released from its envelope, the plaits folg, and the wing returns to its former shape and di- “sions, Thus our little animal, having bid adieu to i shirt and drawers, becomes, but in a very harmless “else, a genuine descamisado and sansculotte. It does Mot Seem improbable, that the pellicle we have been. ‘Peaking of is analogous to that which, in addition to the . Suter skin, incloses the limbs of Lepidoptera, &c. in the Pupa state, but which they cast at the same time with the parium, and leave adhering-to it *. he body of newly-disclosed insects commonly ap- “ars at first of its full size; but the aphidivorous flies IPhus F, &c.), and some others, in about a quarter of a hour after leaving the pupa become at least twice as S as they were at their first appearance : this appa- t sudden growth, which is also noticed by Goedart, a ti io Reaum. yi, 505—. z xlvi. f. 9. Comp. De Geer ii, 627—. 298 STATES OF INSECTS. Reaumur found to depend upon the expansion of the previously compressed segments of the animal by means of the included air è. Both in this instance and in tha of insects whose wings only require expansion, the size of the zmago often so greatly exceeds that of the pups that we can scarcely believe our eyes that it should have been included in so contracted a space. The pup? z one of the beautiful lace-winged flies (Hemerobius parla is not so big as a small pea, yet the body of the fy j nearly half an inch long, and covers, when its wings an antennæ are expanded, a surface of an inch square” When the development of the perfect insect is co” plete, and all its parts and organs have attained the 1% quisite firmness and solidity °, it immediately begins ” exercise them in their intended functions; it walks runs, or flies in search of food; or of the other sex of it own species, if it be a male, that it may fulfill the g"°° end of its existence in this state—the propagation of 1° kind. Previously to thus launching into the wide worlds or at least immediately afterwards, almost all insects 4” charge from their intestines some drops of an excreme?” titious fluid, often transparent, and sometimes red. © have before related to you the alarm that this last cit- cumstance has now and then produced on the minds f the ignorant and superstitious®. Whether this ex? 2 Reaum. iii. 378. b Tbid. 385. AA -© Insects of the beetle tribe, especially such as undergo their me tamorphosis under ground, in the trunks of trees, &c., are often ® considerable time after quitting the puparium before their orga” acquire the requisite hardness to enable them to make their way to the surface. Thus, the newly-disclosed imago of Cetonia auth remains a fortnight under the earth, and that of Lucanus Cervus, $ cording to Rösel, not less than three weeks. a See above, Vor. I. p. 34—, s STATES OF INSECTS. 1299 Ment is produced indifferently both by males and females Cannot positively assert; but a circumstance related by Jurine affords some ground for a suspicion that it S peculiar to the latter. A specimen of a female of dsiocampa Rubi, when killed emitted some of this fuid, which dropped upon the floor: this appeared to attract the males to the apartment in which it happened, and to the very spot—from whence it may be conjectured, that the scent of the fluid brought them there, and that the use of it is to bring the sexes together soon after .ex- lusion from the pupa. The colour, sculpture, and other peculiarities which distinguish insects in this state I shall consider at large U another letter, when I treat of their external parts and gans, Under the present head I shall confine myself to Pointing out the characters by which the sexes of many ‘Pecies are distinguished from each other; as likewise the duration of their life in their perfect state; together With the circumstances on which this duration depends. T Sexual Distinctions. The first general rule that- May be laid down under this section is,—That among Msects, contrary to what mostly occurs in vertebrate “himals, the size of the female is almost. constantly larger an that ofthe male. Even in the larva and pupa states, ` practised eye can judge, from their greater size, which Ndividuals will become females. There are, however, , “ome exceptions to this rule. Thus amongst the Coleo- | Bera, the male Dynastidæ, remarkable for their horns, |` a Jurine Hymenopt. 9. Note 1. 300 STATES OF INSECTS. as as you may see in D. Aloeus, Antæus, Actaon, XC likewise those of Lucanus, are larger than the unarme | females*. In the Neuroptera žhe female Libellulid@ ve - \ sometimes sensibly smaller, and never jareer, than the!” females b, Inthe Hymenoptera the male of the hive-be® but more particularly that-of Anthidium manicatum ane other bees of that genus, is much more robust than the other sex®. In the Diptera, the same difference is ob servable in Syrphus Ribesiz, and some other aphidivoro® flies, and also in Scatophaga stercoraria*, And amongst the apterous tribes, we are informed by De Geer that the male of Argyroneta aquatica, which builds an aria palace in the bosom of the waters °, usually exceeds the female in bulk £. The reason of tlis rule seems in so™” degree connected with the office of the female as a M” ther, that sufficient space may be allowed for the vast number of eggs she is destined to produce; and it ® when impregnation has taken place, and the eggs are ready for extrusion, that the difference is most sensible In the majority of cases this sexual disproportion is nol very considerable, but in some few itis enormous. Rea mur mentions a beetle, of which he intended to give the history, the male of which is so small compared with the female, that a bull not bigger than a sheep, or eve! 4 hare, set by the side of the largest cow, would aptly co” trast with them. This little beetle, he says, has wing? CONNELL of N3 tif ubh tv. fo t, vi. f. 5. t. xiii. f. 124, a b. b Reaum. vi. 423. © Kirby Mon. Ap. Angl. ii. t, xvi. f. 12, 13. t. xvii. f. 10—12. 4 Reaum. iv. 393. e See above, Vor, 1, 473—. f De Geer vii. 304, STATES OF INSECTS. : 301 ‘nd elytra, while the giant female has no vestige of either, ‘ving the upper surface of its body naked and membra- nousa, The species to which this illustrious Naturalist ere alludes, does not appear to have been ascertained. ‘he female of many gall-insects (Cocci) is so large in “omparison with the male, that the latter traverses her ack as an ample area for a walk”. But this is nothing compared with the prodigious difference between. the sexes of Termes fatale, and other species of white ants, Whose males are often many thousand times less than the males, when the latter are distended with eggs*. Acci- ental differences in the size of the sexes sometimes arise: às when the female larva has, from any cause, been de- Ptived of its proper supply of food, it will occasionally be "ss than the male. De Geer has stated a circumstance with respect to the Aphides that produce galls, that ‘Mould be mentioned under this head—the first, or mo- ther female, is larger than any of her progeny ever be- Ome a, The second observation that may be generally applied %0 the sexes of insects is, that, size excepted, there is a, “ose resemblance between them in other respects. But © this rule the exceptions are very numerous, and so im- Portant that it is necessary to specify examples of each nder distinct heads. i. In some species the sexes are either partly or wholly a different colour. Thus, in the order Coleoptera, the “Ytra of the male of Rhagium meridianum F. are testa- “cous, and those of the female black. Leptura rubra of a . z ° . w Reaum. iv. 30, » Thid. tiv. f. sits SoBe A ~ (Leer iW s "ce above, Vou. IL. 36. 4 De Geer iii. 25. 302 STATES OF INSECTS. Linné, with red elytra, is the female of his Z. festace® iw which they are testaceous. Cantharis dermestoides © the same author is the other sex of his Meloe Maret; one of which is chiefly testaceous, and the other black! which seems to have so misled Linné, that he plac them in different genera. One more instance in this order, the female of Cicindela campestris, as was first ob- served to me by our friend Sheppard, has a black dot 0” each elytrum, not far from its base near the suture, which the male has not. Amongst the Orthoptera, the male Locusta F., as Pe fessor Lichtenstein has informed us ?, have a fenestrat ocellus, which is not to be found in the other sex. I was once attending to the proceedings of a Hemipterous sp“ cies, Pentatoma oleracea Latr., which I found in union the paired insects had white spots, but another individué was standing by them, in which the spots were of a sa guine hue, I mention this by the way only—the spol in the prolific sexes being of the same colour: but might not the red spotted one be a neuter ? The sexes of many Lepidoptera likewise differ in thei! colour. I must single out a few from a great number ° instances. The males of Lycena Argus F. have the UP per surface of their anterior wings of a dark blue, while in the female it is wholly brown. The wings of the for mer sex of Hypogymna disparyare gray, clouded wit brown; but those of the latter are white, with bla¢ spots. In the brimstone butterfly (Colias Rhamni), which is one of the first that appear in the spring, the wings ° the male are yellow—of the female whitish. In the co ® Linn, Trans. iy. 54—. STATES OF INSECTS. 303 Mon orange-tip (Pieris Cardamines_F.), one sex has not €or ange tip to the upper wings: and, to name no more, € male of Lycena,dispar, one of our rarest and most “autiful butterflies, has only a single black spot in the isk of its fulgid wings; while in the other sex, the pri- Mary pair have nine, and the secondary are black, with à transverse orange fascia near the posterior margin. ut the most remarkable difference in this respect ob- “ttvable in the insects of the order in question, takes Pace in a tribe, of which only one species is certainly own to inhabit Britain—I mean the Papiliones Equites Linné; what he has called his Trojani and Achivi in “ome instances have proved only different sexes of the “ame Species. Mr. MacLeay’s rich cabinet affords a sin- ar instance confirming this assertion;—a specimen of : Papilio is divided longitudinally, the right hand side “ng male, and the left hand female. The former be- mgs to p, Polycaon, a Grecian, the latter to P. Lao- m LOCUS, a Trojan. An instance of two Grecians thus united t “ecorded in the Encyclopédie Méthodique, as exhibited à specimen preserved in the Museum of Natural Hi- . it at Paris; which on the right hand side is P. Ulysses, the left P. Diomedes ?. u the Neuroptera, the Libellulide are remarkable for € differences of colour in the sexes. In the common o lla depressa, which you may see hawking over w pool, the abdomen of the male is usually slate- ._ Ut; while that of his partner is yellow, but with darker : “spots. Reaumur, however, noticed some males that “te of the same colour with the females®. Schelver a ix. 65, n. 110, b yi, 423, 304 STATES OF INSECTS. observed, when he put the skins of Libellula depressa into water, that the colours common to both sexes were ™ ` the substance of the skin, and remained fixed; while those that were peculiar to one could be taken off with hair-pencil, and coloured the water: which therefor? were superficial, and, as it were, laid on*. The yellow males, therefore, that Reaumur observed, were probably such as had the superficial blue colour which distinguish® them washed off. In Calepterya Virgo Leach, the for- mer are of a lovely silky blue, and the latter green. ; Agrions F. nature sports infinitely in the colours of the SEXES. In the order Hymenoptera there are often difference equally great; the sexes of many of the Ichneumons 2 Saw-flies are of quite different colours. The former tribe Linné has divided into sections, from the white annuli observable in the antennæ of some, and from the colo! of their scutellum: but these are often merely sexu? characters». The male of Anthophora retusa Latt» kind of wild bee, is wholly black, the female wholly gt and of so very different an aspect that they were long regarded as distinct species; a mistake which has likew? occurred with regard to the sexes of Osmia carulesce™ another bee, of which the male has a bronzed and the female a violet abdomen ©. The nose of male Andr" Latr. is often yellow, or white, as in A. hemorrhoidalis— when that of the female is blackd. The labrum also is fl of a different colour in the sexes, as in Ceratina Lat Entomologische, &c. 224. De Geer ii. 847. 850. Jurine Hymenopt. 100. Kirby Mon. Ap. Angl. ii. 296. 264. Ibid. ii. 142—, 144, 147, 148, &c. a b a d STATES OF INSECTS. 305 Th the Diptera, Aptera, Arachnida, &c., I am not aware any striking difference in the colours of the sexes. le, The skiis of insects vary (but more rarely than in r) in their sculpture also, and pubescence. Thus the Vita of the females of many of the larger water-beetles os) are deeply furrowed, while those of the males . Tute smooth and level*.. The thorax of the female ‘everal species of Colymbetes of the same tribe, as 7 Hybner; and t¢ransversalis, on each side has several tous impressed lines or scratches, like net-work, ty, are not to be discovered in the male. Hyphydrus a i Latr., which differs solely from H. wass (ipiis: ie Ilig.) in being thickly covered with minute ‘sed puncta, is, from the observation of the Rev. i. €ppard, the other ws gf this last, vih which he tha aken it coupled; and it is by no means improbable “Ydroporus picipes ( Dytiscus punctatus Marsh.) and peg between which, as Gyllenhal has justly ob- te? the same difference only exists,—are in like man- à “Xtal varieties. With respect to pubescence, Ihave | lea te say. Another aquatic beetle, Acilius sulcatus E has not only its elytra sulcated, but the furrows | Se aN and a transverse one of the thorax, are thickly | Par i hair; while the male is smooth, and quite naked. tha ular care seems to have been taken by the Creator, the en all the above inhabitants of the water are paired, ‘le should be able to fx himself so firmly, by means a uni remarkable anomalous exception to this rule sometimes oc- Male (Guy male of D. marginalis, which has smooth elytra like the My. Da = Ins. Suec. i, 467—). I have this variety from the Rey. y » Of Copgrove, Yorkshire. E IFI, x 306 STATES OF INSECTS. of his remarkable anterior tarsi, (which I shall afterwards describe,) and these asperities, &c. in the upper su me of his mate, as not to be displaced by the fluctuations ° that element, the reluctance of the coy female, O" an other slighter cause. sA In a moth called the ghost (Hepialus Humuli} | posterior tibia of the male is densely bearded, but es the female +.— Some Hymenoptera, as Ammophila ‘ : he and Stigmus Jurine, have the upper lip of the male clot i with silver pile, while that of the female is not 50 nA mented. The legs of some bees are distinguished m sexes by a difference in their clothing. That obser™ in those of the hive-bee has been before noticed ”. Andrena of Latreille © the posterior tibia of the fema d covered externally with a dense brush of hairs, for a lecting the pollen; and the posterior legs at their ™ have a curled lock of hair—which are not to be fou? P the male. In Dasypoda, Melecta, Anthophora, ce Epicharis, &c. of the same author, the first joint ° ie. tarsus of the female, and in Xylocopa almost the ® pë tarsus, is also similarly signalized from that of the ot 7 sex. In Bombus, as in the hive-bee, the poster d d of the females and neuters are furnished with a bask? ig hairs for carrying their pollen paste, which you si p vain look for in the male *. The latter, however, in species of this tribe are distinguished from the form? o the longer hairs of their legs, but not in the posté be ones. Thus, in Anthophora retusa the first joints ef * De Geeri ziyi AIR b See above, Vor. I. 125, Note »®. ¢ Melitta ** c. Kirby Mon. Ap. Angl. i. 140. 1 Tho, s £ e f 20. a a Ford. t. iv. f. 10. a, b. f. 14. e Thid. te KIJ” ‘ STATES OF INSECTS. 207 “termediate tarsus are bearded internally with a thin nge of long hairs, and the first externally with a tri- Sular one of short ones at the apex: but what is most markable, the last or unguicular joint, which in al- Ee other bee is naked, is on both sides fringed | ong hairs. In that remarkable genus Acanthopus wt of which the male only is known, the first and last nt Te of the intermediate tarsus have a dense external i of stiff hairs, which probably is also a sexual cha- r, Another sexual kind of clothing is exhibited a females of those bees that have their labrum or ig E inflexed (Megachile Latr.)°. Their abdomen in E” ed underneath with a brush of stiff hairs, involved k Ich they carry the pollen they collect. In the males join Me of this tribe, as of M. Willughbiella, the first four lo S of the anterior tarsus on their inner side have a algo dense fringe of incurved hairs‘: a circumstance Whig © be found in the same sex of Xylocopa latipes, in the the claw-joint also is bearded *. In Andrena Latr. bin “St dorsal segment of the abdomen of the same sex is > while that of the male is naked f. In the humble- vith ‘ ombus), the mandibles of the male are bearded ate p ea hairs, while those of the females and neuter latr tthout them. Some bees, as Andrena and Halictus tha} “ave the anus of the female bearded, and that of the e : Naked: in some Bombyces the reverse takes place. a Kir ie HE PY Mon, Ap. Angl.i. t. xi. Apis **. d. 2. a. B.f.18 a. b. c. d. = Kin, ert Ilustr, Icon. i. t. vi. f. 6. ` e, on. Ap. Angl. i. Apis **. c. 1. æ. ¥*. c. l. B. **, €. 2. E ee 2.3, ` Kirby a VIL f. 28. f. g. e Christ. Hymenopt. t. iv. f. 3. b. Ton. Ap. Angl. i. t. iv, Melitta **, c.f. 1. a, eA 808 STATES OF INSECTS. iii, With regard to the general shape of their body the male and female usually resemble each other: there are some exceptions to this rule. The male oft : . hive-bee is much thicker and more clumsy than eitbe : : 5 the female or the worker; but in Halictus Latr. the male pile are nearly cylindrical in shape, and very narrow 5 s pdo” the other sex are oblong or ovate, especially their 2 men: and in Andrena Latr. the former are much se derer than the females, and of a more lanceolate shap” But a still more striking difference in this respect tween the sexes is exhibited by some species of the ger Ptinus E., in which the male is. long and slender, and female short and thick. This, in more than one insta” : has occasioned them to be mistaken for distinct insett thus, P. Lichenum and P. similis, P. ovatus and P. € taceus, of Mr. Marsham, are mere sexual varieties. j the most entire abalienation of shape at present know is that which distinguishes the male from the f j Coccus; these are so completely dissimilar as scarce) d have any part in common. In Bombyx vestita Fy i others of the same family, while the males are of the it dinary conformation of the order, the females are Wit a even the slightest rudiments of wings; they have pe j tennæ, the legs are extremely short, not longe! p those of the caterpillar; and the body is entirely K tute of scales, so that they altogether assume the a appearance of hexapod larvse*, A conformation ™ y similar takes place in the female of Tinea Lichenell@ a) in this the feet are longer, and the anus is furnishe by a long retractile ovipositor °. r a Scheven Naturfors. stk. 3 TE ‘ [bid * 12 r Naiurfors. Stk. XX. 65. ts 1. f. 4, Compare b Reaum. iit. ż. xv. f. 18,19. STATES OF INSECTS. 309 iv. In many cases, the structure of particular parts and "gans of the body differs in the sexes. As the facts con- nected with this part of our present subject are extremely , merous and various, it will be convenient to subdivide and consider the sexual characters that distinguish— © Head, Tr unk, and Abdomen of indects, and their se- veral appendages. l. The Head. This part in some females is consider- y larger than it is in the male. This is the case with * ants, and several other Hymenoptera ; while in some ndy ene, as A. hemorrhoidalis, and Staphylinide, as ‘olens, that of the male is the lar gest. But in none is ( € difference more conspicuous than in the stag-beetle . in which genus the male not only exceeds the “tale in the length of his mandibles, but also greatly "the Size and dimensions of his head. In the Apion “tus, the rostrum of the female is generally longer and “Nderer than that of her mate; and in Brentus, the im of one sex (probably the male) is long and fili- m, while in the other it is thick and short. This is “ticularly visible in B. dispar and maxillosus è, &c. he of the most striking: distinctions of the vale in ay = of their body, are those threatening horns, usu- ollow, with which the heads of many of the male gcticomn i insects and some others are < armed, and which dry them some resemblance to many of the larger qua- vit peds, Many are unicorns, and have their head armed lis only a single horn; which in somie, as in Oryctes 8 Dynastes Endymion”, &c. is very short; in others, i Oliv. no. 84, Brentus, t. i.f. 1. b. c. t. ii, f 17. ab Oliv, no. 3. Scarabæus, t. xviii. f. 169. 310 STATES OF INSECTS. very long, as in Dynastes Enema, Pan, Elephas >, one, again, it is thick and robust; as in the clumsy Dy - nastes Actæon®: in another very slender, as in Ontho- phagus spinifer. With respect to its direction in BY phastomus proboscideus MacLeay, it is horizontal? 2” straight; in Phaleria cornuta horizontal and broken; a the apex turning outwards and forming an angle with base €; in Dynastes Hercules horizontal, and recurv’ at the apex‘; in D. Acton, Elephas, and T ‘yphons aft curving from the base. In Geotrupes dispar it is 1” curved, so that its point exactly coincides with that ° the porrected thoracic horn, with which it forms a kine? forceps. In Copris lunaris F. and Diaperis horrid& ©, horn is nearly upright *. In Onthophagus Xiphias it is ’ lated at the base, and reclining upon the thorax; and ‘ the apex attenuated, and bending forwards, or noddi? In Passalus cornutus it rises a little, and then bends wh? forwards. In Dynastes Milon, a most remarkable pect! it slopes backwards in a waving line'; and in Onthophie spinifer it is recurved and reclining.—In speaking off direction of the horn, you must recollect that it will v? és in proportion as the head varies from a horizontal p° tion: so that an upright horn will become inclined reclined, as the head bends forwards or backwards; ; I speak of it as it appears when the head is horizo” ut a Oliv. Scarabeus, t. xii. f. 114. t. xv. f- 138. a. > Ibid. t. v. f. 33. c Ibid. t. xii. f. 112- * Linn. Trans. vi. t. xix. f. 12. t. xx. fi 2. Oliv. no. 57. Tenebrio, t. i. f. 2. £ Oliv. ubi supr. No. 3. t. i. f. 1. 8 Oliv. no. 3. £. iii. f. 20. a. h Ibid. no. 55. Diaperis, t. i. f. 3. i Oliv. Scarabeus, t. xx. f. 185. e STATES OF INSECTS: _ SIE Again, it varies in its teeth or branches. In Dynastes &rcules it is armed with several teeth. In D. Elephas Ad Acteon it has only one large one at its upper base *. a D. Milon it is serrated above. In D. Alcides, Tityus, Seon, Copris lunaris, &c> the horn is unarmed and sim- at the apex. In D. Oromedon, Gedeon, Enema, “eon and congeners, it is bifid. In some the horn is first a broad lamina or ridge, which terminates in two "aches, as in Onthophagus Vacca. In this the branches > E Might; but in another undescribed species in my “binet (O. Aries Kirby, MS.) they are first bent in- “ards, and then at the apex a little recurved: and in of ` dichotomus it is divided into two short br anches, each Which is bifid». Other males emulate the bull, the “goat, or the stag, in having a pair of horns on their “d. In Onthophagus Taurus, these arms in their curva- X exactly resemble those of the first of these animals °. Goliathus pulverulentus, the straight, robust, diverging, aP horns are not unlike those of some of the goat or wl tribe. I have a beautiful little specimen in my ca- het, (I believe collected by Mr. Abbott of Georgia,) in ae the horns have a lateral tooth, or short branch, € those of a stag; and which I have therefore named “rvicornis. In O. Vacca, Camelus, &c. the horns are “ry short, and nearly perpendicular. In the male of aie Dynastes Acteon, Elephas, Typhon, &c. differ from D, Her- thei, € not only in their general habits, horns, &c., but also in * maxillæ and labium,—the former in D. Acte@on being simple, in D, Hercules toothed, and the labium of the first bilobed at ‘Pex, and i in the last entire and acute,—according to the modern Wo SMe ought, therefore, to be considered as distinct: genera. restrict the name Dz ynastes to D. Hercules and its affinities: p on, &e. I would call Megasoma. liv. Scar 'abæus, t. xvii. f. 156. © Ibid. t. viii. f. 63, 312 STATES OF INSECTS. Copris Midas, the two longer perpendicular horns hav? ‘ deep cavity between them, which, together with its plack colour, give it a most demoniac aspect; so that you wou think it more aptly representative of a Beelzebub or Beek zebul than a Midas*, or than Phaneus Beelzebul Mac™* A similar cavity is between the occipital horns of pir peris hemorrhoidalis Payk. Some species of Ryncham® as R. Taurus, have a pair of long horns upon the rostri! of the male, the rudiments only of which are to be tt ace in the female>. Other species go beyond any o quadrupeds in the number of horns that arm their head ThusDitomus calydonius Bonelli, belonging to Car rabus Ls has three equal horns *. ‘The same number distinguish™ Onthophagus Bonasus ; but the intermediate one is ai short. In Goliathus Polyphemus the middle horn, 0? the contrary, is much longer and thicker than the latet? ones, and forked at the apex; so that it looks as if it ba four of these weapons‘. A little Diaperis (D. vir idip™ nis F.), a native of Carolina, has four horns upon t head of the male; namely, two long ones on the occipt and two short dentiform ones on the nose. In a speci? nearly related to this, sent me by Professor Peck fror New England, there is a cavity between thé two oc tal horns. The same number distinguishes Onthophit quadricornis (Copris ¥.). The situation also of © horns varies: In some it is in the middle of the b° l as Oryctes nasicornis, Copris lunaris, &c.: in other® ; in Onthophagus nuchicornis, Xiphias, &e. it isa prov? p 5 a This insect is beautifully figured in M. Latreille’s Znsectes * ee des Egyptiens,f. 11. See Luke xi. 15. Heb. ayoya Dominus stert » Oliv. no. 83. 160. 4. vi. f. 60. 8- t.v. fi 45. ¢ Ibid. no. 36. t. ii, f. 12. 4 Ibid. no. t viif. 61. STATES OF INSECTS. $18 of the occiput or hind-head; and in O. Oryx F. the two rns proceed from the anterior part of the head. In t € other sex, in insects the head of whose males is armed “ith horns, they are usually replaced by mere tubercles, ®t very short elevations, as you may see in the female of Pris lunaris; or by transverse ridges, as in the Ontho- Phagi: or else the head is without arms, and quite smooth, yas) Diaperis, Phaleria, &c. What may be the use of “se extraordinary appendages, as well as those on the ®rax, and in some cases on the abdomen, (which I shall Mention afterwards), to the males, has not yet been ascer- tained, Whether the individuals of this sex are more ““posed to the attack of birds and other enemies, in con- “quence of being more on the wing than the females, “nd are therefore thus provided with numerous project- M8 points for defence, is a question worth considering *. tis the only probable conjecture on the cud bono of these ams that I can at present make. Under this head I “Ught to notice the remarkable membranous process of M obovate shape, which like an umbrella covers the “fad of Acheta umbraculata F.» Whether the sharp. “ved horns which arm this part in another Acheta sured by Stoll*, in an incumbent posture, with their “Int towards the mouth, are a sexual distinction, we are met informed,—probably they are. The organs of the head also present maniy sexual di- à See above, Vor. II. 224—. : Oquebert Zl/ustr. Icon. iii. t. xxi. f. 2. toll Cigales, t. xvii. f.a gc. Grillons t.iv. f. 16—18. This sin- N animal, which was found by Mr. Patterson at the Cape of instan ' Ope, is stated to be an aquatic ; and affords the only known otal ce of an Orthopterous insect inhabiting the waters. The Gryl- Pa loves the vicinity of water. ` 814 STATES OF INSECTS.. stinctions. The upper lip (labrum) in Halictus Latt.» a tribe of wild bees, in the female is furnished with an in- flexed appendage, which is not discoverable in that ° the male*; and the shape of this lip in Sphecodes Latr differs in the sexes?. Perhaps the horn or tubercle ob- servable on this part of some female Nomade F. © may be wanting in the male. , The under-lip (Jabium)—taken in a restricted sense for that central part from which emerge the labial palpi, a” which is often considered as the mentum,—does not offer any striking variations in the sexes. One, however? " of importance, as it helps to prove which are the true female Lucani. In the male the labium is emarginat® in the female it is intire. This may be seen both m L. Cervus and femoratus, and probably in other species The sculpture also is different, the lip being smooth 1” the former and covered with excavated puncta in the Jat ter. The tongue (lingua or ligula) of the sexes is usually the same; except in the hive-bee, in which that of the neuters is longer than that of the male and female. The upper-jaws (mandibule), however, often affo! striking sexual characters. ‘The enormous protendé ones of the common stag-beetle (Lucanus Cervus) attract the attention of the most incurious observer; and the are now generally allowed to be of this descripti” Geoffroy and Mr. Marsham, indeed, have asserted that they have taken in coitu those with long mandibles: bu ‘ it. as these males are pugnacious, and attack each other wi great fury, as Mr. Sheppard informs me, it is not ii . att bable that these gentlemen may have mistaken a b 2 Mon. Ap. Angl.i. Melitta **. b. 139. t. ii. f. 4—6. gift b Ibid. **. a. f. 4, 5. c Ibid. Apis *. b. 190—. t.v. f 18 L STATES OF INSECTS. 315: for an amour : since not only have those with long man- dibles been often taken united with those that have short nesa, but the same difference obtains in the sexes of other species, This is particularly observable in Lucanus moratus, of which I received from Brazil many speci- Mens agreeing in every respect except in this, that one ad short and the other very long mandibles. These gans vary in different specimens, as to the number of their teeth and branches. They are singularly robust in ' Alces>; but in none more threatening than in L. Ele- Phase, in which they curve outwards and downwards. a Mr. W. MacLeay’s genus Pholidotus, they are almost Parallel to each other, and curve downwards; in Lucanus nebulosus Kirby, they assume a contrary direction į; as they 0 likewise in Lamprima Latr.¢ In Lucanus Capreolus the Points close over each other’. In Lethrus F. in the \ “male, but not the male, the mandible is armed below with . long incurved horn. In Lucanus serricornis they form * Complete forceps s, In Stagonium quadricorne Kirby * € mandible is furnished at its base with an exterior tn, which is probably a sexual distinction. The male. Ynagris cornuta, a kind of wasp, is still more conspi- “tous in this respect; for from the upper side of the base Fits straight slender mandibles proceed a pair of crooked, “curved, tortuous, sharp horns, not only longer than Geer! . In Dinetus Jur. the male antenn® are moniliform at the base, and filiform at the apex; the female, on the contrary, are entirely filiform €. * Mon. Ap. Angl. i, Apis **. c. 2. y. t. ix. f. 7. g-9. 8. > Ibid. Melitta **. a, t, ü. f. 8. 9.9. 8. and **. b. t iif 6 F 7.38. **.ctiv.f. ll. 9.12. 3g. e Jurine Hymenopt. t, 11. f. 2. STATES OF INSECTS, 319 The antennz of the sexes also sometimes differ in Magnitude and length. This is the case in the three ge- nera of wild bees just mentioned; those of the female be- Ng thicker than those of the male, while these last are nger than the former. But in this tribe the males of the Fabrician genus Eucera are most remarkable for their mg antennæ è. With regard to the different length of these organs in the sexes, no insects are more distinguished. than some species of the capricorn-beetles (Cerambyx L.). A Lamia Sutor the male antennee are twice the length of the female; and in another Brazilian species in my cabi- Net, related to Z. annulata (Stenocorus F.), they are thrice their length. Some of the Anthribi F. approach the Corambycide, not only in some other characters, but also M this circumstance :—thus the antenne of A. albinus, a Native of Britain, are vastly longer in the male than in the female; and in A. cinereus (Macrocephalus Oliv.) >, “hich I suspect to be of the former sex, they are as long ‘early as is usual in the tribe just named, called in France “pricorn-beetles. may here observe, that sometimes in the sexes a dif- “rence is also to be found in the direction or flexure of teir antennae. Thus in Scolia F., Pepsis F. &c., in the Males the antennæ are nearly straight, but in the females ~nvolute or subspiral. The reverse of this takes place «| Epipone spinipes, a kind of wasp, and its affinities; and Wtropha Illig., a kind of bee: for in these the male an- “tna is convolute at the apex °, and the female straight. ù the various tribes of bees (Anthophila Latr.), these 3 Mon. Ap. Angl. i. Apis **.d. 1. t. x. f. 7 b Oliv. no. 80. Macrocephalus, t. i. f. 2. e Latr. Gen. Crust. et Ins. iv. 156.- STATES OF INSECTS. the organs in the latter are what is denominated broken, first main body of the antenna forming an angle with the joints: but in the former this does not take place. The antennæ of the sexes do not always agree in number of joints. In the bees, and many other Hymen™ ptera, the male has one more joint than the female; 35 a the case also in Œdemera notata (Cantharis acuta Marsh.) In Pteronus Laricis, a kind of saw-fly, the latter has only sixteen joints in its antennae, while the former has twenty“ four?è. In Rhipicera marginata, a beetle, the beautift antennæ of the male consist of thirty-two joints, while the female has no more than eleven! In Chelonus JU. the male, on the contrary, has the smallest number © joints, namely sixteen; while the female has twentY” five >. In nothing do the sexes differ more materially than in the ramification of these organs, and their plumage. BY the attending to this, you may often detect the sexes in al instant; since the antennæ of the males in numerous in- stances are much more complex than those of the females For what end the Creator has so distinguished them is not quite clear; but most probably this complex structure a for the purpose of receiving from the atmosphere infor™ tion of the station of the female. A tendency to branching will be found in the antennæ of some males, in tribes wher? these organs are usually perfectly simple in both sexe” Thus, in the male of Chelostoma maxillosa,—mistaken for another species by Linné, which he names Apzs florisom nis,—the intermediate joints on their inner side proje? into an angle‘; and those of the same sex of the commo” è Jurine Hymenopt. 61. t. vi. RE b Ibid, 289. e Mon. Ap. Angl. tI Apis **. e2, y. f. 9. STATES OF INSECTS: 821 hor a by means of a central sinus, have two obtuse i on each. With regard te: mote direct ramifica- ai iale antennæ terminate in a fork, or two es. This is the case with Hylotoma furcata Latr., Stw-fly2; and the peacock-louse (Nirmus Pavonis “a ». Others, again, have three lateral branches, Bae ulophus Geoffr. a little parasite, the male anten= a send forth a hairy external and rather long ints $ from the base of the fourth, fifth, and sixth tte 4 : In Elater flabellicornis L., the eight last joints aa 5 ellate, or elongated and flat, resembling the sticks a in the malet; in todi fomiolg they are shorter, and teeth Properly may take their denomination from the of a comb. In Lampyris Latreillii Kirby, the an- a of the former are flabellate on both sides, while S the latter are little more than serrate ®. These $ S are extremely beautiful in the males of the Rhi- th: © of Latreille. In R. marginata K. they consist of r e DAT the Y~two joints, from thirty of which issues a branch, lage very short, but the rest gradually increasing in Maat, they approach the middle of the antenna; then g y decreasing to the end, so as to represent an S fanf. Butin none are they altogether so re- R le as in those moths that Linné denominates the ‘ a Attaci, and some others. In these, in the males, wo Tgans in their contour are lanceolate, and every on 'S furnished with a couple of parallel equal branches ea, eh sides, In the females these branches are shorter a k Prarg XI. Fre319. b Pyare V. Fra. 3. 3 pee XI. Fre. 18. d Ibid. Fre. 17. è SR CCN Fic. 11, Linn. Trans. xi. t. xxi. f. 4. a. Voy, a d. f. ® Prare XXV. Fie, 22. 0 L X 322 l STATES OF INSECTS. on the whole, and alternately one long and one short; but in some, as Saturnia Pavonia, there is only one shot branch or tooth on each joint in this sex*. In Bombyz™ galis &c. only the first part of the antenna is so branche and those of the femaleare setaceous and without pranche In B. versicolor, &c. there is only one branch from eat” side on every joint; those of the female being ne shorter than those of the male. The latter sex of P pero nus Laricis Jur., a saw-fly, afford an example of a O ferent structure, the antennæ on one side sending fort a branch from every joint but the two first; but oP iy other side, the nine or ten last joints also are without? branch. The female antenna is serrated®. In anoth® of this tribe, Pterygopterus cinctus Klug, the male tenna resembles a single-toothed comb, being branch? only on one side: that of the female, like the forme p stance, is serrated °. Whether the remarkable antes? ý that distinguish the known individuals of the genus pit godes (Lampyris plumosa F.) is a sexual characte! 4 not been ascertained; but it is not improbable that may be, as in other Lampyride. A pair of deli j fiexile and almost convolute plumose branches prow from the apex of each joint except the basal ones, Y f have something the air of cirri, and give a more ; é, usual degree of lightness and elegance to these org 3 Other antennee, especially in the Diptera order, asst an appearance of plumes—not from the branches that P at ceed from them, but from the fine long hairs that P ne and adorn them. These are universally indications? De Geer i. ¢. xix f. 11, 12. » Jurine Mymenopt. t. vif: © Prare XXV. Fie. 25, 26. 4 Ibid. Fra. 4. STATES OF INSECTS. 823 S Sex, those of the females being generally compa- ely naked. If you take the common gnat, you will p~ the antennæ of one individual are thickly fringed “ach side, and tufted at the end with fine long hairs, € in the other only four or five placed at intervals in hor] are to be perceived*. In Chironomus Meig., a Ind of Tipula L., resembling a gnat, the male antennse "e beset on all sides with the finest hairs, and resemble “tutiful plume, while the females to the unarmed lng Pear naked. Even in some Elymenaptere, the an- for a of the males are thus feathered, in a less degree: stance, in Hylotoma Latr.* Whether the tufts fringes which ornament, in a remarkable manner, “antennz of many Cerambycide 4, are sexual charac~ 's, is not certainly known. © are now to consider other sexual differences in : Ş Organs, resulting from the size or configuration of e More individual joints. To begin with the fires > Or scapus. In many of the Hymenoptera, particu- sg fe Anthophila Latr., this is elongated, and the ne in Ng joints form an angle with it in the females: while Yi € other sex it is much shorter, and in the same line the rest of the antennæ; and in Hylæus dilatatus ete dilatata Kirby) the first joint in the male is di- ch and shaped something like a patella °. , In Mala- lye z- y i i. bipustulatus, &c. the sex just mentioned is pecu- y distinguished by a white excrescence on the first a ne, Nair 2 A 324: STATES OF INSECTS. four joints of the organs in question, most conspicuo™” in the second and fourth. The antenne of male Cero come are not very different?. Mr. Marsham has de- scribed a little Haltica under the name of Chrysom”t nodicornis, from a peculiarity of the same sex not to found in the other. The fourth joint is very large “a obtriangular; in the female it is merely longer than , rest. In H. Brassice and quadripustulata the fifth jou is larger and longer than all but the first in the males y their females it is only longer. In some moths tge nia Latr., Crambus F.) there is also a knot in the midd of the male antennee>. In Noterus, a water-beetles 5 six intermediate joints are thicker than the rest, peg” ning from the fourth, and the last but one ends inter? in a truncated tooth. The fifth and two following ig in the male antennæ of Meloe are larger than the 1% which distinguishes them, as well as a remarkable ber observable at that part °. tr Variations of the kind we are considering are also ° servable in the clava, or knob, in which antenne 0 i terminate. You have doubtless observed that the 4 i mellated clava of the antennæ of the common cockch® j í is much longer and more conspicuous in some individ™ : than in others—the long clava belongs to the male t; i another species, M. Fullo, that of this sex is nine or ys times the length of that of the other. In Colyn s serricornis, a water-beetle, the male has a serrated © i of four joints. In Dorcatoma dresdensis °; and also plium damicorne, two beetles, it is nearly branched # | 2 Prate XI. Fic. 22, =b N. Dict. d’Hist. Nat. xiv 395. © Prate XII. Fic. 7. à Prate XXV. Fic. 1. » "Ibid Pies 21, ea STATES OF INSECTS. 325 male, but much less so in the female. In a little destruc- » a New Holland genus of the weevil-tribe, in the ale the last joint, also, is much longer than it is in the Male a Prin cip SeXes - These examples will give you some idea of the al variations that take place in the antennz of the > and of the wonderful diversity of forms in this re- tto which mere sexuality gives rise amongst insects. nthe eyes, or stemmata, this diversity is less remarkable. ON has described two ants, Formica contracta and pon the neuter of which he could discover no eyes?: € former, the female, however, had large ones. The iS € he appears not to have known, but it probably was destitute of these organs; of the latter he was ac- pa only with the workers. The neuter of Myre tho rubra, another ant, has no nee or aire ae Ugh the male and female are provided with them °. Yare discoverable only in the former sex of that sin- i fetes related to the ants, Mutilla ee en Other a differ in the size of the eyes of their sexes.. In op, e-bee, and some Ephemera, the eyes of the drone k X “are much larger than those of the worker and below and also meet at the Mertens having their stemmata Wi a the conflux; whereas in these latter they are Y distanta, In Stratyomis, Tabanus, and many other a Lir b ‘eg Trans, xii. t. xxi, fi Bie. g. ff 9. ye Nat. des Fourmis, 195—. 270—. eer ii, 1094, q bid. ex ; = 43, = 650. Mon, Ap. Aadha. t. xi, Apis xx. e. EAA 8. t. xii. 326 = STATES OF INSECTS. two-winged flies, the male eyes meet at some point below the stemmata, and above the antenna. In the forme! they touch more at an angle; for the vertex forming * narrow isosceles triangle, and for the anterior part of the face one nearly equilateral: while those of the female ae ‘separated by a considerable interval. In Heptat™ and Hematopota in that sex, a similar interval obtain while in the other, after forming a minute short trian? they unite for a considerable space, and then diversi? form the face. This is also the case in Tabanus; but the female, the space that intervenes between the pow rior part of the eyes is much narrower than in these! j cognate genera of the horse-flies. In some othe! this order, as Musca Latr., the eyes of the male do p al o touch, but approach posteriorly much nearer to @ other than those of the other sex. In a few insta -the sexes vary even in the number of their eyes; 3f w as the size. This occurs in some species of Ephemet™ (E: diptera, &c.), in which the male, besides the © í aan lateral ones, has two large and striking inte" j diate eyes, that sit upon vertical pillars or footstalks 2. The Trunk. The thorax of many coleopt males, especially of the Dynastide and Copridæe an the petalocerous tribes, exhibits very striking aifter™ from that of the female. In many Lucani the y if angle is more prominent. In Anthia it is pilobed P’ 4 riorly, while in the last-mentioned sex it is entire ™ 10 Phaneus carnifex MacLeay (Copris F.) itis elevat? m a plane triangular space, with the vertex of the tri : Prare XXVI. Fic. 39. De Geer ii. 651 659- Voet Colcopt, i. t. xxxix. f. 47, 48. 3. 46. 9- STATES OF INSECTS. 327 Pointing to the head; but in the female it is convex, with ù anterior abbreviated transverse ridge ê. lha large proportion terrific horns, often hollow, like Ose of the head lately noticed, arm the thorax of the Tie of which you will usually only discover the rudi- ay i the other sex. ; In the first place, some are seit È > or armed only with x single thoracic horn, which eet: in conjunction with the annex! itself not a little es a tunnel reversed: of this description are Dy- es Hercules, Tityus, Gedeon, Enema, &c.” In the | ae this horn js porrected, or nearly in the same line X pee body; but in the last, and D. Pan, it forms an Ste with it; and in D. Ægeon it is nearly vertical °, iy Hercules it is very long; in D. Alcides? and Tityus J Short; in the two last, and in Oxytelus tricornis ich is similarly armed, it is undivided at the apex; a m D. Gedeon, Pan, bilobus, &c.® it is bifid or bilobed. bj X Usually rather slender, but in D. Chorineus* and us, itis very stout and wide. In D. claviger it is ee at the apex In D. hastatus it is short and k B h, Others, again, have żwo thoracic horns. ; “pris nemestrinus these are discoidal, diverging, and : “mning forwards i. In Phanaus floriger* they are late- vie triangular, and incline towards each other, with, as Wer e they S » a deep basin between them. In P. splendidulus ink into two longitudinal ridges, most elevated = Oliv. no. 3. z. vi. f. 46.a. 8.5.9. ° Ibid. z.i. f. 1. iv. x. f. 31. xi. f- 102. Xii. f. 114. : Ibid. ż. xxvi. f. 219. 4 Ibid. £ if. 2. : Ibid. t. xxiii. f. 35. f [bid. fiat f. 7. Ibid. z. v. f. 40. h Ibid. xix: f. 175- _ bid. z. xi. f. 115. Copris floriger Kirby in Linn. Trans. xii. 396. 328 STATES OF INSECTS. posteriorly, with an intervening valley*. In p bellicost they are posterior, compressed, truncated, and èmarg” nate at the apex, and include a basin?. In Copris Sabet they are merely two acute prominences °.— Three horn distinguish the thorax of many. In D. Aloeus* and 1# affinities, they are arranged in a triangle, whose vert is towards the head. In D. Anteus* these horns at? nearly equal in length, and undivided at the apex D. Titanus‘ the anterior horn is longer than the resh and bifid at the apex; in D. Atlas and Endymion’, bo of which have a horn on the head, it is much short?” In others, as in Megasòma Kirby, the vertex of the 1 angle is towards the anus. In M. Typhon» it is Jong” than the anterior ones, and bifid at the apex; in Me g: nigerum they are equal in length’, In M. Elephas a Acteon * it is merely an elevation of the thorax; in last almost obsolete. In Geotrupes Typheus, comm” on our heaths, the anterior of this part is armed by thre’ horizontal horns, the intermediate one being the short est}. Copris lunaris also, another of our own peet?” has three short posterior thoracic horns, two lateral a triangular ones, and ‘a transverse intermediate elevati” with a notch in the middle™. In Dynastes Neptunus t horns are porrected, the middle one being very long a? ; the lateral ones short”, In D. Geryon the point of thë ” a Oliv. no. 3. £. ii f. 18, > Ibid. t. xxii. f. 32 I-80. a Tbid. ż. ii. f. 22. e Ibid. ż. xiii. f. 124. a. f Tbid. ż. v. f. 38. £ Ibid, ż. xxviii. f. 242. t. xviii, f. 169. = Tid. ¢. xvi. f. 152. i Ibid. ¢. xxviii. f. e Ibid. t. xv. f. 138, a. t. v.f. 33. : Samouelle’s Compend. t.i. f. 1. 1 = Oliv. no, 3, ty. f. 36. a. . 2 Schon, Synon, i. “7 gA7s STATES OF INSECTS. 829 feral horns is towards the anus, and the base of the in- termediate one covers the scutellum è. Others have four of these singular arms: this is the case with one of our tarest beetles, Bolbocerus mobilicornis K., which has four “entiform horns, the intermediate pair being the short- est, arranged in a transverse line on the anterior part of the thorax>, In B. quadridens these are merely teeth. A Phanæus Faunus ° it has two lateral, elongated, com- Pressed, truncate, horizontal horns, and two intermediate teeth, Dynastes Milon has a still greater number of Orns on the thorax of the male, there being two lateral terior ones and three posterior ones—the intermediate Mg the longest; and Copris Antenor Fabricius and Olivier describe as having a many-toothed thorax; and tom the figure of the latter *, the male appears to have “even prominences. ut the males of insects are not only occasionally di- Pane * guished by these dorsal arms—in a few instances they aikoi furnished with pectoral ones. The illustrious "aveller Humboldt found in South America a species š Weevil (Cryptorhynchus Spiculator Humb.), the breast . Which was armed witha pair of long projecting horns; a : à ad I possess both sexes of four species, three at least mi Brazil, that exhibit in one individual the same cha- a À . . Cter, One, concerning the country of which I am un- R . Rate recedes somewhat from the type of form of the ‘e k st, and comes very near that of Rynchenus Strix F. £ A the individual which I take to be C. Spiculator, the e : : *toral horns are very long, curving upwards at the a . : piv no. 8. t. xxiv. f. 208. è Ibid. t. x f. 88. E dare a Ibid. t. xx. f. 185. ' É Vif. 42, a. f Ibid. n. 83. Curculio t.xxii. f 295. 330 STATES OF INSECTS. apex, and nearly in a horizontal position ; while in thé three others they are much shorter, and inclined towards the horizon. The males of some species of Rynchitess as R. Bacchus and Populi*, are also armed with a pair s lateral horns or spines, which may be termed pectot? rather than dorsal. I shall now advert to the sexual characters that are m be found in the instruments of motion attached tO the trunk—beginning with those for flight. In the female © the common glow-worm (Lampyris noctiluca) not the slightest vestige of elytra or wings is visible, and it adi sembles a larva rather than a perfect insect; yet its mate js a true beetle furnished with both. The same circu stance distinguishes the female cockroach (Blatta) ® is more universally prevalent in that genus than in Lar pyris, in which a large number of females have both elf tra and wings. The males of Bombyx antiqua and Gon” ; i a stigma, and of many other moths, have wings of the ust ere y rudiments. This is the case, also, with some of the Idle neumonide», In the tribes of Ants, Termites, X¢ t ample dimensions, while those of their females are m neuters or workers are without wings. Amongst the plant-lice (Aphides) there are individuals of both gee” some of which have wings, and others not °. Among? the Coleoptera, the female of Tenebrio Molitor, the com” mon meal-worm, has elytra and no wings; while ¢ ; - s2 male has both 4.—Sometimes these organs vary #7 á . A . yi in the sexes: thus in Aradus Betulæe F., a kind of be e > - (h the hemelytra and wings are narrower and shorter !? $ a Oliv. nc. 81. Attelabus t. ii. f. 27. 8. 28, » De Geer ii. ¢ xxxi. f. 18—22. ; © Ibid, iji. 2) 4 Lesser L. i. 185. STATES OF INSECTS. 331 female than in the male*. In the genus Blaps F., the mucro that arms the apex of each elytrum is longer in the former sex than in the latter. In Ateuchus gibbo- eee SS.) al dung-beetle, the elytra have a basal gibbosity hear the suture in one sex that does not obtain in the Other, In the Orthoptera order, the sexes are often to € known, almost at first sight, by a difference in the veining and areolets of the wings; but upon this I en- larged so fully when I treated of the sounds produced by sects, that it is not necessary to repeat what I have “aid ; which observation also applies to the drums which distinguish the male Cicade”. The wings of some but- terflies, and of most moths and hawkmoths (Spine L.), are furnished with a singular apparatus for keeping them Steady, and the under-wing from passing over the upper m flight. This appears to have been first noticed by oses Harris, and was afterwards more fully explained Y M. Esprit Giorna*. From the base of the under-wing Proceeds a strong bristle, received by an annulus. or Socket, which springing. between the two principal ner- Vures of the upper-wing terminates in the disk of the Wing: in this annulus the bristle moves to and fro, and Prevents the displacement of the under-wing. This ap- Paratus is perfect only in the males, which alone have ®ceasion for long flights; the females, though they have often several bristles, having no annulus ^. The other instruments of motion, the legs, also differ. in the sexes, In some instances they are disproportionably hg. This is particularly the case with the anterior pair a : De Geer iii. 308. b See above, Vor. H, 394—. : Linn, Trans. i. 145. 135—. Cu t. xiii. f. 1.2.3.3, 9. 832 STATES OF INSECTS. of some beetles, as Macropus longimanus, Scarabaeus long manus L., in which they are so long as to make the males of these individuals rather inconvenient in a cabinet. Amongst British beetles Clytra longimana and Curcult? longimanus Marsh. are also remarkable in this respect In some other males the middle pair are the longest; a5 ™ Anthophora retusa Latr., a kind of wild-bee*. There 3° two known instances of remarkably long posterior legs w the Capricorn tribe, which I suspect belong to the present head. One is Saperda hirtipes Oliv.?, in which the hind-leg® are longer than the whole body, and adorned with a sin- gular tuft of hairs; and the other a Clytus, I think, which Mr. MacLeay purchased from the late Mr. Marshant$ collection, in which the hind-legs are not only very long but have tarsi convolute, like some antenne. From a0” logy I should affirm that these were the characters ° male insects. To come to the parts of legs. Sometimes the cov@ of the last mentioned sex are distinguished from those ° the female by being armed by a mucro or spine. Thus the male of Megachile Willughbiella, and others of that tribe, have such a spine on the inner sides of the anterio" coxa’. The Trochanter also of some differs sexually’ and you will find that the posterior one of the male Anthidium manicatum is of a different shape from what it is in the female*. In Sphodrus leucopththalmus, one © the beetles called black dors, in one sex the same tt% 4 a Mon. Ap. Angl. i. t. xi. Apis **, a. 2, æ. 8. f. 18. » Oliv. no. 68. Saperda t. i. f. 8. * Mon. Ap. Angl. i. t. viii. f. 28. c. S Ibid. t. ix. Apis **. 0. 2. 6. f. 12. 3.3 STATES OF INSECTS. $33 ch . ae : : anter terminates in along mucro or spine *, and in the Other 44: ther it is rounded at the apex. Peculiar characters in their thighs also often indicate differ Spi i ; Lag at the apex of the anterior ones in the female that Snot; Pigs ; ; Not in the male; while in Macropus longimanus, at their. ent sexes. In Prionus damicornis there is a short ase externally the male is armed with a mucro, which I “annot find in the female”. In Scarabæus longimanus L. This thigh is furnished with two teeth *.—The znterme- og thighs also sometimes differ. In an Onitis from ae a variety perhaps of O. Sphinz, those in the male y olabriform, and in the other sex of the ordinary a In Odynerus spinipes they have on their lower © two sinuses, so as to give them the appearance of ag petted. The posterior thighs are sometimes in- a sated in the male, and not in the female. This you and see - a weevil, oa jivna ippies Betulæ, a also in many species of Cimbex E., a kind of saw-fly ; the same circumstance distinguishes the latter sex in nany species of Lygeus F., a kind of bug: I discovered yi from Z. cruciger, of which I have both the sexes; and m Stoll’s figure of L. Pharaonis 4, Jn some of these fee ale thighs are enormously large. A remarkable oe in this respect is observable in the goleopteroyg “Ta Œdemera (Necydalis L.). In Œ. Podobne these in S are incrassated in one sex and not in the other €; | Œ. cerulea they are so in both sexes; and in Œ. ceram- a . b ae Ent. Helv. ii. t. xii. f. B- iv. Ins. no, 66. t. iii. iv. f. 12. e Ibid. no. 3. t. iv. f. 27. Unaises, t. iii. sa 20. i r. Marsham has made two species of this from this circum- Stan “ace, yj 7, . 3 ; VIZ. Necydalis Podagraria and simplex. 334 STATES OF INSECTS. boides in neither. In Pelecinus Polycerator F., one of the Ichneumon tribe, or an insect very near it from Bra- zil, these thighs in the female are armed with two spine? underneath, which are not in the male. The anterior tibie in Scarabaus longimanus L- differ remarkably in the sexes. In the female they are of the ordinary shape, and serrated externally ; but in the male they are very long, incurved, and without teeth or ser tures*. In the males of the genus Onitis F. they are pent like a bow, and acute at the end; but in the females they are formed on the common type>. In Hispa spinipes , they are armed internally with a crooked spine °. the most extraordinary sexual variation of this joint g the leg may be seen in the male of Crabro eribarius * and several other species of the same family, in kj these tibiæ are dilated externally into a concavo-conv™ plate, or rather have one fixed to them and part of the thigh, of an irregular and somewhat angular shape ’ with numerous transparent dots, so as not badly t gr semble -a sieve: whence the trivial name of the speci Rolander, who first described it, fancied that this plat? was really perforated, and that by means of it the anim actually sifted the pollen; but it is most probably p sexual purposes. In another species, the plate is orn mented with transparent converging streaks. In ihe ` bee-tribes (Anthophila Latr.) the posterior tibia of af working sex is generally bigger than the correspondió part in their more idle partners: this is particularly com * Oliv. n. 3. é. xxvii f. 27. 9. and tiv. f. 27.8: »-Thid. ¢. vii. f. 58. 3. f- 57. 2. e Thid. n. 95. Hispat.i.f.4. Piare XXVII. Fre. 2* * Prats XV, Fic. 3. STATES OF INSECTS. 335 Spicuous in the genus Euglossa, in the females of which this part is triangular, very broad towards the apex, and ttted for carrying a large mass of pollen paste. ‘The tibiæ of the males of some Lepidoptera are remarkable in this respect. That of Hepialus Humuli is much more airy ; but in Hi. Hectus it is a dilated mis-shapen mass, Without a tarsus, and with long scales pendent from the iska, Differences of this kind also occur in the calcaria spurs that arm the apex of the tibiæ of a large num- ® of insects. Thus. in Acanthopus Klug, a singular ĉe, in the male the spur of the intermediate leg is dilated * the apex, and armed with six strong spines, the inner Me larger than the rest®. ut the part of the leg in which the sexes most vary S the tarsus ; and this variation takes place both in the “Umber of the joints, and their form and circumstances. he first case has been observed only with regard to cer- ~ species of Cryptophagus Herbst, as C. fumatus, &e. F Which the female is pentamerous, OT having five joints l ; Vall the tarsi; and the male heteromerous, or having five Joints in the two anterior pairs, and only four in the Posteri oy c, With respect to the form of the tarsal joints, AE Sexes more frequently differ; and by inspecting this art, especially in the predaceous and carnivorous Co- “Ptera, you may often, without further examination, “Scertain whether any individual is male or female. ven in the slender-footed Cicindelide, the three first “Nts of the anterior tarsus of the male are more dilated M the two last, and covered underneath with a brush p De Geer i. ¢, vii. f. 14, 15. è Poquebert Illust. Icon. i. t vi f.6. Prare XXVII Fra. 32. lig, Mag.iv. 214. Gyllenhal. Insect. Suec. i. 168. 336 STATES OF INSECTS. of stiffish hair; in the female all are equally slender, and not so hairy. In Carabus, Feronia, &c. Latr. the four first joints of these tarsi in the males are dilated, and furnishe with a brush or cushion: in the Silphida, also, the sane circumstance takes place. In Harpalus Latr., and Si” pha americana, the four anterior ones are similarly forme in this respect. But one of the most remarkable ses” characters, in this tribe of insects, that distinguish the males, are those orbicular patellæ, furnished below wit suckers of various sizes, and formed by the three first joints of the tarsus, which are to be met with in the Dy tiscida, &c.; but as I shall have occasion to treat of thes? more fully in another Letter, I shall only allude to them now. ‘The second pair of tarsi have in these also the three first joints dilated and cushioned. In Hyd” philus piceus, another water-beetle, the fifth joint of the tarsus is dilated externally, so as to form nearly an ed” lateral triangle >. Christian, a German writer on the By menoptera, has described some very singular appendag” which he observed on the first joint of the four poster!” tarsi of Xylocopa latipes F. These were battledot™ shaped membranaceous laminze, with a reticulated sur face, of a pale colour; which were fixed in pairs by the intervention of a footstalk to the above joint, on whit _ they sometimes amounted to more than a hundred: ! i; use of which, he conjectures, is the collection of polle” ; I possess two specimens of this bee; one has nove ý these appendages, and on the other I can discover ther? only in one of the tarsi—from which circumstance 1 aw a Prate XV. Fic. 9. b Ibid, Frc, 8. e Christ, Hymenopt, 118, t, iv. f. 3. STATES OF INSECTS. 337 led to conjecture that, like the supposed Clavarie that me imagined to grow on some humble-bees, but which "e how ascertained to be the anthers of flowers—these belong to the kingdom of Flora, and are spoils which € bee in question has filched from the blossom of some blant, The individuals that have been thus circum- stanced are males; whether the female is guilty of simi- = Spoliations is not known. In my specimen there are ® traces of them. In many bees, the first joint of the *Sterior tarsi is much larger in the females and workers "in the males; but in the hive-bee this joint is larg- x in the latter*. In Beris clavipes and Empis nigra, 0 flies, the joint in question is large and thick in the , ale, but slender in the female. The penultimate tarsal Wint in the posterior legs is dilated internally, and termi- a > in a mucro in one sex of Anoplognathus Dytiscoi- i of Mr. W. MacLeay”. In some insects the anterior “US of the males has been supposed to be altogether. | ag I allude to the petalocerous genus Onitis F.; W have a specimen of Onitis Apelles of this sex, or a is ee Nearly related to it, in which one of tied tarsi ah found; which, though very slender, siete of ti Joints, and is armed with a double claw: from which a “nstance it may, I think, be concluded, that although, D hanceus, these tarsi are very minute, they = not st ‘he. What renders this more probable is, a circum- 3 = Which every collector of insects, who has many bina es of Mr. W. MacLeay’s Scarabeide in his ca- > Must have noticed: namely, that in all, except Co- a i 1 lon, Ap. Angl. i.t. xi, Apis **,e. Nogo SeS e. and e xii. **. » , cut. £19. x Yor or, Entomolog. 144. e PLATE XXVII Fic. 45, A “M, Z 338 STATES OF INSECTS. pris and Onthophagus, the anterior tarsi are usually broker off, Out of seventeen individuals of Scarabeus Macher in my own, not a single one has a relic of an anterio! ie | sus; and scarċely one in a much greater number of P. i nei. The tarsus in question in the nobler sex in Crab at leastin C. cribrarius and its affinities, is also very shot especially the three intermediate joints; but at the a time very broad and flat. In the species just named, ; external claw forms a kind of hook; and in the rest considerably longer than the other 2. The claws, inde? i occasionally vary in the sexes in other Hymenopt thus in Melecta Latr., a kind of bee, in the female y are intire, but in the male they are furnished with a? r i ternal submembranaceous tooth or process”. In ca at oxys conica and others, those of the latter sex are pide _the apex, but those of the former acute °. In Megael 7 the male claw is as in the instance just mentioned, p the female has a lateral tooth 4; and a similar chara distinguishes the sexes in the hive-bee €. 4 3. The abdomen. ‘This part. affords many este sexual characters, whether we consider its general she Ae the number of segments that compose it; its bas® i dle, or extremity. p In general shape it often differs in the sexes. e the abdomen of female Tipule is lanceolate; that m male cylindrical, and thickest at the extremity ” De Geer ii. ¢. xxviii. f- 2. Mon. Ap. Angl. i. t: v. Apis **. a.f. 10. 8.11. 9: Ibid. t. vii. Apis **. c. 1. æ. 17. 9.18. g. Ibid. t. viii. f. 30. g. 31. 9- n € Ibid. t. xi. Apis **. e. 1. mas. f. 9. t. xii. Apis **. e 1. fe and neut: f. 22. f De Geer vi. t xviii. f. 1% 15: STATES OF INSECTS. 339 Molo, chus F, it is l n the latter, Sept; nting som convex above in the former, and flat —the female of this beetle not unaptly repre- e female Ichneumons in this respect, and the z their males^. In Andrena it is oblong in the one, anceolate in the other. In the hive-bee the drones "e a thick, obtuse, and rather long abdomen; in the “Males itis long, and nearly represents an inverted cone; in the workers'a three-sided figure, or prism. the number of segments, also, is generally different in i two Sexes—the male having one more than the female; i X Dytiscus marginalis; &c. the se oe this takes aled the female, if you reckon the bipartite half-con- anal segment as one, having seven ventral seg- ts, and the male only six. She has also eight dorsal, the male seven.—In the ant tribes (Formica L.), the 3 vertical scale, at the base of the abdomen in one leg "ption of them, or the double knot in another, is M the male than in the female. In a very singular Y insect belonging to the Vespide, and related 4 Sy- bing E (which I purchased from the late Mr. Drury’s ca- i >) the second ventral segment sends forth from its ing.” remarkable parallel very acute ad rather long S The same sex of Chelostoma mazillosa has like- itg we on 3 l . the ‘ch on the fifth is a cavity which receives it, when the mal rolis itself up to take its repose”. Imanother Cie n] PC. Campanularum, the segment in question has Ya tubercle ¢, nthe second segment of the abdomen of some spe- the same segment a concave elevation, opposite p De Geer y. 151—. o Mon. Ap. Angl. i, 177. t ix. Apis **, c. 2. y. f. 11.a, d. Ibid. f. Te ad. fae 340 STATES OF INSECTS. cimens, probably males, of the remarkable Africa? ge nus Pneumora before alluded to, there are thirteen ii tle elevated ridges, placed rather obliquely in an oblig series; and gradually, though slightly, diminishing ” size towards the belly: on their upper side they are fla forming nearly a horizontal ledge, but on the lowe! u slope to the abdomen. - The posterior thigh in its natt ral position covers the three first of them, and, if mov? t > rê downwards, would strike them all>. I conjecture, the oun? an fore, that these are the animal’s instruments of § imitating the harp or violin rather than the drum» Th that the thigh acts the part of the hand or bowe -y abdomen of these insects being blown out like a pladd” and almost empty °, must emit a considerable sound Y if the thigh of the animal passes briskly over these ridg?” and their different length would produce a modula in the sound. When struck with a pin, they emit # g” ting noise. In Staphylinus splendens, the penultimate ventr ment is very deeply cleft, and the antepenultimate em? j ginate in one sex, and intire in the other. In S. Jam tus, an allied species, the penultimate segment is © gi less deeply, however; but the antepenultimate isat j short and intire; while the fourth is extremely long ; F rounded at the margin, appearing as if it was only b elevated part of the last-mentioned segment; for © pl it was mistaken by Gravenhorst 4, while it is of the uw form in the other sex. al 8° 47 2 See above, Vor. II. 395. : b Prare XXIX. Fic. 13. Stoll. Spectres, &e. t xxv. f ca e Sparrman. Voyage, i.312—. 4 Coleopt. Micropt. 16. STATES OF INSECTS. $41 Sa extremity of the abdomen or its anal segments i Organs furnish a variety of sexual characters. Some- s the Jast dorsal segment is emarginate in the male, Rot in the female; as in Megachile ligniseca, one of © leaf-cutter bees, Cimex haemorrhoidalis, &c.2 At a times little lateral teeth are added to this notch, as other of the same tribe, M. Willughbiella®. Again, aa males, both the ventral and dorsal anal segment armed each with a pair of teeth or mucros, as in lostoma maxillosa®. In Anthidium manicatum, an- y bee, the anus terminates in five spines*. In Cæli- p Cmca of the same tribe, in which this part in the n is very acute, that of the male is armed with six Mts e vhi - In that singular Neuropterous genus Panorpa, i the abdomen of the female is of the ordinary form, à pair of biarticulate palpiform organs attached tothe $ eee or è 2 ; t retractile joint, or ovipositor, that of the male termi- of “Sina jointed tail, not unlike a scorpion’s, at the end Which is an incrassated joint armed with a forceps‘. In ~ Common earwig (Forficula auricularia) the two sexes a Considerably in their anal forceps: in one it is armed ; internal teeth at the base, and suddenly dilated, above Ich dilatation it is bent like a bow: in the other it is . without teeth, grows gradually narrower, is Pike crenulate from the base to the end, a is E t except at the very samena sid it curves in- - Misled by these and similar differences, Mr. Mar- a ‘ “ad Ap. Angl. i.t. viii. f. 25. De Geer iti. 255. t. xiv. f. 8. l pys 4P. Angl. i.t.viii.f.24, © Ibid. t ix. Apis xx. €. 2. y. f. 12, e pad. Apis **, 0, 2,6, f. 11. t pitt. vii. Apis**, c. 1. æ. f. 11, 12. 9. 13, 14. 3. £2 a ATE XV. Fic. 12. De Geer ii. £. xxiv. f. 9,10. 9. t. xxv: wg, 342 STATES OF INSECTS. sham has considered them (the sexes both of F. aurit laria and F. minor) as distinct species. The tail of some species of the genus Ephemera iti nished with three long, jointed, hairy bristles. Welea™ from Reaumur with respect to one, that though in th? female these are all equal in length, yet in the male ther? is only a rudiment of the third. On the belly neat tH anus these males have four fleshy appendages, th rior ones setaceous and long, and the anterior pair form and shorter. They are supposed to represent ti anal forceps of other imsects*. In Ephemera yulga described by De Geer, both sexes have three pristi? but those of the male are the longest ;. and he deseri”? the forceps as consisting of only a pair of jointed piec” y forming a bow not unlike the forceps of an earwig” : : ; eh v. All the differences I:have hitherto noticed beta the sexes of insects occur in their bodily str ace there are others of a somewhat higher descriptio” ° a servable in their character. You may smile at the eid? of character in beings so minute; but if you recollect" I formerly related to you when treating upon the 5° d ties of insects, you will allow that something of this f ; does take place amongst them. In general the males y more fitted for locomotion and more locomotive? the females, on the contrary, are necessarily more . tionary. And this for an obvious reason :—the Ja | that the male shall seek the female, and therefor? peculiarly gifted for this purpose, both in his oe ns sensation and motion: while his partner in many © has very simple antennæ, he has very complex ones; * gb Ww 4 i J. « . s. $ — * Reaum. vi. 494. t. xliv. f. 3—11. b De Geer ii. £. xvii. 5 STATES OF INSECTS. 843 While she has either no wings or only rudiments of them, a amply. provided with them. Again: amongst the ects that suck the blood. of man or beast, such as the (Culex) or horse-flies (Tabanida), it is me female that is bloodthirsty, the males contenting them- > es with the nectar of flowers?. But the difference of aracter in the sexes is most conspicuous, at least it has ea more noticed, in those that live in societies, and is Wite the reverse of what takes place in the human spe- “les, While the females and workers (which are now Snerally considered as sterile females, in which the ova- Nes ay : j ns S are not developed) are laborious and active, diligent ‘nd skilful, wise and prudent, courageous and warlike;— a on the contrary, take no part in promoting the ONN weal, except merely a sexual one. Though till a "tain period they are supported at the expense of the SSW they take no part i its labours, either in pe and forming the public stores, or in feeding a attending the young. They are idle, cowardly, and. be have neither art nor skill of any kind, and hi tnprovided with the usual offensive weapons of thei . These observations in their full force apply par- _“Ularly to the hive-bee, and partially to the other social Sects; amongst which, if you consult my former com- nications, there are some exceptions to this slothful aracter in the males >. ; u. Age. There is less diversity in the duration of the y : ‘ : ; €s of insects in their perfect than in their larva or pupa w a N, Dict. @ Hist. Nat. xxxii. 448. b See above, Vor. I. 110, 118. 344 STATES OF INSECTS. state. Some, like several species of Ephemera, live only a few hours; some never even see the sun?: others, s flies, moths, and butterflies, and indeed the majority ° insects, a few days or weeks; and a comparatively 5%? number, such as some of the larger Coleoptera, Ortho- ptera, &c., six, nine, twelve, or fifteen months—a perio beyond which the life of perfect insects rarely extends Some, however, certainly enjoy a longer existence in the perfect state. Mr. Baker kept one of the darkling peetles (Blaps Mortisaga) alive under a glass upwards of thre? ; ‘years. The rose-beetle (Cetonia aurata), Rosel inform? | us he fed with fruit and moist white bread for as long® ` period’. Esper kept our most common water-bee á (Dytiscus marginalis) in water in a large glass ves’ feeding it with meat, for three years and a half*. Ww regard to the Arachnida, from the very slow growth f: Scorpio europæus, Rosel suspects that it must live two or three years; and Audebert is stated to have kept * spider for several‘. In this respect insects follow 4 we very different from that which obtains amongst verte brate animals. In these the duration of their life 1 ij proportion to the term of their growth: those which al tain to maturity the latest, in almost every case living the longest. In insects, on the contrary, we often meet wit the very reverse of this rule. Thus the larva of the great a Vox. I. 283. > FLAG; : ° Clairville Ent, Helvet. ii. 214—. I have seen it asserted in som popular work on Natural History, (the title of which I do not rec lect,) that Mantis religiose has been known to live ten years ; and * flea, when fed and taken care of, six. But this is so contrary t° exp™ rience,in other cases, that the statement seems quite incredible: è Rosel IM, 379. N. Dict. d Hist. Nat. ii, 285. STATES OF INSECTS. 345 Soat-moth (Cossus ligniperda) is three years, that of the “abbage-butterfly (Pieris Brassice) not three months, in attaining maturity; yet the perfect insects live equally — ng. Melolontha vulgaris, which in its first state lives “ur years, as a beetle lives only eight or ten days?. Some Ephemera, whose larvee have been two years Acquiring their full size, live only an hour; while the “sh-fly, whose larva has attained to maturity in three or our days, will exist several weeks. here is yet another anomaly in the duration of the a perfect insects. This is not, as in larger animals, “Xed period liable to be shortened only by accident or | Sease, and incapable of being prolonged; but an inde- “Minate one, whose duration is dependent on the ear- “t or later fulfilment of a particular animal function— a of propagation. The general law is, that a few days, . at most weeks, after the union of the sexes, both pe- “ah the female having first deposited her eggs. If, ~tefore, this union takes place immediately after the Sclosure of the insect from the pupa, their existence in i “Perfect state will not exceed a few days or weeks, or Some cases hours, as in that of the Ephemera, and like- i Se of the Phalene Attaci L. &c., which fall down dead — _ediately after oviposition®. But if by any means it i a off or prevented, their life may be protracted to © or four times that period. Gleditsch asserts, that Sts apart the sexes of a grasshopper, their lives Prolonged to eight or nine weeks, instead of two or : N their ordinary length; and under similar circum- S Ephemere, which usually perish in a day, have * DD meril Traité Elément. ii. 87. n. 683. b De Geer ii. 288, 846 STATES OF INSECTS. ' been kept alive seven or eight. It is in consequence of this very curious fact, which has not received from phy siologists the attention that it merits, that many puttet- flies and other insects, which, when excluded from ae pupa in summer, perish in less than a month, iv? through the winter, if excluded late in the autumn, the union of the sexes does not ensue. It is probabi? that the great age to which Baker’s Blaps, Rosel’s C= nia, and Espers Dytiscus attained, was owing to the! being virgins when taken, and subsequently kept from any sexual intercourse. A parallel case happens in th? vegetable kingdom :—if annual plants are kept from su ing, they will become biennial; as, likewise, if they ate sown too late in the year to produce seeds. In the case, however, of the earlier or later exclusi” of the imago, another agent has probably some nfl” ence. Buffon found that, other circumstances being alike the silkworm-moths placed in a northern, lived long? than those exposed to a southern aspect : whence it w pears that the stimulus of heat shortens the lives ie sects, and consequently that cold tends to lengt? them. : It must be observed too, that as the death of the á male insect does not take place until all the eggs are "a cluded, the term of her life, though usually short wP ; majority of species, which lay their whole number ie once, is proportionably long in those which, like ; queen-bee, have a longer period assigned them for”, important office. Huber affirms, that he had oon proofs that she was engaged for two years in laying os all impregnated by a single sexual union *; and 2 : a Huber i. 106. STATES OF INSECTS. - 847 females of most insects that live in society, several months are required to mature the last eggs that are in the vary. There is one tribe of insects, however, the fe- Males of which are affirmed to survive this operation : Mean Dorthesia Bosc; after which they even moult, t ough not so often as before *. I formerly related to you the singular fact, that the Tones in a beehive at a certain period are without mercy slaughtered by the workers”. A fact the reverse of this 'S recorded by Morier with respect to the locusts: he affirms that the female, when she has done laying her "ges, is surrounded and killed by the males. He says ‘at he never himself witnessed this extraordinary cir- Amstance; but that he heard it from such authority that © gave full credit to it®. It is a fact, however, that ‘eins to require further evidence to entitle it to such cre- dit, These are instances in which, by a law of nature, the life of these insects is shortened by violence. It does ot appear to have been ascertained how long those ‘ones live that, under particular circumstances, as stated Na former letter 4, are exempted from the usual slaugh- - ter. Iam, &c. è N. Dict. d Hist. Nat. ix. 553. b Vor. IT. 173—. ° Morier’s Second Journey through Persia, 100. * Vou. II. 175. LETTER XXXIII. EXTERNAL ANATOMY OF INSECTS TERMS, AND THEIR DEFINITION. HAVING shown you our little animals in every stat? and traced their progress from the egg to the perfect insect, I must next give you some account of their stri” ture and anatomy. And under this head I shall intr duce you to a microcosm of wonders, in which the ha? of an Aumicury workman is singularly conspicuo” One would at first think that the giant bulk of the ele- phant, rhinoceros, or hippopotamus, must include a% chine far more complicated, a skeleton more multifario” in its composition—covered by muscles infinitely mot? numerous—instinct witha nervous system infinitely mo” 2 ramified—with a greater variety of organs and vascula" systems in play, than an animal that would scarcely cou” terpoise a ten-millionth portion of it. Yet the revers? n this is the fact; for the Creator, the more to illustrat? his wisdom, power, and skill, has decreed that the W : : ; e nute animals whose history we are recording, shall r sê much more complex in all the above respects than thes mighty monarchs of the forest and the flood. of th ° $ > rer in the present and subsequent letters you will find ! EXTERNAL ANATOMY OF INSECTS. 349 Peated and scarcely credible instances, which in every tightly constituted mind are calculated to excite, in an “Xtraordinary degree, those sensations of reverence and Ove for the INVISIBLE AuTHOR of these wonders, and that faith and trust in his Power and Providence, which a attentive survey of the works of Creation has a natu- Tal tendency to produce. And you will not only be Struck by this circumstance, but equally by the infinite Variations in the structure that will present themselves to Your Notice; and that not sudden and per saltus, but by *Pproaches made in the most gradual manner from one orm to another. And all along, where the uses of any Particular organ or part have been ascertained, if you “Ohsider its structure with due attention, you will find in tthe nicest adaptation of means to an end: a circum- stance this, which proves most triumphantly, that the OWEr who immediately gave being to all the animal ‘Sms, was neither a blind unconscious power, resulting om a certain order of things, as some philosophists love '© speak a; nor a formative appetency in the animals ‘emselves, produced by their wants, habits, and local . “tteumstances, and giving birth, in the lapse of ages, to all the animal forms that now people our globe”; but a ower altogether distinct from and above nature, and its LMIGHTY AUTHOR". X Lamarck Hist. Nat. des Anim. sans Vertèbr. i. 311, 214. Ibid. 162. Compare the Systéme des Anim, sans Vertebr. of the ame author, p. 12—. . The doctrine of Epicurus—that the Deity concerns not himself es the affairs of the world or its inhabitants, which, as Cicero has ‘lously observed (De Nat. Deor. 1. 1. ad calcem), while it ac- p Owledges a God in words, denies him in reality; has furnished "© original stock upon which most of these bitter fruits of modern 350 EXTERNAL ANATOMY OF INSECTS. . I trust that what I have here advanced will excite your attention to the subject I am now to enter upon; and flatter myself, that although at first sight it may promis’ nothing more than a dry and tedious detail of parts ap organs, you will find it not without its peculiar interest and attraction. This department of the science—the Anatomy of Jo sects—may still be regarded as in its infancy; and const infidelity are grafted. Nature, in the eyes of a large proportion of A enemies of Revelation, occupies the place and does the work 9 ~ Great Author. Thus Hume, when he writes against miracles, ap” pears to think that the Deity has delegated some or all of his powel to nature, and will not interfere with that trust. Essays, ii. 797 And to name no more, Lamarck, treading in some measure in the steps of Robinet (who supposes that all the links of the animal king- dom, in which nature gradually ascends from low to high, were o periments in her progress towards her great and ultimate aim—t j formation of man. Barclay On Organization, &c. 263), thus states n opinion : “ La nature, dans toutes ses opérations, ne pouvant y céder que graduellement, n’a pu produire tous les animaux à-la- se elle wa d’abord formé que les plus simples; et passant de ceux +f, jusques aux plus composés, elle a établi successivement en eu% é é férens systêmes d’organes particuliers, les a multipliés, en a augme? de plus en plus l’énergie, et, les cumulant dans les plus parfaits, A a fait exister tous les animaux connus avec l'organisation et 125 4 cultés que nous leur observons.” (Anim. sans Vertébr. i. 123.) - The denying to the Creator the glory of forming those works of ¢ ation, the animal and vegetable kingdom (for he assigns to poth ' same origin, did. 83), in which his glorious attributes are most ce “4 spicuously manifested; and ascribing them to nature, or @ cont order of things, as he defines it (214)—a blind power, that operat necessarily (311); which he admits, however, to be the produt ‘ the will of the Supreme Being (216). It is remarkable, that 1? earlier works, in which he broaches a similar opinion, we f” mention of a Supreme Being. (See his Systéme des Animaua sans tèbres, Discours d'Ouverture.) Thus we may say that, like bis runner Epicurus, Re tollit, dum oratione relinquit Deum. But tho he ascribes all to nature; yet as the immediate cause of all the a a fore” ug ant EXTERNAL ANATOMY OF INSECTS. 351 dering the almost insuperable difficulties which, from the minuteness of the objects, oppose themselves to the skill ‘nd instruments of the entomological anatomist, we can Scarcely hope that it will ever attain to that certainty and Perfection to which, as far as the larger animals are con- cerned, anatomy has arrived. Yet infinitely more has ĉen accomplished than might have been expected, and new accessions of light are daily thrown upon it. When a forms, he refers to the local circumstances, wants, and habits of lvidual animals themselves; these he regards as the modifiers of t er Organization and structure (162). To show the absurd nonplus ° Which this his favourite theory has reduced him, it will only be ne- “sary to mention the individual instances which in different works Ba iiduces to exemplify it. In his Systéme, he supposes that the S -footed birds (Anseres) acquired their natatory feet by frequently Parating their toes as far as possible from each other in their efforts °sWim, Thus the skin that unites these toes at their base con- "acted a habit of stretching itself; and thus in time the web-foot of wh; duck and the goose were produced. The „waders (Grallæe), ch, in order to procure their food, must stand in the water, but fr not love to swim, from their constant efforts to keep their bodies vigh submersion, were in the habit of always stretching their legs this view, till they grew long enough to save them the trou- dA (13—). How the poor birds escaped drowning before they àd got their web feet and long legs, the author does not inform us. another work, which I have not now by me, I recollect he attri- ntes the long neck of the camelopard to its efforts to reach the . Ughs of the mimosa, which, after the lapse of a few thousand years, oe length accomplished!!! In his last work, he selects as an ex- Ple one of the Molluscæ, which, as it moved along, felt an incli- “tion to explore by means of touch the bodies in its path: for this “pose it caused the nervous and other fluids to move in masses E fsively to certain points of its head, and thus in process of £ tt acquired its horns or tentacula!! Anim. sans Vertebr. 1. 188. : p ians that this eminent zoologist, who in other respects Ea at the head of his science, should patronize notions so con- y absurd and childish. 352 EXTERNAL ANATOMY OF INSECTS. i — as we consider what has been done by Malpighi, Leeuwe! hoeck, and especially Swammerdam, we admire the P% tience, assiduity, and love of science, that enabled thems E spite of what seemed insurmountable obstacles, to asce!” tain, the first with respect to the silk-worm, and the Jatte! in numerous instances, the internal organization of thes? minute creatures, as well as their external structure Reaumur, and his disciple De Geer, extending their 1% searches, have also contributed copiously to our know ledge in this branch of our science. But in this field no one has laboured so indefatigably and with so much success as the celebrated Lyonnet; 9 though his attention was confined to one object—the 0% terpillar of the goat-moth (Cossus ligniperda F.),—eve one who studies his immortal.work must admire ihe patient and skilful hand, the lyncean eye, and keen ve tellect, that discovered, denuded, and traced every orga” : muscle, and fibre of that animal. Much is it to be 1a gretted that his proposed works on the pupa and imag? of the same insect, which, he informs us, were far ? j vanced*, were never finished and given to the world Our regret, however, is in some degree diminished by the elaborate work of M. Herold on the butterfly of the cabbage (Pieris Brassice), before eulogized; in whic? he has done much to supply this desideratum. In more modern times, besides Herold, MM. Latreille Illiger, Marcelle de Serres, Savigny, Ramdohr, Trev" 2 Lyonnet Traité, &c. Pref. xxii. Want of due encouragemen’ it is to be feared, caused the abortion of these valuable treatise The MSS. are, I believe, still in existence. It would probably A swer now to publish them. b See above, p. 52—. . EXTERNAL ANATOMY OF INSECTS, 853 re — “nus, Sprengel, Audoin, Chabrier, and, above all, M. UWier in his celebrated Lectures on Comparative Ana- ‘omy, have considerably extended the boundaries of our nowledge in this department: and much of what I have 0 say to you in my letters on this subject, will be derived tom these respectable sources. In the exterior anatomy of Msects, I flatter myself that I shall be enabled to make ‘ome Material additions to the discoveries of my prede- “Sons ; though few have occurred to me with respect to er internal organization. “tag treating of the anatomy of the vertebrate animals, oe ‘sual, I believe, to consider, first, the skeleton and i integuments, whether of skin or muscle, and their “Cessories ; and afterwards the organs of the different tal functions and_of the senses. But in considering + atomy of Insects, the difference before stated 2, ‘ob- . “able between them and the sub-kingdom just men- ae as to their structure, renders it a to iii Subject into two parts—the first treating of their terna] anatomy, and the second of their internal.— “hall begin by drawing up for you a Table of the No- “lature of the parts of their external crust; its ap- ny, Ses and processes », external or internal, accompa- 1 y eq by definitions of them; and followed by such obser- N “Ons respecting them as the subject may seem to re- l e . . Te for its more full elucidation. Natomists have divided the human skeleton into three `N b m c above, p, 43—. tna eare certain processes which are a continuation of the in- Poin Surface of the crust ; and serve, as well as the rest of it, for terna] of attachment to the muscles : these, though completely in- > Must be considered as parts of the external skeleton. vor, TIT, 2a 354 EXTERNAL ANATOMY OF INSECTS. : mbs greater sections—the Head, the Trunk, and the Limb : ee ee Ss . ‘yal That of insects, likewise, is resolvable into three prime y e . . > . ` . e+ sections, but without including the limbs (which, 38 : e ing appendages, and therefore secondary, had best considered under the section of which they form & part” for the abdomen in insects, as well as the rest of the boef” being covered with a crust, and forming a distinct par may be properly regarded as a primary section. An p fact these three parts may be received as primary un ; another view—the head, as containing the principal gi gans of sensation ; the trunk, as containing those of mo” tion; and the abdomen, as containing those of generation ‘ Under each of these primary sections, I shall conside” 7 respective organs, members, and parts. i You are not to expect to find every part included iy the following Table in every insect; since ithas bati aim to introduce into it, the most remarkable of thos? with Be respect to these, I shall generally refer you to the indi” that are peculiar to particular tribes, genera, &e. duals in which they may be found. DEFINITIONS. j + cel Corpus (the Body). The whole crust of the ins? j consisting of the Evoderma or external coverings is the Esoderma or internal cuticle that lines it 5 Si ee ih divided into three primary parts, or sections- Truncus, Abdomen. logous to the Periosteum of Vertebrate animals ? — CORPUS TRUNCUR Be iss ad EXODERMA. «ss... Caper Aas chee ee Synoptical Table of the Nomenclature of the Parts of the external Crust of Insects f Labrum a’ ........ 4 Appendicula Rabim Dees Mentum a’ Palpi Labiales b” Prostheca c” Mandibulæ e’...... | POR OR ieee eiia S UOU eaa ea E 8 { Cardo e” Marie ducatu rG 4 Stipes £” | Lingua 2. ope ns Paraglosse i” Utet en 4 eae, E 'ypopharynaæ f Nasus a .......+.. 4 Rhinarium 2g’ Postnasus b Frons c Vertex d Occiput e Gene f Tempora g Oeu W aas +. de. antus D Stemmata i { Torulus ï | 4 Me anteni keert i eee Kia e BUA { 5 Pedicellus I’ a ve 7 ] r . Subfacies ê ...... } ae A | Clayola m’........ 4 Capitulum m” Colum OAR ea Nucha n.......... 4 Myoglyphides n’ LCephalophragma Gula o ( Ora a’ ie : Patagia J’ E ETE AEREN PEA { Beane 4 L Phragma f Manitruncus Pass [ Spiracula Antepec- toralia č Prosternum d’ $ | | Clavicula | Antefurca e’ Scapula Humerus ; | L Antepectus b .... Brachia P ROS a x x lad Pteropege b Tegmina d” f Collare g’ | Prophragma %# r Mesothorax c...... ea y che eohins Frenum # LPnystega m / AS HESoDERMA .. ives + 11 L Tegule g { Peristethium 7’ | Scapularia o'...... f Medipectus d.. <... 3 Mesosternum p ria h | ABDOMEN C....... 2 LAlitruncus é ....<. 2 CADS 2... ; Medifurca g Pedes Intermedii 7’ | { Mesophragma s' Postdorsolum 7¢ Postscutellum 2’ Postfrenum v | Metathorax e...... | POUS U os sce bes eee i Ale Inferiores i’ Metapnystega k” L Metaphragma wv’ ... 3 Septula Ù’ ( Mesostethium y’ Parapleura 2'.....000 Sven UR ritica m Metasternum at... 2 Pectines n” Postfurca 6 Opercula c | Postpectus f ...... 4 Coxa p” Trochanter q’ POMBO taa s L Pedes Postici df... ¢ PRE ce sts L Tarsus t” PPer A a ra, f Segmenta Dorsalia A’ Pulmonaria B' ...... 4 SpiraculaDorsalia A” Hypochondria C Maaro ae" Enpigastrium D sss.. $ Tympana C” lia .D" Weer: OP ys es» wees F Segmenta Ventralia E’ L Elastes { Funiculus esa Petiolus C ........ 4 Foramen Œ Belg HT’ Nodus I’ Cauda D......+-+ 2 Contris (Podex K' Hypopygium L Unci E” yn yor at’ Valve F” vipositor Re. Gs 4 Vaginula Gg" | Terebelæ H” serres 2 Actileus N'........ ¢Spicula I’’........ : (Forceps K” Forfex L” Furea M” Styli N” Foliola O” Appendices O' .... 4 Flosculus P” Cerci Q” Caudulæ R” y Fila Ss” Mammule T” esee 3 Fusi B” _Siphonuli U” 4 Retinaculum A” N. B. The Letters in this Table that follow the Names of the Parts, are Lobi g LEZE EEEEEETTEET | Palpi Maxillares h" BEOU A aa tee } Palma JEU Te RA EE NEEE Hamolytra E os aaa Ale superiores f” Spiracula scapula- Spiracula Parapleu- C Wees ODTUD peau Ea re Incisores a” Laniarii b” Molares c’” Superior d” Inferior €e” Ungues f” Pe a ee TA, f Coronula Calcatian es i A .. 4. Velum a' Dictus nN.. 4 Ungula ... { Hypoderma a’” ji J Axis 6” ae < Sutura c” Peri d SRU ae Palmula A vit Alula e” - $ Corium f” Membrana g” { Axes 4%” | ARIE Cesk skate pa hes o N Costalis b° Intermedia c° Analis d- Basilares e' | Areole K” seee 4 Media f- . f. Rae Wo } Phialum Hamus Postcostalis i+...... 4 Subcostalis a * Neuree 2’ ....000. d Mediastina k mee’. Externo-media l’ .. j Subexterno-media} * Interno-media m*.. < Subinterno-media ec * Analis n° Azillaris o° ( Spuria p> — Jtt Stigma m Parastigma | Lobuli v” i { Commissura o” | Tendo .. § Hamuli | Pterygium Alula Halteres p” r f Acetabula 0” sasssssse 4 Pessella g” .. 4 Gonytheca 7” { Epicnemis s” | Molula #” .. 4 Talus w” | Calcaria v” L Coronula [ Planta W see 2 Cale q: Arthrium d * Unguiculi e * Plantula f* ... 3 Pseudonychia a 1 A Ungula sises itse Prothorax & Mesothorax e Metathorax e Antepectus 5 Medipectus d Postpectus f Prosternum d’ Mesosternum p Metasternum at Antefurca e Medifurca g Postfurea 5 + ( THORAX Wi ssc PECTUS € ssscoseesees Truncus quoad Pars ; supina et prona si- 4 | mul suMPtAsseorere | OTERNUM ` 4 eeecoeosecnve Os sse | ENDOSTERNUM used in the Plates to indicate the same Parts. ~o ~ EXTERNAL ANATOMY OF INSECTS, I. CAPUT (The Heap). The Flead is the anterior section of the body; con- “sting of a kind of box without suture or segment, which „cCeives the organs of sensation and manducation. It chides the Os, Facies, Subfacies, and Collum. * Os (the Mouth). That part of the head which re- Ceives and prepares the food for passing into the Stomach. It includes the Tvophi*. - Ropu (the Trophi). The different instruments or organs contained in the mouth, or closing it, and “mMployed in manducation or deglutition. They in- lude the Labr um, Labium, Mandibula, Maxille, Lingua, and Pharyna. ABRuMm (the Upper-lip). A usually moveable or- San; which, terminating the face anteriorly, covers the mouth from above, and-is situate between the Mandilule>. It includes the Appendicula. PPENDIcULA (the Appendicle). A small piece some- times appended to the upper-lip*. Ex. Halictus ? p, Walck. (Melitta **.b. K.) ABIUM (the Under-lip). A moveable organ, often larticulate, which terminating the surface ante- rior] iy, covers the mouth from beneath, and is situ- ate between the Mazille*. It includes the Men- Pte, and Palpi Labiales. MENTUM (the Chin). The lower joint of the Labium, € employ this term instead of Instrumenta Cibaria F., to avoid p ution, t TEs VI VIT. &e. a’, and XXVI. Frc. 30— 33. a v Ete, 30. Mon. Ap. Angl. i. 139. Melitta **. b. tii.. f. 4, 5 “TEs VI, VIT, &e. and XXVI. Fre. 23—29. b’. EE. es “teu 856 EXTERNAL ANATOMY OF INSECTS. where it is jointed; in other cases its base. ra usually seated between the base of the Masil- le. d b Parr Lasiares (the Labial Feelers). Two jit sensiferous organs, the use of which is not clearly ascertained, which emerge, one on each side, from the Labium, mostly near its summit >. ; C ManpisuL (the Upper-jaws). Two transverse i ral organs, in most insects used for manducatio”? generally corneous, moving horizontally, and lor ing the mouth above, under the Labium ° include the Prostheca, Dentes, and Mola. a Prosrueca (the Prostheca). A subcartilaginous m cess attached to the inner side, near the base, of t Mandibule of some Staphylinide*, Ex. On? ý similis K., Creophilus maxillosus K., &c. ne b Denres (the Teeth) The terminating points of K Mandibule. 'They include the Jncisores, Lanin and Molares €. . at A Inctsores (the Cutting-teeth). Teeth somes wedge-shaped, externally convex and inter”? W * Prates VI. and VIL a’, and XXVI. Fic. 34, 35. The part in this work tegi ded as the mentum, does not s ed cases accord with what MM. Latreille, Savigny, &c. have reg? pe as entitled to that denomination. Thus in Hymenopter® , „< the Mentum is what we term the Labium, while our Mentum ? F small piece upon which that part sits feat VII. Fie. 3. a”): is called the Fulcrum in Mon. Ap. Angl. (See i. Explan. © P Plates.) Our Mentum may generally be known by its situatio” tween the hinges and base of the Maxille. b PLATES VI., VII., and XXVI. b’. c Ibid. a PLATE XI. Fie: ae ° Marcel de Serres Comparaison des Organes de la Masticatio" Orthopteres, 7. Aun. du Mus. 11. EXTERNAL ANATOMY OF INSECTS. 357 Concave*, Ex. Gryllotalpa Latr., Gryllus Latr. (Acheta F.), &c. &e. ANIARII (the Canine-teeth). Very sharp and usu- ally long conical teeth”. Ex. Forficula L., Man- tis L., Libellula L. OLAREs (the Grinding-teeth). Teeth that terminate in a broad uneven surface, fit for grinding the food ¢. x Ex. the herbivorous Orthoptera. Mora (the Mola). A broad, flat, subrotund space, transversely grooved or furrowed, observable on the y inner side of some mandibles that have no grind- ing-teeth at their apex 4. Ex: Huchlora MacLeay, Anoplognathus Leach, Larva of Lucanus °. AXILLE (the Under-jaws). ‘Two organs moving Subhorizontally, fixed on each side at the base of the Labium, and often parallel with it—which in Masticating insects seem primarily designed to hold the food’. They include the Cardo, Stipes, Lobi, and Palpi mazillares. * Cardo (the Hinge). A small, transverse, usually. triangular, corneous piece, upon which the Maxilla Commonly sits 8. . Stipns (the Stalk). The corneous base of the Maz- illa, below the Palpus *. Lon (the Lobes). The parts of the Mazilla above the Papus i, They include the Lobus superior, the Lobus inferior, and the Ungues. a b Prarg VI. Fic. 6. c, a”, and XHI. Fic. 5, a” e aa VIL Fic. 12b and XIII. Fie. 5. b’”. Late XXVI. Fie. 16. ¢’”. a Ibid. Fre. 20. d”. Uv. Anat. Comp. iii. 322—. ea VI. VIL d. and XXVI. Fre. 9—15: id. e tibid. f’. 1 Ibid. and XAVI, Fic. 134i 358 EXTERNAL ANATOMY OF INSECTS. A Losus Superior (the Upper-lobe). The outer Jobe of the Maxilla, incumbent on the inner one. ip the Predaceous Beetles this lobe is biarticulate @” palpiform*; and in Staphylinus olens, &e. it als? consists of two joints. It is called the Galea by Fabricius, in Orthoptera, &e. © B Logus Inventor (the Lower-lobe). The inner Job? of the Mavilla, covered by the outer one 4. C Unauss'(the Claws). One or more corneous sho? claws which arm the lobes of the Maxilla e. In ‘ ; Predaceous Beetles there is only one terminatilé the lower lobe, with which, in Cicindela, it artici lates; in the Orthoptera and Libellulina there ate several. d Pater MAXILLARES (the Maxillary Feelers). TA jointed sensiferous organs, the use of which is ”° P 5 . l clearly ascertained, emerging from an exterior ! teral sinus of the Maxilla €. E Lineva (the Tongue). The organ situated wit , > : i ects the Labium or emerging from it, by which inse? þin in many cases collect their food and pass it dow” to the Pharynx, situated at its roots above. Ht ™ ries considerably in different orders and tribes: the Orthoptera, Libellulina, &c. it is linguifor™™ and quite distinct from the Labium s ; it appe” also distinct in the lamellicorn beetles, &c." In many 2 Prare VI. Fic. 3. d’”. > Phare XXVI. Fie. 11. d^- e Prare VI. Fie. 6, 12. d’”’. 4 Ibid. Frc. 3, 6, 12. and XXVI. Fic. 9, 10, 2”, © Ibid. VI. Fie. 3, 12. f, e * Prane VL VIE b2 XII. Fre. 1—4, 8. h”. and xx} Fic. 1—8. s Prate VI. Fic. 6, 12, e’. » Prate XXVI Vic, 26, 29,-e', EXTERNAL ANATOMY OF INSECTS. 359 Hymenoptera it emerges from the Labium, and is fitted to collect liquids and pass them downwards *. In Formica it appears to be retractile®. In a con- siderable proportion of insects it seems connate With the Labium, and forming its inner surface? According to circumstances it might perhaps be denominated Lingua or Ligula. Itincludes the Pa- raglosse. a Paracioss® (the Paraglosse). Lateral and often membranous processes observable on each side of _ the tongue in some Hymenoptera, &c. © * Puaryyx (the Pharynx). The opening into the gul- leta, It includes the Epipharynz and Hypopha- rYNL. PIPHARYNX (the Epipharynx). A small valve under the Labrum, that in many Hymenoptera closes the Pharynx, and is an appendage of its upper mar- gin ®, Hypopuaryyx (the Hypopharynz). An appendage I ` Plane VII. Fie. 2, 3, e'.—What is here called the Lingua in Jmenoptera hasbeen usually regarded as the Labium; but surely that San which collects, and as it were Japs the honey, and spasses it nie to the Pharynzx, is properly to be considered as the tongue. t € Labium itself appears to be represented by what has been called entum, and the true Mentum, as was lately observed, ïs at the The. of the part last mentioned, in the usual situation of that piece. n 3 though long since noticed (Kirby Mon. Ap. Angl. i, 103—), ha cen much attended to by modern entomologists. i Tuber Fourmis, 4—. , Puare VIL Fic. 2, 3. and XXVI. Fie. 28.1”. «VATE VIL. Fie, 14. f: 3S bid. Fic, 2, k”. This is M. Savigny’s name for this part. It also been called Epiglossa. Latreille Organisation Extéricure des "ectes 185. 360 EXTERNAL ANATOMY OF INSECTS. i of the lower margin of the Pharynx, observable ™ Eucera F. 2 The seven organs of the mouth above defined, viz, the Labrum, Labium, ¢he two Mandibule, the two Maxille, and the Lingua, constitute what may be denominated i perfect mouth, peculiar to those insects that masticate the” food>. In those that take it by suction, the Tropbi, to adapt them for that purpose, assume a variety of forms and should be distinguished by as many appellations. In almost every case, however, the rudiments or representa- tives of the above organs have been detected by the elabo rate researches of that learned ånd able zoologist, M. Sa vigny’. T shall next subjoin definitions of the princip l kinds. of suctorious mouths. 2. Promuscis (the Promuscis). The oral instrument of Hemiptera, in which the ordinary Trophi are !© ` placed 4 by a jointed sheath, covered above at ° base by the Labrum, without Labella (Liplets) k the end, and containing four long capillary lancet and a short tongue €. It includes the Vagina, © Scalpella. * Vide Savigny Mém. sur les Anim. sans Vertébr. I. i. 12—. d e The majority of Hymenopterous insects, though they have A ordinary Trophi, are not masticators, using their mandibule only purposes connected with their economy. © See his Mémoires sur les Animaux sans V. ertèbres, I. i. a I have used this word here and on a former occasion (see abov’s p- 29), perhaps not with strict propriety, in the sense of the F rene word remplacer, for which we seem to have no single corresponds word in our language. € Prata VI, Fic. 7—9. EXTERNAL ANATOMY OF INSECTS. 361 A VAGINA (the Vagina). The jointed sheath of the Promuscis, representing the Labium in a perfect mouth 2, SCALPELLA (the Lancets). Four pieces adapted for ‘perforating the food of the insect, which when united form a tube for suction. The upper pair: represent the Mandibule”, and the lower the Maz- alle ©, $ Progoscrs (the Proboscis). The oral instrument of Diptera, in which the ordinary Trophi are replaced by an exarticulate sheath, terminated by Labella, and containing one or more lancets covered by a valve’, - It includes the Theca, and Haustellum. Turca (the Theca). ‘The sheath or case of the Pro- boscis, representing the Labium in a perfect mouth. It includes the Basis, and Labella. * Basis (the Base). The whole lower part of the Theca, from the mouth of the insect as far as the Labella, Probably to be regarded as representing the Men- tum 2 | Lasera (the Liplets). A pair of tumid lobes, often Corrugated and capable of tension and relaxation, Which terminate the Theca, and perhaps represent — the termination of the Labium &? AUSTELLUM (the Haustellum). The instrument of Suction contained in the Theca*. It includes the V, aloula, Cultelli, and Scalpella. >p t * Thi ; rat ; ld. VIL. Fic. 5, 6. e Ibid. b’. f Ibid. Fie. 6. b’. CENERE. 79. p. » Ibid. c © Ibid. d’. a. . met bid, a, The Labella have been usually thought confined, or Nine 50, to the genus Musca L.; but they may be traced in all ge- © Diptera, i. e. excluding Hippobosca L. TATE VIL. Fie, 5. a, c’, d’. 362° EXTERNAL ANATOMY OF INSECTS. hich a Vaura (the Valvule). A corneous piece W A i ; t- covers the instruments of suction above, represe! ing the Labrum in a perfect mouth è. ; b Cure. (the Knives). The upper pair of the 1" struments of suction, which probably make the first incision in the food of the insect; they represent the Mandibulæ of the perfect mouth». c ScALPELLA (the Lancets) A pair of instrume? usually more slender than the Cultelli, which Pp! bably enter the veins or sap-vessels, and togethe with them form a tube for suction °, 4, ANTLIA (the Antlia). The oral instrument of LP” doptera, in which the ordinary Trophi are replat? by a spiral, bipartite, tubular machine for suction” ; with its appendages ¢. It includes the Solena’™ and Fistula. A Sorenarta (the Solenaria). 'The two lateral subeY” lindrical air-tubes of the Anilia®. B Fisrura (the Fistula). The intermediate subg" drangular pipe, formed by the union of the two branches of the Antlia, which conveys the necta? to the Pharynx’. These two branches represe” the Maville of the perfect mouth.—N. B. M. Sa- vigny discovered the rudiments of the remainine Trophi in this kind of mouth £. ae 5. Rosrrutum (the Rostrulum). The oral instrum?” {Sy @ Prater VII. Fic. 5, 6. a’. b Tbid. c’. pet © Ibid. d. It has not yet been satisfactorily ascertained, whet thy all the ordinary Trophi are represented in every Dipterous mou the number of the lancets seeming in some cases to vary. 4 Puare VI. Fic, 13. en Ww, f Ibid. & £ Ibid. Labrum a’; Mandibulæ ec’; Maxillary Palpus h”. EXTERNAL ANATOMY OF INSECTS. 863 of Aphaniptera (Pulex L), in which the ordinary Trophi are replaced by a bivalve beak, between the Valves of which there appear to be three lancets °. It includes the Lamine, Scalpella, and Ligula. A Lamina (the Lamine). Two corneous plates which are laterally affixed to the mouth of a flea, proba- bly representing the Mandibule of the perfect mouth, which somewhat resemble the beak of a bird >, B SCALPELLA (the Lancets). ‘The two upper or outer instruments, probably for making an incision in the Skin; these are flat and acute, and seem to repre- Sent the Mazille of the perfect mouth $. Ligura a (the Ligula). A capillary instrument between the lancets; probably representing the tongue of the perfect mouth 4 * Rosternum (the Rostellum). The oral instruments _ of Pediculus and some other Aptera, in which the ordinary Trophi are replaced by an exarticulate re- tractile tube, which exerts a retractile siphuncle.. It includes the Tubulus and Siphunculus. Tosurus s (the Tubulet). ‘The tube or retractile base of the Rostellum. ŠIPHUNCULUS (the Siphuncle). - The real instrument of suction, which when unemployed is retracted Within the tubulet. sides the above variations from the type of what I l a Per ‘fect Mouth, there are others in which the parts the Trunk appear to aid in the conversion of the food, * Prats VH. Fre. 8. b Ibid. c’. * Ibid. d’, Maxillary Palpi h”. d Ibid. e’. 364 EXTERNAL ANATOMY OF INSECTS. and become a kind of accessory Labium, Maxilla, i Thus in the Myriapods, the anterior pair of legs assume a Maxillary form and office*; the Prosternum those of Labium’: in the Arachnida, also, the anterior Coxe 4”? accessory Maxille. In this Class, likewise, as has bee” more than once observed‘, the representatives of the inte- rior pair of Antenne of the Crustacea, are thought to assume the form and the functions of suctorious Mar- dibles 4, Facixs (the Face). The upper surface of the head “ It includes all the parts that lie between its junc! : with the Prothorax and the Labrum: viz. Nas! Postnasus, Frons, Vertex, Occiput, Gene, T empor” Oculi, Stemmata, and Antenne. Nasus (the Nose). That portion of the face, often elevated and remarkable, situated between the La brum, Postnasus, and Gene, and with whicb the Labrum articulates; called by Fabricius the Ciy- peusf. It includes the Rhinarium. A Rmwarium (the Nostril-piece). The space betwee? the anterior margin of the Nasus and the Labru™ in which, in vertebrate animals, the nostrils are of@ situated £.—N. B. This is remarkable in some P“ mellicorn beetles, as Anoplognathus Leach. In Ne crophorus, and some others, it is membranous. nace Postnasus (the Postnasus). That part of the F by Je immediately contiguous to the Antenna, that J z Prate VII. Fic. 11, 13.f’. b. Thid. Fre. 11.d’. i € See above, p. 18, &c. d Prare VI. Fic. 10. °° ¢ Prate VI. Fic. 1, 4, 10. a. 3% Ibid a. z Ibid. g', : EXTERNAL ANATOMY OF INSECTS. 265 behind the Nasws, when distinctly marked out.— Ex. Sagra, Prosopis. rons (the Front). That part of the Face which lies behind the Postnasus, and usually between the Posterior part of the eyes. This is sometimes the region of the Stemmata ; or they are partly in this ` or partly in the Vertex *. Verrex (the Vertex). The horizontal part of the Fa- cies, next the front, that lies behind the eyes and between the temples>. This also is often the region of the Stemmata. $ Occrpur (the Occiput). The back part of the head when it is vertical, or peg so, to its point of junc- tion with the trunk °.— Ex. Meloe, Ripiphorus, Hymenoptera, Diy Grn x (the Cheeks). Those parts which lie on the Outside of the anterior half of the eyes, and inter- vene also between them and the Mandibule 4 Tempora (the Temples). Those parts which lie on the outside of the posterior half of the eyes, between which the Frons and Vertex intervene °, Ocuni (the Eyes) The principal organs of sight, Most commonly two in number, placed in the sides of the head. In the majority they are compound, Consisting of hexagonal lenses. In the Arachnida they are simple’. ANTHUS (the Canthus). A process of the face, which enters the notch or sinus of the eye §.—Ex. Scara- bæus L., Cerambyx L. * Sremmara (the Eyelets). Two, or more commonly a : vate Vic. b Ibid. d. ¢ Ibid. e. awed £ TN g. ¢ Prares VI. VIL. and XXVI.h. LATE VI, Fre. l. and VII. Fra. 2. b. 866 EXTERNAL ANATOMY OF INSECTS. > . hearvable three, convex, crystalline, simple eyes, obser vab in the Frons or Vertex, or common to both a, — EX Orthoptera, Hemiptera, Hymenoptera. 10. ANTENNA (the Antenne). Two moveable and joint- ed sensiferous organs, situated in the space betwee? or before the eyes, but in no instance behind the™ ° They include the Torulus, Scapus, Pedicellus, ane Clavola. A Torutus (the Bed). The cavity or socket in w the base ofthe Antenna is planted °. B Scarus (the Scape). The first and in many cases we most conspicuous joint of the Antenne’. Tt W cludes the Bulbus. l i a Bureus {the Bulb). The base of the Scapus, by which i inosculates inthe Torulus, often subglobose, and look- hich ing like a distinct joint °. It acts the part of a Roiul being the pivot upon which the Antenna turns. C Pepicen.us (the Pedicel). The second joint of the Antenna‘: in some insects acting also the part of # ftotula in the socket of the Scapus, to give separat? motion to the Clavola. D Cravota (the Clavolet). The remaining joints of the Antenna taken together’. It includes the Capitulu a Caprrutum (the Knob). The last joints of the C vola when suddenly larger than the rest *. iii. SuBractes (the Subfwce). The lower surface or unde! side of the head‘. It includes the Lora and Jugulu™ * Prats VI. Fic. 4, 10. VIL Fie. 1,2, 4.and XXVI. Fre. 39—41 > Prares XI. XII. and XXV. © Prats VI. Fie. 1, 2. and VII. Fre. 1. 7. a Ibid. XH. Fra. 6, 9. K. © Tbid. 1’. t Tpid. 1. e Ibid. Fre. 6. w. a Ibid, Fre. 6, 8—10. m”. i Prate VI. Fic. 2, 8, & EXTERNAL ANATOMY OF INSECTS. 367 k Lora (the Lora). A corneous angular machine ob- Servable in the mouth of some insects; upon the in- termediate angle of which the Mentum sits, and on the lateral ones the Cardines of the. Mazille; and by means of which the Trophi are pushed forth or retracted. *.—Ex. Hymenoptera. * Jueunum (the Throat). That part of the subface that lies between the temples °. 4 Contum (the Neck). The constricted posterior part of a pedunculate head, by which it in tosculates in the trunk*. It includes the Nucha, Gula, and Myoglyphides. UcHa (the Nape). The upper part of the neck 4, Tt includes the M lyoglyphides. YOGLYPHIDES (the Muscle-notches). Notches in the Posterior margin of the neck, usually two in num- ber, esas alas in Coleopterous insects, to which the levator muscles are attached °. ' Gora (the Gula). The lower part of the neck *. * Copy, ALOPHRAGMA (the Cephalophragm). A Y-shaped Partition that divides the head internally in Locusta ach, into two chambers, an anterior and posterior. II. TRUNCUS (The Trung). he Trunk is the intermediate section of the body, ich lies between the Head and the Abdomen’. It in- SS the Manitruncus, and the Alitruncus ». peat VII. Fic. 2.1. Mon. Ap. Angl. i. t. xiii. f. 1. a, e. ` EVI, » Fic. 2. m. c Ibid. i. a jga rr T XXVII. Fre. 1,3,4.n'. £ Prave VI. Fre. 2 T E IX, Fie. 7, 10, 11, &c. and XVI. Fira. 4, 8. B. Chabrier, in his admirable Mémoires sur te Vol des Insectes, 368 EXTERNAL ANATOMY OF INSECTS. i. Manirruncus (the Manitrunk). The anterior °° ment of the trunk, in which the head inosculates ” on which it turns*. It includes the Prothoraz ™ Antepectus. 1. Proruorax (the Prothorax). The upper pa't yi the shield of the manitrunk, in Coleoptera, Or tho- ptera, &c. called by way of eminence the Thr vax”, It includes the Ora, Patagia, Umbones, ® Phragma. A Ora (the Ora). The inflexed or inferior lateral m% gin of the Prothorax, separated in many g genel® from the Antepectus by a suture €. B Paraera (the Patagia). Two corneous scales 9 servable in Lepidoptera, fixed on each side of tbe trunk, just behind the head, and covered with ° long tuft of hair 4, C iA (the Bosses). Two moveable bosses 5 mounted by a spine, with which the Prothora# ° the Coleopterous genus Macropus is armed. D Puraema (the Phragm). The Septum that clos? the posterior orifice of the Prothorax in Gri ~yllotalp Latr. 2. ANTEPEcTUS (the Forebreast). The underside ° breastplate of the manitrunk, and the bed of the Arms®.. It includes the Spiracula Antepector alit Prosternum, Antefurca, and Brachia. H A SPIRACULA ANTEPECTORALIA (the Antepectoral © cles). A pair of breathing-pores fixed in the mem uses the term Zrone Ali ifére, which suggested the terms here ie ployed. % * Prare IX. Fie, 3, 12,16, &c. © è Ibid: Fre. 1,2, 10, 115° e Ibid. Fie. 2, a’, ' 4 Ibid. IX. Fie. 4. * Ibid. VIII, Fic. 3, 11. EXTERNAL ANATOMY OF INSECTS. 369 brane that connects the Antepectus with the Medi- Pectus è, ProsrerNUM (the Forebreast-bone). A longitudinal r other elevation of the Antepectus between the Brachia’, ÅNTETURCA (the Antefurca). An internal vertical Process of the Antepectus, consisting usually of two br anches, which afford a point of attachment to Muscles of the Brachia ©. Racuta (the Arms). The first pair of legs of Hez- “pods, the direction of which is usually towards the head ; when spoken of with the other legs, called the forelegs. They include the Clavicula, Scapula, Humerus, Cubitus, and Manus. Lavicuna (the Clavicle). The first joint of the Bra- Chium, answering to the Cora in the legs. “CAPULA (the Scapula). The second joint of the Bra- chium, answering to the Trochanter in the legs. Vmerus (the Humerus). The third and elongated Joint of the Brachium, answering to the Femur in d the legs, "Brrus (the Cubitus). The fourth and elongated Joint, answering to the Tibia in the legs. It includes the Coronula and Calcaria. °RonvLA (the Coronula). A coronet or semicoro- net of spines, observable at the apex of the Cubitus ~ a e pene XXIX. Fic. 12. d. > Pirate VIII. Fie. 2, 11. d’. dy 78 XXIL. Fic. 7. e. uy a Latreille, in his Organisation Extéricure des Insectes (Mem. _ Pedes a b viii, 198.) proposes calling the fore-legs of Hexapods Pro- oD, = having long ago applied this term to the false legs of ca- "S (see above, Vor. JI. p. 288. &c.), we shall not adopt it. OL : Suy 2B 370 EXTERNAL ANATOMY OF. INSECTS. or Tibia of some insects.—Ex. Dilophus Latta Fulgora L. B Caucarta (the Spurs). See the definition unde Postici. 'They include the Velum. a VELUM (the Velum). A membrane attached to inner side of the cubital spur in Apis L. ° í e Manus (the Hand). The terminal jointed portion ° the Brachium, answering tothe Tarsus in the leg’ * It includes the Pulvilli, Palma, and Digitus. ped y Pedë the £ Purvu (the Pulvilli) See definition under *™ Postici. g Parma (the Palm). The first joint of the Mart when longer and broader than the subsequent one® or otherwise remarkable; answering to the P Jan in the legs °. , ; A Dierrus (the Finger). See definition under Pelt Postici. It includes the Ungula. i a Uneuta (the Claw-joint). See definition under B y Postici. It includes the Pollex, Unguiculis Paimula. | a PoLLeEx (the Thumb). A small accessory joints A tached to the Ungula of the Manus in Mantis * rs B Uneuicutt (the Claws). See definition undet pelt Postici. . afk y Patmuta (the Palmlet) A minute accessory H between the claws, answering to the Plantula © legs. It includes the Pseudonychia. „eop * PsEUDONYCHIA (the Spurious Claws). See defini under Pedes Postict. ‘A 9. 2 Prare XXVII. Fic. 36. a. b Prare XV. Fie. 6 e Phare XXVII, Fic. 59. a. EXTERNAL ANATOMY OF INSECTS. 371 Mh Atrrruncus (the Alitrunk). The posterior segment of the trunk to which the abdomen is affixed, and Which bears the legs and wings ^. It includes the Mesothorar and Medipectus, and the Metathorax and Postpectus. ’ MESOTHORAX (the Mesothorax). That segment of the alitrunk which bears the Elytra, or the anterior Pair of wings, and the intermediate pair of legs >, It includes the Collare, Prophragma, Dorsolum, Scutellum, Frænum, and Pnystega. OLLARE (the Collar). The first or anterior piece of the Mesothorar. In most insects that have a con- SPicuous Prothorax, as the Coleoptera, this piece *ppears scarcely to have a representative ; but in the Libelulina it co-exists with it, and is more con- SPicuous c, It is particularly remarkable in Hyme- B Optera and Diptera. : ROPHRAGMA (the Prophragm). A partition of an elastic substance, rather horny, connected posteriorly With the Dorsolum, which passes down into the an- terior cavity of the alitrunk, of which it forms the a Ste VII, Fic, 3, 4, 12--14, 16, 17. IX. Fre. l, 3, 7, 8; 1215 b Tbid. c. Bler S IX. Fic, 7, 11, 12, 15, 19. g’. The Collare of Hymeno- p thora iptera has usually been regarded as representing the «bie, ® of Coleoptera, Orthoptera, &c. But this difference obtains is hy > them—the latter evidently belongs to the Manitrunk, and es do not appertain at all to the Alitrwnk ; whereas the Col- is a part of the latter, its museles belong to it, and We sh ssisting in flight are important. ‘These reasons, and re all state hereafter, induced us long ago to consider this representing the Prothorax ; and they seem to have in- `nabrier almost to adopt a similar opinion. Sur le Vol des Ann, du Mus, 3eme Ann. 414. et 4eme Ann. 54--. 2B2 ‘372 “EXTERNAL ANATOMY OF INSECTS. upper separation from that of the manitrunk- affords a point of attachment to several muscles 3 the wings, &c. # C Dorsoxvum (the Dorslet). The piece which lies D” tween the Collare and Scutellum, to which the pr” praghm is anteriorly attached, and which beats ie It incl upper or anterior organs of flight. the Pteropega, Elytra, Tegmina, Hemelyit% Superiores, and Tegule. a Preroprea (the Wing-socket). The space in the organs for flight are planted. That for condary or under-wings is in the Metathor' ans p” Exyrra (the Elytra). The upper organs for fg g when they are without nervures, and uniform) at a thicker harder substance than membrane whet corneous, or coriaceous; lined by a fine memb" yi and when closed, united by the longitudinal gutt „lh They include the Axis, Sutura, Epipleura, “y and Hypoderma, and are peculiar to the Cole? and Dermaptera. A Axis (the Avis), A small, prominent, irregular P cess of the base of the Elytrum, upon which it and by the intervention of which it is affixed © Dorsolum, in the anterior wing-socket °. J” B Surura (the Suture). The conflux of the sutu? el inner margins of the two Elytra, where when © they unite tomna : * Prats XXII. Fic. 8,11. X. » Ibid. Fre, 8. Prars VIIL Fre. 3, 12, 14, 16. TX. F 10--12, 15, 19, 21.7. g. © Puare VIIL Fic. 14, 20; IX. Fre. 11, 12, and XIE a Prate X. Fie. 1.; and XXVIII. Fre. 1—8, 10. 4A * Prate XXVII. Fre, 3—5. 2". f Pratt X xe. wh ih the * e! as EXTERNAL ANATOMY OF INSECTS. 373 ‘ Eerereura (the Epzpleura). The inflexed accessory Margin observable underneath in many Elytra, Which covers the sides of the alitrunk and abdo- mena, e Atura (the Winglet). A small, membranous, wing- ike appendage, attached to the Elytrum on one side and the Franum on the other; which probably erves to prevent the dislocation of the former >.— X. Dytiscus. N. B. A similar organ for a similar Purpose is to be found in Blatta and the Diptera. YPoprrMA (the Hypoderma). The skin, in some - Species beautifully coloured, that lines the Elytra °. "B. This skin is also found in some Hemelytra, but tem in Tegmina. temina (the T. egmina). The upper organs of flight, When of a uniform coriaceous or pergameneous tex- ture, veined with nervures, and lapping over each q thera, Ex. Orthoptera ®. EMELyTRa (the Hemelytra). The upper organs of flight, when they are corneous or coriaceous at the ase: and membranous at the apex ‘.—Ex. The heteropterous Hemiptera. They include the Co- An n and Membrana. RIUM (the Corium). The corneous or coriaceous Part of the Hemelytrum £. a t at XXVIII. Fic.6—8. d”. è? Prare XXII. Fie. 6. e”. dye. = XXVII. Fie. 2. a”. | “my * tic. 19. and Piate X, Fic. 2. Xf the $ upper organs of flight of many of the homopterous section Rely k “Mptera seem altogether membranous, and may almost be “Pi, Under the term Ale Superiores. ATE X, Fic. 3, E Ibid. f”. TA EXTERNAL ANATOMY OF INSECTS. B Memprana (the Membrane). The membranous pan of the same ?. y e ALÆ SUPERIORES vel Primarræ (the Upper oY P d mary Wings). The upper or anterior orga” 4 flight when formed of membrane, or of the wW substance with the under-wings b, They inclu the Axes, Aree, Arcole, Neure, Stigma, Parastig¢® and Lobuli. E A Axrs (the Azes). Several osseous or horny pe by which the wing is connected with the Dor soli One usually to each area. 5 B Arex (the Areas), The larger longitudinal spe into which the wing may be divided4. They a clude the Area Costalis, Intermedia, and Analis. ’ a AREA Cosrauis (the Costal Area). That part of 7 wing lying between the anterior margin an pi post-costal nervure®. In Hymenoptera and A ptera it includes all the space bounded by the E vures that spring from the postcostal. pps! b Area INTERMEDIA (the Intermediate Area). d part of the wing lying between the costal are? the interno-medial nervure, in Diptera; % p Anal in Orthoptera, Hemiptera, Hymenopteres a c ÅREA ANALIS (the Anal Area). All that part ° wing which in Diptera lies between the int®™ @ * Prare X. Fie, 3, 2’. > Ibid. Fic, 5—9, 11—15. and Prare XXVII. Fie. 18. TO A a N.B. In the Plate the Costal Area is red, the I ntermediate é and the Azal yellow. When the Hemelytra are considered a? i ; into Areas, the Membrana might be denominated the Apical P Pave X. Fig. 2, 3,5. f [bid, ¢'. pills de! EXTERNAL ANATOMY OF INSECTS. 375 Medial nervure; or in Orthoptera, &c. between the anal nervure and the posterior margin +. ARnoLa (the Areolets). The smaller spaces into which the wing is divided by the nervures. They include the Areole Basilares, Media, and Apicales. P Arnot» Basriares (the Basal Areolets). The pa- rallel areolets of the base of the wing?. Arroum MEDIE (the Middle Areolets). ‘The ects of the wing that lie between the basal areolets and the apical €. © ÅREoLÆ APICALES (the Apical Areolets). ‘Those areolets of the wing that terminate in or very near the apex 4, Nrurm: (the Nervures). Corneous tubes, for expand- ing the wing and keeping it tense, and to afford Protection to the air-vessels—commonly called the Nerves, They include the Neura Costalis, Post- costalis, Mediastina, Externo-media, Interno-media, ; Analis, Axillaris, and Spuria. Neura Costaris (the Costal Nervure). The first, Principal nervure of the wing, close to or forming the anterior margin in Lepidoptera, Hymenoptera, and Diptera; but sometimes remote from it in Teg- minae, It includes the Phialum and Hamus. Bras uns (the Phial). A little bag to receive fluid at the will of the insect, by which the weight of the Wing is increased. It is found also in the under-. Wings in Coleoptera’. a peax. Mie. 2) gd b Ibid. Fic. 7—15. e% Be f. à Jbid. g. e Ibid. }. deme abrier Sur le Vol des Insectes, Ann. du Mus. 3eme ann. 428 ann, 325—, 3d Cahier 78. 376 EXTERNAL ANATOMY OF INSECTS? B Hamus (the Hook). A Hook fixed to the Costa! Nervure, near its base on the under-side, in the wings of some Lepidoptera, in which the tendo” runs 2, Nrura Postcosratis (the Postcostal Nervure)- gh second principal, and often strongest, nervure y the wingè. It includes the Newre Subcostales Neuræ Sugcosrares (the Subcostal Nervures). Ne vures springing from the under-side of the p% costal nervure, or from each other; called the, irs second, third, &c. in the order of their occurrence “ Neura Mepiastina (Mediastinal Ner vure). Aust ally slender nervure, springing from near the bas? of the postcostal; between which and the costal ii intervenes. In the Lepidoptera Diurna, howeY®” it is often a strong nervure 4, Neura Exrerno-mepra (the Externo-medial Ne vure). - The third principal nervure of the wiP$ ’ It includes the Neura Subexterno-media. NEURA SUBEXTERNO-MEDIA (the Subexterno-medi Nervure). A nervure that in some cases interve™ between the externo-medial and interno-medial © NEURA ĪNTERNO-MEDIA (the Interno-medial Nero’? The fourth principal nervures. It includes * Neura Subinterno-media. d _Nrura SUBINTERNO-MEDIA (the Subinterno-medi" Nervure). A nervure that sometimes inter yen between the externo-medial and the anal}. * Linn. Trans. i. t: xiii. Jf. 2. 3. d. > Prats X; Fie. 5—l5.” c Tbid. a*, 4 Ibid. Fic. 6. k°. © Ibid. Z, f, Ibid. Fic. è ð; 6, 13. 4*. € Ibid. Fic, 5—~15. me * Thid. Fic, 5, 6, 13. ce. EXTERNAL ANATOMY OF INSECTS. 377 3 Neura Anais (the Anal Nervure). The principal Nervure nearest the interior or posterior margin, with which it includes a space often subtriangular, traversed in most Diptera and many Hymenoptera by another nervure; and in many Tegmina and Femelytra by several*. In these kinds of upper- Wing it is in many cases accompanied by a fold; and the part between it and the interior margin seems often capable of separate motion. Neura AXILLARIS (the Axillary Nervure). ‘The short - hervure, where there is only one, intervening be- tween the anal nervure and the interior margin ; replaced in some Muscide by a spurious ner- Vure>, Neurz Spur (the Spurious Nervures). Very ob- Solete nervures, sometimes found in addition to those usually occurring; as in Syrphus ©. Stigma (the Stigma). A corneous spot or plate, sup- Posed to contain fluid, in the anterior margin of the Upper wings; often produced by the conflux of the Costal and postcostal nervures 4. ARASTIGMA (the Parastigma). A corneous spot be- tween the costal and postcostal nervures, distinct from the Stigma observable in the Libellulina. “OBULI (Lobuli). One or more rounded portions of the base of the wing, separated from the rest by fis- “ures peculiar to the Muscide, and the under-wings ae Some Hymenoptera °. EGULÆ (the Tegule). Small corneous concavo-con- : Prarg X. Fie. 5—15. w. ; b Ibid. o. : Ibid, Fic. 14. p. 4 Jbid. Fie. 31. mi: bid. Frc, 14, 15. x”. 378 EXTERNAL ANATOMY OF INSECTS. vex scales, which in many Orders, particularly Hy menoptera, cover and defend the base of the Upper Wings*. D Scurentum (the Scutellum). A piece, usually tri- angular, which follows the Dorsolum; and in C leoptera is often only a continuation of it—place between the base of the Elytra or upper wings», E Frau (the Frenum). A piece that lies under t lateral margin of the Scutellum and Dorsolum, 0 ss s t0 he adjacent to it; and which in many cases con with the base of the upper organs of flight, so # prevent their dislocation, by being pushed too far outwards ¢. E Pyystreea (the Pnystega). A corneous scale or plate which covers certain pneumatic vessels, usually supported by the Scapularia, in Libellulina, &e- pe- coming dorsal ¢. 2. Meprrrctus (the Mid-breast). The underside of the first segment of the alitrunk®. It includes the Peristethium, Scapularia, Mesosternum, Medifure™ and Pedes Intermedii. ; A PERIsSTETHIUM (the Peristethium). The anterio" piece of the Medipectus, which intervenes betwee? the Brachia and mid-legs £. ; B Scaruraria (the Scapulars). ‘Two pieces, one ” each side the Medipectus, which succeed the P er stethium, and lie between the midlegs and the Pits * Prare IX, Fre. 5,11.g’. > Pravas VIIL IX. XXVIL * ; Ibid. /’. a Prare-LX. Fie. 7. m. Prare VIL. Fre. 4, 13, 17.5 and IX. Fie. 3, 8, 12. d f Ibid. x’. a, EXTERNAL ANATOMY OF INSECTS. 379 ropega or wing-socket*. It includes the Spiracula Scapularia. - SPIRACULA Scapuraria (the Scapular Spiracles). Two spiracles observable, one in each scapular, in Acrida laurifolia, &e. Mrsosrernum (the Mid-breastone). The elevated and central part of the Medipectus, between the mid- legs, often terminating anteriorly in a mucro; some- times, as in Elater, in a cavity, receiving the mu- cro of the Prosternum °. Dd Mrpirurca (the Medifurca). ` A branching vertical process of the Endosternum, which serves as the point of attachment to the muscles that move the midlegs °. Pedes InrermeDI (the Mid-legs). The intermediate pair of legs, consisting of the same parts as the posterior legs 4. O arinoiax (the Metathoraz). The posterior seg- ment of the Alitruncus®. It includes the Meso- Phragma, Postdorsolum, Postscutellum, Postfreenum, Pleura, and Metaphragma. | à Mrsopuracma (the Mesophragm). A partition of a firm consistence, connected by its posterior margin with the Postdorsolum, and passing down vertically into the mid-chest; serving as a point of attach- ‘ment to several of the muscles that move the wings’, This, with the prophragm, forms the an- _ Prates VIII. IX. o'. b Prare VIIL Fie. 4, 8, 13, 17. p LATE XXII. Fie. 6.¢. 4 Prare XVI. Fic. 4—6. 2’. Stark VHI. Fre. 3, 12.; and IX. Fie. 1, 7, 10, 11, 12, ae: XXII. Fie. 9, 11.5’. 380 EXTERNAL ANATOMY OF INSECTS: terior cavity of the alitrunk, and with the meta- phragm it forms the posterior cavity. b Posrporsotum (the Postdorsolum). The middle- piece between the mesophragm and the Posiscir tellum. In Coleoptera it consists of a tense elast! membrane, which is quite covered by the Meso thorax *, : c Posrscureiiu (the Postscutellum). A narrow chan- nel running from the Dorsolum to the Abdomen 1» Coleoptera, forming an. isosceles triangle reversed. In other orders it is either a triangular elevation of the middle of the posterior part of the Postdorsolum™ or a distinct triangular piece >. d Posrrranum (the Postfrænum). In Coleoptera the part of the Metathorax in which the Postscutellu™ lies, at first nearly horizontal, but posteriorly it takes a vertical direction towards the abdomen. In ge neral it. may be defined, the part that intervene between the Postscutellum and the Abdomen; and which in many cases is connected with the posterio” basal margin of the under-wings, and prevents the being pushed too far forwards ©. e Prevur# (the Pleure). The space behind the scap™ lars, on which the lower organs of flight are fixed “ They include the Ale Inferiores. . A Aux Inreriorss (the Under-wings). The lower ° secondary pair of organs for flight *. They include the Commissura, Tendo, Hamuli, Pterygium, Alults and. Halteres. * Prare VIIL Fic. 3, 12, 20. and IX. Fre. 7, 10—12, 15, 20: f- b Ibid. u. © Prares VIN. IX. XXVII v- a Prates VII. and IX. w. ° Prare X Fre, 4, 10. EXTERNAL ANATOMY OF INSECTS. “381 @ Commissura (the Commissura). A joint in the costal -hervure of the wings of Coleoptera, where | bend to take a transverse fold *. 6 Trnpo (the Tendon). A strong bristle, or bristles observable at the base underneath in the under- wings of many Lepidoptera, which plays in the Ha- mus of the upper-wings ”. € Hamun (the Hooklets). Very minute hooks in the middle of the anterior margin, observable in some Hymenoptera, by which the under-wing is fixed to the upper, to cause both to act as one organ in flight °. d Preryerum (the Pterygium). In under-wings this is a small wing-like appendage, fixed at the base of the wing in some Lepidoptera‘. e Avra (the Winglet). A small concavo-convex sca- rious appendage, fixed behind the wings at their base, in many Diptera °. f Haxreres (the Poisers). Small capitate processes or organs, observable under the wings of Diptera, at- tended by a spiracle f. Merrapnysreca (the Metapnystega). A. corneous scale or lamina that covers the pneumatic organs in the Metathorax, situated sometimes in the Pleu- ræ, as in the Coleoptera; at others in the Post/re- num, as in Tenthredo L.; and sometimes, as in the Libellulina, between that part and the abdomen £. * Prate X. Fie. 4.0”. b Linn. Trans. i. t, xii. f. 1.5. 3. a. : Kirby Mon. Ap. Angl. i. t. xiii. f. 19. _ De Geer ii. t. ix. f. 9. d. e Ibid, vi. t. ii. f. 23.a a , Prarr IX. Fic. 19. g “Ibid. Fre. 7, and Prater XXII. Fia, 14, X. 382 - EXTERNAL ANATOMY OF INSECTS. C Maetapuracma (the Metaphragm). A nearly verti cal septum or partition, attached behind to the Postfrænum, and usually deeply cleft at its apex 1” Coleoptera, of a rather horny consistence, which forms the upper separation of the second cavity ° the Alitrunk from that of the Abdomen. It affords a point of attachment for many muscles of both alitrunk and abdomen. It includes the Septula. a Seprouua (the Septula). The lesser ridges and pa titions raised on the surfaces of the metaphrag™» and on those of other parts of the cavities of thé trunk, serving as points of attachment to various muscles », 4. Posrrectus (the Postpectus). The underside of thé second segment of the alitrunk*. It includes thé Mesostethium, Parapleure, Metasternum, Posifurc% Opercula, and Pedes Postici. A Mesosrenium (the Mesostethium). A central piec? between the intermediate and posterior legs, 2° bounded laterally in Coleoptera by the Parapleur® —along the middle of which, where it exists, th® Metasternum runs 4. B ParaPLeurs (the Parapleure). Two pieces, one %” each side of the Postpectus, included between tH? Scapularia, Mesostethium, and Pleure*. They clude the Spiracula Parapleuritica. a Sprracuta PARAPLEURITICA (the Parapleuritic SP” racles). Two spiracles, one in each of the Pare pleure of Tetyra €. > 2 Pirate XXII. Fic. 10, 11, 2’. b Ibid. Fre. 9——11. 2”. © Prarss VIII. and IX. f. 4 Thid. 9’. 4 e Ibid, 2’. t Prarr XXIX, Fic. 15.” * EXTERNAL ANATOMY OF INSECTS. 383 © Merasrennum (the Metasternum). The central and often elevated part of the Mesostethium. Its anterior mucro, in Coleoptera, often meets the posterior one of the Mesosternum, and sometimes appears to form one piece with it, as in Hydrophilus, and many Lamellicorn beetles. Sometimes, as in Cetonia vit- ticollis, it even passes between the arms, and covers the Prosternum, or supplies its place. Behind, it often terminates in a bifid mucro. It is not present in many Orders: as in the Hymenoptera, papira &c.2 It includes the Pectines. Prcrinzs (the Pectines). ‘Two moveable processes, fixed one on each side by its base below the posterior legs to the Metasternum in Scorpio: on the lower side is fixed a series of parallel biarticulate processes, re- Sembling the teeth of a comb». Posrrurca (the Postfurca). A process of the £n- dosternum, terminating in three subhorizontal acute branches, resembling the letter Y, and forming an acute angle with the Endosternum, to which the Muscles that move the hind-legs, &c. are affixed °, Orrrcura (the Opercula). Plates that cover the Vocal spiracles in humming insects; and likewise two large cartilaginous plates fixed to the posterior Part of the Postpectus, which cover the Zympana in male Tettigonia F. Perhaps these may be re- garded as a kind of Metapnystega in a new situ- p ation. Penns Postict (the Hind-legs). ‘The pair of legs : pates VIII. IX. a+. b Prare XXVIL Fro. 50,’ a p ATE XXIL Fic. 3. bt. LATE VIIL Fic, 18; and XXII. Fic. 13. ¢ +. 884 "EXTERNAL ANATOMY OF INSECTS. affixed to the postpectus*. They include, the Act tabulum, Coxa, Trochanter, Femur, Tibia, ® Tarsus. a ACETABULUM (the Socket). The socket in the P ost- pectus in which the leg is planted ». -It includes the Pessella. A Presse. (the Pessella). Two little acute process fixed one in each, in the socket of the hind-legs n male Tettigoniæ, which appear designed to keep down the Opercula®. b Coxa (the Hip). The first joint of the leg which plays in the socket4. c TROCHANTER (the Trochanter). The second joint of the leg, by which the thigh inosculates in the Co™ It appears to have no motion separate from that 4 the thigh. It is sometimes biarticulate €. d Femur (the Thigh). The third jojnt of the leg, 10° 6 and usually compressed‘. It includes the Gory theca. A Gonytueca (the Knee-pan). A concavity at the ape of the thigh, underneath, to receive the base of the Tibia £. l e Tresa (the Skank). The fourth joint of the leg, vel} : : e long, and usually triquetrous*.. It includes th Epicnemis, Molula, Talus, Calcaria, and Co nula. a Pirate XIV. Fie. 5—8. y : P Prare VIL Fre. 2, 4, 11, 13, &c.0". © Ibid. Fic. 18.9 7, @ Prare XIV. Fre. 6—8; and XXVII Frc. 12, p”, ° Ibid-4 f Prate XIV. Fic. 5—8; and XXVII Fic. 6—8. 7”. t Prate XXVII. Fic. AS 15a, ; h Prare XIV. Fic, 5—8. 9”. EXTERNAL ANATOMY OF INSECTS. 385 4 . s . e Evrcxzmis (the Zpicnemis). An accessory joint at a £ q e f Vor EF the base of the Tibia in many Arachnida, which does not appear to have separate motion 2. OLULA (the Knee-baill). ‘The convex-and sometimes bent head of the Tibia, armed with a horny pro- ess on each side, by which it is attached to the thigh b, 4Lus (the Ankle). The apex of the Tibia, where it iS united to the Tarsus. ; ALCARiA (the Spurs). One, two, or more moveable Spines, inserted usually át the apex of the Tibia; and in many Carabi L., Lepidoptera L., and Tricho- Ptera K., in the middle also. They may be regarded as a kind of fingers auxiliary to the Tarsus, and fur- Nish often an important character in the discrimina- tion of genera 4, ORONULA (the Coronula). A coronet or semicoronet of fixed spines observable at the apex of the poste- tior Tibia in Fulgora candelaria, &c. “Rsus (the Tarsus). The fifth principal portion of the legs; consisting in the majority of insects of 15 joints, but in the Phalangide of sometimes as Many as 50°. It includes the Planta, Digitus, and Olea, VANTA (the Instep). The first joint of the Tarsus is 50 called when it is remarkably long and broad f. t includes the Calz. RoN a E XXVII Fic. 21.5”. è Ibid, Fie. 9, 10, 16, 17. £”. jid. Big, 34—36. 21", L p, XIV, Fre. 6; and XXVII. Fie. 29—36. v”. L p ATE XIV, Fic. 5—8; and XXVII. Fic. 44, 45, 62, 63. £”. La mT 74r a tE XXVII. Fic. 25, 26, 41. w”. u, oC 386 EXTERNAL ANATOMY OF INSECTS. a Catx (the Heel). The curving part of the Plant by which it inosculates with the Tibra. B Dierrvs (the Toe). The remaining joints of the Ti sus taken together*. It includes the Alux and Ur gula. a` ALLUX (the Toe-ball). The last joint but one of the Tarsus, when remarkable, as in Rhyncophoro™ beetles (Curculio L.)°. b Uneuta (the Claw-joint). The last joint of the Tar: y which bears the claws °. It includes the Arthrii Unguiculi, and Plantula. e a ÅRTHRIUM (the Arthrium). A very minute joint the base of the claw-joint, in most TetrameroU i . Trimerous beetles 4. ple B Uneurcuts (the Claws). One or two pair of mov™ the incurved claws, which usually arm the apex ° Ungula °. y Puantuta (the Plantula). A minute accessorfieng sometimes attached within the claws to the oe K the Ungulaf. Ex. The Lucanide. It include Pseudonychia. oe claw” * PsEuponycuia (the Spurious Claws). Two stiff d like bristles, that terminate the Plantula&. C Sorra (the Sole). The underside of the Tarsus ý includes the Pulvilli. e a PuLviLu (the Pulvilli). Cushions of short hairs ae closely set; or of membrane, capable of peing ft Pirate XXVII. Fre. 25, 26. æ”. Prate XXVI. Fie. 47, 48; and XXVII. Fie. 43. 7°: j Ibid. s. d Prare XXVI. Fre. 47 a ft Pirate XXVII, Fie. 37—57. e*. f£ Ibid. Frc. 56; i Z g Ibid. Fic. 56. aw. a Tpid, Fre. 597 * 4, EXTERNAL ANATOMY OF INSECTS. 387 flated, or very soft; or concave plates, which cover the underside, or their apex, of the four first joints of the Manus or Tarsus, and sometimes even of the ends of the Calcaria, as in Cimbex; which act so as to produce a vacuum, and enable the animal to sus- pend itself, or walk against gravity®. Ex. Timar- cha, Buprestis, Priocera K., the Gryllina, Musci- de, &e. Ill. ABDOMEN (the Abdomen). a Abdomen is the third or posterior section of the ‘ Y which follows the Truncus®. It includes the Ter- ™s y, enter, Petiolus, Cauda, and Anus. : Tereum (the Tergum). The upper or supine surface Of the abdomen è. It includes the Segmenta Dorsa- lia, and Pulmonaria. ; StemeNTa Dorsauta (the Dorsal Segments). Trans- Verse segments of the back, the sides of which often A lap over and cover those of the ventral segments 4, `ULMONARIA (the Pulmonary Space). Two longitu- dinal soft spaces, capable of tension and relaxation, e on each side of the back of the abdomen, in Which, where they exist, the dorsal spiracles are à Planted e, They include the Spiracula Dorsalia. PIRACULA DORSALIA (the Dorsal Spiractes). Late- ral breathing-pores observable in the dorsal seg- Ments, often covered by the preceding segment f. i b mins XV. Fic.9; and XXVII. Fic. 35, 59—61. £. c ia VHI. Fre. 5, 6, 9, 15, 18, 19. “Tig gece 5, 15. 4. a Ibid, 4’. Fre. 5,9. BY. l Ibid. Fre. 5, 9, 15. A”. Been 388 EXTERNAL ANATOMY OF INSECTS. . VENTER (the Belly). The lower or prone part of the abdomen ^. It includes the Hypochondria, Epig" strium®, Segmenta Ventralia, and Elastes. is oe eo ca (the Hypochondria). Two poti of segments, one on each side; which in some 8“ nera*® (Carabus L., &c.) intervene between the firs intire ventral segment and the posterior part of the Postpectus. 2. EPIGASTRIUM (the Epigastrium). The first intire VP" tral segment‘, It includes the Muero and Ty pana. A Mucro (the Mucro). The central posterior point ° er ac the Lpigastrium observable in many of the Ord which reposes between the posterior legs ; and, cording to M. Chabrier, is useful to the insect O" ring flights, B Tympana (the Drums). Two deep cavities, conta” ing a complex machinery on each side of the Epi strium in male Tettigonie, which are the instr ume” of sound f. 3. SEGMENTA VENTRALTA (the Ventral Segments). w verse sections of the belly 8. In Elytrophor ous * sects they are usually of a firmer consistence those of the back. They include the Spiracula t” tralia. A Sprracuta VENTRALIA (the Ventral Spir aches’ Va 2 Prare VIII. Fic. 6, 9, 15. B. en” > The scientific reader must recollect that these terms are o sent” ployed, not because these parts are thought to be true repte” ts, tives of the Epigastrium and Hypochondria of vertebrate # but merely on account of some analogy between them. , e Prare VII. Fra. 6. C’. @ Thid. D’. e hid. B f Ibid, Fig. 18, 19. C”, € Ibid. Fic. 6, 9, 15. Æ pin? EXTERNAL ANATOMY OF INSECTS. 389 Breathing-pores observable in some genera in the intermediate ventral segments, one on each side?. Ex, Dynastes. Aloeus, &c. ELAsTES (the Elastes) The elastic organs on the ventral segments of Machilis polypoda which assist i e insect in leaping. ` + ETIOLUs (the Footstalk). A slender part by which the abdomen of many Hymenoptera is united to the trunk, in some genera very long, in others very short, and in others wanting >. It includes the Fu- À p oas Foramen, Squama, and Nodus. ` “UNIcuLUs (the Funiculus). A small cartilaginous cord, passing through a minute orifice of the Post- Jrænum, just above the point where the footstalk is fixed, to an opposite hole above it, which enables the animal the better to elevate or drop the abdomen €. ORAMEN (the Foramen). The orifice in the abdo- Men, through which the above cord passes ¢. ' Souama (the Scale). A vertical flat scale, observable "On the footstalk of the genus Formica, &e. € ODI (the Knots). One or more subrotund protube- rances of the footstalk in the genus Myrmica €. ' Cauna (the Tail). Where the abdomen grows sud- denly slenderer, and terminates in a long jointed fail, as in Scorpio and Panorpa’. It includes the Centris. ) CenTgis (the Centris). The last inflated joint of the tail, terminating in the Sting. a TRR 2 ete VIL; Fie} 9.0’. b Prate IX. Fie. 17, 18, C. : Sy Fig, 13. F, a Ibid. G. tp en. f Ibid. Fic. 18. Z’. CEV Fic.-12. ; 390 EXTERNAL ANATOMY OF INSECTS. . Anus (the Anus). The termination of the abdome” consisting of the two last segments. It includes t° Podex, Hypopygium, Culus, Ovipositor, and APP m dices. . Popex (the Podex). The last dorsal segment ° abdomen ?. j . Hypopryerum (the Hypopygium). The last venti? segment of the abdomen °. . Curus (the Culus). The orifice at the end of th? f the anus. l Ovirosrror (the Ovipositor). The instrument 2 oviposition, by which the insect conducts the E to their appropriate nidus, and often bores a way! it; the same instrument is by some genera used ° 7 a weapon of offence, when it is called the £eulet | It includes the Unci, Tubulus, reales Vaginuld, a Terebelle. A Uxo (the Uncz).. Two pair of robust organs, gi upper incurved and the lower recurved, with whe the anus of Locusta Leach is furnished 4. B Tusuwus (the Tubulus). A tubular ovipositor; sisting of several pieces often retractile within eat other, like the tubes of a telescope °. a C Varva (the Valves). Two lateral lamine, often cor ceous, by which the ovipositor when unemploy® covered f. D Vaernuxa (the Sheath). A corneous case, coer with a Prare VIIL Fic. 5,15. K. > Ibid. Fre. 6, 15, 18- 2: e Pirate XV. Fic. 18—22; and XVI. Fig. 1—3. ; 4 Prate XV. Fic. 18. F. e Prare XV. Fic. 22; and XVI. Fie. 2, 3. t Ibid. Fic. 20, 21; and XVI. Fic. 1. F”, EXTERNAL ANATOMY OF INSECTS. 391 two grooves, in which the Terebella or Specula Play 2, EREBELLE (the Terebelle). Instruments by which ET the insect saws or bores a passage for its eggs to the place in which her instinct directs her to deposit them », 5, AcuLEus (the Sting). The above instrument, when fitted for an offensive weapon‘. It includes, besides the Valve and Vaginula before defined, the Spicula. Sprcua (the Darts). The proper stings which inflict the wound: retractile within the sheath, externally ser- rulate at the apex 4. They include the Retznaculum. * Rermacuum (the Retinaculum). A minute horny Moveable scale or plate with which the darts are fur- nished, which prevents their dislocation by being Shot forth too far €. ~ Apprnpices (the Appendages) Other instruments and organs, with which the anus of various insects is furnished. They include—the Forceps, Forfex, Furca, Styli, Foliola, Flosculus, Caudule, Fila, Mam- mule, Papille, and Siphonuli. Forcurs (the Forceps). A pair of anal organs that Open and shut transversely, and meet at their inner Margin, or at the apex. Ex. Forficula. 3 Porrex (the Forfex). A pair of anal organs, which Open or shut transversely, and cross each other f. Ex. Male of Raphidia Ophiopsis. : o XV. Fie. 20.6". : > wid. Fie. 20, 21; and XVI. Fic. 1. H”. aay Mon. Ap. Angl. i. t. xii. Apis **. e. 1. neut. f. 23—25; and Ht f. 27, 28. d x 3 x t. xiii. f. 30, 31. © Ibid. a. LATE XV, Fic, 12, I”. . 392 EXTERNAL ANATOMY OF INSECTS. 3. Furca (the Fork). An inflected elastic anal org? ending in a fork, by which the animal is enabled t° leap*. Ex. Podura. . Srvti (the Styles). Rigid, exarticulate, long "4 narrow anal organs®, Ex. Staphylinus. . Forrora (the Leaflets). Rigid, exarticulate, dilate leaf-like anal organs °. Ex. Libellulina. 6. ILoscutus (the Foret) A small, tubular, Junulat? anal organ, with a central style‘. Fulgora cande- d, laria, &c. . Cerci (the Cerci) Two short, flattish, sublance™ late, jointed, lateral anal organs®. Ex. Blatta-— N.B. Analogous organs are observable in the Gry! lina, but usually conical and without joints £. In Gryllus Latr. they are setiform £. . CAUDULE (the Caudle). Two or more slender; fili- form or setaceous, jointed, flexile anal organs”. ES. Lepisma, Machilis, Ephemera. 9. Fina (the Threads). Two exarticulate, slender; fili- form anal organsi. Ex. Machilis. 10. Mammuræ (the Mammule). Anal protuberance containing instruments for spinning web «. EX Araneide. They include the Fusi. Fusi (the Spinners). Organs, consisting of two ee tractile pieces, issuing from the Mammule, and 1e™ dering the threads !. Prate XV. Fic. 14. M”. > [bid. Fic. 17. NV”. Ibid. Fie. 15. O”. + Thid, Pra, 138, 2” e bid Pre- 23.9". 1 De Geer iii. £. xxii. f. 10.aa. € Ibid. £. xxiv. f. 2. c; and fi)” “h Prare XV. Fic. 16. R sn Sse k [bid. Frc. 10; and Prare XXIII. Fre. 16, 17. T”. t Tbid. Fie. 12. F". 15. EXTERNAL ANATOMY OF INSECTS. 393 12, SIPHONULI (the Siphonets). Truncated, fistular, seti- form anal organs, emitting a saccharine fluid*. Ex. Aphis. You will observe, that when the whole upper-side of © Truncus is spoken of, it is called the Thorax ; and as in Coleoptera, and some other Orders, the whole of the “Sothorax except the Scutellum is covered by the Tho- "an, and the whole of the Metathorax by the Mesothorax nd Elytra—the Thoracic shield may without danger of mistake be denominated the Thorax, as it has always n, When the whole under-side of the Trunk is spo- d of, it is called the Pectus. When the three Sternums " spoken of together, they may be called the Sternum ; the whole interior elevation of the Pectus may be leq the Endosternum. a De Geer ubi supr. t. iil. f. 5,20, 21. c. LETTER XXXIV. EXTERNAL ANATOMY OF INSECT THE HEAD, AND ITS PARTS. BEFORE I confine my observations to the head of ied sects, which I propose to consider separately in the pt sent letter, I must premise a few words upon their b0% in general, or rather its crust, or external integune In this we may notice its substance, general, form, soul ture, pubescence, and composition. ee u i. I have already noticed the substance of this integ shall 2°” ment in the preparatory states of insects?; I i ct BY jf therefore, here repeat what I then said, but restri self chiefly to the consideration of it as it is found i” t j last state, in which it is usually firmer than in thet” i 4 vious stages of existence. In this respect, howeve” if varies much in the different Orders, and even in the f ferent genera of the same Order. In some Coleoptet? , insects, for instance, it is very hard, and difficult t° p forate; while in others it is soft, flexible, and a pi® = passes through it®. And in general, from a substa” a See above, p. 86, 110, 243—. : i ex o Many species of Hister, Curculio L., Doryphora Iig: are EXTERNAL ANATOMY OF INSECTS. 395 hardness resembling horn or shell, it passes through € intermediate degrees of that of leather and parch- Rent, almost to a thin membrane. Yet in all cases there S enough of rigidity and hardness to answer the princi- Pal uses of a skeleton—to afford, namely, a sufficient Point of attachment for the muscles, and to support and fend the interior organization; so that the play and tion of the vital and secretory systems may not be in- ‘trupted or impeded. ith respect to the principles which enter into the “Mposition of this integument, very little seems to be Own at present; but few insects having been submitted ? a chemical analysis. The blister-beetle (Cantharis “Stcatoria), from its importance in medicine, has, how- “Yer, been more than once analysed; and though the Moducts have not been very precisely stated, yet we find Miongst them phosphate of lime, albumen, and some & usual components of the substance of vertebrate “Nimals2, But which of these products belong to the tegument, and which to its contents, cannot be ascer- ‘hed, without a separate process for each; which would Not, | conceive, be very feasible. The substance, how- Ye, of the integument of insects, though we know not — ‘Precise contents, which probably vary in different ge- ‘ta, &e., appears not to be exactly of the nature of any those substances after which it has usually been deno- qcnely hard, while Cantharis Geoffr., Meloe F., and Telephorus J r., are very soft. $ henard Traité de Chimie Elémentaire, iii. 637. n. 2005. The ba Products he mentions are—a green oil, a yellow substance, a Cant dtto, acetic acid, uric acid, phosphate of magnesia. The vesi- ” Matter consists of little micaceous laminæ soluble in boiling al- Oho] A 5 r l and oil, but insoluble in water. 396 EXTERNAL ANATOMY OF INSECTS. minated : it is not properly analogous either to real hors shell, skin, or leather, &c. This seems to result from the following circumstance :—Most of the excretions of ver tebrate animals, as horn, skin (at least when tanner” feathers, wool, hair, &c. when exposed to the action Ý fire liquify, more or less, before they incinerate; emitting at the same time a peculiar and disagreeable scent: bu! upon applying this test to the parts of insects of the dif ferent Orders, I found, in every instance, that inciner® tion took place without liquefaction, and was unaccon” panied by that peculiar scent which distinguishes ae others. Even the claws, which to the eye appear, 35 A their substance, exactly like those of Mammalia, pire &c. burn without melting, and retain their form afte red heat. That the insect integument is not calcareo like that of the Crustacea, and the shells of Mollust™ you may easily satisfy yourself, by immersing them ms j acid test. I made this experiment upon portions of uF sects of several of the Orders, in an equal mixture of mr riatic acid and water, and the result was, not only tha all hexapods, but octopods, Arachnida, and even Scolo pendridæ, upon immersion only emitted a few air-bub- bles; while, when the other myriapods, Polydesmus, f lus, Glomeris, &c. and the Oniscidæ, were immersed, violent effervescence took place; proving the differe” nature of their substance. It is remarkable that the & great branches of the Myriapods, the Scolopendrid@ ae Tulide (Chilopoda and Chilognatha Latr.), should A this respect be so differently circumstanced—the Jatte” having a calcareous integument, and the former not” A further difference distinguishes these two tribes: ” specimens of the Juid@ usually lose their colour and ture EXTERNAL ANATOMY OF INSECTS. 397 Whi . E 5 4 hite, like Oniscidæ ; while those of the Scolopendride retain it a The form of insects is so variable, that it can be Uced to no other general rules—than that, for the Most part, the length exceeds the breadth, and the “eadth the depth, and that the upper surface is usually or. But to these rules there are numerous excep- Xs. Thus many Tetyræ F. (Scutellera Latr.), a kind y% bug, are as broad as they are long?; in the genus Myleptes K.? amongst the Aptera, and Epeira cancri- “mis, a crab-shaped spider, the breadth exceeds the “Dgth ; in Cynips, and several other Hymenoptera, in iy K.* (Locusta F.), and other Orthopterous in- 8, the depth exceeds the breadth; and in that singu- y beetle, Eurychora; the cockroach (Blatta), &c. the Pper surface is flat. ii, The sculpture of the integument of insects is often V os : “Y remarkable; but as this will call for attention here- a : ter, I shall only here observe in general, that ornament a. w Variety seem not to be the sole object of those eleva- l0 : i i ns and depressions which form so prominent a feature Many of the animals in question; for by means of these, t My important purposes, that at first sight do not strike € observer, may be served: such as giving firmness 0 TET : the crust in those places where it is most wanted; di- a , Coquebert iusér. Icon. ii. t. xviii. f. 14, 15. mm. Trans, xii. t. xxii. f. 16. 1s name I would give to Locusta F., reserving, with Dr. Leach, atter name to the true locust ( Gryllus F.). The name Conoce- Aly « 5 Sayre a z. ; to > by which Locusta F. has been distinguished, is better restricted 9se with a conical head. 398 EXTERNAL ANATOMY OF INSECTS. minishing its powers of resistance in others, so that A may yield somewhat to the action of the muscles; ™ creasing or deducting from the weight of the body, 5° é to produce a proper equipoise during its motions, whe- ther on the earth, in the air, or in the water. The de- pressions of the outer surface of the crust, in many m stances, produce an elevation of it in the interior, 2” ; i gı so afford a useful point of attachment to certain ae This observation seems more especially applicable ® those excavations that are common to particular e or genera: thus the dorsal longitudinal channel tO met with on the prothorax of most of the Carabi of a on the inside of the crust have a corresponding ridge In Locusta Dux, also, (a Brazil locust,) the same pan has four transverse channels, corresponding with whe on the inside are as many septa, or ridges, to which mus cles are attached; and those larger impressed pan denominated puncta ordinaria, which distinguish the same part in Geotrupes and many of the Scarabaeidé ; within are elevated, so as to form a kind of einglymo” articulation with the base of the anterior coxe. other impressed puncta so often to be seen on the di” rent parts of various insects, which sometimes so intiveld cover the surface that scarcely any interval is discov?” able between them, though in many cases they appe™” “ be mere impressions that attenuate but do not perforat? the crust—yet in others, perhaps equally or more ” merous, they are real pores, which pass thr ough the e tegument. If, for instance, you take the thoracic shie! of the cockchafer (Melolontha vulgaris), and after j moving the muscle &c., hold it against the light, wit the inner side towards the eye, you will see the lig? EXTERNAL ANATOMY OF INSECTS. 399 through every puncture: or take the elytra of Geotrupes “ercorarius, or any common beetle in which these or- Sas have punctate striæ, and examine them under a s on the inside, and you will see distinctly that the Ptnctures pass through the elytrum, and the membrane that lines ita. Itis not improbable that in the case last Mentioned these pores may be of use, as the spiracles are ‘Sally closely covered by the elytra, for the better trans- Mission of the air to those respiratory organs. Whe-. ther the pores in the other parts of the body are for tanspiration, is more than I shall venture to affirm ; but "S insects sometimes perspire, at least this has been ascer- tained with respect to the hive-bee, this must be by the Means of some pores. iv. The integument of insects is often clothed, either Partially or generally, with pubescence, or hairs of vari- Ws kinds—a circumstance which seems to have more one object. In Parnas, Heterocerus, Gerris, Argy- "heta aquatica, and some other aquatic insects, the end M view seems to be to keep the water from wetting the ust; and in this case the covering of hairs is dense, ky, and decumbent. Another object is preventing tiction from being injurious: thus humble-bees, that tom their mode of nidification °, are usually more par- “ularly exposed to it, are well clothed with hair; and n those articulations of insects where much friction takes place, we may often observe a dense fringe or coating of € same substance. This you may see in the common ^ Prare XXVIII. Fic. J, 2. e Huber Nouv. Obs. ii. 317. e Vor. I. p. 502—. 400 EXTERNAL ANATOMY OF INSECTS. receives stag-beetle (Lucanus Cervus), where the thorax rece! the head; and very remarkably at the same point in the Hercules-beetle (Dynastes Hercules MacLeay): but ber sides these uses, there is probably one more univers” which will apply as well to those thinly scattered bristles and hairs, here and there one, to be noticed in many insects : but concerning this I can only throw out acon jecture, as I do not recollect ever to have seen any om periments with regard to this use of animal hairs. may they not act as conductors, either to introduc’ - some invisible fluid into the body in a positive stat gh to convey it out, when received by other means, 10 ane gative state? Every one knows that the fur of a cat be electric properties, and there may be an important gene ral use of this kind attached to the fur and hairs of ai mals. But, as I said, I give this as a mere conjectt"®’ and only wish it may excite your attention to the subje and put in exercise your natural tact for experiment M. Cuvier regards the hairs of insects as merely ® continuation of the epidermis, with which they fall whe” the animal changes its skin œ; but this will apply only ” the hairs of larvæ: for the hairs of perfect insects m many cases are implanted in a pore, and pass throug epidermis or crust to the membrane that lines it, in whic they terminate. v. We are now to consider the composition of the m tegument; under which term I would include the diffe- rent layers of which it consists, and its articulation. 2 Hair, in the Holy Scriptures, is used as the symbol of st” engh or power. Judges xvi. 17—. 1 Cor. xi. 10. > Anat. Compar, ii. 624. EXTERNAL ANATOMY OF INSECTS. 401 1. With respect to the first of these circumstances, the ers of which the integument consists, it seems to ex- Ibit Some, although not an exact, analogy with the skin, ather than the skeleton, of the vertebrate animals. In Cse last, the skin is stated to consist of four layers. these the exterior one is the epidermis, or scarf-skin: i er this is the rete mucosum, OY mucous tissue, which- Ses its colour to the skin; next follows the papillary -a formed by the saremitise of the nerves, and in a the sense of touch principally resides; the last and _ Most layer is the skin proper, or leathér, called Der- ‘a Derma, = Corium®. Two of these layers M. Cu- ty, gns to SDAP SE They have, he observes, in every > a true epidermis’; and in their state of larva he S that the infinite variety of colours that so adorn Ee them is paruo by a mucous substance ob- Sein e between the epidermis and the muscles fa this 5 analogous to the rete mucosum. To this, dried the mixed with their horny substance, he attributes also th ĉolours of the perfect insect: “for,” says he, “when €pidoptera are in the chr salis, the little coloured Stal p y S ski ‘of Mucosity similar to that which is found under the be Of the caterpillar. The colours of the Arachnida,” o i ‘ SAUS Stes On, “ are also due to this mucosity: it is disco- Which are to ornament their wings, are then ina Ve ta : ee: dy ble under the skin, and has the appearance of mi- e ; : ; ab Slandular points of which the shades vary consider- T Bat in the Coleoptera, and many other Orders, the ; Anat, Compar. i. 119. ” Ibid. ii. 540. ` Ibid, 547, » Hy, Vor 4 Ibid, 553. 402 EXTERNAL ANATOMY OF INSECTS. colours of the skin are mixed in its horny tissue, nearly ® those of the Testacea are in their calcareous shells *- the perfect insects, therefore, in most cases, we may pe sider the epidermis and rete mucosum as together for ing the exterior and coloured integument of insects that part which in the table, since it is not properly yi epidermis, I have distinguished by the name of oe derma. ; The learned author just quoted has observed nothite under the skin of white-blooded animals that he regards g analogous to nervous papille». In some parts of inset? as in the lamellæ of the antennæ of the Petalocera, a9. Bs extremities of the joints, especially the last, of many per’ there is however an appearance of them; and it seer” reasonable to suppose that where the sense of touch * y sides, there must, even in insects, be something of af : pillary tissue. 4 With regard to the innermost integument of the © tebrate animals, —the Zeather, or real skin, —this lea comparative anatomist finds nothing analogous to % it the integuments of insects °; but as he does not notic? -i he appears to have overlooked the substance that a the outer crust, or evoderma, in the Coleoptera and ye other orders. This is not always easily detected; j at’ may generally be discovered by breaking, or ratb! yo ing (not cutting), after having cleared away the nse We any part of the body of an insect. It is always very ple sible on the under side of elytra 4, but is not discov” a Anat. Compar. ii. 553. b Ibid, 557. c [bid. 560: 4 Prate XXVIII Fie. 2. œ”, EXTERNAL ANATOMY OF INSECTS. 403 re ina It appears to consist, in many cases, of se- y layers of a whitish membrane, and generally breaks fibres. In some elytra of the larger Dynastide, Wards the sides the exterior layer is separated from the ty by a kind of cellular substance: The fibrous struc- Te of this inner skin (which I call the Zsoderma) seems l eit some affinity to the skin of vertebrate animals 2. many parts of the body, however, it appears to be ho, a thin pellicle. A medical: friend, to whom I by ed Specimens of it, thinks it a kind of cellular mem- me, $ A few words are next necessary with regard to the lation of the integument, or the mode by which the N pieces of which it and its members consist, are of €d to each other. In some, as in several of the parts the 4 head, the occiput, vertexy. temples, cheeks, O ES of distinction is merely imaginary; in others an h tessed line separates a part from its neighbours, as is eoe with the nose in Vespa, &c. the head in the ty mda, But in the majority of instances ‘the parts King, Pavated by a suture, or form a real jomt. The an} of articulation observed by anatomists in vertebrate hay as do not all occur in insects, and they seem to the ‘ome peculiar to themselves. Thus, for instange, M ave no proper suture; for though they exhibit the l ance both of the harmonic and squamose (ecail- . Uv.) sutures, yet these parts being all limited by a bat Compar., ii. 557. tong o monic suture is when the margins of two flat bones simplý ach other, without any intermediate substance ; and a squa- en the thin margin of one covers that of the other. Anat. 1 124. With regard to the flat portions of the integument of 2 D2 > ar, 404 EXTERNAL ANATOMY OT INSECTS. the esoderma, or skin, above noticed as lining the ae gument, and all admitting a degree of motion more ° less intense, rather afford examples, as the case may. ? of other kinds of articulation*. Again, they have a proper Enarthrosis, or ball and socket; though the r terior coxæ of the Capricorn-beetles (Ceramby” L.) p proach very near to this kind of articulation, as W' i shown more fully in another place. The inosculat! i segments or rings, which distinguish the abdome” sometimes other parts of insects, are an example. kind of articulation not to be met with in the Fi ertebT@ The ginglymous articulation, in which the promine? j Pane the! ° io. § of the ends of two joints are mutually received by en” mary 1 cavities, and which admits only of flexion and ext often prevails in the limbs, &c. of insects ; but 12 cases the joints are merely suspended to each othe? of : ; : ; p ligament or membrane ; and, in fact, the integume she ° ° . . . e insects, with regard to its articulation, even wher of ons o! joints ginglymate, may be said in general to € ‘a yan pieces connected by the internal ligament, memb , skin that linesit; for even in the legs, where the ea ip? if mous articulation is sometimes very remarkable ; 0 complex, as will be shown to you hereafter, the J i < ay SÈ are also connected. by this substance, as you may you examine the legs of any Coleopterous insect: n insects, they have some motion; whereas a suture is an artic? without movement. did. pol a Their connexion by means of a ligament classes be ev Synneurosis (Monro On the Bones, Dr. Kirby’s edit. 29), p gno this not strictly, since a common ligament connects them*" Di of the trunk, as admitting a slight degree of motion, belo? a W” phiarthrosis (Anat. Compar. i. 126), and those of the abdome are capable of larger movements, to Diarthrosis (Ibid. 124) EXTERNAL ANATOMY OF INSECTS. 405 _ The number of articulations or pieces that form the Mtegument and its members in these animals, varies Steatly in different tribes, genera, &c. Thus, in the com- Mon louse (Pediculus humanus) they scarcely reach fifty, ile in some cockroaches (Blatta) they amount to more Han eight times that number. aving premised these observations on the external Matomy of the body in general, in the remainder of the Present letter I shall confine myself to the consideration 0 : the head and its parts. I. The Head of insects, as the principal seat of the "tgans of sensation, must be regarded in them, as well » in the vertebrate animals, as the governing part of the Ody.” It may be considered with respect to its sub- pte figure, composition, spon ficiees proportion, direc- "5 articulation with the trunk, motions—and more par~ “ular ly as to its parts and appendages. _§ With regard to its substance—the head may be said- eneral to be the hardest part of the crust: and it is for very good reasons. In the first place, as it has to , ake way for the rest of the body when the animal moves, 8 thereby best fitted to overcome such resistance as aY be opposed by the medium through which it has to ee in the next, as it bears the organs of manducation, i m requisite that it should be sufficiently firm and so- i © Support their action, which is often upon very hard . “Stances ; and besides this, as no motion of its parts a. $e, as in the case of the trunk, is requisite to fa- Utat : oaee fate the play of its organs, a thin integument was t wanted, 406 EXTERNAL ANATOMY OF INSECTS. ii. The most general law relative to the figure or shape of the head seems to be, that it should approach to that ° an equilateral triangle, with its angles rounded, and the vertex being the mouth; and that the vertical diamete should be less than the horizontal, whether longitudr” or transverse. But the infractions of this law are num“ rous and various. ‘Thus, in some insects an isosceles tri- angle is represented by the head, the length being ga than the breadth; in others, instead of being flat cy compressed, so that the horizontal diameter is less thar the vertical; in others, again, itis orbicular, or round a?” depressed; in others nearly spherical: occasionally iti rather cylindrical. In many instances it is very Jong? in others the width exceeds the length. Though ofte” narrowest before, in some cases the reverse takes place Its anterior end is often attenuated into a long or sho! snout or rostrum, and its posterior into a long oY sho! neck. Its contour, though usually regular, is sometin® either cut into lobes, or scooped out into sinuosit But to enumerate minutely all the variations of for which take place in the head of insects would be 7 less; I shall therefore proceed to the next particular. _ fot, exclusive of its organs, it consists only of a single pier ure iii. The composition of the head is very simple; ` or box, without suture or segment, with an apert the end below to receive the instruments of manducatio” 50 others for the eyes and stemmata when present, and a” 4 for the antennæ. In the Arachnida, &e., in which o head is not separated from the thorax, it is mere? plate, the under-side or cavity of which is occupied j filled by the above instruments. EXTERNAL ANATOMY OF INSECTS. 407 ly. With regard to its superficies, the head of insects 8 Senerally more or less uneven, though in some cases it Presents no inequalities. In many of the Lamellicorn tribes, and a few other individuals, in one sex at least, *S has been before observed ?, it is armed with long orms, or prominent tubercles; it is often covered with Umerous puncta, or pores; and some of its parts, as the Ose, after-nose, &c. in particular groups, marked out Yan impressed line’. In many Hymenoptera, Diptera, = its upper surface is convex, and the lower concave; M others both surfaces are convex. _ Y- Itis the most general rule, as to its proportion, that t shall be smaller than either trunk or abdomen; but in ‘ome instances, as in the S. American ant, Atta megace- bhala, it is much larger than either. : vi. By the direction of the head, I mean its inclina- lon with respect to the prothorax. The most natural lection, or that which obtains most generally, is for it ? form an angle more or less obtuse with the part just ĉntioned. This seems to obtain particularly in Coleo- Plera ; but in some, as Mylabris, it is inflexed, forming n acute angle with it. In the Heteropterous Hemiptera tmex L, &c.) it is generally in the same line with the ody, or horizontal; and in many Diptera it is vertical. Vii, We now come to a circumstance which will de- £ See above, p. 309—. ars a ie, the hornet and other wasps, this line on the inside of the Nos Urnishes a foundation for a septum, which in the sides of the € is very high, and connects also with the hind part of the head. 408 EXTERNAL ANATOMY OF INSECTS. tain us longer, namely, its articulation with the trunk; or rather with its anterior segment, the prothorat-— M. Cuvier makes two principal kinds of articulation 9 the head upon the prothorax, in one of which the po! of contact are solid, and the movement subordinate the configuration of the parts; in the other, the articular tion is ligamentous, the head and the thorax being unite and kept together by membranes. : 1. The first of these kinds of articulation—that by se contact of solid parts—takes place, he says, in four di ferent ways. ‘In the most common conformations m the part that corresponds to the neck, the head ben” one or two smooth tubercles, which receive correspo? ing cavities of the anterior part of the prothorax obs i able in the Lamellicorn and Capricorn beetles. In this case the head can move backwards, and the mouth for- wards and downwards. The second mode of solid 2* culation takes place when the posterior part of the he is rounded, and turns upon its axis in a corresponding cavity of the anterior part of the prothorax; as may j seen in Curculio, Reduvius, &c. The axis of motion ® then at the centre of articulation, and the mouth of the insect moves equally backwards and forwards, upwa” . and downwards, to right and left.—The third sort of a ticulation, by solid surfaces, takes place when the hea” truncated posteriorly, and presenting a flat surfaces j articulated, sometimes upon a tubercle of the thora® and sometimes upon another flat and corresponding aa! face, as in almost all the Hymenoptera and the majority of the Diptera. The disposition of the fourth kind ° articulation allows the head only the movement of the + 1.4 ‘ = $ fi UA id angular hinge (le seul mouvement de charnière angula EXTERNAL ANATOMY OF INSECTS. 409 The only examples at present known are in some species of Attelabus F. The head of these insects terminates ehind in a round tubercle, received in a corresponding “ity of the thorax: the lower margin of this cavity has è notch, and permits the movement of the head only in we direction 2.” 2. The second kind of articulation, the ligamentous, he affirms takes place only in orthopterous and some "europterous insects: “ The head in this kind of articula- tion js only impeded in its movements towards the back, ĉcause it is stopped there by the advance of the pro- : rax; but below it is quite free. The membranes or '$8ments extend from the circuit of the occipital cavity 0 that of the anterior part of the prothorax, which gives ` great extent to the movement °.” When I consider the well-deserved celebrity of the Steat author whose, words I have here quoted, and the Steat and useful light that the genius and learning which “Snducted his patient labours and researches have thrown Ver every department of comparative anatomy,—a sci- nce he may be almost said to have founded,—I feel the Most intire reluctance to differ in any thing from an au- rity so justly venerable to all lovers of that interesting Study, But, however great my diffidence and hesitation 9 Xpress an opinion at all opposed to his, the interests 3 truth and science require that I should state those Particulars in which my own observations, made upon a Arefu] examination of various insects of every Order, We led to results in some respects different from the ` Anat. Compar. i. 445—. v Jbid. 447. 410 EXTERNAL ANATOMY OF INSECTS. > : d above. Aliquando bonus dormitat Homerus ;? ® if the Genius of Comparative Anatomy ever nodded, H sometimes happened when he was examining the strut ture of insects. An instance of this with regard to the mouth of the bee has been noticed by Mr. SavighY 5 and indeed it is not wonderful that in so extensive ™ undertaking, in which the number of examples to be u amined upon every branch of his subject must be 1 mense, that he did not always scrutinize minutely thos? that seemed less important. Every writer on every de- partment of Natural History, especially where the ob jects of research, as in the insect world, are so infinite A number, will be liable to such mistakes; but these W meet with due allowance from every candid mind— “ Hanc veniam damus, petimusque vicissim :” and I shall express my trust that you will overlook avy errors of mine; and doubtless I shall not be free from them— EE ______— Quas aut incuria fudit, Aut humana parum cavit natura —— The two kinds of articulation of the head which ow learned author has stated as the principal ones, will, think, be found upon examination not so widely dist?” as his expressions seem to indicate; for in fact in all sects, as well as the Orthoptera, this part is suspended a membrane or ligament which unites the margins of ; occipital cavity with those of the anterior one of the P a thorax: thus forming all round some protection tot 32 7 A m“ a Mém. sur les Anim. sans Vertèbr. I. i. 11—. Comp. Anat. Co par. iii, 314—. EXTERNAL ANATOMY OF INSECTS. 411 °rgans that are transmitted from the head through the latter part to the rest of the body. Though the head in Most Orthoptera is not partly received into the cavity of the prothorax, as is the case in the Order Coleoptera, Ut is rather suspended to it, yet in some instances, for “Xample in the mole-cricket (Gryllotalpa vulgaris), it is Partially inserted. gain: when, in his frst mode of articulation by con- Bet of solid parts, he speaks of one or two smooth tu- “tecles of the neck, with their corresponding cavities in `~ Prothorax, as forming the most common conforma- Hon, you would expect to find examples of this in very many insects; yet upon a close examination, unless in "Yctes nasicornis*, and perhaps in others of the Dy- "astidæ MacLeay, you would scarcely meet with any . Qg that could be called a tubercle and its correspond- acs Cavity in the neck or prothorax of any Lamellicorn “t Capricorn beetle that you might chance to examine. u would find, indeed, that the occiput was usually Xooth and very slippery, as if lubricated; that in its gin were one or two notches (Myoglyphides), with Muscles attached to them; that in the former of these 8s, the Lamellicorns, it projected on each side so as to vem a more or less prominent angle; and that the throat JUgulum) was very convex, and lodged ima cavity of the woe margin of the prothorax: but further appearances a tubercles &c. you would in vain look for even in this arti Itis probable that M. Cuvier took his idea of this first kind of sation, by contact of solid parts, from this individual insect; ĉe, besides its very prominent throat, there is on each side of the lo ka Part of the occipùt a small elevation, or approach to a tu- le; 412 EXTERNAL ANATOMY OF INSECTS. tribe; and in the Capricorns you would find that the 8° neral conformation in this respect belonged to our Jearne author’s second mode of solid articulation, resembling in which Dri g the head has no projecting angles or tubercles, oF othe r cavity that of the majority of the weevils (Curculio L.), elevation, but is received usually into the circula of the prothorax. His third mode of this articulation, that of the Hymen ptera and Diptera, is so peculiar, thatit ought to be e sidered as a primary kind; since in this the head mover upon the prothorax as upon a pivot, and has a kind ° versatile motion. With regard to his fourth mode, which from bis a scription appears to be that of Apoderus Oliv., he allow motion to the head only in one direction, observing tha the lower margin of the prothoracic cavity has a note £ But M. Latreille calls the articulation of the head 1 thi genus an Enarthrosis*, which admits motion in every & rection; and if you examine the common species (A. ryli), you will find that the prothorax has a sinus take out of its upper margin, as well as out of its lower one” which at any rate will allow a motion upwards. I merely mention these little inaccuracies, with du” diffidence, as some apology for giving you a different e at least a more popular and general view of this part f my subject, which I shall now proceed to state tO a It seems to me most convenient for the Entomologist, ™ most consonant to nature, to divide insects, with respe? to the articulation of the head with the trunk, into thre? . Ek ps = wir primary sections, each admitting one or more subd! sions. * Gen. des Crustac. et Ins. ii. 246. Regne Anim. ti. 325. EXTERNAL ANATOMY OF INSECTS. 413 l. The frst consists of those whose head inosculates more or less in the anterior cavity of the chest; and Whose articulation, therefore, seems to partake in a greater oF less degree of the ball and socket (Enarthrosis). ‘The ead, however, is often capable of being protruded from this cavity. If you take into your hand any common Har- Palus that you may find under a stone, you will see, if Pressed, that it can shoot forth its head, so as to be en- tirely disengaged from the prothorax: a neck of ligament Mtervening between them?: of course this power of pro- tuding the head enables the animal to disengage it at its Will from the restriction imposed upon its motions by the Surrounding margin of the prothoracic cavity. To this Section belong all the Coleoptera, the Heteropterous He- Mipterg (Cimex L., &c.), and some of the Neuroptera ( Ra- Phidia, Semblis, &c.).—It may be further divided into two Subsections—those, namely, whose head inosculates in the prothorax by: means of a neck: as for instance La- teles Tyachelides, Apoderus, and the Staphylinde, Amongst the beetles; the Reduviade amongst the Hete- “Opterous insects, and Raphidia in the Neuroptera ; and ose whose head inosculates in the prothorax without the intervention of a neck; as, the Petalocera, the aqua- tic beetles (Dytiscus, Hydrophilus, &c.), and most of the Senus Curculio L. in the first of these orders, the great dy of the Cimicide in the second, and Semblis, Cory- dalis, 8e, in the third. 2. The second section consists of those insects. whose ead does not inosculate in the chest, but is merely sus- 4 * This was written directly after the experiment recommended in 1e text had been tried, with the result there stated. ALA EXTERNAL ANATOMY OF INSECTS. pended to it by ligament or membrane. To this belong most of the tribes of the Orthoptera Order, with the €% ception of the Mantide, the Dermaptera, the Homo- pterous Hemiptera, and such of the Aptera as have the head distinct from the prothorax.—This section admits of a ¿riple subdivision: those, namely, whose head i wholly covered by the shield of the prothorax, as yi Blatta L.; those whose head is partly covered by it, ® Gryllotalpa, and other Gryllina; and those whose head is quite free, not being at all impeded in its motion by the prothorax, as the Dermaptera, Nirmus, Pedic lus, &c. 8. The third section consists of those whose head ® truncated posteriorly, and flat or concave, with a vety small occipital aperture, and is attached to a neck of thé prothorax upon which it turns, or is merely suspende to that part. This includes the Lepidoptera, Hymen” ptera, Diptera, the Libellulina, &c. in the Neuropter™ and the Mantide in the Orthoptera. Three subsectio®® at least, if not more, present themselves in this sectio?‘ the first is, of those whose head is united to the prothe- rax, without the latter forming any neck. To this beloPs the Lepidoptera, Trichoptera? The second is of thos the upper side of whose thoracic neck is ligamentous and here you may range most of the Hymenoptera. Te third is. of those in whom it is a continuation of the ord nary integument. In this subsection the Diptera, Libel ‘ lulina and Mantide will find their place. In this last section the head appears to turn upon the thorax as up a pivot. Before I finish what I have to say on the articulation of the head, I must direct your attention to the analo- EXTERNAL ANATOMY OF INSECTS. 415 Stes that hold in this respect between the different tribes. hus the Coleoptera are analogous to the Heteropterous emiptera; the Orthoptera, with the exception of the antide, tothe Homopterous Hemiptera; the Mantide tò the Libellulina; the Lepidoptera to the Trichoptera ; the Hymenoptera to the Diptera, with a slight variation, and probably others might be traced; vii. A word or two upon the motions of which the fad of insects-is capable. M. Cuvier, in the extracts ately laid before you, speaks of different powers of move- Ment as the result of different configurations of the parts the head. This probably is correct with regard to Many cases ; but a great deal will depend upon the power ae insect has of protruding its head and disengaging ve base from the restriction of the prothorax; for where, like the Harpali, Staphylini, &c. it is able to do this, it m probably move its head in every direction. It is nly where the ligaments are less elastic, or allow of lit- € tension, that its movements are confined; and few Ving : ving insects have been sufficiently examined to ascer- ain how far this takes place. In those cases belonging to the third section of articulations, in which the head Moves upon the thorax as upon a pivot, as is the case With Hymenoptera and Diptera, the movement is nearly Versatile. I have seen a fly turn its head completely “ound, so that the mouth became supine and the vertex Prone; and from the form and fixing of the head, it : ould seem that those of the Mantide were endued With the same faculty. ix. The parts and appendages of the head are now in 416 EXTERNAL ANATOMY OF INSECTS. the last place to be considered. I shall begin with the Mouth, or rather the orifice in which the trophi or orga of manducation are inserted. In some insects, as was bee fore observed, they occupy all the under-side of the head, as in the Arachnida, Myriapoda, &c.; but in the great majority they fill an orifice in its anterior part, which ‘a some instances, as in Lampyris, the Lepidoptera, Cr mex L., Truxalis, appears to be nearly under the hea i but in general it terminates that part, though it exte” ‘ further below than above. In Chermes, a Homoptero”” genus, the promuscisis stated to be in the Antepectus, consequently the mouth ; but, as I shall endeavour to prove to you hereafter, this is a fallacy. In the males of the species of Coccus there is no mouth at all. In that of the elm (C. Ulmi) in lieu there are ten little shining point arranged two before and two behind in a line, and tht on each side ina triangle*. It is to be observed that the orifice of which I am speaking is usually much smalle" in those insects which take their food by suction, tbe Hemiptera, Lepidoptera, Diptera, &c., than in the P” ticating tribes. With regard to the real mouth, or that through which the food enters, I have nothing at preset to observé, except that it lies between the upper-lip a tongue, 1s sometimes covered by a valve, as in Ap eas : i Vespa’, &c., and is different in the masticators ™ suckers. ; 3 ; ae . they I shall next offer a few observations seriatim, aS the) : jos stand in the Table, upon the organs of manducat! which, to avoid circumlocution, instead of Instrumen 4 Reaum. iv. 40. Latreille Fourmis, 328-—. & Prare VIL F16 2k EXTERNAL ANATOMY OF INSECTS. 417 e . oi the name Fabricius gave them, : shall call ¢rophi ers. It is upon these parts, you are aware, that . "System of the celebrated Entomologist just mentioned unded ; and could they always, or even for the most "tt, be inspected with ease, they would no doubt afford i as various and discriminative as those of the “orate animals. Differences in these parts indicate. ference in the mode in which the animal takes its x ~Y often in the kind of food, and sometimes in its o pepiomy and habits,—circumstances which are i tfal and weighty in supporting the claim of any set Mimals to be considered as forming a natural genus Soup, Trifling variations, however, of these parts, i X Supported by other characters and qualities, ought Sry have much stress laid upon them, since, if we in- be e these, in some tribes almost every species might ade a genus. have « respect to their ¢ropfz in gt insgets of late w, en divided into two great tribes *, mastzcators and “rss the first including those that are furnished with isty ; ah Aments to separate and masticate their food; namely, tn YPper- and under-lip (lalrum and labium), upper- and b t-jaws (mandibulæ and maxillæ), labial and maxil- y palpi, and a tongue (lingua): and the second those at lch these parts are replaced by an articulate or ex- lc a ulate machine, consisting of several parts and pieces gous to the above, which pierce the food of the ani- ‘i and form a tube by which it sucks its juices. If, ey, 4 sey eS 5 Yer, the mode in which insects take their food be a Clairy; l Classe fe (Ent. Helvet. i. 44) appears to have been the first whe "sects according to their mode of taking their food. y OL, II, 2E 418 EXTERNAL ANATOMY OF INSECTS. strictly considered; it will be found that in this view pe? ought rather to be regarded as forming three tribes; ff the great majority of the Hymenoptera order, and pe haps some others, though furnished with mandibles ® maxillee, never ‘use them for mastication, but really f their food with their tongue: these, therefore, might denominated lappers. “When a mouth is furnished with the seven ordinal organs used in taking the food and preparing it for 2 elutition—I mean the upper-lip and the two upper sy the under-lip and the two under-jaws, including the a bial and maxillary palpi; and the tongue—I denom™ F “is . : e it a perfect mouth; but when it is deficient in any oft is organs, or they exist merely as rudiments, or when t à ; 2 2 ° 7 na place is supplied by others, (which, though they ® y p analogous parts, have little or no connection with t e re in their use or structure,) I denominate it an amp in mouth. This last I would further distinguish, acco! we to the- nature of its trophz, by other and more disti”? terms, as Í shall presently explain to you. e 1. Labrum*.—I shall first consider the orga” n sent ina perfect mouth, beginning with the upper-UP nO brum). This part, which Fabricius sometimes CO? 3 w ed with the nose, miscalling it clypeus, is usually * a ip able? piece, attached by its base to the anterior ie d of the part last named, and covering the mouth p ‘sometimes the mandibles, from above. In inset nit their last state it is usually of a horny or shelly subsi@ pi yet in some cases, as in Copris and Cetonia, beetle a Puare VI. VIL. XXVI. x. de” j r eY b In Lucanus, Lamprina, &e. the labrum seems to form ; side of the nose, and to be connate with it. EXTERNAL ANATOMY OF INSECTS. 419 i Ae e o on - Re 3 F piaz y k Mbibe Juices, it is membranous. In form and shape it aieg greatly, being ‘sometimes nearly square, at others “ost round; in some insects representing a parallelo- stam, in others a triangle, and in many it is oblong. In ‘ome lastances it is long and narrow, but more generally ort and wide. It is often large, but occasionally very Ute, In the majority it has an intire margin, but it is * Seldom emarginate or bilobed, or even dentate. Its. “face is commonly even, but it is sometimes uneven, metimes flat, at others convex, and in a few species med With ashort horn or tubercle?. As to its pubescence, % Often naked, but now and then fringed or clothed ie down or hairs, or sprinkled ss bristles. It con- *t almost every instance of a single piece; but an n “Ption to this occurs in Halictus, a little bee; iti “the ales of which it is furnished with a slender appen- ‘a >The direction of the upper-lip is various. Itiis ely horizontal, or in the same line with the nose, often *tieal ; it sometimes forms an obtuse angle with the p tior partof the head, and occasionally an acute one, à it is more or less inflexed; ‘Fhé:xse-of this part is „arily to close the mouth from above, to assist in re- N ing the food while undergoing the process of masti- “HON ; but in many Hymenoptereus insects its:principal in, Seems to. be, ‘to-keep the trophz properly folded zand Em cases where it is cnfiesees 8 in the leaf-cutter diy) (Megachile Latr.), to defend its ones wile the man- es are employed, from injury by their action €. 1 Bey Mon. Ap, Angli. t.v. Apis *. b. f. 18. b. ep ell. Melitia.**..b. f. 4,5. Prate XXVI. Fre. 30. fig ‘Se XXVI. Fic. 31. Mon. Ap. Angli. t. x. Apis **.c. 2.3, pgs A 420 EXTERNAL ANATOMY OF INSECTS. ad Op” 2, Labium®:—On the under-side of the head, % be thet posed to the upper-lip, the mouth is closed by an° ure and aii moveable organ, concerning the nomenclat sideraDlY’ _logies of which Entomologists have differed con At the first view of it, this organ seems a ver plex machine, since the under-jaws or maxille aà f tached to it on each side, and the tongue is often seei emerge from it above, so as to appear merely a part oP art y con re at % a but as the former answer to the upper-jaws, and the y i ame ter is the analogue of the part bearing the same n% ; stin“ the vertebrate animals, I shall consider these as di ; and primary organs, and treat of the under-lip (labi of which I am now speaking, by itself, Linné take y notice of this part, but his illustrious compatriot and temporary, De Geer, did not so overlook it: he app? to consider the whole apparatus, including the mare i as the Zabium?; but sometimes he distinguishes the mt dle piece by that name °; and the tongue, in the cas? . ; ype) | the stag-beetle, he denominates a proboscis (tromp ; 3 ip In the Hymenoptera he calls this part tongue, unde! i i ca and proboscis: but seems to prefer the last term”: 4 lod bricius originally regarded the whole middle piec®? ‘ a labium f; but afterwards (though his definition is n° . > B. curate, since he assigns the palpi to the ligula, which á s0 affirms is covered by the labium—circumstances by d ; : +. ag o means universal in Coleoptera) he considers this as J + at : = 3 - yar sisting of ligula and labium®. Latreille at first reg? 2 Prates VI. VII. and XXVI. b. b De Geer iv. 124. ¢. iv. f. 12 iii. 415. t. xxi. f. 4. e Ibid: iv. 281—. t. xi. f. 7. @ Ibid. 329. 4. xii. f3 e Ibid. i: 775-- t. xxvi. f. lO bebe. y £ Philos. Entom, 18. & Syst, Eleuth. i. præf 1 EXTERNAL ANATOMY OF INSECTS. 4.2] the ligula of Fabricius as the labium, and called the la- co of that author the mentum; but afterwards he gave ° name of labium to the whole middle piece of the ie Touria of the serous the upper piece, k abricius, the ligula, and retaining the denomina- of mentum for the lower ?. : the circumstances of the case are duly considered, “he you will be convinced that the term under-lip, B abium, should be confined to that part which the med Dane so named. For I would ask, Which is i Part on the under side of the head that is the anta- L> if I may so speak, of the upper-lip or labrum ? t not that organ which, when the mouth is closed, “ets that part, and in conjunction with it shuts all in? W in numerous insects, particularly the Lamellicorn Cage €s (Scarabeus and Lucanus L.), this is precisely the ; ` Inthe Predaceous beetles, indeed, (Cicindela, Ca- “sS; Dytiscus L. &c.) the under-lip does not meet the Per, to close the mouth and shut in the tongue; nei- a fan the tongue be said so to do, but only, from some - 2 mstances connected with its manner of taking its > It is requisite that the last-mentioned organ should a retractile or covered; but its miscalled mentum N the analogue of Ga part which helps to close the Y ba in the former tribe. Should oe — therefore, ain So often performs the a be distinguished by the A of a lip? Again, is it not rather incongruous to Bin. €r that organ which confessedly more‘or less per- it ofte the office of a tongue, as a part of the lip? Though N wears that appearance, yet I believe, if the mat- a ‘ G 7 Cn. Crustac. et Ins.i.180. > N. Dict. d Hist. Nat. iv. 246. 4.29 EXTERNAL ANATOMY OF INSECTS. ter is thoroughly and patiently investigated, it will pe found that.on their.upper side its roots are: attached to the interior of the upper side of the head, as well as 02 pr lower: side: to the Zabium; so. that it may be regarded ? common-to the two lips,: and: therefore not properly i sidered as an appendage of the under-lip alone. r Having assigned my reasons for preferring the pe given.to the part in question by Fabricius, r rather t? ig that of: Latreille, I shall next make my observations © ale the part itself. In many cases the Jabium, or the. mi piece of the lower oral apparatus, appears to consist ® two joints: this you may see in the great water-bee ž (Hydrophilus piceus), the burying-beetles (Necrophor” ; the Orthopterous tribes *, the Hymenoptera», and othe In this case the upper or terminal piece is to be reg arc as the labium, and, the lower or basal one (which MacLeay calls the stipes) as the mentum or chin” other times, .as-in some Lamellicorn beétles, the only zi de paration-is.a transverse elevated line, or an obtuse ane by formed. by the meeting of the two parts, and: very ie quently there is-no separation at all, :in which case whole.piece,. the mentum merging in it, may be genon nated the labium, . wii n K With respect to'its substance, the labium in most leopterous insects. is hard and horny, in Necrophorts is membranous, and‘ the mentum harder; Im prio coriarius, our largest Capricorn-beetle, “bothĘsat® : pe af branous; in the bee-tribes, Apis L.y the labium Y yat 7 resembles leather, while the: mentum is hard, Its sw is often convex, sometimes plane, and sometimes ° "i A f : R; e @ Prats VI, Fic. 6. paat b Prare VH. Fic. 3. b EXTERNAL ANATOMY OF INSECTS. 4.23 c ; = ‘ cave; as for instance in Melolontha Fullo, a rare chafer occasionally found on the coast of Kent. In some AS Covered with excavated points; in others it is quite Mooth, „In numbers, ‘as. in the Predaceous beetles, both Wium and mentum are perfectly. naked ; in others, as in € common cockchafer, they are hairy; in Geniates bar- us Kirby, another chafer in the ‘male insect, the Ja- um is naked, while the mentum, which forms a piece ‘tinct from that part, is covered with a dense rigid “arda, In shape the whole labium varies considerably, Much more than the labrum; for in addition to most of 1 forms I enumerated when I described that organ, ich I shall not here repeat, you may meet with exam- = of many othe: Thus, to instance in the Petalocerous Mibes (Scarabceus L.), in’ some, as in the Rutelide, thè “ium is urceolate, or representing in some degree the “Rape of a pitcher®; in others it is deeply concave, ‘and “La little resembles a basin or a bowl‘; this form is ĉculiar to the labium of Cremastocheilus Knoch, asearce rth American beetle; in another related. to this, but Han African type (Genuchus Kirby MS. -Cetonta cru- Miq E), it is a trapezoid plate, which is elevated from the head, and hangs over the throat, like a chin 4; In the Ymenoptera it is extremely narrow and long, and em- taces the sides of the tongue, as well as covering it from Po W; so that it wears the appearance.of a kind of tube ®. ĉnerally speaking, the length of the labium exceeds its *eadth ; but in the Predaceous beetles the reverse of : Kirby Linn. Trans. xii. t. xxi. f. 8.f- . bid. z, xxi. f. 10. d.. MacLeay Hor. Entomol. i. t. iii. f. 26,27. a ATE XXVI; Fic. -35. d` Ibid. Fie. 34. Lave VH, Fic. 3. bs 24 EXTERNAL ANATOMY OF INSECTS. this takes place, it being very short and wide, and wst ally terminating towards the tongue in three lobes 0 teeth which form two sinuses varying in depth *. The mentum taken by itself affords no very striking characters to which I need call your attention : J sha only observe, that in Hymenoptera it is generally of? triangular shape’; but before I proceed to consider the labial palpi, it will be proper to notice the remarkabl? labium of Orthopterous insects, and of the Libellulin® between which there is no little analogy. At first pe would imagine the terminal part of this organ in the for- mer to be the analogue of the tongue, or ligula Fa if is indeed generally regarded by modern Entomologis® * It seems, like the tongue of the Carabi L., Dytisci, ® J be a distinct piece, which has below it both labium er mentum; but when you look within the mouth, you wil find a linguiform organ 4, which evidently acts the s of a tongue, and therefore ought to have the name; ap the piece just alluded to must either be regarded 4° ; termination of the lip, or as an external accompani™ e of the tongue, analogous, it may be, to the paragloss@ g bees®. In a specimen of Acrida viridissima (Locust F) which I dissected, the tongue is as long as the app” dage of the under-lip, and by its upper surface see” to apply closely to it. In the Libellulina a similar org” is discoverable f, which on its upper-side terminates f the pharyna, like that of one of the Harpalide b° p mentioned. In the Orthoptera, therefore, I regard f labium as consisting of three articulations, the upper ° a PLATE XXVI. Fie. 24, hes b PLATE VII. FIG- F a © N. Dict. @ Hist. Nat. xxiv, 171. è Prare VI. Fra. 6 €; °” Prate VI. Fre. 3.1”. f Prare VI. Fic. 1% ©* EXTERNAL ANATOMY OF INSECTS. 425 divided into two, three, or more lobes*; the intermediate ne more directly answering to the labium of other in- ‘ects, and the basal one or mentum. This organ in the ellulina is of a different structure: it has only two articulations representing labium and mentum; but the mer consists of three parallel pieces, the two exterior Mes rising higher than the intermediate one, and at their ther angle having an acute sinus from which the palpi Merse: and the intermediate piece, which is longitudi- nally channelled, lapping over the inner side of the lateral Pieces, < From the angle of the covered part of these Pieces, a subulate short horizontal horn points inwards wards the tongue, which it must keep from closing Mith the labium?. 3. Palpi Labiales *.—The last-mentioned organs, the bial palpi, next claim our attention ; but before I advert Particularly to them, it will be proper to premise a few Words upon palpi, or feelers, in general, These are usual- Y jointed moveable organs, of a corneous or coriaceous. “Ubstance, attached by ligaments to the labium and Maril e, and in the Crustacea even to the mandibule. eir joints, which are usually more or less obconical, E ilac ‘also in eachother by ligaments, with perhaps ‘ome little mixture of the ball and socket. Their ends, Ne last joint especially, seem furnished with nervous Papille which indicate some peculiar sense, of which they “te the instrument. What that sense is has not been “early ascertained, and concerning which I shall enter re into detail in another place. - Their motion seems * Prave VI. Fie. 6. b'. b pid. Fre. 12. b”, * Prares VI. VI. XXVI b”. 4.26 EXTERNAL ANATOMY OF INSECTS. : ; ee ds restrained, at least in some, to two directions, towalt and fromthe mouth. They were called palpi or feele because the insect has been supposed to use them ine% ploring substances. There seem to be no organs in ie vertebrate animals directly analogous to the palpi of 5 sects and Crustacea, unless, perhaps, the cirri that emerge from the lips of some fishes, as the cod, red mullet, & which Linné defines as used in exploring (preetentamer Whether the vibrisse, miscalled smellers, of some quadt U5 peds and birds have any reference to them, I will not venture to affirm; but the feline tribe evidently use the bristles as explorers, and they are planted chiefly inh r5) vicinity of the mouth. Having made these general remarks, I shall now cone fine myself to the labial palpi. I call them labial palp 4 because that term is in general use, and becausein map cases they really do emerge from, what I consider a5 $ labium, as in most of the chafers; but they might wit equal propriety be denominated lingual palpi, since Cy sometimes appear to emerge from the tongue (as yt stag-beetle ( Lucanus Cervus). In some instances, *° the Predaceous beetles, they seem to be common to be p labium and tongue, being attached m their base 0 p upper side to the former, and on the under side t° $ latter. As to their situation: they emerge from the ba of the labium in the locusts (Locusta Leach) *; fro. i middle in Hister maximus’; from its summit in AA rus MacLeayt; and from its lateral: margin in Dy n tes MacLeay, &c. They, consist , of from one, tO fos * Prare VI. Fig, 6. b”. > Hor, Entomolog, is t. if. 18 c [eid Cf 18.8. EXTERNAL ANATOMY OF INSECTS. | AQT 1 Joints ; which, I believe, they never exceed. They vary in length ; though generally shorter than the maxillary palpi, yet in the ferocious tiger-beetles (Cicindela: L.) €y equal them in length; and in the hive-bee and hum- le-bees, and many other bees, they- are considerably Snger 4, The two first joints of these palpi, however, U these Jees are different in their structure from the two ast, being compressed and flat, or concave; and the two ast joints, instead of articulating with the apex of the ‘cond, emerge from it below the apex: so that these two first joints seem rather elevators of the palpi than Pally parts of them». With respect to the relative pro- Portions of their joints to each other: in some cases the tst joint is the longest and thickest, the rest growing Stadually shorter and smaller €; in others, the second is e longest4; in others, again, the third, and sometimes 7 €lastf; and often all are nearly of the same size and ‘igths, They are more commonly naked, but some- times either generally or partially hairy. Thus in Cicin- dela, the last joint but one is usually planted with long ‘how-white bristles ina double series, while the rest of € joints have none; and in Copris Latr. all of them are “Xtremely hairy. In shape they do not vary so much as © maxillary palpi, being most frequently filiform or ‘ubclayate, and sometimes setaceous; the last joint varies Nore in shape than the rest, and is often remarkably * Kirby Mon. Ap. Angl. i. t, xii. neut. f. 1. g. c Ibid. 93, 103—. t. vi. Apis **. b. f. 3. bc. ° Ibid. t.i *. a. fa B: b. a [bid. tix. Apis **. 0.2. yf. 3. 5. * Clairv, Ent. Helveteii. t. xxiv. f. lc. , Prare KXVI Fic. 24,28.b". | * Mon, Ap. Angl i. t. ti. Melitta **. b.f. 2. ce EXTERNAL ANATOMY OF INSECTS. large, triangular, and shaped like the head of a hatchet and at others it resembles the moon in her first quar ter>, In the great dragon-fly, or demoiselle if you pre fer the gentler French name (Æshna F.) the labial palp” which are without any visible joints, are terminated by j minute mucro or point®. With regard to their direction and flexure, they frequently, as in the instance just men- tioned, turn towards each other, and lie horizontally up" the end of the labium. Sometimes, as in the Cicindelid@ they appear to point towards the tail of the insect, the las? _ joint rising, and forming an angle with the rest of the feeler. In other instances they diverge laterally from He labium, the last joint turning again towards it at 4 very obtuse angle. 4. Mandibulæt.— Having considered the analogues s the Zips in our little beings, I must next call your atten” tion to the representatives of the yaws. The vertebral? animals, you know, are mostly furnished with a sing” pair ofjaws, one above and the other below, in which th? teeth are planted and which have a vertical motion. But insects are furnished with ¢wo pair of jaws, a pai" i upper-jaws and a pair of under-jaws, which havè ” teeth planted in them, and the motion of which is hor” zontal, shall begin with an account of the upper-jav” These by modern Entomologists, after Fabricius, ar? i a Prare XII. Fic. 2. Linn. Trans. xii. t. xxi. f. 6. 6. » This is the case with Oxyporus F. Prats XIII. Fre. 4. ¢ Prare VI. Fre. 12. b”. Latreille, N. Dict. d’ Hist. Nat- _ 545, seems not to regard these as palpi; but from their tubular and insertion in the socket of the labium, it is clear that they ous to be so considered. è Prares VI. VIL XXVI € xvii. for™: t EXTERNAL ANATOMY OF INSECTS. 429 nominated mandibles (mandibule): a term appropriated - by Linné to the beaks of birds. The upper-jaws of in- “ects this great naturalist named maxil/e@—and not im- Properly, since the office of mastication is more pecu- liarly their office than that of the under-jaws, which Fa- ricius has distinguished by that name: as the term man- ible, however, is generally adopted, I shall not attempt to disturb it. The mandibles close the mouth on each side under the Arum or upper-lip. They are generally powerful or- Sas, of a hard substance like horn; but in the Lamellicorn Setles of Mr. MacLeay’s families of Scarabeide and Ce- toniade, they are soft, membranous, and unapt for masti- “ation, In Coleopterous insects they commonly articulate Mith the head by means of certain apophyses or processes, of Which in many cases there are three discoverable at i € exterior base of the mandibles; one, namely, at each mele, and one in the middle. That on the lower side is "Sually the most prominent, and wears the appearance y the condyle ofa bone: it is received by a correspond- Hg deep socket (or cotyloid cavity) of the cheek, in hich, being perfectly smooth and lubricous, it moves eadily, but without synovia, like a rotula in its aceta- tlum, The upper one projects from the jaw, forms the Segment of a circle, and is concave also on its inner “ce, A corresponding more shallow, or, as anatomists ‘Peak, glenoid cavity of the cheek, where it meets the *Pper-lip, receives it, and the concave part admits a lubri- Cous ball projecting from the cheek, upon which it turns?*. a : “re th; A corresponding articulation takes place between the tibia and igh of some of the Scarabeide, which will be hereafter described. ° Phare XXVIL Fic. 8—11. A3O EXTERNAL ANATOMY OF INSECTS. This structure you will find in the stag-beetle, and some other timber-devourers.’ Other Coleoptera have only # process of a similar structure at each of the dorsal angles of the base of the mandible, the intermediate one being wanting; and the articulation does: not materially differ as far as I have examined them, in the Hymenoptera ™ Neuroptera. In the Orthoptera, the structure approache’ more nearly tọ that of the stag-beetle, since there ai three prominences: it is thus well described by M. Mar- cel de Serres: This articulation,” says he, ‘takes place in'¢two ways. At first, in the upper surface of the ma” dible, and at its base, may be observed two small prom nences and a glenoid cavity; these prominences are 1% ceived in two glenoid cavities excavated in the shell 0 the front, as the cavity of the mandible receives a s»? prominence of the same part. Below the mandible, 9” at its base, there is a kind of condyle, which has its PY in a cotyloid cavity excavated in the shell of the templ? far below the eye, and at the extremity of the coriaceo™ integument of the head *.” Within the head in this 0 der, at least in Locusta Leach, is a vertical septum whic! divides the head into two chambers, as it were, an 0° i ; RET - an pital and à frontal, consisting of a concave triang™’ stem, terminating in two narrower concave triangul’ branches, so as to resemble the letter Y, and formi” three openings, an upper triangular one, and two late? subquadrangular ones, which last are the cavities that 1% ceive the base of the mandibles. This partition, whic would name Cephalophragma, doubtless affords a po r attachment to many of the muscles of the head. It doe? ° x Q; a Comparaison des Organes de la Mastication des Orthoptere® * EXTERNAL ANATOMY OF INSECTS. 431 Not’ appear to have been noticed, unless it be synonymous with the zntermaxillary arcade of Marcel de Serres?. tobably a corresponding support to the muscles, &e. May exist, as we have seen it does in /% espa L.?, in many other heads of the different Orders, which have not yet N under examination. Many mandibles, as those of te hornet &c., appear to be suspended to the cavity of the head on the inside by a marginal ligament suffi- “ently relaxed to admit of their play: those of the Or- Optera, M. Marcel de Serres informs us, are united to € head by means of two cartilages, the outermost being Much the shortest, to which their moving muscles are tached. These he considers as prolongations of the “thstance of the mandible *. The bottom of mandibles, en cleared of the muscles &c., inclines almost univer- Sally to a triangular form; but in some cases, as in the ee beetle, it is nearly a trapezium. I cannot conclude is subject without noticing the motions of the mandi- les, What the author lately quoted has said with re- Sard to those of the Orthoptera, will, I believe, apply “qually well to all the mandibulate orders. * The arti- “lation of mandibles with the skull appears to take place -J two points solely; and as these parts only execute Movements limited to a certain direction, they may be teferred to ginglymus *.—The movements of mandibles ate Miaa to those from within outwards, and from Without inwards *.” Whether they are restricted from oe degree of vertical motion, has not yet been proved, S the jaws of vertebrate animals move horizontally as a i n Comparaison des Organes de la Mastication des Orthoptères, 2. ‘See above, p. 407. noteb: © Ubisupra, 4. è Ibid. ° Ibid. 5 4.39 EXTERNAL ANATOMY OF INSECTS. well as vertically—so those of insects may have some motion vertically as well as horizontally; and it seem necessary for some of their operations that they should: I am not anatomist enough to speak with confidence w the subject, but the ball and socket articulation at m lower part of the mandible, and the curving one at the upper, though a kind of ginglymus, seems to imply 4 de- gree of rotatory movement, however slight. e of I must next say something upon the general shap these organs. . Almost universally they incline to # 2 | quetrous or three-sided figure, with their external su face convex, sometimes partially so, and their intern? concave. Most frequently they are arched, curving wi wards; but sometimes, as in Prionus octangularis*, ? pricorn beetle, and others of that genus, they are nea) straight; and in Rhina barbirostris *, a most remarkabi? Brazilian weevil, their curvature is outwards. In P hol dotus lepidotus MacLeay, and Lucanus Elephas, tW° K sects of the stag-beetle tribe, they are bent downwat?’ and in Lucanus nebulosus K. (Ryssonotus MacLeay) they turn upwards. They are usually widest at the base and grow gradually more slender to the apex, but i» une hornet (Vespa Crabro) the reverse takes place, and thet increase in width from the base to the apex; and in A hive-bee, and others of that tribe, they are dilated y at base and apex, being narrowest in the middle; othe i hos? are nearly of the same width every where. Int i . > p Bar ose insects. that use their mandibles principally for purp d . > yor connected with their economy, they are often more b a Oliv. Ins. no. 66. Prionus. t. xii. f. 54. » Tid. no. 83. Curculio. t. iv. f. 37. © Linn. Trans. xii, te xxi. f. 12. EXTERNAL ANATOMY OF INSECTS. 43S ; EEE ; 3 Proportion to their thickness, than they are in those lch use them principally for mastication. In the lo- SSO à E tribes (Locusta Leach), they are extremely thick ag Powerful organs, and fitted for their work of devas- tion; } `] ut in the glow-worm (Lampyris), they are very ender a nd minute. In those brilliant beetles, the Bu- Stes, they are very short; but in the stag-beetles, and Ose giants in the Capricorn tribe, the Prionz, they are “4 very long*. ‘They either meet at the summit, lap Vv x * each other, cross each other, or are protended i ight from the head; as you have doubtless observed t $ € stag-beetle, whose terrific horns are ee ee of b description, These organs are usually symmetrical, : m some instances they are not: thus in Hister levus, hy of dung-beetle, the asi hand inetidibie is longer ln, the right; in Creophilus eee de K (Staphy- . E, a common rove-beetle, in the left hand man- € the tooth in the middle is bifid, and in the right One intire; and in Bolbocerus K. the mandible of à ; side, in some species the dexter, and in others the ster, has two teeth, and the other none. hich Next circumstance vun BENS to re ana th demands our attention, is the zeeth with which § Y are armed. These are merely processes of the sub- a of the mandible, and not planed in it by PRIOR > 3S anatomists speak, as they are in vertebrate ani- a They have, however, in their interior, at the base a TA Mandibles of Locusta see Piate VI. Frc. 6. c. of Limupyris Luc, as. No. 28. z, i. f. 1. of Buprestis, Ibid. no. 32. t. iii. f. DOr b s, Ibid. no. 1. £. i—v. and of Prionus, Ibid. no. 66. t. iif. 8. thaj ; Mphosis is, when one bone is immoveably fixed in another as Ma board, 0 L, ‘eke 2 F 434 EXTERNAL ANATOMY OF INSECTS. at least, in the Orthopter a, a coriaceous lamina that ° parates them in some sort from the body of the mand ble*. Many insects, however, have mandibles with? teeth; some merely tapering to a sharp point, others s tuse at the end, and others truncated®. Of those im have teeth, some have them on the inside at the bas, Manticora, an African tiger-beetle *; others in hemi dle, as Staphylinus olens, a rove-beetle, Lethrus cep” r lotes, &c.4; others at the end, as many weevils (Cs lio L.)*; others again on the back, as the Rutelida@, ^" es of chafers oe and Lethr ti beetle just named r ofa tooth or spine, as in Melitia spinigera, a wild-bee, and some of its affinities 5; and lastly, on the upper side of the base in the form of a = i nil tuous horn, as in that singular wasp Synagris cor : before noticed as a sexual character". In the tet g beetle tribes ( Lucanus L.) these teeth are often elong of into short lateral branches, or a terminal fork. oi are sometimes truncated, sometimes obtuse, and 5° times acute. ado of But with regard to their kind, it will be best t° f ye the ideas of M. Marcel de Serres; for though Fe marks are confined to the Orthoptera, they may Pe plied with advantage to the teeth that arm a the mand? 2 Marcel de Serres ubi supra. 7. aif 13 b See Prate XIII. Fic. 7. Kirby Mon. Ap. Angl. i. t a: and ¢. xii. neut. f. 10. c Prare XXVI. Fie. 19. a Oliv. Ins. no. 42. t. i. f. 1. and no. 2. t. ie b. e Prare XXVI. Fic. 16, 18. f Ibid. Fic: ?} € Mon. Ap. Angl. i. t. iv. Melitta. f. 5—8. h Drury Ins. ii. t. xlvii. f. 3. See above, p. 315. i Oliv. no. 1. t. v. f. 16. &c. t. ii. f. 7. EXTERNAL ANATOMY OF INSECTS. 435 a insects in general. He perceives an analogy between °se of this Order and the teeth of quadrupeds; and divides them into incisive or cutting, lanzary oT and molary or grinding teeth. He denomi- s those incisives that are broad, having in some de- oy the shape of a wedge, their external surface being vex, and their internal concave; whence they are evi- atly formed for cutting. The laniaries are those which "Ve a conical shape, are often very acute, and in gene- C longest of any; and in some insects, as the carni- i us Orthoptera (and the Libellulina), they cross each r. The molaries are the largest of all, and their Purpose is evidently to grind the food. There is never y à single one to each mandible, while the number of k Neisives and seis niga is very eae As the mo- 4 act the principal part in mastication; they are O the inner base of the mandible o point of sup- .* they serve to grind the food, which has been first l a See a by the incisives or torn by the laniaries. The ‘ 'nivorous tribes are destitute of them; in the omnivo- "8 ones they are very small, and in the herbivorous ates they are very large?. So that in some measure May conjecture the food of the animal from the teeth arm its mandibles. Of incisive teeth you may find of *Xample in those that arm the end of the mandibles be ost grasshoppers (Locusta), and of the leaf-cutter- egachile Latr.)»; of the /anzary or canine teeth, Will find good examples in the mandibles of the on: flies (Libellulina); the two external teeth of the * Comparaison des Organes, &c. 1—. è Prate VI. Fic. 6. and XIII. Fie. 5. a”. og Es 436 EXTERNAL ANATOMY OF INSECTS: ded #° apex of those of the leaf-cutter bees may be reg#! ji d ma” between the incisives and laniaries; and the pointe dibles without teeth may be deemed as terminating J$ A laniary one*. ‘The lower part of the inner or contat surface of the mandibles of grasshoppers will supply yr with instances of the molary teeth, and the apex, also» those of some weevils, as Curculio Hancocki K5 the most remarkable example of a molary organ js ex bited by many ofthe Lamellicorn beetles, especially hai that feed upon vegetables, whether flower of lea" is Knoch, who indeed was the first who proposed callie mandibles according to their teeth, incisive, Janiaty molary, but who does not explain his system clea" observed that the mandibles of some Melolonthé hav’ projection with transverse, deep furrows, resemblins j file, for the purpose of bruising the leaves they feed up” y and M. Cuvier, long after, observed that the larv the stag-beetle have towards their base a flat, strial? molary. surface; though he does not appear to have ihe ticed it in any perfect insect’. This structure, wit w exception of the Scarabeide and Cetoniada, seem? it extend very generally through the above tribe; sine wy may be traced even in Geotrupes, the common “ 2 Pyare VI. Fic. 12. and XIII. Fic. 5. b”. >’ Prare XXVI. Fic. 16. e I was not aware that Knoch had observed this parts time after the publication of my paper On Mr. William MO é Doctrine of Affinity and Analogy (see Linn. Trans. xiv- 105 Ae I happened to meet with it in a letter from a friend, receiv? i than thirteen years ago; but without any reference toO the W a Knoch, in which it was stated. It was doubtless taken BF Beiträge zur Insektengeschichte. ; a Anat. Comp. iii, 821—. till EXTERNAL ANATOMY OF INSECTS. 437 a F i TEY afer, in which at the base of one mandible is a con- E molary surface, and in the other a convex one, but Aout any furrows: a circumstance that often distin- SUishes those that have furrows.—In the Dynastide © affinity of structure with the Melolonthide &c. is E pronounced, the furrows to which ridges in the “er mandible correspond being reduced to one or two vide and deep ones; whereas in some of the latter tribe SY are very numerous. These mandibles, in many e at their apex are furnished with incisive teeth to * Off their food, and with miniature mill-stones to snd ita, The part here alluded to I call the Mola. th ere I to ask you what your idea is with regard to Use of the organs we are considering, you would haps reply without hesitation, ‘ Of what possible use , the jaws of insects be but to masticate their food?” utin this you would in many instances be much mis- ĉn; as you will own directly if you only look at the "ndibles of the stag-beetle—these protended and for- able weapons, as well as those of several other bee- . s Cannot be thus employed. ‘ Of what other use, : : can they be?” you will say. In the particular in- E here named, their use, independent of inastita- Oth ‘ has not been satisfactorily ascertained; but in many cases it has. Recollect, for instance, what I told r in a former letter, of those larvee that use their un- Stiform mandibles as instruments of motzon®. Again: s ngst the Hymenopterous tribes, whose industry and Med €conomy have so often amused and interested you, a 0 20, D “Upp, t €g © of these mandibles is represented in Prate XXVI. Fic. * Mcisive teeth d”. molary plate. Comp. Linn. Trans. ubi mb f. 4. et bs » Vox. II. p. 275—. 4:38 EXTERNAL ANATOMY OF INSECTS. s z F “ ous many have no other tools to aid them in their vai labours and mechanical arts: to some they supply place of trowels, spades, and pick-axes; to others that y saws, scissors, and knives—with many other uses p might be named. In fact, with the insects of this ie Order mastication seems merely a secondary, if it m j any time their use. Still comprehending in one vieW et the mandibulate Orders, though some use their mat bles especially for purposes connected with their economy? yet their most general and primary use is the divisio” laceration, and mastication of their food; and this mo” exclusively than can be affirmed of the under-jaws y co? : ; : «oral der that insects in their larva state, in which univèrs? Ww excep” ille). This will appear evident to you, when you their primary business is feeding, with very fe i . : . st tions use the organs in question for the purpose of ma : aS : p cation, even in tribes, as the Lepidoptera, that have ° rudiments of them in their perfect state—while the mi k illæ ordinarily are altogether unapt for such use: exceptions I have just alluded to are chiefly confine e wi the instance of suctorious mandibles; or thos being furnished at the end with an orifice, the animal 5 serting them into its prey, imbibes. their juices throug 3 it. This is the case with the larvee of some Dytisct, merobius, and. Myrmeleon*; and spiders have a sim! 7 opening in the claw of their mandibles, which is sup” posed to instil venom into their prey °. ar Under this head I must not pass without notic? , appendage of the mandibles, to be found in some of a In the Myrmeleon, or ant-lion, the suction is promoted by “a action of a piston, that pumps up the juices. Reaum. vi. 369. b De Geer iv. 386—. ż. xv. f. 10. See above, p. 121. EXTERNAL ANATOMY OF INSECTS. 439 "0ve-beetles (Staphylinide), as in Ocypus, Staphylinus, and Creophilus Kirby. In the first of these itis a curved, narrow, white, subdiaphanous, submembranous, or rather “artilaginous piece, proceeding from the upper side of " base of the mandible ?; in the second it is broader, aighter, and fringed internally and at the end with 3 and in this at first it wears the appearance of be- § attached laterally to the mandible under the tooth®, = if closely examined, you will find that it is separate: > Creophilus maxillosus it is broader. This is the part k ave named prostheca. Itis perhaps useful in provoi E food from working out upwards during mastica- Ñ k Maxille °. The antagonist organs to the mandible . e lower side of the head, are the under-jaws, or mag- “~so denominated by the illustrious Entomologist of el. Linné appears to have overlooked them, except the case of his genus Apis, in which he regards them, - Properly, as the sheath of the tongue. De Geer keg upon them in general as part of the apparatus of. ne Under-lip or Jabium; and such in fact they are, as appear when we consider them more particularly. abricius has founded his system for the most part upon "ese Organs, the principal diagnostic of ten out of his Tteen Classes (properly Orders) being taken from them; x u the modern, which may be termed the eclectic, sy- m, although the Orders are not founded upon them, wi the characters of genera, and sometimes of large es, are derived from them: and as they appear less a Prate XIII. Fre. 7. c”. b Oliv. Ins. no. 42. Staphylinus. t. i. f. 1. b. © Prares VL VIL XXVI. d. 440 EXTERNAL ANATOMY OF INSECTS. liable to variation than almost any other organ, as Me W. S. MacLeay has judiciously observed, there seems good reason for employing them—it is therefore of 2” portance that you should be well acquainted with them Their situation is usually below each mandible, on each side of the labium; towards which they are often some what inclined, so that their tips meet when closed: some cases, as in the Predaceous beetles (Carabus L. Roo) they exactly correspond with the mandibles; but in othe! their direction with respect to the head is more longi dinal, as in the Hymenoptera, &c. In substance the may be generally stated to be less hard than thos¢ i gans; yet in some instances, as in the Libellulind, - Ano plognathidæ, &c. they vie with them, and in the Sear baide and Cetoniade exceed them, in hardness. Int bees, and many other Hymenoptera, they are soft 2 leathery. Their articulation is usually by means of ° hinge on which they sit: it appears entirely ligamento ; and they are probably attached to the labium at se base, or mentum—at least this is evidently the case wi? the Hymenoptera, in which the opening of the mas pushes forth the dadum and its apparatus, In that e markable genus related to the glow-worms, now © j Phengodes (Lampyris plumosa F.), and in the case-woF flies ( Trichoptera K.), the mazille appear to be cont with the /abium, or at least at their base.—As tO se composition, these organs consist of several pieces OF per tions, At their base they articulate with a piece Be or less triangular, which I call the hinge (Cardo)*- f on its inner side is often elongated towards the interi? @ Puare VI. Fre, 3,6, 12, VIL Fic. 3: e EXTERNAL ANATOMY OF INSECTS. 44l of the base of the Jabiwm, to which it is, as I have just “served, probably attached. This elongate process of € hinge in Apis, Bombus, &c. appears a separate arti- “ulation ; and the two together form an angle upon which € Mentum sits*, and by this the maxilla acts upon the abia] apparatus. the next piece ,is the s¢ipes or stalk of the mazilla. Us is the part that articulates with the hinge, and may € regarded in some cases, as in the Orthoptera &c., as “Whole of the mazilla below the feeler; and in others, i N the Geotrupide, Staphylinide &c., as only the back ù w the inside forming the lower lobe. This piece is . “0 harder and more corneous than the terminal part, ` linear, often longitudinally angular, and in the bee- “Ides (Apis L.) is remarkable on its inner side for a se- s of bristles parallel to each other like the teeth of a romb v, In Pogonophorus Latr., a kind of dor or clock- “ttle, it is armed on the back with four jomted spines, € intermediate one being forked*. M. Latreille has x Us described the stipes of the mawille of Coleoptera: “ext comes the stalk,” says he, ‘ which consists of tee parts: one occupies the back and bears the feeler ; “second forms the middle of the anterior face, and its Süre ig triangular; the third fills the posterior space . “prised between the two preceding; and is that which * of most consequence in the use of the maxilla; the an- tior feeler, where there are two, the galea, and the ler appendages that are of service in deglutition, are Part of that piece FE a T 3 Pare VIL Fic. 3. a.e”. Mon. Ap. Angi. i.t. xii.f. 1. e. a ÜL f.3.a. © Clair, Ent, Helvet, ii, 146. t xxiii. f super. 5. N. Dict. d’ Hist. Nat. iv. 243. 4 AQ EXTERNAL ANATOMY OF INSECTS. The third and terminal portion of the maxilla is formed by the lobe, or lobes (Lobi). ‘This may be called p most important part of the organ, since it is that whe often acts upon the food, when preparing for deglu” tion. When armed with teeth or spines at the ee its substance is as hard as that of the mandibles; put when not so circumstanced, it is usuálly softer, 1” sembling leathery or even membrane ?; and someti™® the middle part is coriaceous, and the margin memb?” nous. This part is either simple, consisting only of om Jobe, as you will find to be the case with the Hymen ptera, Dynastide, Nemognatha, and several other Pe” tles; or it is compound, consisting of two lobes. In OF former case, the lobe is sometimes very long, as in t bee tribes, and the singular genus of beetles mention? above>, Nemognatha; and at others very short, asi” Hister, &c. The bilobed mazille present several dife rent types of form. Nearest to those with one lobe ® those whose lower lobe is attached longitudinally ©, inner side of the stalk of the organ, above whic scarcely rises. Of this description is the magilla me common dung-beetle (Geotrupes stercorarius), and 100” beetle (Staphylinus olens).¢ Another kind of formatio” is where the lower lobe is only a little shorter tha? the upper: this occurs in a kind of chafer (Macraspis petro dactyla MacLeay).‘ A third is where the uppe lo “ covers the lower as a shield; as you will find in the 7" a In Anoplognathus, however, though it has neither teeth "7 spines, it is as hard as the mandibles. b See above, p. 317. c Prats XXVI. Fic. 10, 11, d”. e”. + a Ibid. Fic. 9. d”. €”. EXTERNAL ANATOMY OF INSECTS. 443 hoptera order, and the Libellulina, and almost in Meloe?. fourth form is where the upper lobe somewhat resem- | °S the galeate maxilla just named; but consists of two Joints, This exists in Staphylinide, &c.® The last kind Mall notice is when the upper lobe not only consists of Wo joints, but is cylindrical, and assumes the aspect of a feeler or palpus®. This is the common character of almost all the Predaceous beetles (Entomophagi Latr.). his lobe, which has been regarded as an additional te » is strictly analogous to the upper lobe in other in- “tts, and therefore should rather be denominated a pal- Piform lobe than a palpus. Where there are two lobes, © Upper one is most commonly the longest; but in $ MY species of the tribe last mentioned the lower one Wals or exceeds it in length 4, he lobes vary in form, clothing, and appendages. . © Upper palpiform lobe in those beetles just men- ti : ; ; med, in general varies scarcely at all in form; but the = Cychrus (which is remarkable for a retrocession : ™ the general type of form of the Carabi L. making an: p Proach towards that of those Heteromera which, from ) 4 black body and revolting aspect, Latreille has named ; “somes,) affords an exception, the upper joint being ‘a €r flat, linear-lanceolate, incurved, and covering the €r lobe ¢, which it somewhat resembles. The lower a fy Phare VI. Fic. 6, 12. d”. e”. Oliv. Ins. no. 45. Meloe. t. i. founa, These are what Fabricius calls galeate maxilla, on which he » êd his class Ulonata. - ep ATE XXVI. Fic. 11. &”. e”. a ATE VI. Fic. 3. d”, F lairy, Ent, Helvet. t. i. t. xviii. f. super. b. 1d. £ xix. 6, This genus may be the analogue of some hetero- Aedes EXTERNAL ANATOMY OF INSECTS. lobe also in this tribe varies as little as the uppe”; being shaped like the last joint of that lobe in Cychrus just dr scribed, except that in Cicindela it is narrowest in the middle*. In other tribes the upper valve is sometime? linear and rounded at the apex, and the lower truncate” as in Staphylinus olens®; sometimes the upper one #8 truncated or obtuse, and the lower acute, as in 77 „ogosit and Parnus*. In Ptinus, another tribe of beetles be- fore noticed as injurious to our museums 4, the reverse ° this takes place, the upper-lobe, which is the smalles and shortest, being acute, and the lower truncated °. Blaps both are acute f. In Rhipiphorus and Scolyt™s ©, lobes are nearly obsolete. The lower lobe is pifi ' Languria, a North American genus of beetles, so p give the maxilla the appearance of three lobes £; 4” Erotylus, a South American one, the upper is riang" lar®: it is often oblong, quadrangular, linear, gc ! others.—In those that have only one lobe the shape als? varies. In Gyrinus, the beetle that whirls round # round on the surface of every pool, which, though it longs to the Predaceous tribe, has only one lobe, the 10 represents a mandible in shape of the laniary kind, bei? merous one yet undiscovered, as Calosoma is of Adelium (Kirby Es Trans. xii. t. xxii. f. 2.) a Clairv. Ent. Helvet. ii. t. xxiv. f. super. b. b Prare XXVI. Fic. 11. © Oliv. Ins. no. 19. Trogosita. t. 1.f.d. no. 41 bis. DryoP* fie 4 See above, Vor. I. p. 238- © Oliv. Ins. no. 17. Ptinus. t.i. f: 1. ¢. £ Ibid. no. 60. Blaps. t. i. f- 2. c & Ibid, no. $8. Languria. t.i. f. 2. c. h Ibid, no. 89. Erotylus. t. ii. f. 12. c. EXTERNAL ANATOMY OF INSECTS. AAS trigonal and acute; and in the Anoplognathide, a New Olland tribe of chafers, in which it is, as it were, roken, the lobe forming an angle with the stalk, it. is “Oncayo-convex and obtuse, and somewhat figures a Molary tooth®. In the first tribe into which the bees (Apis L.) have been divided (Melitta Kirby), the lobe is Often linear or strap-shaped, and bifid at the apex; and u the second ( Apis K.) lanceolate and intire ©. In Cero- “oma it is long and narrow‘. More variations in form Night be named, but these are sufficient to give you a Scheral idea of them in this respect. With regard to eir clothing, I have not much to observe—in examin- ing the Predaceous beetles you will observe, that the in- terior margin of the lower incurved lobe is fringed with Stiff bristles or slender spines, and in many other beetles “ther one or both lobes have a thick coating or brush of Stiffish hairs €; but in several cases only the apex of the obe is hairy. In the Orthoptera order, and many of the elolonthide or chafers, the whole marilla is without airs, or nearly so. The appendages of the mazille are next to be dontik ese are principally their claws, or laniary teeth ; for €y are seldom armed with incisive or molary teeth. the whole tribe of Predaceous beetles, with few excep- tions, have the inner lobe of their maxilla armed with a terminal claw, which in the Cicindelidæ articulates with € lobe, and is moveable, but in the rest of the tribe is s Oliv, Ins. no. 41. Gyrinus. t. i. f. 1. e. * Prare XXVI. Fre. 13. Hor. Entomolog. i. t. ii. f. 29, 30. E. : a Mon. Ap. Angl. i.t. ii. Melitta. **. a, f. 2. t.v. Apis. *. b. f. 4. &e. ` Oliy, Ins. no. 48. Cerocoma. t.i. f- 1. ¢. ` Prane XXVI Fre, 10—12. 446 EXTERNAL ANATOMY OF INSECTS. fixed. In Phoberus MacLeay the lower lobe has ee spines». In Locusta this lobe has three or four spine or laniary teeth, and in Æshna there are six, which, lis? the claw of Cicindela, are moveable*. In others bot lobes terminate in a single spine or claw: this is the cas? ‘with Paxillus MacLeay*. In Passalus, nearly relate to the last genus, the upper lobe is armed with a sing™ spine, and the lower one with two*. ‘Those maxillé tha terminate in a single lobe are also often distinguished the spines or teeth with which it is armed; thus in ? nondescript chafer belonging to the Dynastidæ (4 chon K. MS.) it terminates in zwo short teeth ; in that m markable Petalocerous genus Hexodon Oliv. in three trun cated incisive ones‘; in Dynastes Hercules in three ac / spines’. Four similar ones arm the apex of the matt in that tribe of Rutelide which have striated elytra; ™ five that are stout and triquetrous those of Melotontl® Stigma F. Many others have six spines, sometime gi ranged in a triple series", Besides teeth or spines J some cases the lobes of mazillæ terminate in several long and slender lacinie or lappets fringed with hairs» least those of a Leptura (L. quadrifasciata L.) describ? by De Geer, appear to be thus circumstanced. He cow jectures that this beetle uses its mazxille to collect the honey from the flowers’. a Clairy. Ent. Helvet. ii. Cicindela. t. xxiv. f. super. b. for Cara” dz, Dytiscide, his other plates. p ® Hor. Entomolog. i. t. i. f. 13. E. ¢ Prare VI. Fre. 6, 12.4 ' 4 Hor. Entomolog. t.1. f.3. E. € Ibid. f. 4. E. £ Oliv. Ins. no. 7. Hexodon. t. i. f. l. e. g Ibid. no. 3. Scarabeys. t. 1. f. 1. f. h Kirby in Linn. Trans. xiv. 102. t. iii. f. 4. d. i De Geer v. 417. Liv. f. 12. EXTERNAL ANATOMY OF INSECTS. 44.7 As the principal use of the mandibles is cutting and Masticating, so that of the organs we are considering Seems to be primarily that of holding the food and pre- venting it from falling while the former are employed "pon it. I say this is their primary use; for I would by no means deny that they assist occasionally in commi- Nuting or lacerating it. In fact, were there no organs *Ppropriated to this use, and if both mandibles and maz- le were employed at the same time in comminuting the ‘Sod, it seems to me that it must fall from the mouth. 1a large proportion of insects the lobes of the maaille àre not at all calculated for laceration or comminution ; “hd in those tribes—as the Melolonthida, Rutelide, Dy- "astidee—in which they seem most fitted for that pur- Pose, the mandibles have incisive teeth at their apex, and “t their base a powerful mola or grinder: circumstances $ ich prove, that even in this case the business of mas- cation principally devolves upon them. 6. Palpi Mazillares*. There is one circumstance that Particularly distinguishes the mazillæ from the mandi- ĉs—they are palpigerous, as well as the under-lip. The ĉelers, or palpi, emerge usually from a sinus observable N the back of the maville where the upper lobe and ‘talk meet, Their articulation does not materially differ tom that of the labial palpi. Each maxilla has properly nly one feeler; but, as was lately observed , in certain TTibes the upper lobe is jointed and palpiform, which àS occasioned it to be considered as a feeler, and these tri : aor = have been regarded as having six feelers. The Ost general rule with regard to the length of the palpi * Pirates VI. VIL b”. b See above, p. 443. 448 EXTERNAL ANATOMY OF INSECTS. al; but is, that the maxillary shall be longer than the labi i axl the reverse often takes place. In many bees the m lary consist only of a single joint, and are very shorts while the labial consist of four, and are very long’: and in some insects (as in Pogonophorus Latr.) the four palp are of equal length>. The antennæ are most common longer than the palpi; but in several aquatic beetles, # _Elophorus, Hydrophilus, &c., whose antennze in the We" ter are not in use, the organs we are considering are the longest.—As to the number of their articulations, ee ries from one to six; which number they are not know? to exceed. In each of the Orders a kind of law seem? to have been observed as to the number of joints | in the maxillary and labial palpi, but which admi several exceptions. Thus in the Coleoptera, the natr” number may be set at four joints for the maxillary, an three for the labial palpi: yet sometimes, as in Sten Notoxus, &c., the former have only three joints, and the latter, as in Stenus and Tillus, only two. In the orth ptera the law enjoins, jive for the maxillary, and three a the labial; and to this I have hitherto observed no om ception. In the Hymenoptera, the rule is six and fow” but with considerable exceptions, especially as tO ihe maxillary palpi, which vary from six joints to a sing! one: thus in the hive-bee and the humble-bee, the ler bials, including the two flat joints or elevators, have fou joints, while the maxillaries are not jointed at all °- in Chrysis, in which the latter consist of five, the forme? j reduced to three. The Libellulina may almost be 7” sae l. 2 Mon. Ap. Angl. i. t. ix. 2. c. 2. B. f. 2. d. g. 4. t xii. neut. f. e t. xili. fi 3. b, b Clairy. Ent. Helv. ii, t. xxiii. f l e Prats VII, Fic. 3. b”. h”. EXTERNAL ANATOMY OF INSECTS. 449 a as having no maxillary palpi, since they exhibit _ that is distinctly palpiform. it seeiis to me o e upper lobe of their maxilla, which articulates the stalk in the same manner as a feeler, ma “regarded as an instance in which that lobe and the = Coalesce into one; and the mucro that proceeds ™ the lobe has the aspect of an emerging feeler, and fg Ponds somewhat with the labial one above no- ade, In the remainder of the Neuroptera and the “choptera, the prevailing number is jive and three. A the latter there are exceptions, which will furnish oa characters for genera. In the Lepidoptera we find a, ian Sometimes three, the maxillary boig nary api ty . The Diptera Order presents two tribes in this ty quite distinct from each other. The most natu- lite "mber of joints in the maxillary palpi of the Tipu- Ny Culicide, &c. is four or oe the last joint, how- i D Tipula, Ctenocera, &c. like that of the antennse 7 ee L., appears to consist of a number of very à tejoints®; but in the Asilide and Muscide, &c., the iin 3 two seems to be most prevalent’. The labial pal- _ JS order are obsolete.— “Sa, wild bees, they are setaceous, growing gradu- a UONI - . lç 9 ° . ‘a ` = t iii e Fra; 13. h”. Savigny Anim. sans Vertèbr. I. i 29—, A e De Geer vi. t. xix. f. 4. d. q m i, - : pa fix. f. 8. b b.t. xii. f 20. b. t. xiv. f. 15. ii For, ate XXVI. Fic. 6. f Ibid. Fre. 5, ait. ge. 450 EXTERNAL ANATOMY OF INSECTS. ally more slender from the base to the summit*: 2 tribe of small water-beetles (Haliplus), the saw-flies (Ten thredo L.), and several other Hymenoptera, have the thickest in the middle’. Their most important part however, and that which varies most in form, is the m minal joint:—of this I have already related some singul” instances °, and shall now describe a few more. E : n joint is sometimes acute, at others blunt, at others j ; ee net cated: in figure it is ovate, oblong, obtriangular, hatel ; ; te shaped, lunate, transverse, conical, mammillate, subula®” branched, chelate, laciniate, lamellate, &c. geit te í which I shall more fully explain to you hereaftet, gi . . i which I only mention here to show the numerous val 2 Kirby Mon. Ap. Angl. i. t. x. Apis. **. c. 2.0. f.3. @ and ** a} Pe Be Ua 43 b Clairy. Ent. Helvet. ii. t. xxxi. f. super. b. Mon. Ap. Angl} j Fett POSS. & c See above, p. 317. Jø _ 4 Prare XXVI. Fie. 1. As the very remarkable maxillary k to of that extraordinary Coleopterous genus Atractocerus seem Ya have been so fully described as'they deserve, I shall give here he nute detail of their composition. They consist of four joints" ai first is wide and short, and somewhat platter-shaped; the sec? od much smaller and shorter: the third is concavo-convex, O! ee like a shallow bowl: towards the breast this joint is elevate’ phe on the elevated edge sits the last joint, which is longer than è ast | rest taken together. In my specimen it points towards the mate its under side is entire and slightly curved, but in the upper p” a two rows of lamellæ (b), placed alternately nine on each side, ; ant odd one at the end: these lamellz are full of minute pap’ i! ait furrowed on the side next the mouth. From between the a slender exarticulate hairy branch or appendage emerges \@” pal labia e ig which I haye named 4, Gigas, EXTERNAL ANATOMY OF INSECTS. 451 wa as to figure, of which this joint exhibits examples. he palpi in general at their vertex are often rather con- Cave. RT : ; ave; and this concavity is formed by a thin papillose Membrane, which it is supposed the animal has the Power f of pushing out a little, so as to apply it to sur- aces, The primary use of the palpi of insects will be “nsidered when I treat of their senses; but they proba- Y answer more purposes than one. For instance, when Was once examining, under a lens, the proceedings of * Species of Mordella, which was busily employed in the Sssom of some umbelliferous plant, it appeared to me ° Open the anthers with its maxillary palpi, and they “ten held the anther’ between-them: when: not so em- “Yed; they were kept in intense vibration, more than “Ven its antennee; and at the same time, as far as I could eS) ait Elater made the saitie we’ of them. T. Lingua a. This name was applied by Linné to the art in insects representing the tongue in vertebrate ani- Tals; and as it performs most of the common offices of 3 tongue, and the pharynx is situated with respect to it, ` We shall presently see, nearly as it is in those ani- als, there seems no more reason for giving it a new “Ihe, than there is for giving a new name to the head "8s of insects, because in some respects they differ m those of the higher animals. I shall not therefore wi it Ligula, with Fabricius and Latreille, oo Labium, ; Cuvier and others, but adhere to the original term, Uch every one understands. he tongue lies between the two lzps—the labrum and abi i “um, On its upper side, at the base, it meets the pa- 4 Prate VI. VIL. XXVI. e. hg Cede 452 EXTERNAL ANATOMY OF INSECTS. - late or roof of the mouth, below which it is attached; it may be presumed, by its roots to the crust of the head, on each side the pharynx or swallow; and on its lowe? side, in many cases, it is attached to the labium, and that very closely, so as to appear to be merely a part of ib and to form its extremity: but in the Orthoptera eS Libellulina, it is more free, and in form somewhat "° sembling the tongue of the quadrupeds *.—In substant? the tongue varies. . In general it seems something Pe tween membrane and cartilage; but in the Predaceo™ beetles, in which it is not covered by the faéium, it ap” proaches nearer to the substance of the general inte gument, and in Anthia F. it is quite hard and horny ee that just mentioned of the Orthoptera and Libellulim® is more fleshy>. With regard to its station, jn many cases, as in the instance just named, in the Lamellico™ tribe (Scarabeus L.) and others, itis, when unemploy®”’ concealed within the mouth; the lips, mandibles, an maxillæ all closing over it. The tongue of some J menoptera also is retractile within the mouth.. “ whee ants are disposed to drink,” says M. P. Huber, “ ther comes out. from between their lower jaws, which igi much shorter than the upper, a minute, conical, flesh yellowish process, which performs the office of a tong? x - A grs being pushed out and drawn in alternately: it appe?” to proceed from the lower-lip.—This lip has the age 7 Jowe" of moving itself forwards in conjunction with the jaws: and when the insect wishes to lap, all this appr ratus moves forward; so that the tongue, which is p short, does not require to lengthen itself much to reat? a Prats VI. Fic. 6, 12. e. Cuvier Anat. Compar. iii. 347. b Cuvier Ibid. EXTERNAL ANATOMY OF INSECTS. 453 the liquid 2.” M. Lamarck thinks that the labium of Msects has a vertical motion (de haut en bas ou de bas = haut) >. This it certainly has in some degree; but it w also, as in the above case, a more powerful orizon- one, which is produced, in Hymenoptera at least, Y the opening of the maxillee—as I have already ob- Served c Thave little to say with respect to the structure of the Neue: it generally seems to be without articulations ; Y m many bees it articulates with the labium where it ers it, so as when unemployed to form a fold with it. ù the hive-bee it terminates in a kind of knob or button, Mich has been falsely supposed to be perforated for im- i mg the honey by suction. The upper part of this Mgue is cartilaginous, and remarkable for a number transverse rings: below the middle, it consists of a “mbrane, longitudinally folded in inaction, but capa- € of being inflated to a considerable size: this mem- "thous bag receives the honey which the tongue, as it ‘te, laps from the flowers, and conveys it to the pha- ` ee Ty Stenus this organ is retractile, and consists two joints £. he shape of the tongue of insects probably varies as Ach as any other part; but as it is apt to shrink when E, and is not easy to come at, we know but little of Various configurations :—in the bees it is very long, ig other insects very short. Though frequently ay © and undivided, in many cases it presents a diffe- conformation. Thus in the saw-flies (Tenthredo L.) Huber Fourmis, 4—. b Anim. sans Vertèbr. iii. 304. ` z above, p- 440. € Reaum. v. 309—. LATE XXVI, Fic. 23. f Clairv. Ent. Helvet. ii. Pref. xxii. 4 EXTERNAL ANATOMY OF INSECTS. it terminates in three equal lobes è; in Stomzs and Geo- trupes in three unequal ones, the intermediate being very short’; in Carabus, in three short teeth; in Pogonop as rus it represents a trident 4; in the wasp it is bifid, om lobe being tipped with a callosity®; in Melolontha Stign er Š = E ser” it is bipartite f; in Elaphrus, the analogue of the tig? beetles, it terminates in a single tooth or point; in k aquatic beetles, Dytiscus L., it is qùadrangular and wi” out teeth £; in some Ichneumonide it is concayo-conv™ and forms a demitube; and in others it is nearly cy drical 5, In many insects it has no Aairs, but in the Predace™ beetles it generally terminates in a couple of pristle® ’ In the hive- humble- and other bees, it is extrem? 4 hairy *; a circumstance which probably enables it cit effectually to despoil the flowers of their necta trupes stercorarius, the common dungchafer, are fringed with incurved hairs’; and in LEishna 3 hairy on the upper side, each hair or bristle crowns minute tubercle. In many cases the tongue is atte? ú i and sometimes sheathed at the base, by two usually m° p branous appendages:—these the learned Illiger has de? é u lontha Stigma lately mentioned, the lobes of the tong s a Kirby Mon. Ap. Angl. i. t. xiv. (1) 2. 6. ts b Prats XXVI. Fic.-24. €. © Clairy. ubi supr Ý y à Prats XXVI. Fic. 28. €. oD ° Kirby ubi supr. fig. (8) 1.ce. The lateral pieces in the A in Vespa (Ibid. c c.) have been regarded as lobes of it, put th rather Paraglosse. e £ Prate XXVI. Fic. 29. e’. ® Clairv. ubi supr- t noytt h Kirby ubi supr. no. 2. f-1,3. ` Prare XXVI. Fie. ? Ls i xi £ Kirby ubi supe, t x, Apis. Pe 2. af. 5. t xii, nent. fo” faa ! Prare XXVI. Fre. 26, 29. EXTERNAL ANATOMY OF INSECTS. 455 minated paraglossæ; and I shall adopt his term. You will find them frequently attached to the tongue of the "edaceous beetles a, and to that of many Hymenoptera, "the hive-bee and humble-bee they are short, and take - eir origin within the Jabzal feelers ®; in Euglossa, an- Other bee, they are long, involute at the tips, and, what Shot usual with them, very hairy °: in the wasp, like © lobes of the tongue, they are tipped with a callosity. Under this head I may observe to you, that the inə — “ects Whose oral organs we are considering besides a tongue appear likewise to be furnished with a palate ( Pa- tum), This, though a part of the roof of the mouth, ù not precisely in the situation of the palate of vertebrate Minals, since it seems rather the internal lining of the “rum, If you take the common dragon-fly (Aishna *atica), you will find that the under side of this part "Nd of the rhinarium is lined with a quadrangular fleshy “UWhion, beset, like the upper surface of the tongue, with Mute black tubercles, crowned with a bristle. This “Ushion is divided transversely into two parts by a de-. tession ; the anterior or outer piece being attached to € labrum, and the other piece to the rhinarium. The “ther has a central longitudinal cavity, black at the ttom, on the sides of which the tubercles are flat and tthout a bristle. From its base on each side a spini- rm Process emerges, forming a right angle with it. €se processes seem the antagonists of those mentioned ved, that emerge from the labium. The posterior or a à , Prane XXVI: Frc. 28. i”. e tby Mon. Ap. Angl. i. t. xi. neut. fe l. hh. t xii. f. 1. f f. : Ibid, ¢, x. **, d, 1.2.5 8. e above, p. 425. 456 EXTERNAL ANATOMY OF INSECTS. inner piece has on each side a roundish space, attache to the under surface of the two sides of the rhinariul™ beset also with bristle-bearing tubercles. You will fm something similar lining the labrum and nasus of some Coleoptera,—say Geotrupes, Necrophorus, and Dytiset® The first piece I regard as the analogue of the palates itl the second as connected with the sense of smelling: Necrophorus the circular pieces are covered with @ finey F ; : i ittie striated membrane, and in Dytiscus each has 4 jiw nipple. 8. Pharynx *.—On the upper side of the tongue, ust ally at its base or root, is the pharynx, or apertutTé which the food passes from the mouth to the cesophast™ This orifice, which is situated with respect to the tong” ý of the Orthoptera and Libellulina nearly as in thos? y sects (at least as far as I have been able to examine them? whose tongue is called a ligula or labium,—of cours? © ists in all the mandibulate Orders whose mouth we J by’ valve, the Epipharynx of Savigny; and it appeared tow to be so likewise in one of the Harpalide that I examin? now considering. In the Hymenoptera it is covered The formation seems different in Geotrupes, as far d can get an idea of it; but it is so difficult to examine 7 interior of the mouth without laceration of some ° parts, that I can only tell you what the appearances y in one instance, upon removing the labrum from the m? p dibles; and in another, separating the whole appar ; of the labium, including the maxille, from the mandib coina s ere fa and labrum. In the former case, the mandibles a Prate VIL, Fic. 14. fh EXTERNAL ANATOMY OF INSECTS, 457 at the base, the two molary plates (molæ), which in this Senus are narrow, transverse and not furrowed, are so aPplied as evidently to have an action upon each other, & the mandible opens and shuts, proper for trituration. ithin these is the base of the tongue, under the form of a ventricose sack. The upper part of this last organ, Which forms the internal covering of the labium, appears t0 consist of three (in the recent insect fleshy) lobes, -the Middle one being bent downwards internally, so as to am a kind of sloping cover to an orifice in the part Call the base. After two or three days, the tongue Shrinks and dries to a hard substance;—between the man- ibles and the base of the tongue I could not discover he phar; yng. The above apparent opening covered by the tongue was the only one I could perceive. In the latter “se, the form and structure of the base of the tongue is Nore visible: it is an oblong ventricose ‘tubular sack, : Projecting above anteriorly into an acute angle formed Ja fine white membrane, most beautifully and deli- ey striated with oblique striæ, to be seen only under à Powerful lens: on the anterior side of this sack are two b ‘allel cartilaginous ridges close to each other, fringed with short hairs, which take their origin from the angle. Could not be certain whether the orifice covered by € intermediate lobe was only apparent, or real; but. I id not succeed in my endeavour to find any other pha- "Yna, though from the molary structure of the base of . mandibles one may conjecture that there must be one Situated at the base of this sack to receive the food they “ender after trituration. The excrement of this animal š Rot fluid. In the ZLibellulina the pharynx seems Sed by two valves meeting. This part in Hymeno- 458 EXTERNAL ANATOMY OF INSECTS. ptera, and probably in other Orders, has the aspect of being cartilaginous and fitted to sustain the action of the substances that have to pass through it ?. The Epipharyna is a valve, called by M. Latr sublabrum (sous labre®), attached by its base to the uppe margin of the pharynx, or that next the labrum- H the bees itis said by Reaumur to be of a fleshy substanc® and capable of changing its figure. He seems to thn = . ay it the real tongue of the bee °; but as it does not pem close eille to have any of the uses of a tongue, and merely the orifice of the mouth, it surely does not merit tha name. M. Savigny calls it a membranous appendas? which exactly closes the pharynx’, De Geer has est mined the epipharynx of the wasp, which he describes a of a scaly substance, and regards merely as the cove : the part just named °. With regard to the Hypopharyna, which Latreille c siders as a support and appendage of the epiphary™ have little to add to the definition I have given of it abov™ In the Libellulina the base of the tongue terminate? towards the pharynx in a fleshy cushion, armed at eat angle next to that part with a short hard horn or toot of a black colour. This cushion, I suppose, may be ae logous to the hypopharynz of M. Savigny €. On the oPP j site side the pharynx is closed by another fleshy cushio? (epipharynæ?), which appears to line the nose, a those two mammillee before described’, which for™ ý internal covering of the rhinarium. 2 Reaum. v: 317. — ‘> Organisation exterieur des Ins: 184: © Ubi supra.’ à Anim. sans Vertebr. I. i. 12. e De Geer ii, 778—. ż. xxvi. f. 11. m. Prare VIL Fie. 2. k £ Ubi supra. & See aboye, p. 455. wv EXTERNAL ANATOMY OF INSECTS. 459 Before I call your attention to what I would denomi- Nate an imperfect mouth, in which some one or more of € seven organs above enumerated exist under another rm, or only as rudiments,—I must say something upon the mouth of the Myriapods and Arachnida, in which there seem to be redundant organs of manducation.— - Latreille, in the Essay ‘lately quoted, in which, ush some of his notions seem fanciful, he has shown “Vast depth and range of thought and research, has as- Serted —from the admirable and curious observations of ' Savigny, and those which since their publication he às made himself,—that the masticating organs of an- lose animals (called by him condylopes) are a kind of 68*, And M. Savigny, whose indefatigable labours "ad unparalleled acuteness have opened the door to a Rey and vast field in what may be denominated analo- Slcal_ anatomy,—has observed, that with certain Apiro- Pods> the organs that serve for mandueation do not dif- fer essentially from those which, with the other Apzro- Pods and the Hexapods, serve for locomotion ©: and. the guiform mandibles of the larvæ of certain Diptera, You haye before been told, are used not only in mandu- “ation, but also as legs4, ‘These remarks will satisfac- torily prove to you, that organs which at first sight pos- Sess no visible affinity or analogy—as for instance, jaws and legs—may, if traced through a long series of beings, exhibit a very great one ;—and will lessen your surprise $ Organisation &c. 182. ; nder this name M. Savigny includes the Myriapoda, Arach- Ge and Crustacea. Anim. sans Vertèbr. I. i. 40. Ibid, 43. a $ Vox. II. p. 275—. Also see above, p. 121—. 4.60 EXTERNAL ANATOMY OF INSECTS. when you find, that in certain tribes such commutation of organs and their use take place. -A The following is the structure, as to its organs, mouth of the myriapods, as exhibited by the centipede (Scolopendride). The part which appears to perform the office of the upper lip (but which M. Savigny rega" f as the nose, calling it the chaperon,) is a transverse p! jec? of the with a deep anterior sinus, in the centre of which is 4 minute tooth 2. This piece is separated from the. fore part of the head by a suture; but it probably is not move" able: however, it covers the mouth, and may be regarde rather as analogous to the labrum. Below this are ew mandibles, armed at their end with five sharp triangl” teeth>, under which are the mazille, terminating in moveable concavo-convex lobe, resembling the yalve i a bivalve shell*; and between them is the labium, © i rhomboidal shape, divisible into two lobes, attached y terally to the maxillae: these lobes M. Savigny terms second. maxille, forming with the others, according © him, the labium4. Affixed to the base of this labium “A covering it on the outside, are a pair of pediform palp y which he considers as the first auxiliary Jabium, and? z presentative of the first pair of legs of hexapods and Juh’ I imagine them to be also the analogues, in some dg of the labial palpi.of a perfect mouth. The last of the organs in question is a large rhomboidal plate affixe the first apparent segment of the trunk, crowned 2t i vertex with two truncated denticulated teeth, and from a Anim. sans Vertébr. I.i. t. ii. f. 2. a. a. b Prats VII. Fic. 13. č. ; c Ibid. d’. a Anim. sans Vertèbr. I.i. 106. Prare VII, Fre, 13. b- ° Ubi supr. 45. EXTERNAL ANATOMY OF INSECTS. 461 the Upper sides of which emerge a pair of moveable or- terminating in a powerful incurved claw, and which rely covers all the other parts of the mouth è. This, Bey deems as a pesona auxiliary labium, and the la- w pe of prehension, —which may be regarded each . “kind of maxillary hand, and as the only representa- Nes'in this tribe of the maxillary palpi, though widely erent, —he looks upon as really analogous to the second 3 of legs in Zulus and the hexapods>. These two pairs Pedipalpes (to use an expressive French term) show N relation to legs by their general structure, and their ogy with palpi by their use as oral organs, though : nging to the ¢runk : so that here we see the legs and — pe appendages assume a material function in mandu- o forming a singular contrast to what we had ob- ed before with regard to mandibles becoming instru- “ts of Jocomotion. The mouth of the Tulidæ, with lit- > Variation, is upon the same plan* with those here de- tibe d. i = next type of form with regard to the oral organs © at of the Arachnida. In these, as you know, the “dis confounded: with the trunk; so that they are a Md of Blemmyes in the insect world. Their organs of } Mducation, amongst which there is no labrum or upper b, are, in the first place, a pair of mandibles planted Ee and parallel to each other in the anterior part of ra y head, which they terminate. In the spiders they con- of two tubular joints, of which the first is much the To, - a R : Ssst, more or less conical or cylindrical, and armed * Prave VII. Fie. 11. f’, a’. p Ubi supra, 45. ° Ibid. 44— : 462 EXTERNAL ANATOMY OF INSECTS. : E underneath with a double row of stout teeth; and th terminal one is more solid and harder, in the form ° i ed? very sharp crooked claw, which in inaction is fold i ity the first joint between the teeth. Under its extrem'™ the outside is a minute orifice, destined to transmit 4 ge nomous fluid, which is conducted there by an intern? canal from the base of the first joint, where is the poiso”! bag. In the scorpion and harvest-man (Phalang™ the mandible consists of two joints terminated by 4 ^ í or double claw, the exterior one being moveable” , M. Latreille, as has been before observed, regards the? i not as representatives of the mandibles of hexapods; # as replacing the interior pair of antennæ, in the situati of which they are precisely placed, of the Crustal and M. Savigny is of opinion that the Arachnida may j 5 ap some sort be defined as Crustacea without a head, fe nv er with twelve legs, of which the two first pair are co he into mandibles and maxille*. From the situation © `; ‘ ; ae r organs in question, the first of these opinions seems P : i a ferable; but the conversion of the legs in other w s0 least the core, into organs of manducation, gives - j 5 34 weight to the last. With regard to their use, it i to be to retain the insect which the animal has i eye x bs i j and to facilitate the compression which the maxille & e r : : ie pe cise upon it for the extraction of the nutritive matte e If this be correct, in this respect the mandibles a fae said to represent the maxille of the mandibulate hes” äi , = pave pods; and, vice versa, the sciatic maxille, as they è N. Dict. @ Hist, Nat. ii. 275—. Prane VII. Fic. 10. C- ay > De Geer t. xl. f. 4. t. x. f. 7, 8. © See above, P- 1 a Savieny Anim. sans Vertebr. 1. i. 62. e N. Dict. d Hist. Nat: ii. 277. EXTERNAL ANATOMY OF INSECTS. 463 been denominated è, of the Arachnida, their mandibles. he palpi are pediform, and the first joint of the coxa, r hip, acts the part of a maxilla :—this is composed of * Single piece or plate, more or less oval or triangular, Sometimes straight and sometimes inclined to the labium, With the interior extremity very hairy. The Zabium con- Sists also of a single piece, and is only an appendage of € anterior extremity of the breast. ‘The interior of “mouth, or palate, presents a fleshy, hairy, linguiform plece, which is usually applied to the internal face of the Wium, An opening is supposed to exist inits sides, for the transmission of the alimentary juices». If you ex- ‘Mine the under side of the body of a scorpion, you will hd that not only the palpi, but the two anterior pair of "88, by means of their core, are concerned in mandu- “ttion: so that these insects have in fact żhree pairs of MBXill goa circumstance that M. Savigny has observed © take place also in the harvest-men (Phalangium L.) °. he Palpi of the scorpion, which may be called its hands, e the anterior legs of the lobster and crab, terminate x à tremendous chela or forceps, consisting of a large angular joint, armed at the end with a double claw “ternally toothed; the exterior one of which, contrary ° what takes place in the animals just named, is move- le, and not the interior ¢. Having given you this full account of the ¢rophi of se animals that have all the organs of manducation Eye loped, I must next advert to those in which one part t . © V- Dici. & Hist. Nat. ii. 276. > Ibid. | Jhi supr. 58. : 4 Prate XV. Fic: 7. 4.64 EXTERNAL ANATOMY OF INSECTS. receives an increment at the expense of others, and the whole oral machine is fitted for suction; or where some parts appear to be deficient, so that this may be calle an imperfect mouth. At first sight one would regard the trophi of a bee as of this description; but this is not the case, since it has all the ordinary organs, though w ‘tongue is unusually long, and looks as if it was made for suction; which, however, as you have been informed, ® not the case. ` | There are five kinds of imperfect mouth to be with in insects that take their food by suction, each © which I shall distinguish by a separate denominatio” The first is that of the Hemiptera Order :—this I term” _ the Promuscis; the second is that of the Diptera, whic with Linné I call Proboscis; the third, peculiar to the Lepidoptera, is with me an Antlia; the fourth, which name Rostrulum, is confined to the Aphaniptera orde” or genus Pulex L.; and the last is Rostellum, which employ to denote the suctory organs of the louse trib? (Pediculide). l met 1. Promuscis*.—The organ we are first to conside” has usually been denominated Rostrum: but since that term is likewise in general use for the snout of insects ý the weevil tribes (Curculio L.), I think you will conc with me in adopting the one here proposed, for the ve different oral instruments of the Hemiptera. Illiger p employed promuscis to denote those of bees?: but sie a I have just observed, they consist of all the ordinary ei S k . ‘on: gans, they seem to require no separate denominatio 4 Prate VI. Fic. 7-9. a’, b’, c,d’. >» Magaz. 1806. EXTERNAL ANATOMY OF INSECTS. 465 the term, therefore, may be applied to represent a diffe- rent Set of trophi, without any risk of producing confu- Oe This part consists of jive pieces: viz. a minute, ong, conical piece, commonly very slender, which covers ‘ $ base of the promuscis, and represents the labrum TA Jointed sheath (vagina), consisting of either three or four Mints, the analogue of the labium, and four slender rigid “Neets (scalpella), the two exterior ones, according to : Savigny, representing the mandibles, and the inter- diate pair the mazille>. By the union of these four “ces a suctorious tube is formed, which the animal in- “ets into the substance, whether animal or vegetable, ~ Juices of which form its nutriment. These pieces are i : ; ‘ “ted at their base, and serrated at their apex; and the 9 central ones, though at their origin they are asun- Y form one tube, which has often been mistaken for a g piece. A pharynx and tongue have been disco- ed by M. Savigny in this apparatus; who thinks that epa there are also rudiments, but very indistinct, of “ty palpi: so that the maxillary palpi seem to be the . § Y part absolutely wanting °. the 4 Promuscis when at test is usually laid between is ag but when employed, in most cases its direction i TEI In the genus Chermes L. (Psylla Tatr.) the SN of the promuscis has been supposed to be in the cast but if closely examined, this anomaly in nature 4 € found not to exist. If you take ans of these in- iy the first thing that strikes you upon inspecting the SRS : z . . > IS a pair of remarkable conical processes into which * Prare VI, Fie. 7. a’. ° Ibid. Labium W. Mandibule c’. Maxille d’. “ Savigny Anim, sans Vertèbr. I. i. 37. Vo L, ur, Qu 4.66 EXTERNAL ANATOMY OF INSECTS. the front appears to be divided. Look below theses and you will there discover the upper-lip: and from this y0” may follow the promuscis till it gets beyond the foreleg” when it takes a direction perpendicular to the body * : circumstance which has given rise to the above false us tion. Though in Coccus, Chermes, &c. this instrument 4 short, in some Aphides it is longer in proportion tha? 2 any other insect. In A. Quercus it is three times © length of the body; so that when folded, it stretches a beyond it, and looks like a long tail”; and in 4. Abie it even exceeds that length °. re Sd ; „i fae ij. Proboscis 4.—Linné long since, and after hım F bricius, has employed this term to designate the 0” , . 7 . . a struments, or rather their sheath, in the Muscidé geshy (4 some others, calling the same organ, when without lips, rostrum and haustellum: but as the parts of ios i mouth in all true Diptera (for Hippobosea and its affini 2 z E , a can scarcely be deemed as co-ordinate with the rest) ; are” 6 analogous to each other; although in some they and rigid, in others flexile and soft, and in Estris £ cept the palpi) mere rudiments, —the same appa ; ought to designate them all. I am happy to fin jis M. Latreille agrees with me in this opinion; av abe riu sensible observations on this head, if you wish fo g -ene information, I refer you ®. The mouth of Dipte! om ld sects appears to vary in the number of pieces that 1t a De Geer iii. 1387—. ż. ix. f. 4. b Reaum. iii. 335. #. xxvii. f. 8—14. © De Geer iii. 117. ż. viii. f. 22. b. a Prare VII. Fic. 5, 6.a, b,c’, d ` e N, Dict. d Hist. Nat. iv. 253. EXTERNAL ANATOMY OF INSECTS. 4.67 ‘ents ; but in all, the ¢keca or sheath is present, which re- Presents the Jabium (including the mentum) of the man- dibulate Orders. It consists of three joints, the last of Which is formed by the liplets (Labella). ‘Those in the Uscide@ are large, turgid, vesiculose, and capable of dilatation ; in the Bombylide and other tribes they are Small, slender, long and leathery, and sometimes re- ®urved, The second joint or stalk, which may be said to represent the mentum, the liplets being properly in a testricted sense the analogue of the labium ; its sides being turned up, forms a longitudinal cavity, which contains the haustellum. The upper piece of this, the valvula, is “hg, rigid, and very sharp, representing the labrum”. neath this cover, in the above cavity, are the lancets ; “hich, as far as they are at present known, vary in num- et and form: sometimes there are five of them, some- Mes four, sometimes wo, and sometimes, it should seem, “aly onec, In the gnat (Culex) they are finer than a Nir, very sharp, and barbed occasionally on one side 4; A the horse-fly ( Tabanus L.) they are flat and sharp like he blade of a knife or lancet ®. In this tribe the upper Pair, or the knives (Cultelli), represent the mandibles ; © lower pair, or the lancets (Scalpella), usually palpi- Crous, the maville ; and the central one the tongue. In å horse-fly Reaumur has figured only four, exclusive *f the labrum and labium; but in a specimen I have pre~ i Piare VIL Fie. 5, 6. 2’. b Ibid. Reaum. iv, z£. XVI. Fie. 13. z. Authors are not agreed as to the precise number of lancets con- Sy ina gnat’s proboscis. Swammerdam affirms there are six, m- five Mg the labrum. i. 156. b. ż. xxxii. f. 3. Reaumur could find only e WV. 597—. z. xlii. f. 10. And Leeuwenhoeck only four. laTE VII. Fic. 5. 2#2 468 EXTERNAL ANATOMY OF INSECTS. served there appear to be five, one of whieh, as slende? as a hair, I regard as the analogue of the tongue as? When the lancets are reduced to two, they probably gi present the mavzille, the mandibles being absorbed ™ the Jabrum ; and where there is only one, the maxilla also are absorbed by the Jabium, which then bears the palpi, the lancet representing the tongue”. The Jancets are so constructed in many cases, as to be able by the union to form a tube proper for suction, or rather w forcing the fluid by the pressure of the lower parts tO the pharynx’. Labial palpi appear not usually present r the proboscis; but M. Savigny thinks he has discovet®“ vestiges of them in Tabanus*. In this genus the maxi” lary ones are large, and consist of two joints ®. The pro boscis is often so folded, as to form two elbows; the bas? forming an angle with the stalk, and the latter with th? lips, so as in shape to represent the letter Z, only that the ‘upper angle points to the breast, and the lower one $ the mouth: this is the case with the flesh-fly and many others. In other flies, as Conops and Stomoxys, whos? punctures on our legs so torment us f, there is only * single fold, with its angle to the breast. The probost! 5 received in a large oblong cavity of the underside of t anterior part of the head. : ‘ EES and 2 Pyare VII. Fic. 5. This figure is copied from Reaumu!» was engraved before this discovery was made. tg 10° b M. Savigny is of opinion that the central lancet or laneta i 0 present the Epipharyna and Hypopharyne ; for which he doc! i state his reasons: but as these are properly covers of the phat) the idea seems incorrect. Ubi supr. 15. ¢ N, Dict. d’ Hist. Nat. ix. 489. and iv. 253—. : a Ubi supr. 36. * Ibid, ERN f. 1. 0. % * Vor. I. p 48, H=. EXTERNAL ANATOMY OF INSECTS: 469 kt may here be observed, that in the promuscis the Clongation of the organs seems to be made chiefly at the “Xpense of all the palpi, but in the proboscis at that of © the labjal only; and in some cases at that also of the Mandibles or maxille,—the former merging in the la- rum and the latter in the labium. üi, Anla *,—'The third kind of imperfect mouth is that a the Lepidoptera, which I have called Antlia. Fabri- Mus denominates it lingua; but as this organ has no ana- 8Y with the real tongue of insects, this is confessedly Proper, and it appeared necessary therefore to exchange t for another denomination: I have endeavoured to ap- bly a term to it that indicates its use—to pump up, name- Y, the nectar of the flowers into the mouth of the insect. n a former occasion I described to you the structure of this instrument >; but further discoveries with regard to it having since been made by MM. Savigny and La- teille, I shall here give you the result of their observa- fons, The former of these able physiologists has de- N in the mouth of the Lepidoptera rudiments of al- E all the parts of a perfect mouth. Of the correct- “SS of this assertion you may satisfy yourself, if you con- “ult his admirable elucidatory plates, and compare them "ith the insects. Just above the origin of the spiral gue or pump, the head is a little prominent and “ounded ; and immediately below the middle of this pro- Mmi ; à F Mence there is a very minute, membranous, triangular OP cons: ; ; - ie ; semicircular piece; which from its position, as cover- n 3 i ; § the base of the antlia, may be regarded as the rudi- * Piare VL Fic. 13. Wo 505. b Vou, I. p. 394—. ATO EXTERNAL ANATOMY OF INSECTS. ment of the upper-lip (labrum) a, On each side of the outer base of the antlia is another small immoveab? piece, resembling a flattened tubercle, the end of whi¢ is internally hairy or scaly: these pieces appear to repre" sent the mandibles». Near the base of each half of the antlia, just below a sinus, may be distinctly seen the m* nute, usually biarticulate rudiment of a maxillary PO pust; demonstrating to a certainty that these spiral pe gans, at least their lateral tubes or Solenaria, ave és maxille4?. The rudiment of the under-lip (Labium) a the almost horny triangular piece united by membrane’ to the two stalks of the maxille, and supporting at 3 base the recurved labial palpi; which are so well know? that I need not enlarge upon them*. Amongst thes? parts there seems at first sight no representative of the tongue; but M. Latreille has advanced some very ing?” nious, and I think satisfactory arguments f, which go t0 prove that this part, at least the tongue of Hymenopte™ has its analogue in the intermediate tube or Fist formed by the union of the two maxilla, and which a veys the fluid aliment of this Order to the pharyn#: in Diptera the maxille sometimes merge in the Jabiut so here the tongue (as it were divided longitudinal} ) merges in the maville. He further observes, that 1» transverse section of the maxilla of the death’s-h? hawk-moth (Sphinx Atropos), the lateral tube appear @ Prate VI. Fie. 13. a’. Savigny Anim. sans Vertebr. Lie; t, i.—til. a. b Joid. i, Prave VI. Fie. 13. C c Ibid. Fic. 13. h”. Savigny ubi supr. o. à Prats VI. Fic. 13. d. Savigny ubi supr.t, 1—3. 0. e Ibid: o. Prare VI. Fic. 13. b. £ N. Dict. d Hist. Nat. xvii. 467. EXTERNAL ANATOMY OF INSECTS. 471 to be divided into two by a membranous partition, and to contain in the upper cavity a small cylindrical tube, Which seemed to be a frachea*. To animals that are Without lungs, and breathe by ¢rachee, suction must be Performed in a very different way from what it is by those that breathe by the mouth : and as in the very ex- ended organs in question the fluid has a long space to Pass before it reaches the pharynx, in some way or other these lateral tubes may have the power of producing a Vacuum in the middle tube, and so facilitate its passage thither, We see, in the antlia, that the maxille receive their vast elongation at the expense of all the other or- Sans, except the Zabial palpi. iv. Rostrulum*.—An animal very annoying to us af- ords the type of the next kind of imperfect mouth—I ĉan the flea. Its oral apparatus, which I would name "Strulum, appears to consist of seven pieces. First are a Pair of triangular organs, the lamine, which together ‘Omewhat resemble the beak of a bird, and are affixed, Me on each side of the mouth, under the antennze: these "resent the mandibles of a perfect mouth ®. Next, a Pair of long sharp lancets (Scalpella), which emerge from € head below the laminæ: these are analogous to Maa- illea, a pair of palpi, consisting of four joints, are at- ' Med to these near their base €, which of course are O iy y palpi. And lastly, in the midst of all is a ae setiform organ (ligula), which is the counterpart °“: the tonguef. Rösel, and after him Latreille, seem to a N. Dict. d? Hist. Nat. iv. 253. Py saree © fhid. č. Late VII. Fic. 8. c,d, e, h’. ) " Thid, d’, we ote Pie E WEN : f Ibid. €. 4.72 EXTERNAL ANATOMY OF INSECTS. have overlooked this last piece, since they reckon only six pieces in the flea’s mouth?: but the hand and eye k our friend Curtis have detected a seventh, as you se? i his figure. From this account it appears, that the elon- gation of the organs of the Aphaniptera Order is at the expense of the labium and its palpi. v. Rostellum.—So little is known of the compositio” of the next kind of imperfect mouth, that I need not ‘ai large upon it. It is peculiar to the louse tribe (Pedit lide), and it consists of the tubulet (Tubulis), and 5” phuncle (Szphunculus). The former is slenderer jn the middle than at the base and apex, the latter being tus gid, rather spherical, and armed with claws which py bably lay hold of the skin while the animal is engaged » suction. When not used, the whole machine is with? drawn within the head; the siphuncle, which is the sue torious part, being first retracted within the tubules of the same way as a snail retracts its zentacula®. T his ap” paratus seems formed at the expense of all the othe organs. There are some other kinds of imperfect mouths which, though they seem net to merit each a disti??? denomination, should not be passed altogether without notice. The first I shall mention is that of the family f Pupipara Latr. (Hippobosca L.). It consists of # pa” of hairy coriaceous valves, which include a very slend rigid tube or siphuncle, the instrument of suction, whe Latreille describes as formed by the union of tw en a Rosel. ui, 4.1. f. 15. Latreille Gen. Crust, et Ins. iv: 365: b Swammerdam Bibl. Nat. t. i, f. 4, EXTERNAL ANATOMY OF INSECTS. 473 form pieces. In Melophagus, the sheep-louse, the union “ the valves of the sheath is so short, that they appear ike a tube; but if cut off they will separate, and show the siphuncle, as fine as a hair, between them. This or- gan is of a type so dissimilar, as was before observed, to that of the Diptera in general, and approaches so neat to Mat of the dog-tick (Ixodes), that they may be deemed ra- ther apterous insects with two wings, than to belong to that rder: and the circumstance that some of the family are “Pterous confirms this idea. In fact they are a transition amily that connects the two Orders, but are nearest to © Aptera. In Nycteribia the oral organs differ from Ose of the other Pupipara in having palpi. This also S the case with those of the genus Ixodes, the palpi of Which are placed upon the same base with the instru- Ment of suction, than which they are longer: they ap- Pear to consist of zwo joints, the last very long and flat. ‘he instrument of suction itself is formed by three hard "gid laminæ; two shorter parallel ones above, that co- er the third, which is longer and broader, and armed X each side with several teeth like a saw, having their Points towards the base®. Many of the other Acari i; “Ve mandibles, and several have not: but their oral or- Sas have not yet been sufficiently examined; and from le extreme minuteness of most of them, this is no easy fask; nor to ascertain in what points they differ or agree, tf you consider the general plan of the organs of man- Cation in the vertebrate animals, how few are the va- k see rad : N. Dict. d’ Hist. Nat. xxviii. 266. bid, xvi. 432. De Geer vii. f. vi. f. 4. Not quite accurate. ATA EXTERNAL ANATOMY OF INSECTS. riations that it admits! An upper and a lower jaw planted with teeth, or a beak consisting of an upper ” a lower mandible with a central tongue, form its prine! pal features. But in the little world of insects, how ve derful and infinite is the diversity which, as you 8° 7 this respect they exhibit! Consider the number of the organs, the varying forms of each in the different tribes adjusted for nice variations in their uses :—how gradua’ one sé too, the transition from one to another! how of instruments is adapted to prepare the food for deg!” tition by mastication; another merely to lacerate it, d that its juices can be expressed; a third to lap 2 fiw aliment; a fourth to imbibe it by suction—and you m see and acknowledge in all the hand of an almighty all-bountiful Creator, and glorify his wisdom, pow®” and goodness, so conspicuously manifested in the strut” ture of the meanest of his creatures. You will see also» - that all things are created after a pre-conceived plan; is which there is a regular and measured transition fro one form to another, not only with respect to beings ther” selves, but also to their organs—no new organ being pro duced without a gradual approach to it; so that scarce any change takes place that is violent. and unexpecl? ; and for which the way is not prepared by intermedia? gradations. And when you further consider, that ever being, with its every organ, is exactly fitted for its fune” tions; and that every being has an office assigned, up?” the due execution of which the welfare, in certain ii spects, of this whole system depends, you will clea perceive that this whole plan, intire in all its parts, mus have been coeval with the Creation; and that ale x 3 oe Š A species,—subject to those variations only that climé EXTERNAL ANATOMY OF INSECTS. 475 and a: erat 5 ud different food produce,—have remained essentially “same, or they would not have answered the end for “hich they were made, from that time to this. Having given you this particular account of the trophi an organs of the mouth of insects, I must now make some A servations upon the other parts of the head. I have “vided it, as you see in the Table, into face and subface ; € former including its upper and the latter its lower “itface, Strictly speaking, some parts of the face, as the Mples and cheeks, are common to both surfaces; but do not therefore reckon them as belonging to the sub- 3N which, exclusive of the mouth and its organs, con- Sts Only of the throat, and where there is a neck, the Sula, i, Nasus*.—I shall consider the parts of the face in the ‘er in which they stand in the Table, beginning with € asus or nose. Fabricius has denominated this part : clypeus, in which he has been followed by most mo- M Entomologists. You may therefore think, perhaps, “t Ihave here unnecessarily altered a term so gene- y adopted, and expect that I assign some sufficient “sons for such a change. I have before hinted that , ee is good ground for thinking that the’ sense of smell sects resides somewhere in the vicinity of this part; d when I come to treat of their senses, I shall produce: „ge those arguments that have induced me to adopt 'S Opinion: and if I can make out this satisfactorily, U wil] readily allow the propriety of the denomination. th shal] here only state those secondary reasons for the 4 Praves VI. VI. XXVII- a. 476 EXTERNAL ANATOMY OF INSECTS. term, which, in my idea, prove that it is much mor? ig the purpose than clypeus. This last word was originally applied by Linné in a metaphorical sense to the amp fi covering of the head of the Scarabeida, and the thoracl® shield of Silpha, Cassida, Lampyris, and Blatta : in @ which cases there was a propriety in the figurative use of it, because of the resemblance of the parts so illustrate to a shield. But when Fabricius (though he sometime employs the term, as Linné did, merely for illustratio™ admitted it into his orismological table, as a term t° a present universally the anterior part of the face of inse? to which the labrum is attached (though in some a he designates the labrum itself by this name), it beca® | extremely inappropriate ; since in every case, except of the Scarabeide, the part has no pretension t° called a shield ;—so that the term is rather calculate mislead than illustrate. This impropriety seems at leng ; a he has y gr ou Ss to have struck M. Latreille, since in alate essay changed the name of this part to Epistomis, a term 5 fying the part above the mouth. But there are re exclusive of those hereafter to be produced concer? the sense of smell, which seem to me to prove that nas : oN x > * op ity? is a preferable term; not to mention its claim of prio” y O , as having been used to signify this part a century ag When we come to consider the terms for the othe! pat of the head, as Zips, jaws, tongue, eyes, temples, chee 7 Jorehead, &c. the concinnity, if I may so speak, ane. mony of our technical language, seem to require that) ; i ; ot verte’ part analogous in point of situation to the nose of ver * Organisat. Extér. des Ins. 196. b In the Transactions of the Royal Society, this part in A tessellatum is so called. xxxii. 159~, nobitl™ poor pat EXTERNAL ANATOMY OF INSECTS. Fa ra : 4 ; te animals should bear the same hame. And any per- SOn w ; ; š ; i n who had never examined an insect before, if asked O Hoji ; š 3 j Point out the nose of the animal, would immediately “st his eye upon this part: so that one of the principal 3 of imposing names upon parts—that they might be E readily known—would be attained. If it is object- È that calling a part a nose that has not the sense of ell, supposing it to be so, might lead to mistakes—I Yould answer, that this objection is not regarded as. va- “in other cases: for instance, the maxille are not ge- “erally used as jaws, and yet no one objects to the term ; sme from their situation, they evidently have an ana- ‘ Me the organs whose name they bear. But enough is subject—we will now consider the part itself. i z enable you to distinguish the nose of ineen when E separated from the rest of the face by an impressed > you must observe that it is the terminal middle part $ y Sometimes overhangs the upper-lip, and ag others “Siig in the same line with it; that on ae side of it ey the cheeks, which run from the anterior half of the Sy x the base of the mandibles. Just below the an- ‘ næ is sometimes another part distinct from the nose, ich ĮI shall soon have to mention; so that the nose ust not be regarded as reaching always nearly to the - or insertion of the antennæ, since it sometimes oC- “pies only half the space between them and the upper- P, which space is marked out by an impressed line. ùt you will not always be left at such.uncertainty when ee to ascertain the limits of the nose ; for it is in W J cases a distinct piece, separated by an elevated or pan line from the rest of the face. This separa- ls either partial or universal. Take any species of 4.78 EXTERNAL ANATOMY OF INSECTS. the genera Copris, Onitis, or Ateuchus, and you will se the nose marked out in the centre of the anterior parte the face by two elevated lines, forming nearly a triang” and bounded by the horn è. Or take a common wasp hornet, and you will find a similar space, though ap; proaching to a quadrangular figure, marked out by pressed lines*. In Rhagio and Sciara, two Dipterous gf nera, this impression is so deep as to look like a suture Between these lines, in those cases, is included what call the nose. As to substance, in general it does not | pi fer from the rest of the head; but in the Clerid@ * almost membranous. You must observe, that in all thes what at first sight appears to be the termination of i front, is not the nose, but the narrow depressed piec? that intervenes between it and the lip. With regal its clothing, it is most commonly naked, but in some 2 nera it is covered with hair; in Crabro F. often "i golden or silver pile, which imparts a singular brillian to the mouth of the insects of that genus: M. Latre supposes that the brilliant colours of the goldenw®? (Chrysis L.) may dazzle their enemies, and so prom their escape °; the brilliance of the mouth of the 6” bro may on the contrary at first dazzle their prey is i moment, so as to prevent their escape. The form ° nose, where distinct from the rest of the face, admits j several variations: thus in the Staphylinide and Cher" it is transverse and linear; in Copris it is triangular, wit the vertex of the triangle truncated; in Vespa Crabro? is subquadrate and sinuated. In many Heteromer o" a PLare XXVII. Fre. 4.a. b Pare VIL Fic. 7 * © Observ. Nouv. sur les Hyménoptéres (Ann. du Mus.) 5- EXTERNAL ANATOMY OF INSECTS. 479 beetles a it is rounded posteriorly: in Pelecotma, a new Senus in this tribe, related to Aszda, there is a deep an- terior sinus; in Blaps the anterior margin is concave; N Cetonia? Brownii, and atropunctata (forming a distinct “bgenus), it is bifid: it varies in the Scarabeide, in Some being bidentate, in others quadridentate, and in thers again sexdentate, including the cheeks: in Myla- bris, a kind of blister-beetle, it is transverse and nearly Oval; in Lamia, acapricorn-beetle, it represents a paral- Slogram; and in most Orthoptera it is oxbicular: in Tet- tigonia F, itis prominent, transversely furrowed, and di~ vided by a longitudinal channel: in Otiocerus K. it pre- ents the longitudinal section of a cone °: in the Diptera "der, with the exception of the Tipulide and some Others, i in which it unites with the cheeks, &c. to form a ostrum, the nose in general, as to form, answers to its “ane, resembling that of many of the Mammalia: in ‘Ome of the Asilid@ it is very tumid at the end, and ter- Minates in a sinus, to permit the passage of the proboscis and fro: in many of the Syrphide, &c. it is first flat ‘nd depressed, and then is suddenly elevated, so as to Sive the animal’s head the air of that of a monkey: in Some tribes, as Rhingia, Nemotelus, Eristalis, &c., in. “onjunction with the cheeks it forms a conical rostrum: i Tabanus bovinus, and other horse-flies, it terminates A three angles or teeth. Many more forms might be Mentioned, but these will suffice to give you a general ‘dea of them. In size and proportions the nose also va- i * Those beetles whose'posterior pair of tarsi have only four joints, the two anterior five, are so called. ; Kirby in Linn. Trans. xii. 464. t. xxiii. f. 6. Ibid. xii. z, i. f. 1.6. 480 EXTERNAL ANATOMY OF INSECTS. ries. It is frequently, as in Tettigonia, the most consp cuous part of the face, both for size and characters; but cely in the Staphylinide it is very small, and often scar ne discernible, being overshadowed by its ample front: 4 it may be observed in general, that when the antenn? approximate the mouth, as in this genus and many other® the front becomes ample, and the nose is reduced tO a minimum : but when they are distant from the mouth, ° reverse takes place; and the nose is at its maximum apt the front at its minimum. Mutilla, Myrmecodes, Scolt4s Bee aD P in the Hymenoptera, are an example of the former; the Pompilidæ, Sphecidæ, Vespidæ, &e. of the latter Myopa buccata, &c. its length exceeds its width; but mor commonly the reverse takes place. The circumscription 7 the nose also deserves attention. Itis usually terminate behind by the front ( frons), or, where it exists, by the pos nasus, in the sides by the cheeks, and anteriorly by the! ji brum. But this is not invariably the case; for in the Cim” cide, in which the cheeks form the bed of the Promus” the front embraces it on each side by means of two Jate? processes, that sometimes meet or lap over each othe anteriorly, which gives the nose the appearance of peing insulated ; but it really dips below these lobes to join the labrum. This structure you may see in Edessa F. o many other bugs. This part sometimes has its arms: Thus in Copris, and many Dynastide, the horns or head seem, in part at least, to belong to this portio” : it; in Tipula oleracea (the crane-fly), &c. it terminate? before in a horizontal mucro. In Osmia cornuta, & kin of wild-bee, each side of the nose is armed with @ Hes tical horn. The margin of the nose in most Lamellico™ insects, though mostly level, curves upwards. EXTERNAL ANATOMY OF INSECTS. 481 ; Tam next to mention a part of the nose which me- “its a distinct name and notice, which I conceive in some Sort to be analogous to the nostrils of quadrupeds, and Which I have therefore named the Rhinarium or nostril- Piece, Thad originally distinguished it by the plural term “ares, nostrils; but as it is usually a single piece, I thought t best to denote it by one in the singular. When I Meat of the senses of insects, I shall give you my reasons, aS Ihave before said, for considering this part as the gan of scent, or connected with it, which you will then 3 able to appreciate. I shall only here observe, that the Piece in question is in the usual situation of the nostrils between the nose and the lip. In a large number of Dsects this part may be regarded as nearly obfolete ; X at least it is merely represented by the very narrow membranous line that intervenes between the nose and € lip and connects them; which, as in the case of the “ad of Harpali before noticed, may be capable of ten- ‘on and relaxation, and so present a greater surface to t : ; “action of the atmosphere. But I offer this as mere “Necture. In the lady-bird (Coccinella) this line is a i : as ee: y ttle wider, and becomes a distinct Rhinarium; as it Oey also in Geotrupes. With respect to its insertion, © thinarium is a piece that either entirely separates © nose from the lip, or only partially: the former is the Most common structure. It is particularly remark- le in a New Holland genus of chafers ( Anoplognathus ach), In A. viridiencus it is very ample, and forms . © Under side of the recurved nose, so that a large space “tervenes between the margin of the latter and the base a the labrum. Yn Macropus Thunb., of the Capricorn "be (Cerambyx L.), the nostril-piece, which forms a YOu. rr, 2Y 482 EXTERNAL ANATOMY OF INSECTS. distinct segment, is narrower than the nose, and the upper-lip than the nostril-piece, forming as it were i triple gradation from the front to the mouth. Again, ” others the part in question is received into a sinus of the nose. This is the case with the dragon-flies (Libellulina) in which this sinus is very wide; in the burying-bee™ (Necrophorus) *, in some species of which it is deep bu narrow; and in a species of Tenebrio from New Hollan® . which perhaps would make a subgenus. If you examin? with a common glass any of the larger rove-beetles (S i phylinide), you will find that the nose itself seems lost 1? the nostril-piece, both together forming a very nart? line across the head above the labrum, without any x parent distinction between them; but if you have recou!” to a higher magnifier, you will find this divided ivt? f upper and lower part, the former of the hard substan” of the rest of the head, and the latter membranoU* once was of opinion that the prominent transversely 2 rowed part, so conspicuous in the face of Tettigonia ~* was the front: but upon considering the situation of th chiefly below the eyes and antennz, and comparing 3 with the analogous piece in Fulgora laternaria and ote insects of the Homopterous section of the Hemipter™ me ; the incline to think that it represents the nose, at longitudinal ridge below it is the nostril-piece °- A Heteropterous section it is merely the vertical term” i tion of their narrow nose. In other insects agai” i part approaches in some measure to the common idea nostrils; there being fwo, either one on each side | nose, or two approximated ones. If you catch the + humble-bee that you see busy upon a flowers you 2 a Prate VI, Fic. 10. 2’. b Ibid. Fie. 7.a. e [hid 8° EXTERNAL ANATOMY OF INSECTS. 483 discover a minute membranous protuberance under each Moe 5 in le of the nose. Something similar may be observed . Some species of Asilus L. In the Orthoptera, espe- “ally in Blatta, Phasma, and some Locuste, two roundish or Square pieces, close to each other on the lower part of the hose, represent the nostrils *-—With regard to Mbstance, in the chafer-tribes, at least those that feed n leaves or living vegetable matter, as the Melolon- ide, Anoplognathide, and in many other insects, the $ narium is of the same substance with the rest of the “ad; but in Macropus Thunb., Staphylinus, Necrophorus, P It consists of membrane. i. Postnasus *,—This is a part that appears to have Ny confounded by Entomologists with the front of in- tS; in general, indeed, it may be regarded as included the hose, and does not require separate notice: but STe are many cases in which it is distinctly marked out . Set by itself; and in which it forms a useful diagno- Fot genera or subgenera. There is a very splendid beautiful Chinese beetle, to be seen in most collec- lo ee SA j ‘ $ p As of foreign insects (Sagra purpurea), in which this a "t forms a striking feature, and helps to distinguish the Pus from its near neighbour Donacia. If you examine ace, you will discover a triangular piece, below the tennæ and above the nasus, separated from the latter from the front by a deeply-impressed line: this is the S nasus or after-nose. Again: if you examine any spe- ae sE a Hymenopterous genus called by Fabricius ba on (Hyleus Latr.), vémarkable for its scent of > Jou will find a similar triangle marked out in a a a Prave VI. Fre. 4, g. b-Prates VE. VIL b. 48A EXTERNAL ANATOMY OF INSECTS. similar situation è. In many Coleopterous insects, besides Sagra, you will discover traces of the part we are const dering: as in Anthia, Dytiscus, and several others of the Predaceous beetles. In Cis¢ela it is larger than the nos? itself; but it is more conspicuous in the Orthopter@ yo ticularly in Locusta (Gryllus F.), in which it is the space below the antennee, distinguished by two or four ratb” diverging ridges*. In the Libellulina, Myrmeleont™™ &e. it is a distinct transverse piece. In Dasyg@ Latt” a kind of bee, itis armed with a transverse ridge of hom —But enough has been said to render you acquaint with it; I shall therefore proceed to the next piece. iii. Frons*.—The Front of insects may be deno” nated the middle part of the face between the ey” bounded anteriorly by the nose, or after-nose, where ; exists, and the cheeks; laterally by the eyes; and y riorly by the vertex. Speaking properly, it is the reg of the antenne; though when these organs are p ace before the eyes, under the margin of the nose, as 2 may Lamellicorn and Heteromerous beetles, they see™ es rather nasal than frontal. ‘This part is often elevat” as in the elastic beetles (Elater), whose faculty of J! if ing, by means of a pectoral spring, has been relatet 5 you. In Anthia, a Predaceous beetle, it has often t jes longitudinal ridges. In many of the Capricor® | + (Cerambyx L.), it is nearly in the shape of a OA a cross, with the arms forming an obtuse angle, an tb # terminating at the sinus of the eyes in an elevatio” the site of the antennæ. In the ants also (Formit! a Kirby Mon. Ap. Angl. i. t. i. Melitta. *. b. f. 3- b Prare VI. Fra. 4. b. i Prares VER oe 4 Vor. H. p. 317—. EXTERNAL ANATOMY OF INSECTS. 485 the front is often elevated between those organs. In Onera, one tribe of them, this elevation is bilobed, ad receives between its lobes the vertex of the post- nasus, In the hornet (Vespa Crabro) the elevation is a Mangle, with its vertex towards the mouth. -In Sagra s is marked out into three triangles, the postnasus mak- Ng a fourth, with the vertexes meeting in the centre. a the Dynastide and Scar abeide the horns are often f Ontal appendages, as is that of Empusa Latr., a leaf- insect, and probably those of Sphinx Tatrophæ F., which affords a singular instance of a horned Lepidopterous one. Sometimes it is an ample space, reducing the nose to a Very narrow line, as in the Staphylinida, or sending lorth a lobe on each side, as before mentioned, which “braces the nose. In a species of bug from Brazil, re- ated to Aradus F., these lobes are dilated, foliaceous, “td meet before the nose, so as to form a remarkable “Xtended frontlet to the head. In others this part is ex- tremely minute: thus in many male flies and other in- Sects, as the Libellulina, where the eyes touch each other, the front is cut off from the vertex and reduced to a small mgle, In the female flies the communication with the ver- tex is kept open, and the front consequently longer. In the horse-flies (Tabanide), in Hematopota, and Hepta- ime, the frontal space is wider than in the rest of that tribe, Many of these are distinguished by a levigated area behind the antenne in the part we are treating of. athe Libellulina, and in the drone-bee, whose eyes are “onfluent, the stemmata are in the front. In many Or- °ptera also, as Locusta Leach, one of them is below ‘€ antennæ; and in the lanthorn-fly tribe (Fulgoride), oth these organs, which are situate between them and 486 EXTERNAL ANATOMY OF INSECTS. the eyes, as they do also in Truxalis, appear to be in ita. In this tribe the rostrum is an elongation of the part in question; and perhaps you would think at first that what I have considered as the nose in Tettigonia x was also a tendency to this kind of rostrum; but if you examine the great lanthorn-fly (Fulgora laternaria)s yo will find besides, at the lower base of the lanthorn, a tri- angular piece analogous to the nose of T ettigonid, 2 below it another representing its nostril-piece:—the how zontal part of the nose in that genus may perhaps þes garded as part of the front. In Truxalis F. the face consists of a supine and prone surface, and the latte? j composed of the front, after-nose, nose, and organs of the mouth. I may notice here a most remarkable and sing™ lar tribe of bugs, of which two species have been figure by Stoll»: in these the head, or rather those parts of it that we have now been describing, the nose, namely, the after” nose, and front, are absolutely divided longitudinally z n its two, each half having an eye and antenna planted i or perhaps, as it is stated to be divided in one instanc? r the commencement of the promuscis, the nose is left 10 tire, and dips down, as in cases before alluded to: s0 that in this the nose appears to leave the lobes of the front, which in others embrace its sides. iv. Vertex *.—We now come to the vertex, OY crow? of the head; which is situated behind the front, 2’ except where the communication is intercepted by gP fluent eyes, adjoins it. It is laterally bounded by the hind part of the eyes and the temples; and posteriorly 4 Prate XXVI. Fie. 41. i. b Stoll Punaises, t. xxxix. f. 279, 280. °-Prares VEVI EXV d. pæ EXTERNAL ANATOMY OF INSECTS. 487 Where that part exists, by the occiput. The vertex may be denominated the ordinary region of the stemmata : for though in several cases, as we have just seen, one or More of them are planted in the front; yet this in the great Majority, especially in the Hymenoptera, is their natural Station, In Blatta and some other Orthoptera the poste- Nor angle of the head is the vertex. In many dung- Chafers of Latreille’s genus Onthophagus, which are said to have occipital horns, as O. nutans, nuchicornis, Xi- Phias, &c., the horn really arms the part I regard as the Vertex, In Locusta Leach, this part is very ample, and ù Truxalis very long; but more generally. it is small, aad not requiring particular notice. V. Occiput?.—The occiput, or hind-head, is that part of the face that either forms an angle with the vertex Posteriorly, or slopes downwards from it. It has for its lateral boundaries the temples, and behind it is either terminated by the orifice of the head, or in many cases by the neck. In those beetles that have no neck, as the Lamellicorn and Capricorn, the hind-head is merely a de- clivity from the vertex, usually concealed by the shield of the thorax, very lubricous, to facilitate its motion in the Cavity of that part, and at its posterior margin distin- Suished by one or two notches, which I shall notice ‘ereafter, for the attachment of the levator muscles: but those beetles or other insects that have a neck, or a Versatile head, the occiput forms an angle with the vertex, often rounded, and sometimes acute. This structure may € seen in Latreilles Trachelides, and several other bee- tles, In the Hymenoptera, Diptera, and others with a 4 Prares VI. VIL. e. 488 EXTERNAL ANATOMY OF INSECTS. versatile head, the part now under consideration curve side inwards from the vertical line, so as with the temples and under parts of the head to form a concavity adapted to its movement upon the trunk. vi. Gene *.—The cheeks of insects (Gene) usually SY round the anterior part of the eyes, and lie between them and the mandibles or their representatives. Where they approach the latter, as in the Predaceous beetles (Cie dela, Carabus L. &c.), they are very short, and of cours? longer where the eyes are further removed from the mouth; as in the Rhyncophorous beetles (Curculio L.) where they form the sides of the rostrum, and often C0” tain a channel which receives the first joint of the ante™ næ, when they are unemployed. In the Scarabaide a9“ many other Lamellicorn beetles, their separation on eat” side from the nose is marked by a ridge?; and in the wasps (Vespa) by an impressed line or channel. M 5 African tribe at present arranged with Cetonia Ea which C. bicornis Latr. and another, which he has name? I believe, C. vitticollis, belong, the cheeks are porrecté on each side of the mouth into a horizontal horn. The? horns have at first the aspect of a pair of open mandible* In the magnificent Goliathi Lam., the horns of the male -are rather a process of the cheek than of the nose. ~ Alurnus, Hispa, and other beetles, these parts, by thet elevation and conjunction with the lower side of the head, form a kind of fence which surrounds and protec the oral organs; in many Cimicide, by a similar eleva” tion of the cheeks, the bed of the promuscis is form?” 4 Prares VI. VIRE > Prater XXVII. Fic. 4+ f E = : n eee © Cuy. Regne Animal. i, t. xiii f: 4. EXTERNAL ANATOMY OF INSECTS. 489 ln the Homopterous Hemiptera they run parallel nearly e the rhinarium or nostril-piece. In the Hymenoptera they are almost always ample, but they are confined to © lower side of the eye. In Sirex Gigas, and others of at genus, the cheek at the base of the mandible is di- “ted so as to form a rounded tooth below it. In the *pricorn-beetles it is considerable, and sometimes ter- Minates, at the base of the mandible, in two or three S In Scaurus and Eurychora, darkling-beetles, € cheek below projects into a lobe that covers the base “the marilla. But the animal distinguished by the "0st remarkable cheeks is a species of Phryganea L. lrysanea personata Spence); for from this part pro- lets a spoon-shaped process, which curves upwards, and Miting with that of the other cheek, forms an ample mask hre the face, the anterior and upper margin of which, ™ the j insect’s natural state, are closely united; and the Posterior part being applied to the anterior part of the 5 Causes the face to appear much swoln. It looks as Nit was a single piece; but upon pressing the thorax if ‘Pens, both above and in fr ont, into two parts, each con- ĉX without and hollow within, and each having attached ° its Inside a yellow tuft of hair resembling a feather. € use of this machinery at present remains a my- tery a Tempora ?.—The temples (Tempora) are merely čontinuation of the cheeks to the posterior limit of the 5 D his j insect was taken both at Matlock and Exmouth. The body Ad thighs are of a light-brown, wings testaceous, legs pale ; antennæ hives setaceous and filiform, two-thirds the length of the body ; : t joing not much — than the rest. Prares VI, VIL. 4.90 EXTERNAL ANATOMY OF INSECTS. head, forming its sides and posterior angles, and includ ing the hinder part of the eyes, the vertex, and the oct put. They seldom exhibit any tangible character, & : . ‘ f -. ange cept in certain ants (Atta Latr.), in which then on anr ge fa) jnt, terminates in one or two strong spines, giving the mal a most ferocious aspect; and in that remarkable nus Corydalis they are armed below with a tooth ot p° which was not overlooked by De Geer *. Bay ° - z „o5 viii. Oculi »,—I must now call your attention to ors ‘ ; TE na of more importance and interest, and which indeed f 0 clude a world of wonders: I mean the eyes (Oculi) insects. These differ widely from those of yertebt" animals, being incapable of motion. They may pe *” garded as of three descriptions—simple, conglomer@ and. compound. o the? 1. Simple Eyes‘. We will consider them as t > : oy aD number, structure, shape, colour, magnitude, situation * arrangement. és ° en ep As to their number, they vary from two to sixt? ; „m In the flea, the louse, the harvest-man (Phalang there are only a pair; in the bird-louse of the go : : A (Nirmus Anseris), and probably in others of the “7 genus, there are four*; in some spiders (Scytodes, f e dera, and Segestria Latr. €), and some scorpions f, , en ‘ y mor are siz. In the majority of spiders and Scolopendra ys a De Geer iii. 561. t. xxvii. fil. > Prarzs VI. VIIL. pee 3 ¢ Prare VIL Fre. 8,9. XXVI. Fre. 43. h. a Viz. one on each side above, and one below. e Walckenaer Aranéides, t. v. f. 50, 52. t. viii f. 82. ool £ Treviranus (Arachnid. 4.) says that Scorpio Europeus ne eso" two eyes. He appears to have overlooked the two on the 2 jarge side of a tubercle at each angle of the head, where they an ' but not conspicuous, at least in my specimen. n EXTERNAL ANATOMY OF INSECTS. 491 Sit ee “ns, Scorpio maurus, &c. there are eight ; and in Po- “ra and Sminthurus Latr. there are sixteen *. As to their structure, nothing seems to have been ascer- ained; probably their organization does not materially fer from that of one of the lenses of a compound eye; Which I shall soon explain to you. Their colour in the many is black and shining, but in € bird-louse of the goose they are quite white and 'ansparent. In spiders they are often of a sapphirine “our, and clear as crystal. In Scolopendra morsitans Many spiders, scorpions, and phalangia?, they ap- “& to consist of iris and pupil, which gives them a Ee glare, the centre of the eye being dark and the teumference paler. In the celebrated Tarantula (Ly- "Osa Tarantula), the pupil is transparent, and red as a Y; and the iris more opaque, paler, and nearly the Sur of amber. here there are more than two, they vary in magni- « € In the enormous bird-spider (Mygale avicularia) the io ur external eyes are larger than the four internal ‘; Ut ‘in the Tarantula and Sphasus, the two or four inter- al are the largest. In Clubiona and Drassus they are all “arly of the same size?; and in the Micrommata family “Y are very small °. hey vary also in shape. In Scolopendra morsitans the tee anterior ones are round, and the posterior one “sverse, and somewhat triangular. In Mygale cal- “ana, a spider, the two smallest are round and the rest , De Geer vii. £, Lf, 8,9, 12. a VATE XXVI. Fie. 43. h. © Walck. Aran. t.i. f. 3. bid. t. v, f, 42—48. © Thid. iiv. f, 4l. 492 EXTERNAL ANATOMY OF INSECTS. oval?. In the trapdoor or mason spider ( Mygale p : : ( mentaria), the four small internal ones are round, 4” the large external ones oval®; and those that are or cumscribed posteriorly with an impressed semicircle, af shaped like the moon when gibbous €. The situation and arrangement of simple eyes 3f? alse various. In many they are imbedded, as usual, int head; but in the little scarlet mite, formerly notice ’ (Trombidium holosericeum), they stand upon a small foot stalk ¢: the hairiness of this animal might otherwise hate impeded its sight. In spiders they are planted oP o4 back of the part that represents the head, sometimes ol! on a central elevation or tubercle, and the remain? ag” as four below it—as in Lycosa; sometimes the whole are on a tubercle, as in Mygale; and sometimes, the common garden-spider (Epeira Diadema) up a three tubercles, four on the central one and two O” e f of the lateral ones. Other variations in this respect wig Þe named in this tribe. In the scorpions a pair are plac? one on each side, on a dorsal tubercle, and the othe" ; 5 or six on two lateral ones of the anterior part ° “ head‘. In the Phalangide the frontal eyes of the A f pion cease, and only a pair of dorsal ones are inse" - : ae vertically in the sides of a horn or tubercle, eithe! „h rps noe er oy of or simple, often itself standing upon an elevatio emerges from the back of the animal. If th were not in a vertical and elevated position, the sig” a Walck. Aran. t. i. f. 2. b Thid. t. i. f 7. Ibid. t. ti. f. 18, 20. a Vor. I. p- 323. ie De Geer vii. 138. tf. viii. f. 15. yy. f Ibid.ż. x1. f- 3.008 Prats XXVI. Fic. 43. h. EXTERNAL ANATOMY OF INSECTS. 4.93 t * Ba. hese insects would be very limited; but by means of the s : tructure just stated, they get a considerable range of sur- t ASTAR F °unding objects, as well as of those above them. With Bars. . “gard to the arrangement of the eyes we are consider- S 3 Do.: : i ao it varies much. Sometimes they are placed nearly E the segment of a circle, as in those spiders that have = eyes only, before noticed *; sometimes in two straight ‘hes b, at others in two segments of a circle °; at others, three lines4, and at others in four*®. Again, in some Nstances they form a cross, or two triangles f; in others, Wo squares; in others, a smaller square included in a alge onet; in others, a posterior square and two anterior Maneles i; sometimes a square and two lines. Though Scherally separate from each other, in several cases two “ the eyes touch *; and in one instance three coalesce uto a triangle!. But it would be endless to mention all the Variations, as to arrangement, in the eyes of spi- ders, 2. Conglomerate Eyes™ differ in nothing from simple “Yes, except that instead of being dispersed they are col- *tted into a body, so as at first sight to exhibit the ap- Pearance of a compound eye :—they are, however, not ‘CXagonal, and are generally convex. They occur in : Segestria perfida, Walck. Aran. t. v. f. 52. &e. Tetragnatha and Latrodectes, Ibid. t. vii. f. 64. and #. ix. f. 84. : Nyssus coloripes, Ibid. t. vi. f. 58. Dolomeda, Ibid. t. i. f. 18, 20. ` Sphasus, Ibid. t. iii. f. 24. à Mygale avicularia, Ibid. t.i. f. 3. Sparasus, Ibid. t. iv. f.41. Puate XXVI. Fie. 37. Evesus, Ibid. t. iü. f. 26. i Storena, Ibid. t. ix. f. 86. ` Argyroneta, Ibid. f. 88. 1 Pholcus, Ibid. t. viii. f. 80. Prare XIII. Fic. 11. 494 EXTERNAL ANATOMY OF INSECTS. Lepisma, the Tulidæ, and several of the Scolopendrid@: In Scolopendra forficata the eye consists of about twenty contiguous, circular, pellucid lenses, arranged in five lines, with another larger behind them, as a sentinel 0 scout, placed at some little distance from the main body: In the common millepede (Tulus terrestris) there uw twenty-eight of these eyes, placed in seven rows, ®” forming a triangle, thus —the posterior row con taining seven lenses, the next six, and so on, gradually losing one, till the last terminates in unity. Each ° these lenses is umbilicated, or marked with a central de- pression. In Craspedosoma Leach, you will find a simila” formation. In Glomeris zonata, a kind of wood-lous? that rolls itself into a ball, the lenses are arranged in ? line curved at the lower end, with a single one by 1% at the posterior end on the outside; they are oblong ®” set transversely, and their white hue and transparent give them the appearance ofso many minute gems, esp? cially as contrasted with the black colour of the animal” Between these eyes and the antenne is another trans verse linear white body, but opaque, seemingly set in ? socket, and surrounded by a white elevated line, like the bezel of a ring. Whether it is an eye, or what orga” cannot conjecture. Its aspect is that of a spiracle. 3. Compound Eyes*.-—These are the most common kine of eye in hexapod insects, when arrived at their perfect state; in their larva state, as we have seen, their €f j being usually simple 4; except, indeed, those whose pe tamorphosis is semicomplete, which have compound ey? + Prare XXIX. Fic. 11.h. b Ibid. a. © Prare XII. Fie. 10. a See above, p. iss EXTERNAL ANATOMY OF INSECTS. 495 ‘i “very state.—In considering compound eyes, I shall j vert to their structure, number, situation, figure, cloth- "E, colour, and size. As to their structure, —when seen under the microscope €Y appear to consist usually ofan infinite number of con- et hexagonal pieces. If you examine with a good glass “eye of any fly, you will find it traversed by numberless Parallel lines, with others equally numerous cutting them ‘ng tight angles, so as apparently to form myriads of little “ares, with each a lens of the above figure set in it. The ‘ame structure, though often not so easily seen, obtains in |“ €yes of Coleoptera and other insects. When the eye $ Separated and made clean, these hexagons are as clear 3 Crystal. Reaumur fitted one eye to a lens, and could ‘ee through it well, but objects were greatly multiplied*. j Coleopterous insects they are of a hard and horny “Ubstance ; but in Diptera, &c. more soft and membra- "ous, The number of lenses in an eye varies in different sects, Hooke computed those in the eye of a horse- J to amount to nearly 7,000; Leeuwenhoeck found More than 12,000 in that of a dragon-fly°; and 17,325 *ve been counted in that of a butterfly¢. But of all in- ‘ects they seem to be most numerous in the beetles of t W., S. MacLeay’s genus Dynastes. In the eyes of these the lenses are so small as not to be easily discover- “Ole even under a pocket microscope, except the eye has "ned white¢: it is not, therefore, wonderful, that Fabri- Reaum, iv. 245. b Microgr. 176. _ Epist. Mar. 6. 1717. à Ameen. Academ. vii. 141. . Possess a specimen in which the eye is partly black and partly : the lenses are invisible in the dlack part, but very visible in White, 4.96 EXTERNAL ANATOMY OF INSECTS. f ; ; v- cius should call these eyes simple 2. In some insects, hor not Bw ever, as in the Strepsiptera Kirby, the lenses are i re € Ir merous: in Xenos they do not exceed fifty, and a . . ei = : p stinctly visible to the naked eye”. These lenses vary! : i ; ; ; : € magnitude, not only in different, but sometimes m th Ga : e same eyes. ‘This is the case in those of male horse- # ) nue and flies, those of the upper part of the eye being 6 tha larger than those of the lower’. The partitions separate the lenses, or rather bezels, in which they are are very visible in the eyes just mentioned, and thos? 7 iple #* pse” gis set Xenos; but in many insects they are only discern the intersecting lines of separation between the le In hairy eyes, such as those of the hive-bee, the h emerge from these septa. Every single lens of a com : av pound eye may be considered as a cornea, or a ery" uhi ith the line humour, it being convex without and concave w but thicker in the middle than at the margin: it I5 only transparent part to be found in these most rema able eyes. Immediately under the cornea is an opad” varnish, varying according to the species, which pr “duces sometimes in one and the same eye spots OY ba? Y of different colours. These spots and bands form ® stinguishing ornament of many of the Tabani and % r ; X i : s 167 flies. And to this varnish the lace-winged flies (He robius, &c.) are indebted for the beautiful metallic j : that often adorn them. When insects are dead, ef ur pitt varnish frequently loses its colour, and the ey° ; 7 : . 3 > 0 white: hence many species are described as having . “tell eyes which when alive had black ones. The consiste 2 Philos. Entomolog. 19. b Phare XXVI. Frc- 38. e Hooke Microgr. schem, xxiv. EXTERNAL ANATOMY OF INSECTS. 497 £ this Covering is the same with that of the varnish of i © choroid in the eyes of vertebrate animals; but it en- ely covers the underside of the lens, without leaving acl Passage for the light. Below this varnish there are Numbers of short white hexagonal prisms +, every one of Meh enters: the concavity of one of the lenses of the Minea, and is only separated from it by the varnish just “scribed: this may be considered as the retina of the Ms to which it is attached ; but at present it has not been “early explained how the light can act upon a retina of ag description through an opaque varnish. Below this Multitude of threads (for such the bodies appear), per- N üdicular to the cornea, is a membrane which serves m all for a base, and which consequently is nearly pa- “el with that part. Itis very thin, of a black colour, t produced by a varnish; and in it may be seen very “White ¢rachee, which send forth branches still finer, at penetrate between the prisms of the cornea: this k “brane may be called the choroid. Behind this is a h €xpansion of the optic nerve, which is a true nerv-- : S Membrane, precisely similar to the retina of red- “ded animals. It appears that the white pyramidal "ads which form the retina of each lens are sent forth y Te general retina, and pierce the choroid oy a oum t 4 almost imperceptible ai b, From this ss Son that the eyes * ae — apt cor- brate ng with the uvea or humours ° tioa of verte- animals, but are of a type peculiar to themselves. aving explained to you the wonderful and complex a p b ATE XXIII Fie. 3. Vat Yoa Anat. Compar. ii, 442—. Compare Swammerdam Bibl. 2 ic 498 EXTERNAL ANATOMY OF INSECTS. : ae oe ic structure with which it has pleased the CREATOR to > g5) O stinguish the organs of vision of these minute being? proving, what I have so often asserted, that when 4°" mals seem approaching to nonentity, where one wou expect them to be most szmple, we find them in ™@ ny cases most complex, I shall now call your attention t° a next thing I am to consider—the number of the ey? J question. Most insects have only #wo; but there are ik veral exceptions to this rule. Those that have occas to see both above and below the head, the eyes ° = being immovable, must have them so placed as to enab them to do this. This end is accomplished in ma y &Cs beetles, for instance Scarabeus L., Heleus Latr., We sot having these organs fixed in the side of the head, : e part looks upward and part downward; but in 0f 5 four are given for this purpose. If you examine oa common whirlwig (Gyrinus Natator) that I have so 0 4 mentioned ?, which has occasion, at the same tune j observe objects in the air and in the water, you wil t itis gifted with this number of eyes. Lamia Torn (Cerambyx tetrophthalmus Forst.) and some othe! ye which I make a genus, under the appellation © trops, are also so distinguished. In these insec eye is above and the other below the base of the ante | næ; in fact, in these the canthus, instead of dividing ite op? 5 S k u eye partially, as in the other Capricorn-beetles, runs 4 # through it at considerable width®. In Ryssonotus ae @ Vor, II. p. 4, 364, &c: b Prate XXVI. Fic. 36. h. Fabricius, and after him ee of” though both quote Forster, regard one of these eyes in ammi . nator as a spot; but they could not haye examined it attent Saperda præusta F. has also four eyes. EXTERNAL ANATOMY OF INSECTS. 4.99 Leay (Lucanus nebulosus K.) the eye appears also to be tivided in two by the canthus. In the Neuroptera Order ‘ere is more than one instance of the same kind. In Ascalanhus there are two considerable eyes on each side the head, which, though clearly distinct, meet like “se of many male flies and the drone. The male, like- “ise, of more than one species of Hphemera, besides the tommon lateral eyes and the stemmata on the back of € head, have a pair of compound eyes on the top of a “ort columnar process è. In the Hemiptera Order, also, "instance occurs of four eyes in the genus Aleyrodes”. Mongst the vertebrate animals, there is an example of Ves with two pupils in Anableps, a genus of fishes ©, but EE biac aaa his Jour of these organs. That y insects should have more than zwo eyes, will not em to you so extraordinary as that any should be found ; àt, like the Cyclops of old, have only one. There is, OWever, an insect, before celebrated for its agility 4 “chilis polypoda Latr.), which has a single eye in its 'reheaq ; or we may say, its eyes are confluent, without y line of distinction between them except a small notch “ind. Now that I am treating of the number of eyes, Must not forget to observe to you, that in some insects ” €yes at all have been discovered. In Polydesmus com- Mamata, on each side of the head there is an eye-shaped hee separated by a suture, in which under a power- Min I cannot satisfy myself tiat 5 = discern any Se 8 like the facets that usually distinguish compound * Th Geophilus electricus, another myriapod, they Pre XXVI. Fre. 39. h. ; 4 “treille Gen. Crust, et Ins. iii. 73. © N. Dict, d Hist. Nat. i, 479. or. TI, 320, 500 EXTERNAL ANATOMY OF INSECTS. certainly do not exist*. Whence we may conclude, * was before observed», that the faculty of emitting light is rather given it as a means of defence than to guide i in its path. The situation of compound eyes differs in differen! tribes. In some, as in the Staphylinida, they are plante laterally in the anterior part of the head; in others, * Carabi &c., in the middle; in others again, Locust? Leach &c., in the posterior part. In some, their statio” is more in the upper surface, either before or behind; a that a very narrow space separates them, or perhaps no” at all. Instances of this position of the eyes occu" W minute weevil (Ramphus Clairv.*), and many pipter &e. Of those that form an union on the top of the hea” some are placed obliquely, so as to leave a divers?” space below them, as in many Lzbellulina d. the drone ’ &e. Others, as Atractocerus, in which the eyes occu}: pis nearly the whole head, and unite anteriorly, have iF diverging space above their conflux. In Rhina barb a stris Latr., another kind of weevil, they are con ue" below the head, at the base of the rostrum, and 2 ve) wor narrow interval separates them above. In a large A ber of the Heteromerous beetles, they are set ransoer h ; in the Capricorn ones longitudinally. Their sur” when they are lateral, has usually two aspects, one?” i to see below, the other supine to see above. In gone the eyes are situated behind the antennæ, so that i position, whether it shall be anterior or posterio”’ m pends upon that of those organs. Often, indeed 9” a De Geer vii. 562. b Vor. II. p.228. © Ent. Heivet. i. t. xil. a Prats VI, Fre. 10. © Kirby Mon. Ap. Angl. i. t. xi. Apis. **. e. 1. f. 2. EXTERNAL ANATOMY OF INSECTS. 501 the last-named beetles, part of the eye is behind and part lore the antenna; but except where there are four “yes, asin Tetrops, they are never placed before or below them, Though the eyes of insects are generally sessile, yet to give them a wider range they are sometimes, but it rarely Occurs, placed, like those of many Crustacea, on a foot- Salk, but not a moveable one. An instance of this in cer- tain male Enhemere has already been mentioned. In the p yi emiptera De Geer has figured two species of bugs- Cimicide) that are so circumstanced*; as are also all the known Strepsiptera K., though in these the footstalk S very short®: but the most remarkable example of co- Wmnar eyes is afforded by that curious Dipterous genus iopsis, in which both eyes and antennæ stand upon a Pair of branches, vastly longer than the head, which di- Verge at a very obtuse angle from its posterior part °. Th their figure eyes vary much. Sometimes they are so Prominent as to be nearly spherical: this is the case with ‘ome aquatic bugs, as Ranatra, Hydrometra, and several Male Ephemere*.. Very often they are hemispherical, as in the tiger-beetles (Cicindela L.), and the clocks or dors Carabus L. ); but in a large number of insects they are at, and do not rise above the surface of the head.— ith regard to their outline, they are often perfectly round, as in many weevils; oval, as in various bees; 3 De Geer iii. £. xxxiv. Ff. 17, 18, 24. 00. F ips Ap. Angl. i, t. xiv. no. 11. f. 1. f. Linn. Trans, xi. t. ix. Py, Late XIII. Fic. 9. Pobsily Archiv. t. vi. f jg Pellenberg Cimices t. xiii. ix. f.l. a. De Geer ii. ż¿ xvii. 502 EXTERNAL ANATOMY OF INSECTS. ovate, as in other bees (Andrena F.); triangular, as in the water-boatman (Notonecta). They are also often oblong? and occasionally narrow and Jinear; as in that singt lar beetle Helæus. In many of the Muscidæ they for nearly a semicircle, or rather, perhaps, the quadrant ° P sphere. The eyes of the Capricorn-beetles (Ceramby® L have a sinus on their inner side, as it were, taken out á them; so that they more than half surround the anten næ, before which is the longest portion of them. Ap approach to this shape is more or less observed in the darkling-beetles (Tenebrio L.); but in these the sinus ” not so deep. I may under this head observe, that a those Mantide that represent dry leaves, and some othe these organs usually terminate in a spine *. Though not distinguished by the beauty and ani tion that give such interest to the eye of vertebrate ane mals, and exhibiting no trace of iris or pupil, yet fro the variety of their colours the compound eyes of insect? though most commonly black or brown, are often very striking. Look at those of one of the lace-winged flies that commit such havoc amongst the Aphides”, and" mar will dazzle you with the splendour of the purest gol : sometimes softened with a lovely green. The lenses ? those of Xenos. blaze like diamonds set in jet °. ee have often noticed the fiery eyes of many horse-fh® (Tabanus L.) with vivid bands of purple and gree? ' Others are spotted €; and Schellenberg has figured one (Thereva hemiptera)‘, that exhibits the figure of a flower a Stoll Spectres, &c. t. iv. F. 14. t. x. f. 38, &e. b Vor. I. p. 261—. © Linn. Trans. ubi supr- 4 Schellenberg Mouches, t. xxvii. f..1, 2. a, d. © Fema dk. fe 3: 8. t Ibid, t. af. 2. a. EXTERNAL ANATOMY OF INSECTS. 503 Painted in red ona black ground. These colours and Markings are all most vivid and brilliant in the living sect, and often impart that fire and animation to the “Jes for which those of the higher animals are remark- able, Take one of the large dragon-flies that you see awking about the hedges in search of prey, examine its “Yes under a lens, and you will be astonished at the bril- lance and crystalline transparency which its large eyes exhibit, and by the remarkable vision of larger hexagons ich appear in motion under the cornea, being reflect- eq by the retina—all which give it the appearance of a Ving eye. This moving reflexion of the hexagonal < “tses in living insects was noticed long since in some “es (Nomada F., Cælioxys Latr.)* ) Compound eyes differ greatly in their size. In some “sects, as Atractocerus, the drone-bee, many male Mus- “de, &c., they occupy nearly the whole of the head; ile in others, as numerous Staphylinide, Locusta fach, &c., they are so small as to be scarcely larger an some simple eyes of spiders: and they exhibit “ery intermediate difference of magnitude in different “Wes, genera, and species. Under this head I must say something of the Canthus f the eye; by which I mean an elevated process of the “eek, which in almost all the genera of the Lamellicorn etles enters the eye more or less, dividing the upper Portion from the lower. Though usually only a process of | i cheek, yet in the Scarabaide the whole of that part ams the canthus®. It only enters the eye in the Ru- lide, Cetonide, &c.; it extends through half of it in ` Mon. Ap. Angl. i. 148. b Prare XXVII. Fie. 4, h'. 504 EXTERNAL ANATOMY OF INSECTS: Copris; it goes beyond. the half in Ateuchus; and in FRYS sonotus MacLeay (Lucanus nebulosus K.) it quite divides the eye into two?, as I before observed. In Lucan Passalus &e. it projects before the eye into an angle j a Lucanus femoralis nearly into a spine; but in Lamprim and Cisalus it does not exist. The part, also, that enter” the eye in the Capricorn-beetles may be regarded as ® kind of canthus, though it is merely a dilatation of the Sront. 4, Stemmata®.—Having given so full an account ° the kinds and structure of the ordinary eyes of ae = ee e you may perhaps expect that I should now dismis5 $ : ne subject: you would, however, have great cause to blaw me, did I not make you acquainted with a kind of aa liary eyes with which a large portion of them are gifte” I mean those pellucid spots often to be found on the post rior part of the front of these animals, or upon the verte” frequently arranged in a triangle. These, Linné, fro his regardihg them as a kind of coronet, called S mata. They have been of late denominated Ocelli ; as this latter term is also in general use for the eyelets a the wings of Lepidoptera, I have adhered to that ° illustrious Swede. Neither he nor Fabricius bas e pressed any opinion as to the use of these organs? Swammerdam and Reaumur were aware that they Y real eyes. ‘The former found that there are nery diverge to them though not easily traced, and that they + at i gaa a This circumstance proves that Mr. W. S. MacLeay is co” ec fas oe k E a. r eo considering this as a subgenus; but it militates against its connected with Lamprima. v Prare VI. Fre. 4, 10. VIL Fic. 1,2, 4, XXVI Fie. 397 + a mg Ke < 42i EXTERNAL ANATOMY OF INSECTS. 505 have a cornea, and what he takes for the wvea?; and the atter has supposed that the compound eyes and these ‘tuple ones have, the one the power of magnifying ob- J€cts much, and the other but little, so that the former are for surveying those that are distant, and the latter those that are'near?. The same author relates some ex- Periments that he tried with the common hive bee, by Which he ascertained that the stemmata, as well as the “OMpound eyes, were organs of vision. He first smeared the latter over with paint, and the animals, instead of- Making for their hive, rose in the air till he lost sight of them, He next did the same with the Jormer, and placing the bees whose stemmata he had painted within a few Paces of their hive, they flew about on all sides among the neighbouring plants, but never far: he did not ob- Serve that these ever rose in the air like the others °. Yom this experiment it seems as if the compound eyes Were for horizontal sight, and the stemmata for vertical. The definition of them by Linné and Fabricius as ‘ooth, shining, elevated or hemispheric puncta, con- "es a very inadequate idea of them; for, except in a ‘ery few instances, they are perfectly clear and transpa- nt, and their appearance is precisely the same as that f the simple eyes of Arachnida &c., under which head Y might very well have been arranged; but as the last aire Primary eyes, and the stemmata secondary, it seemed t0 me best that they should stand by themselves. The Structure of both is probably the same, and their inter- Nal Organization that of one of the lenses of a compound “Ye, and both are set in a socket of the head. * Bibl. Nat. 1. 214. b Reaum. iv. 245, © Ibid, v. 287—. 506 EXTERNAL ANATOMY OF INSECTS. Though a large number of insects have them, they are by no means universal, since some Orders, as the Sere psiptera, Dermaptera, and Aptera, are altogether without them. The Coleoptera, also, have been supposed to 2% ford no instance of species furnished with them; but in the last number of Germar and Zincken Somrher’s Magas!™ it is affirmed that they are discoverable in Gravenhorst”? genus Omalium, but not in the kindred genera Micro peplus and Anthophagus?. Upon examining the forme? genus, I find, that although Omalium planum and affi- nities, O. striatulum, and some others, appear not to hav? them, yet with the aid of a good magnifier they may a discovered in most species of that genus; as likewise ” Eweesthetus Grav. I find them also very conspicuous ™ A, Caraboides and other Anthophagi, but some speci? appear to want them. In these insects they are tw° a number, situated in the vertex a little behind the eyes bu within them, and either at each end of a transverse fur¥™ or at the posterior termination of two longitudinal one” Nor are they found in all the genera of the other Or des In the Orthoptera, the Blattide, unless a white sm0° spot on the inner and upper side of the eyes may per garded as representing them, have them not; but i” al the other genera of that Order they are to be found” In the Hemiptera all the Cicadiade@ are gifted with them as are likewise Tetyra, Pentatoma, with many othe! f a Magas. der Entomolog. iv. 410. b Latreille speaks of Phasma as having no stemmata; but it sf seem that he examined only the apterous ones, all the winged ™ viduals, at least so far as I have examined them, having three ver. visible ones. It may, I think, be laid down as a rule, that the oa and pup of Orthoptera have not these organs. Probably their or is principally in flying ? ; pould di- EXTERNAL ANATOMY OF INSECTS. 507 "cide, and the Reduviade very remarkably; but many “thers in both sections of this order, as Thrips, Coccus, 4p his, Capsus, Miris, Naucoris, Nepa, and Notonecta, &c. ne deprived of them. Of the Neuroptera the Libellu- Ma add stemmata to their large eyes, in the anterior mgle of which they are stationed”; but many other ge- Mera of that Order are without them; as Myrmeleon, As- “laphus, Hemerobius, &c. The Trichoptera and Lepi- *plera universally have them; though in the latter, cept j in Castnia and the Sphingide, they are not ea- iy Seen, In the Hymenoptera they are usually very “Xspicuous, but in Larra and Lyrops, two genera of this “der, the posterior pair are scarcely discernible; and in “Reuter ants they are quite obsolete. In the Diptera, ugh many genera are furnished with them, yet many ‘sy want them; amongst the rest Latreille’s Tipwlaria, ad all the horse-flies (Tabanus L.) The Pupipare inpobosca L.) usually have none; but in Ornithomyia cular; ‘ia, one of that tribe, though extremely minute Yare visible, arranged in a triangle, in the polished . Pace of their vertex. S to the Number of the stemmata, three appears to ^ Most universal. Reaumur mentions an instance in ‘ie he counted four in a fly with two threads at its ; but great doubt rests upon this statement °. Some Opterous genera, as Gryllotalpa, and many Hemi- i$ a Ny r Plata phalenoides F. and affinities have no stemmata, while tgp Cltculata and affinities have them: a proof that these tribes p stinet genera. Late VI. Fic. 10. i. k . dum. iv. 243. He refers for this insect to plate xiv. without 8 any number for the figure; but no such is in that plate, 508 EXTERNAL ANATOMY OF INSECTS. pterous, as Tetyra, Pentatoma, Reduvius*, Cercop™ Fulgora?, &c., have no more than two; and in Lart" and its affinities, as just observed, the posterior ones are obsolete, so as to leave only one discernible. Where there are three of these organs, they are be ally arranged in an obverse triangle in the space bebim the antennee, at a greater or less distance from them In those male flies (Muscide) whose eyes are confluent the stemmata are in a little area behind their conflu*? but, as before observed, in the drone-bee and the Libe lulina they are before it. This triangle is in some case? nearly equilateral, as in Perla related to the may-fie® and many Hymenoptera ; in others it is acutangula’s if in Locusta &c., in which the stemma forming the vette of the triangle is before the antenna °: in others, agai it is obtusangular, as you will see in Pepsis and var" ous Hymenoptera. In the humble-bees ( Bombus), # [ype drawn through them would form a slight curve. sg situation also varies. In insects that have only ill they are sometimes placed a little behind the eyes, al? the back part of the space between them: this is the cas with most of the bugs (Cimer L.) that have them: 7 They are often distant, as in Tetyra F., Edessa F.; p sometimes approximated, as in Reduvius F.4 In man) of the Homopterous Hemiptera, as Cercopis, Led’& ge they are planted in the upper part of the heads, but ? a ; t Tassus their situation is on the under part; and in 4 Wo! 3 ; ex American subgenus, as yet without a name, they are 2 Prare XXVI. Fie. 40. i. Cercopis, Ibid. Fie. 42; and Fulgora, Fre. 41. i e Pirate VI. Fic. 4. i. ; Prate XXVI. Fie. 40. i. © Ibid, Fre. 42-1 `~ EXTERNAL ANATOMY OF INSECTS: 509 actly between the two, being placed in the frontal angle. Q Fulgora their station is between the eyes and antennse?. hey are most commonly sessile, and as it were set in the head; but in some, as Fulgora candelaria, they stand n a footstalk. The stemmata are set in the side of a Tontal tubercle in that four-winged fly of threatening Spect, Corydalis, which in its perfect state: has mandi- NR but longer and more tremendous, like those that Mistinguish the Zarva only of the kindred genus Hemero- ius». These organs differ little in skape, being usually Perfectly round and somewhat convex; but occasionally they vary in this respect. In Fulgora serrata they are long, with a longitudinal depression; in F. Diadema ; €y are also umbilicated, but the umbilicus is circular ; n Corydalis they are oval; in other insects they are vate. in some semicircular, and in a few triangular. They vary much in size: in some of these animals being 80 minute as to be scarcely visible, while in others, as Corydalis, Dorylus, Vespa pallida F., Reduvius, &o.., they are as large as some compound eyes. They differ also in colour, though often black: in Fulgora laternaria they are of a beautiful yellow; in F. candelaria they are White, in many Hymenoptera they are crystalline, in thers red : the fierce look of Reduvius personatus is ren- dered more hateful by its stemmata having a pale iris round a dark pupil °. Let us here stop and adore the goodness: of a benefi- Cent Creator, who, though he has deprived these little cings of the moveable eyes with which he has gifted the a PrLare XXVI. Fie. 41.1. b De Geer iii. ż. xxvii. f. 1. Reaum. iii. t. xxxii. f. 3,9. ¢ Phare XXVI. Fre, 40.1. 510 EXTERNAL ANATOMY OF INSECTS. higher animals, has made it up to them by the var jety iid complex structure of their organs of vision, wher we have only żwo points of sight, giving them more tha? as many myriads. none 5. Antenne.—But of all the organs of insects, A n- appear to be of more importance to them than their tenn, and none certainly are more wonderful and more various in their structure, and probably uses. Up? this last particular I shall enlarge hereafter. Thei" structure, as far as it differs in the sexes, I fully dis- cussed in a former letter ?; and the most remarkab!® kinds of them will be included in a set- of definitio” which I shall draw up for you before our corresponde?* on this part of my subject closes: I shall therefore now confine myself to the following particulars—namely, thet , number, insertion, substance, situation, proportion, genert Jorm and structure, clothing, expansion, motions, and st tion of repose. As to their Number, in the majority of crustaceous ani- mals the antennze amount to four, but no insect has mo" than two. A genus recently established (Otiocerus Kir- by?) seems to afford an exception to this rule, since ™ species composing it at first sight appear to have /0!” and in some instances even six antennze; but as only two of them terminate in a bristle, the other, though P™” ceeding from the same bed of membrane, may perhaps be regarded as merely appendages. Germar, who has de- scribed a species of this genus € under the name of Co bax Wintheri, considers these appendages as analogov® a See above, p. 318—. b Tinn. Trans. xiii. € Mag. der Entomolog. iv. 5. EXTERNAL ANATOMY OF INSECTS. . 511 to Palpi: but as they do not proceed from the oral or- Sans, but from the bed of the antenne at the base of the Rosea, they ought certainly to be regarded rather as ac- “€ssories to the latter, than as representing the former. 3 the Aptera order the mites (Acacus L.) appear to be Without these organs. In the pupiparous tribe Hippo- bosca they seem about to disappear; and in the Arach- nida &e., as has been more than once observed ?, the Nandibule have been thought to represent, not indeed the antennee of insects, but the inner pair of those of the Crustacea, In considering the insertion of antennee, by which I Mean their articulation with the head, we must advert first to the orifice ( Torulus) that receives them*. This Sa perforation of the crust of the head; commonly, i ough not invariably, circular: in Coleopterous insects Often with concave lubricous sides, forming an acetabu~ um, with processes usual in ginglymous articulations, | Uger than the bulb or root of the antennze; and which is “ommonly covered, except the central space occupied by the bulb, with a tense membrane. Though not in gene- tal remarkable, in some cases it merits attention. In the Snus Rhipicera Latr., the elegant antennæ of whose Males I have described in a former letter 4, particularly the Brazilian species, it isa long process on each side of € nose, and might be mistaken for the first joint: in Mother Coleopterous genus, Priocera K.°, it has some- What of the shape of a trumpet: in Cupes a tubercle rises i Palpi quatuor, subæquales, cylindrici, ad basin clypei. Germ. See above, p. 18, &c. ¢ Puare VL Fic. 1, 4.7. ` See above, p- 321. Linn. Trans. xii. t. xxi. f. 3. Ibid, AF: 512 EXTERNAL ANATOMY OF INSECTS. just’ above the base of the antenna: a circular proces’ forms the torulus in Fulgora and others. Itis also ofte” placed in a cavity of the front, as in several wild-bee® Melitta K., and in Locusta Leach on the sides of a? ele- vation of that part?. In a large majority of insects tB? bulb (Bulbus) or ball which is received by the bed, wea? the appearance, especially in the Hymenoptera, of a i stinct joint; but if you carefully examine it, you wil clearly see that it is merely the base of the scape gwellet out into a spherical or other kindred form >; and often marked, as in the Cicindelide, with impressed points" as it is the piece by which the antenna moves in its soc ket, this form of a rotula was doubtless given for its mor? ready motion in all directions. ‘This structure is princ pally conspicuous in the Coleoptera and Hymenopt™ Orders: in the others the base is not so distinguish? from the rest of the scape. If you carefully extract t y antennæ of a beetle, say a Copris or Lamia, and exami”? ‘its base or- bottom, you will find that it is ope? for the transmission of muscles and nerves; that in its YP per margin it has a deep notch or sinus, on each side ° which is a smaller notch; and that all round the marg™ which is very lubricous, a membranous ligament 1$ 46: tached, by which it was affixed in the toruius. Its art culation, therefore, seems of a mixed kind, like that y most other organs and parts of insects, partaking of the ligamentous, ginglymous, and ball and socket. In th? a Prana VI. Fic. 4. c. i’. + re PLATE XI. Fic. 9.1. This circumstance was very recent? discovered ; which will account for this plate not being quite cor gi in this respect, the bulb being represented as a distinct joint : Fic. 6, 10, 26. EXTERNAL ANATOMY OF INSECTS. 513 Orthoptera, Hemiptera, &e. the articulation seems more Purely ligamentous. ith regard to their substance—these organs are re- Slated, in some degree, by the nature of the integu- Ment of the animal of which they are appendages; in the sitter insects being of a softer substance than they are in "td ones, The vertex of the joints, where they receive the Succeeding one, appears in many cases to be softer an the rest of it, and especially towards the apex, often Mpillose, ‘The antenne are generally opaque; but in wo complanata, a beetle common on the sea-coast in a The situation of antennæ must next be considered. t this respect it seems necessary that they should be ., Situated as to be under the direction of the eyes: for You examine ten thousand insects (except, as was be- ote observed +, where there are four eyes), you will not ‘done in which these organs are situated either above i immediately behind them; their station being always _ wither somewhere in the space between the eyes or that ; ow them. In Ptinus F. they are placed near the gs bat in Gibbium, which is so nearly related to at destructive genus, they are beneath them. In gi Melitta K. they are in the middle of the space Ween the eyes; and in many other Hymenoptera and p Dera (Staphylinus &c.), in the anterior part of it. Many Lamellicorn genera, as Melolontha, Cetonia, p anus, &c. they may be regarded as planted in the ‘Se Surface of the cheek before the eyes; but in Co- ©. in which they are inserted further under the les and Lincolnshire, they are semitransparent. Vor * See above, p, 498. v Vor. I. p.231, 238. f ur, Pi í ki li 514 EXTERNAL ANATOMY OF INSECTS. shield of the head, they are properly in the prone surface of the front. In the Capricorn-beetles (Cerambyr L.) ah Cnodalon F. they may be termed znocular, or placed m a sinus of the eye; in the former tribe in its ¿nłeriors an in the latter its anterior side. In the Rhynchophorow* g rostrum-bearing beetles (Curculio L.) they vary in the situation. Thus in Macrocephalus Oliv. they are inserte at its apex; in Anthrtbus in its middle, and in Calandi® at its base?. In the water-scorpions (Nepa, Belostom” &c.) they may be called extraocular, being placed unde the head in its prone part, outside the eyes”. In 4” mus Fringille, a kind of bird-louse, they appear to be oral, being situated, according to De Geer, unde” the head near the mouth, at a great distance from the eyes °. j In their proportions, both as.to length and thickne” antenna vary extremely. ‘Thus sometimes they are be short—much shorter than the head; as in the aqua f beetles Gyrinus, Parnus, and the water-scorpiot i f J : e some land-beetles, as Anthrenus, &e. At other times th far exceed the length of the insect: the males of me ; J F aye Capricorn-beetles are so distinguished. In that of Lam thé ædilis they are more than four times. as long a5 ji body; and every intermediate length between these p may be found amongst them. ‘They vary also great y thickness : in Paussus, whose antennæ emit hight ut $ night 4, and Cerapterus, they are nearly as thick” j least their knob, which forms the chief part of thems a Oliv. Ins. no: 80. Macrocepkalus t. i. f.1—4.;3 Fe and no, 83. Curculio t. ii, Calandra f: 16. è Schellenberg Cimices t. xiv. f. 1. b. e De Geer vii. t iv. f.. aa. a Vor, If. p. 421 EXTERNAL ANATOMY OF INSECTS, 515 the body of the insect ?; while in Mantis, Acrida K. and ocus, they are as slender as a hair. The antenne in Matiy of the Prioni, especially in P. imbricornis, are thick "em base to tip; while in other Capricorn-beetles they ate quite the reverse. It wij not be necessary to enlarge here upon the ge- neral Jorm of these organs: I shall therefore only notice ® two principal divisions of them in this respect.— tenne, regard being had to one of their uses, may be Wided into two sections, distinguished by forms ex- "Emely different: those, namely, that are employed by cts as ¢actors to explore their way, and those that amot be so employed. The great majority are of the “ther kind; but those that may be denominated setige- iung the antennæ of the Libellulina, Ephemerina, of he Homopterous Hemiptera, and of many Diptera, the “st joint of which terminates in a bristle, or is furnished ith a lateral one, and of some gnats that have short “there antennee,—appear not fitted to be used as tac-. "8 to explore by touch, and form the latter description. t t 'S difference in these organs, as I shall have occasion i Prove more at large hereafter, furnishes a strong pre- MiPtion that their primary function is not touch. Were tis the case, it would be common to them all. S to their structure, antenne consist in general of a Waber of tubular joints; each of which having separate ' ton, the animal is thereby enabled to give them every ‘ies necessary for its purposes. The scape, or first- ‘Was by means of the bulb inosculates in the torultis, or “Uspended to it; and the others, sometimes by a simi- * Prares XII. Fie. 28; and XXV. Fre. 9, 24. € E E 516 _ EXTERNAL ANATOMY OF INSECTS. lar, though less pronounced knob at their base, inoscu- late in the preceding one; but in some cases the inoset” lation seems not so perfect, the joints being simply s4“ pended by ligament. In pectinated or lamellated S tennæ, the branch is usually a lateral process of the joint from which it issues; but in Phengodes (Lampyris phe mosa L.) its involute plumose branches appear to artic" late with the apex of each joint*. I have a specie of one of the Cleride, of a genus undescribed, in which each branch is forked. In some tribes of the Capri¢ beetles (Stenocorus, &c.) the antennee are often armè? orn their apex with spines, sometimes on the upper side č x ss: sometimes below. In some aquatic beetles (Gyr™ : ases new Parnus) they are furnished with an auricle at their b which, like the lid of a box, shuts them in when u ployed, and protects them from the water >. j The portions into which antennæ may in general w considered as divided, have been sufficiently expla? j to you above; but it may not be amiss to add here ® ¢ words on the principal variations in their structure we I have-had an opportunity of observing. ‘The scap” or first joint, which includes the bulbus, is usually g most conspicuous joint in the antenna (exclusive, I mea” of the capitulum, in those in which that organ termin? ; in a knob), it being thicker and often longer than the su? ceeding ones. In the Capricorn and Darkling pect indeed (Cerambyx and Tenebrio L.), the third joint is y i longest, but the scape is still the thickest; and a 6 stag-beetles (Lucanus L.), many of the weevil tribe a Prate XXV. Fic. 4. b Prarrs XII Fic. 29; and XXV, Fie, 28. @: © Pratys XI. XI. XXV. k”. EXTERNAL ANATOMY OF INSECTS. 517 (Curculio L.), and those of the bees (Apis L.), except in the Males, it is as long nearly as the remainder of the Mtennæ, which forms an angle with it. In shape it is Senerally somewhat curved and subclavate, or increasing size from the base to the summit; but it is sometimes Straight and filiform, at others oblong or square, at others again triangular, in several instances three-sided : t one (Cetonia cruenta F. Genuchus K.) it is, as it were, - token, the upper part forming nearly aright angle with ‘Ne lower; in Cerocoma Schefferi it is foliaceous ; and it 'S Occasionally suborbicular: and probably many other forms might be enumerated. f The Pedicellus™ is the second, and may be deemed the least conspicuous joint of the antennæ. Though more slender than the scape, it is generally thicker than that Which immediately follows it. In broken antennæ it is the hinge or pivot on which the clavola or upper mem- & turns: it is usually very short, campanulate or bell- shaped, or obconical; but in a species of bug (Tetyra, fom New Holland—T. pedicellata Kirb. MS.) it is Nearly as long as all the rest of the joints taken together. 3 n those species of Lycus, a genus of beetles related to mie glow-worm, that have flattened antenn (as L. reti- CWlatus, fasciatus, &c.), this joint is almost received: into the socket of the scape, so that their antennze appear at “st to have only fen joints, but in those which have those organs filiform (as L. minutus, Aurora, &c.) it is More conspicuous. The Clavola®, or remaining joints of the antennæ taken together, constitutes the principal part of the or- San, which, especially at its extremity, exercises its func- a Pkarrs AL MEL XXV. I: emam 518 EXTERNAL ANATOMY OF INSECTS. tions of touch, or any other sense. The principal varia tions, as to form and structure, that occur in this part will be mentióned in another place. I shall only here observe, that in many instances the first joint of this p° is longer than the rest; but in Tetyra pedicellata just mentioned, it is by far the shortest, and shaped like the pedicel of most insects. In the Libellulina, the Hom pterous Hemiptera, and those flies whose antenne '™ minate in a bristle, the clavolet is represented by the bristle. But in the flies which have a lateral bristle, 9” the last joint, and those with triarticulate antenn® that have no bristle, the terminal joint represents it. bi clavolet often terminates in a knob, or in several joints thicker than that which precedes them. This varie greatly, not only in its form, but also in the numbet 4 joints of which it is composed, Thus in Paussus, P lay pus, and many Calandre, it consists of only a siS joint #; in Anthrenus, Ditoma, &c. of two; in Nitidulth Geotrupes, &c. of three”; in Tetratoma, the Silphid@ Jour’; of five in Scaphidium4; of six in one species ° Languria ; of seven in the common cockchafer (Mel lontha vulgaris*); of eight in Diaperis Boleti, in whic the whole clavolet forms the club‘; of nine in Oenas: ™ ten in Cerapterus £, All the above, you will observes art beetles. In the other orders there are eleven joints knob of some butterflies; twelve in that of Ascalapht and Myrmeleon; and lastly, fourteen in Trachelus'- h * Prates XII. Frc. 28; and XXV. Fic. 13, m”. b Prare XXV. Fie. 2, 5,21. m”. ¢ Prate XII. Fie. 10. m”. à Ibid, Fre. 4. m- e Prare XXV. Fic. L m”, ; £ Prare XI. Fie. 23. e Prare XXV. Fic. 24. ` Ibid. Fre. 30. i Jurine Hymenopt. t. vii. f. 3. EXTERNAL ANATOMY OF INSECTS. 519 Under structure also, the number of joints of which. ‘ntennse in general consist, should be considered. If You examine the insects belonging to the different or- “ts; you will find remarkable variations in this respect. et us run through them :—In the Coleoptera the na- ‘ural number of joints is cleven; but this rule is not Without many exceptions. Thus, many have fewer than the prescribed number: Paussus has only two?, Clavi- čer and Platypus five, Dorcatoma and Calandra eight, “erates K. and Phaneus MacLeay nine‘, and lastly X ‘elolontha tent, Others, again, have more than eleven Joints ; ebrio Gigas, Chrysomela stolida, some Saperda, ‘nd Several others, have twelve. In Prionus imbricornis € female has nineteen, and the male twenty’. Rhip?- re marginata has thirty-two; and in a New Holland Pecies of this genus I counted thirty-eight. In the Or- ptera I can trace no general law in this respect. In _ usta Leach in some species you may count fourteen Joints, in others sixteen, and in others twenty-five. In ne, which appears to be a pupa, I found only thirteen. ® Mantis they exceed thirty ; but in Blatta, from between thirty and forty, they reach nearly one hundred and fifty ; 0 : : SaaS ESS ten varying in number in different individuals of the š Me species. The order Hemiptera exhibits two pecu- ‘ig types of antennze, which, with some exceptions, di- ‘theuish the two natural sections into which M. Latreille as judiciously divided it. In the Heteropterous section SY are without a bristle at their end; and in the Homo- “rous one, with the exception of Aphis, Thrips, &c. a : pete XXV. Fie. 28, b Ibid. Fie. 13. Did, Fre. 5 4 Tbid. Fie. } e x. Qe z nae PLATE ml. Fig. 12. f£ Linn. Trans. xii. t. xxi f. 3. 520 EXTERNAL ANATOMY OF INSECTS. they žave one. In the genera of both these tribes; the number of joints varies in these organs. Thus, exclu sive of the seta, in Flata and Cixius there are only po? joints; in Galgulus, Fulgora, and Cercopis, there #° three; in Lygaus, Coreus, &c. there are four; in Tety" m Pentatoma, Tettigonia, there are five*; in Aleyrodes there are six ; in Aphis seven; in Thrips eight; in Psylla ah? the last of which is terminated by two bristles ”; and # Coccus eleven. The Neuroptera order, as it stands at present, is regulated by no general rule with rega" the number of joints in the antennæ of the insects compose it. Several types of form in these organs di guish its discordant tribes. The jirst is that of the phe mere, in which the antenne consist of two short jon gti crowned bya short, tapering, unjointed bristle. Theseco” is that of the Libellulina, similar to the above, but with ® jointed bristle. The zhzrd is that of Psocus, in which the antenna has two short thick joints at the base, terminal? by a long filiform bristle, consisting of seven of eig” joints, and finer than a hair. Perhaps these three m? be regarded as belonging to a common type. The JE ; type is presented by the short filiform antennæ of yer mes; the fifth by the setaceous ones of Corydalis, e robius, &c.; and the sizth and last by the clavate ap capitate ones of Myrmeleon and Ascalaphus. , In t x h Lepidoptera and Trichoptera orders the antennæ, thoug varying in their general form in the three tribes of tP Linné formed his genera Papilio, Sphina, and phala” with the exception of Hepialus, in which the joints f z . . - 5 jast 2 Latreille says six, but only five are discernible; the threé form a kind of bristle. » Latr. Fourmis, 323. EXTERNAL ANATOMY OF INSECTS. _ 521 few, are always mulizarticulate :—we will therefore, with- Out further delay, proceed to the Hymenoptera. In La- treilles tribe Aculeata the general rule is, that the fe- Males shall have zwelve joints and the males thirteen. n his Ichneumonides the law seems to be, that the an- tennæ shall be multiarticulate and setaceous; but in most f the other tribes of the order, even those that in other Tespects are most nearly related,—as in his Tenthredine- ‘@;—the number of joints of these organs varies without nd. Thus in Hylotoma there are only three joints; mi Cimbex lata” five; in C. axillaris and Perga Leach ¢, ‘IX: and so on to twenty-five or more‘, The same fluc- Nation in this respect runs throughout the rest of the rder, In the Diptera there are two general types of Mtennæ :—those of the Tipularie Latr., consisting usu- ally of from fourteen to sixteen joints, in the males often *esembling beautiful plumes; and those of the remainder £ the order, in which they do not exceed ¢hree joints ©: though the last, or patella, is often further divided into ®bsolete or indistinct ones‘. These antenne may be luther subdivided into filate and aristate, or those Without and those with a bristle, either lateral or ter- Minal : _ The clothing of antennæ also merits attention, since it 'S often not a little remarkable. By clothing I under- Stand the down or hairs of every kind with which they Xe either generally or partially covered. A great number of filiform aud setaceous antenne of Predaceous beetles (Cicindela L., Carabus L.) have the first two, three, or ` Jurine Hymenopt. t. vi. f. 3. b Ibid. f. 2. * Ibid. f.1. Prave XXV. Fic. 7. ¢ Prare XXV. Fie. 25, 26. * Prary XIL Fic, 16—22. £ Ibid. Fic. 19. a. 522 EXTERNAL ANATOMY ÖF INSECTS. » eo: ~ ° a Ve four joints naked, and the rest covered with a fine dow! In insects that have a knob at the end of these orga” whether lamellated or perfoliate, this down is often con fined to it, or to its intermediate joints, and seems intel mixed with nervous papilla. These are particularly y sible in the flabellate antennæ of Rhipicera, Lampy” Latreillii*, Elater flabellicornis®, &c. covering both su faces of the processes of the joints. In some male m these papillæ are inclosed in hexagonal spaces into whic the antennæ are marked out*®. It is to be observ” that in many antennee the joints of the clavolet have ka or two bristles or more at their apex, one above pe haps, and one below; the lower angle in those of HH serrated antenne of Elater is usually so furnished, p sometimes the upper. In many Capricorn-beetles oe various insects the antenne are clothed, instead of dow™ with stiffish hairs or short bristles. Other insects hav? F jals these organs, at least the clavolet, beset with longer har standing out from them on all sides: of this kind # n : ; & those of a singular beetle (Sarrotrium muticum) som times found in this country‘. Again, there are som that have only their underside bearded with longer hails as Lamia curculionoides, speculifera K., and othet ~ _ pricorns*®. In another of this tribe, Saperda hirsutior” nis, the three intermediate joints are ornamented branches of long black hairs, which give them an eleg@” and feathery appearance ®. In Callichroma alpina a Linn. Trans. xii. t. xxi. f. 3,4. Prats XXV. Fre, 11. b Prate XI. Fic. 17. © Kirby Mon. Ap. Angl. i, 184. t. x. **. d. 1. f. 8. è Prare XXV. Fic. 27. e Prare XII. Fre. 26 t Piare XXV. Fic, 32, EXTERNAL ANATOMY OF INSECTS. 523 “Pex of the slate-coloured joints of its antenne is bearded With black hairs, In Lamia reticulata, and Saperda Jüsciculata and plumigera, all also Capricorns, a single Uneh of hairs, resembling the brush of a bottle-cleaner, ‘Ignalizes the middle of the antenna?: in Saperda sco- Pulicornis K, this is star-shaped >. Sometimes the scape ‘Sexternally bearded, as in Zroz, a beetle found in horns aad hones; and in many other Lamellicorns ©. In this t tribe the two exterior leaves of the knob of the an- tennæ are often set with short bristles 4; and in a minute tle called by De Geer Dermestes atomarius, the hairs this part are said to form a brush & When insects, I mean more particularly Colcoptera, we about to move from any station where they have “en at rest, the first thing they usually do, before they “et a step, is to bring forward and expand their antenna, Which have either been carefully laid up in a cavity fitted to receive them, or back upon the body: if they termi- Mate in a lamellated knob, they separate the lamelle as a as possible from each other; or if it is perfoliate, the Mints of it mutually recede. The object of this is evi- “ntly to collect notices from the atmosphere, since the Pabillose part of these joints cannot be applied to sur- aces, When the animal begins to move, in many cases © antennæ do the same, and continue their motion till Stops and returns to a state of repose. In the parasitic bes of the Hymenoptera (Ichneumon L.) they are kept an almost constant vibration. Many other insects Ove them in all directions without any order or regu- ; ; Prare XIT. Fre. 25. > Prare XXV., Fre. 17. . mn, Trans. xii. t xxiii. f. df. 4 Ibid. t. xxi. f. 8g. 9, 10. © Geer iv, 219. Z. viii. f 20. 524 EXTERNAL ANATOMY OF INSECTS. arity; and others, when they elevate one depress the other, and so proceed as if balancing themselves by means of these organs like a rope-dancer. I have befor? stated to you how by motions of their antenne, ants a bees communicate their wants or discoveries tO each other, or make inquiry concerning any, thing they wish to know?. But as I shall have occasion to make some further remarks upon this subject, when the senses ° insects are under discussion, I shall for the present take my leave of it. I shall conclude what I have to communicate tO = relative to the organs of which we are treating; with * few observations with respect to their station whe? insect reposes. In the Capricorn-beetles, Eucera at turn? eae 3 ; ot back or on one side with no particular cavity for the” g i ge other insects with Jong antennæ, they are merely ception when unemployed, but probably the apex pa under the body. In the Predaceous and Darkling P® tles (Carabus L. Tenebrio L.) their station is usually & der the sides of the prothorax, and in the Tortoise be?” tles (Cassida), under its anterior margin. In the Elas beetles ( Elater} they are received into a groove petwe” the under margin of that part and the fore-breast (ani pectus) In Anthrenus, when the animal repose? counterfeits death, the antenne are concealed ip ® yw vity of the underside of the prothoraz, at right angi with the throat. In the kindred genus Byrrhus, ane simulator of death, a large cavity is excavated under t same part, to receive both the forelegs and antenn : O° narrow space being left between the angle of the P’ a See Vou, IL p. 65, 261—. b De Geer iv. ¿vii A 4 EXTERNAL ANATOMY OF INSECTS. 525. thor ax and fore-breast exactly admitting the base of the a » which are quite concealed under the former. In Cyptocephalus and Chlamys, kindred beetles, when at Test they are withdrawn, except their scape and pedicel, With the head within the cavity of the prothoraz. In thers they are turned under the head, without any par- ticular cavity for their reception; as in many moths, Apion, &c. In most of the Lamellicorn beetles their sta- tion is in the cavity formed by the eye and the throat, e€ knob forming an angle with the rest of the antenna. a Heterocerus they follow the contour of the eye 2, In "entus, a genus of weevils remarkably long and slen- er, they are turned back and received by a slight longi- tudinal cavity of the rostrum; but in those of this tribe culo L.) in which the clavolet forms an angle with the long scape, this latter part, bending back, is laid up ty an Paine channel of that part; and the former, Pointing i in the contrary direction, is folded upon it. In Many flies (Muscide) a vertical frontal cavity receives € antennæ, which point downwards during repose ?. "yptocerus, a very remarkable ant, has on its head a Singular square plate, the sides of which form a deep ngitudinal cavity: in this cavity the antennæ, quite “oncealed, repose in safety. ‘A cavity equally remark- able is exhibited by the water-scorpions, particularly lostoma, in which is a very deep kidney-shaped box, tween the eye and.throat, to receive and defend its S gular antennæ €; which, when they are reposing, is “sed by the exterior harder joints, and from which it ‘tems as if they turned out, like a sentinel out of his box. \ ` Pravg XXV. Fie. 35, b De Geer vi. £. if, 5. RPrare XI. Fic. 21. 526 EXTERNAL ANATOMY OF INSECTS. In some aquatic genera of beetles, as Gyrinus, Parnis &c. they are withdrawn within a lateral cavity of the same part, and are defended from the water externally by the auricle at their base*. The flabellated and le mellated antennæ, previous to their being folded for 1% pose, close all their plates; which in action are as wide y expanded as possible, so as to form a knob; and in some the middle piece is entirely concealed, as if in a bor In broken antennæ, or those in which the clavolet forms an angle with the scape, the former is folded upon the latter, with its point downwards. Il. Subfacies—Having dispatched the Facies, or WP per side of the head, I am next to consider the S facies, or under side: but as the principal parts that 0% cupy this side have been already considered, I shall have no occasion to detain you long. i. Jugulum.—This part, which may be regarded analogous to the throat in vertebrate animals, lies betwee? the cheeks; from which it may usually be distinguish by being more lubricous and tumid, and often separ% by an impressed line. It is particularly conspicuous ant elevated in the Lamellicorn beetles, and calculated by m lubricity for easy motion in the lower side of the cavity of the chest. Its apex is the base im which the ment” sits. It is not necessary to enlarge further upon it, #9” seldom exhibits striking characters. III. Collum*.—In a large proportion of insects at head inosculates in the trunk without the interventi” z Prate XII. Fic. 29. a. b Prare VI. m. c Ibid. EXTERNAL ANATOMY OF INSECTS. HIT ofa neck, or a constriction of the head behind. In the Orders Orthoptera, Trichoptera, Lepidoptera, Hymeno- Plera, and Diptera, no instance of it that I recollect oc- “urs: in the Coleoptera there are many. In the Preda- “eous beetles, though several have no distinct neck, yet thers, as Anthia, &c. have a short and thick one; and ‘ome few, as Colliuris, Agra, &c. one more pronounced. atreille has named a tribe in this Order Trachelides, tom the circumstance of their having a neck: in this tribe you will find the blister-beetles (Cantharis and My- abris) both of the moderns and the ancients. In the emiptera order the water-scorpions Nepa, &c. have a thick short neck; and Zelus, (a kind of bug,) one longer ad more slender; and, like Raphidia, the snake’s-head “Ys which is similarly circumstanced, has the air of a Serpent, Other Neuroptera, likewise, have a neck; as emerobius, Corydalis, &c. This part presents no other K ĉatures that merit notice. ly, Myoglyphides *.—The Myoglyphides, or muscle- Notches, are sinuses, some shallow and some deeper, in € posterior margin of the upper side of the head, to Which the levator muscles are affixed. They seem prin- Cipally confined to the Coleoptera; though, in some Cases at least, they may be traced in the Heteropterous ¢miptera. These notches vary in number and depth m different insects. Thus in Buprestis there is only one “ep one>: in Copris there are ‘wo shallow ones, in a “ep sinus separated by a small prominence®: in Flater “nd Lamia there are also two not in a sinus ; and in Ca- * Plate XXVII. Fic. 1, 3—5. n’. b Ibid. Fic. 3, * Ibid. Fic. 4, 528 EXTERNAL ANATOMY OF INSECTS. landra Palmarum there are four, two on each side, with a prominent lobe between them?. To each of thes? notches, at its under margin, below the ligament that aise the unites the occiput to the trunk, a muscle to r head is usually attached. l @ Prate XXVII. Fie. 1. LETTER XXXV. EXTERNAL ANATOMY OF INSECTS, CONTINUED. . THE TRUNK, AND ITS PARTS AND ORGANS. As the head of insects is the principal seat of the organs : Sensation, so is the trunk of those of motion; and in it We contained the muscles by which they are moved: it May therefore be regarded as the great centre of motion, ad as the main support and prop of the two other pri- Mary sections of the body—the head and abdomen, be- Peen which it is situated—it may be deemed the most portant part of the insect, the key-stone of the whole ‘tucture, In treating upon it, for the greater clearness, ‘Shall consider its substance, general form, proportions, ‘Onposition, internal processes, and members. It will first, *Wever, be necessary to assign my reasons for the no- Menclature of its parts that I have adopted. Aad the entomological world been universally agreed "Pon this subject, and there was an established system y Orismology a, I should have proposed no alteration Without great reluctance, and the fullest conviction of the “solute necessity of some change; but as the standard a Se the reascn which induced the authors to use this word in- of Terminology, before employed, see Vou. I. Pref. p. xii—. the ® are gratified to see that M. Latreille has adopted this term in Work quoted on the other side, p. 194. VOL. rrr. 2 M 530 EXTERNAL ANATOMY OF INSECTS. of language in our science is still unsettled, and different terms are used by different writers, there seems full be berty left to me- to~select those that appear upor the whole most appropriate ; and where proper and signifi- M. Le es of tion cant terms seem wanting, to invent new ones. treille, in a late Essay *, has proposed many chang this kind, and seems to hesitate concerning the adop s py itte of some of those recently coined in France for the of the trunk; it may therefore, I think, be pet™ me to labour a little in this hitherto imperfectly culture field, and to suggest such improvements as the subye’ may seem to require or admit. Linné called the part we are now considering gi trunk, its upper-side he usually denominated the thora and its under-side the breast : he notices also the ie f m 2 lum and sternum®. As the prothorax and scutellu : i the only apparent parts of the back of the trunk in j first Orders (Coleoptera, Hemiptera L.),; the rest being covered, in noticing these he puts the part for the wh? A calling the prothorax the thorax, but which strictly we not synonymous with what he called by the same na in the other Orders. Linné’s phraseology with rega” the trunk of insects was adopted by Fabricius and of + a er Entomologists, till Illiger employed the term thora designate the whole of the trunk‘, calling the uppe” ga thorax superior and the lower thorax inferior: $ Blainville, M. Latreille, and other French writers, m à Organisation Extéricure des Insectes, Mém. du Mus. t. viii. g5 » Ibid. 199--. Ihave never been able to procure M. Ando Mémoire on this subject. : © Fundament. Entomolog. in Amæn. Acad. vii, 143. 4 Terminologie, 1578, &c. He afterwards called the ttt dium: Terminologie der Insekten. Magaz, 1806. 14. ink seth EXTERNAL ANATOMY OF INSECTS. 531 Proved upon this, naming the upper part the back (dor- wm), and the lower the breast (pectus); and dividing the trunk, or according to them thorax, into three sections, “ach bearing a pair of legs. But I see no sufficient reason X this alteration—the terms txunk, thorax, and breast, — u the common acceptation are well understood, and lead Eao confusion or glaring impropriety; I shall therefore ere to the old phraseology, especially as French En- Omologists in popular language still do the same. As to the division of the trunk into segments by M. La- treille and others, it has been regarded as consisting of ree primary ones, which have been called in the order their occurrence, reckoning from the head—prothoraz, "Sothoran, metathorax: The first of these segments, *Wever—and the learned Entomologist just named seems hint as much*—is usually more distinct from the other %, than they are from each other. . If this idea be cor» "eet, the trunk is properly resolvable into zwo primary “Bments, the first bearing the arms or fore-legs, and the T the proper legs and the organs of flight. M. Cha- "er calls the latter. tronc alifére; or wing-trunk ;—a PPY term, which Ihave adopted and latinized, call- .'8 it the alitrunk (alétruncus): the first segment, because “ars the fore-legs, I have named ‘manitrunk (mani- uncus), - Iadopt likewise the terms above mentioned, Kothoras, mesothorax, metathorax, to signify the three “SMents into which.the thorax of Linné, or the upper ae of the trunk, is resolvable; and those of the breast “Nominate antepectus, medipectus, and postpectus. If “Ths be thought necessary:to designate the two intire “Organisation, $c. 198, 9M2 EXTERNAL ANATOMY OF INSECTS. the first segments into which the alitrunk is resolvable, ther the may be the meditrunk (meditruncus), and the o potrunk (potruncus). I. Sudstance.—With regard to its substance, the trunk in general is softer than the head, and harder than t» abdomen, especially as to its upper surface ; but in some cases, where it is not protected by the elytra, rove-beetles (Staphylinus L.), the ‘abdomen appea?® iA hard as the trunk. Though usually not very differe"! _ from the elytra in this respect, in Meloe, Lytta, and othe! vesicatory beetles, it is of a firmer consistence. as in the the onl e II. General Form.—In the Coleoptera Order part of the trunk that is visible on its upper-side ist prothorax : the mesothorax, with the exception of the s” tellum, and the metathorax, being entirely conceale it and the elytra; so that, with regard to shape; it W% nearly be considered as merging in the prothoraz- low it is more visible, and may be stated as more one i quadrangular ; in oblong beetles inclining to a paralle ogram, and in shorter or hemispherical ones toa square In the majority it is more convex below than above; exch in the case of the hemispherical or gibbous beetles sa cinella, Erotylus, &c.), in which the under-side is flat y In the Diurnal o ee” wasps and flies, the trunk approaching to the a sphere; in the ants, Scolieæ, crane-flies, &c. t At 144) a cube. The upper part of it in many Tchneumom EXTERNAL ANATOMY OF INSECTS. 533 i : : “male ants, &c. is very elevated, forming an arch, and Sloping towards the abdomen. In general it may be ob- Served. with respect to the remaining Orders, that the form of the trunk merges in that of the whole body, the ; tendency of which is often to a three-sided figure. Ty. Proportions.—The trunk is usually longer and Arger than the head and longér than the abdomen, . but Not wider: but there are exceptions to both these rules. Colliuris, Mantis, &c., it is more slender; and in Atta Negacephala and some neuter ants, itis skorter than the fad ; in Atractocerus, many Staphylinide, Phasma, the ` “tellulina, the Lepidoptera, and various Hymenoptera, is Shorter, and in the Mantidæ more slender than the domen, The greatest disproportion between it and the ast part is exhibited by the genus Evania, parasitic ‘Pon the Blatte, in which the abdomen appears merely 3S a minute and insignificant appendage of the trunk. he vertical diameter of this part, almost without ex- “ption, is greater than that of either head or abdomen.. hen we consider that it contains the muscles that move Oth the organs of flight and the legs, we see clearly the "tason why the CREATOR gave it greater volume. Ty, Composition.—-I lately intimated to you that the hunk, though resolvable into three segments, in most “ses properly consists of only żwo primary ones. Who- Yer examines the perfect insects of every Order, except € Aptera*, will find this distinction strongly pointed a . ` . - . 3 In Nirmus Anseris, &c. however, in this Order, the same distinc- ‘is observable. 534 EXTERNAL ANATOMY OF INSECTS. out, not only by the different direction of the first pair of legs from that of the two last, but also in a large peer portion by a deep incisure; and in all it is further mani fested by the anterior segment having a motion distinct from that of the rest of the trunk, and separating readily from it; and this not only where it is large, as in insect that havea thoracic shield, but also in those in whic the prothorax is less apparent: whereas the other two pedigerous segments have little or no distinct motio” will not readily separate from each other, and in som? cases exhibit no pectoral suture between them. S” y ` times, however, these two last segments are more prom nently distinguished: in Lytta, Mylabris, and othe? sa sicatory beetles, they are separated below by an incisw or rather the first or mid-leg segment, is not nearly © elevated as that of the hind-legs. In some ants (4 Latr.), in the neuters, there is no distinction of segue? in the trunk; but in others (Formica Latr.) it follows the general law, and consists of three. In the Arachmidh with ‘the exception of Galeodes, in which the head i5 K stinct, and, the three segments of the trunk may be trace” these parts together form only a single segment. * ‘ duced by these reasons, I consider the trunk as consist ing in general of two primary segments, the manitrl’ and alitrunk : the latter resolvable into two second” ones. * Manitruncus*.—The manitrunk, then, is the ® gK rior section of the trunk, which bears the arms and con ` tains the muscles that move them. This part has gi motion, or a motion independent of that of the rest of te a Prarns VIEL & IX. å. EXTERNAL ANATOMY OF INSECTS. 535 funk. This indeed seems a necessary result of the di- “ection and uses of the arms. It consists of an upper ‘nd lower part—the prothoraz and antepectus. À Prothorax *.—The upper part of the’ manitrunk in the Coleoptera, Orthoptera, and Hemiptera, is by far the Most conspicuous part of the trunk, but in the other Or- ders it is less so. With respect to it, insects may be di- vided into two classes—those that have and those that ®ve not a prothorax. In the Coleoptera Order it is re- Markable both for size and variations in its shape and Sculpture. In the Orthoptera, though less various, it S almost equally conspicuous, especially in Blatta. In the Homopterous section of the Hemiptera, in many ge- Nera it has become extremely short; while in the Hete- OPterous section its dimensions are not much reduced. A the majority of the Neuroptera, likewise, it is compa- "atively large; in the Libellulina much shorter, and in The Trichoptera and Lepidoptera nearly evanescent ?,— Athe Hymenoptera and Diptera, with very few excep- tions, the thoracic shield altogether disappears, at least lam correct inan idea, which I shall hereafter explain, that the collar usually regarded as the analogue of the Prothoraz, is really a part of the alitrunk. In these last ders, though there is no true prothoras, the mani- tunk still remains under the form of an antepectus, “aring the fore-legs, and containing the muscles that Ove them. The prothorax of insects may in general be considered o Prave VII. a. tak f the head of any individual of these two Orders be car efully so. Off, it will be found that above there is a very short piece repre- ine the prothorax, and quite unlike the collar of Hymenoptera. 536 EXTERNAL ANATOMY OF INSECTS. with respect to its parts, margin, appendages, shape sculpture, clothing, and proportions. 1. The prothorax, regarded as a whole, distinct from the antepectus or fore-breast, consists commonly of 1H? pieces—the shield, or upper part ?, and the ora, or unde! part >. In the shield you are to observe its apex®, 04%? sides®, limb, and disk8. The apex is the part next the head; the base that next the abdomen; the limb the cm cumference, and the disk the central part. In many Or thoptera and Heteropterous Hemiptera, the shield pears further to consist of two pieces, an anterior posterior one. - The ora is a continuation of the shie below the lateral margin, turned downwards and "™ wards towards the fore-breast and the legs, but separate from the former in most cases by a suture, as in Cart bus L.; and in others merely by an impressed line, 3$ 7 Blaps F.; but in Curculio and Cerambyx L., &c. thet j no ora, the shield being without a lateral margin, ™ forming one piece with the antepectus. The part we ar? es eS ‘pes now considering varies in different genera. Somet™ it is very narrow, as in Scarites ; at others very broad, in Buprestis, Nepa, &c. In Lampyris, except L. inalio® and affinities, it projects posteriorly into a lobe or toot which forms a right angle with the rest of the ord j becomes the lower part of the cavity that receives t head; and in Dermestes this part is excavated into a anterior and posterior one which admits the antenn®æ ae arms when folded for repose. 2. The margin of the prothorax is a ridge, eithe de- @ Prare VIU. Fie. 1. » Ibid. Frc. 2. €- ° Ibid. Fre. 1, 10. a. 4 Ibid. b. * Thid, c. f Thid, 3, © Ibid. a. EXTERNAL ANATOMY OF INSECTS. 537 fining its sides or whole circumference. In many cases this Margin is broad and dilated, but in others it is merely ‘thread or bead that separates the shield from the ora. hough generally terminating the upper surface, it some- times, , as in Staphylinus, dips below it. In many insects, Swever, as I just observed, the thoracic shield has no lateral margin whatever. 3. Various and singular are the appendages with ikiii the prothorax of numerous insects is furnished. Many of these are sexual distinctions, and haye been before de- Stribed to you?; but there are others common to both Sexes, the most remarkable of which I shall notice.— Some are distinguished by a long horn which overhangs the head, as Membracis cultrata, ensata, &c.°; in others it stands upright, as in Centrotus spinosus®; C. Tau- "us has a pair of thoracic horns like those of a bull, ly dorsal’; in Ledra aurita they are flat, and repre- Sent ears; in some species of Tingis ( T. chit, Pyri, &c.) a kind of reticulated hood, resembling Jace, is elevated from the anterior part of the prothorax, which receives ‘nd shelters the head‘. In Centrotus globularis and cla- “atus F., especially the former, thepartin question is armed Y a most singular and wonderful apparatus of balls and ‘Pines, —in one case standing erect 8, and in the other be- ing horizontal »,—which gives these animals a most extra- “tdinary appearance. In many of the species here quoted * See above, p. 327—. * Coquebert Illustr. Ic. ii. t. xviii. fo 2, 4.0 ` Stoll Cigales t. xxi. f. 116. d Thid, t. xi. f. 53. * Prare H. Fre. 4. f Prare XII. Fic. 18. a. * Stoll Cigales t. xxviii. f. 163. * Ibid. t. xxi. f. 115. Coquebert Ilust. Ic. ii. t, xviii. f. 5 538 EXTERNAL ANATOMY OF INSECTS. the prothoraz is producted posteriorly into a long sae telliform horizontal horn, which more or less covers the wings and abdomen; a circumstance which also distin- guishes the genus Acrydium F. (Tetrix Latr.). = horn seems to have been sometimes regarded by Linne and Fabricius as a real scutellum, and sometimes only # a process of the prothorax: but that it is merely ° latter will be evident to you, if you examine carefully any insect furnished with this appendage; for if yo" = move that part, you will discover the true scutellum ji other parts of the trunk concealed beneath it. A very a markable prothoracic appendage is exhibited by some species of Mantis. In general the part we are treating of in this tribe is very slender; butin M. strumarids Be gyloides, &c., it appears dilated to a vast width, and 4°" sumes, either partially or generally, a subrhomboid#! form; but if it is more closely examined, it will be fou? that the form of the prothoraz is really similar to that ° the rest of the tribe, but that this part is furnished each side, either on its whole length or anteriorly, with * large membranous flat subtriangular appendage reser” bling parchment*. Perhaps this kind of sail may be u°° ‘ to the animal in flight. In Prionus coriarius &c. its sides arearmed with teeth, and in many Lamia, Cerambycess g other Capricorn beetles, and often in various bugs ce tatoma Latr.) with sharp fixed spines. But the prot” rax has moveable as well as fixed appendages; of this kind are those spines (umbones), whose base is a spe cal boss moving in an acetabulum of the thoracic shie of the Capricorn subgenus Macropus Thunb. Jf I mig + Stoll Spectres t. xi. f. 42. t. xi. f 45. t. xvi. f- 58, 59. EXTERNAL ANATOMY OF INSECTS. 539 hazard a conjecture, I should say that these organs were 8lven to this animal by an all-provident Creator, to en- able it to push itself forward, when in the heart of some tree it emerges from the pupa, that it may escape from lis confinement. Another kind of moveable appendages } àre attached to the thorax of Lepidoptera, usually in the rm of a pair of concavo-convex scales covered exter- Lally with a tuft of hairs?. M. Chabrier, who examined these scales in recent insects, describes them as vesicles, Which appeared to him full of a liquid and of air, and ca- Pable of being alternately inflated and rendered flaccid ; © regards them as accessories to a pair of spiracles, Which he looks upon as vocal, opening into the mani- trunk just above the insertion of the arms. These or- Sans are quite distinct from the żegulæ that cover the ase of the primary wings of insects of this Order °, and ate what, borrowing a term from Mouffet *, I have called a the table patagia, or tippets. Under this head I may Melude the caruncles at the anterior angles of the pro- toras of a genus of beetles with soft elytra, named by < Fabricius Malachius: When pressed, says De Geer F these insects, a red inflated soft vesicle, of an irregu- ar shape, and consisting of three lobes, emerges from the thorax and from each side of the anterior part of the thdomen, which re-enters the body when the pressure is Yemoved¢. M. Latreille seems to think that these vesi- les have some analogy with the poisers of Diptera and 2 Pirate IX. Fic. 4. b Sur le Vol des Ins. c.-vii, 374. t. xvii. f. 9, ii. e Prare IX. Fie. 5. 4 Theatr. Ins. 98. ° De Geer iv. 74. 540 EXTERNAL ANATOMY OF INSECTS. the pectens of scorpions; and that they are connected with the respiration *. 4. We are next to say something upon the shapé o the prothorax. The forms of the thoracic shield, esp% cially in the Coleoptera, are so various, that it would be endless to aim at particularizing all; but it may be use ful to notice a few of the most remarkable. The pr” thorax of Moluris, a darkling-beetle, approaches a nearest of that of any insect to a spherical form, from its remarkable convexity; in the wheel-bug ( Reduvius ser ratus) it is compressed, and longitudinally elevated IP se a semicircular serrated crest: it is crested, also, iN Locusta and Acrida, in some having two parallel ridge? but, generally speaking, its surface is more depress” In Necrodes it is nearly circular, in Blatta petiver ian semicircular, in Nilion and some Coccinellide cresce?" shaped, in Carabus obcordate, in Cantharis and Sag!” approaching to a square, in Languria to a parallelogr™” in many Cimicidæ, Belostoma, &e., it is triangular, s the vertex truncated; it is trapezoidal in Elater, jn Ate chus rather pentagonal, and exhibiting an approach six angles in some other beetles”: but the prothor™ most singular in form is that of some species of M. + treille’s genus Helæus °, as H. perforatus, Brownii, in these its anterior angles are producted, and cu inwards, lap at the end one over the other, so as to a circular orifice for the head, which otherwise wou many ge: rvi” for™ jd be 4 Organisation Extérieure des Ins. 17 T b A subgenus, related to Lebia ( Hexagonia K. MS.) an micidæ, are so circumstanced. © Regne Animal ili, t. xii. D; d some Cr EXTERNAL ANATOMY OF INSECTS. | 541 quite covered by the shield. Thus the upper portion of the eyes can see objects above, as well as their lower por- tion those below. I might enumerate many other forms, Ut these are sufficient to give you some notion of the Yariations of this part. 5. The prothorax is equally various in its sculpture ; but since in the Orismological table almost every instance of it has its place, I shall here only notice it as far as it 18 common to the whole tribes, genera, or subgenera. The Scarabeide of Mr. W. S. MacLeay are distin- 8Uished by a small excavation on each side of this part, Which, as has been before remarked ®, furnishes an ele- Yated base for an internal process. with which the ante- tior cone ginglymate. In Onitis and Phaneus, to these *Xcavations are superadded a pair impressed in the base the prothoraz, just above the scutellum; in Carabus L. à longitudinal channel divides the thoracic shield into two equal portions; and many genera of that great tribe ave in addition, at the base on each side, one or two ĉxeavations or short furrows. Elophorus F. has on this Part several longitudinal channels, alternately straight d undulated. Generally speaking, in Carabus L. the Prothorax has no impressed points; but in one or two sub- Senera of Harpalide (Chlenia &c.) it is thickly covered With them. In numbers of Locusta Leach, the part we ate considering is what Linné terms cruciate, being di- Vided into four longitudinal portions by three elevated ines, the intermediate one being straight, and the late- tal ones diverging from it both at their base and apex, so àa to form a sinus or angle’. In certain Acride K. * See above, p. 398. b Prater XIV. Fre. 17. 542 EXTERNAL ANATOMY OF INSECTS: (Locusta F.} there are only two of these lines or ridge” but notched or toothed; and in some of the genus first named only one*; in Locusta Dux and affinities the pr” thorax has several transverse channels or rather folds > with corresponding ridges on its internal surface 6. With respectto the clothing of the prothora#, not much to say: in Coleopterous insects this part is ¢ monly naked; but in some genera, as Byrrhus, Anthré Dermestes; and many weevils (Curculio L.) it is par”? or totally covered with hairs or scales. In the other 80 racic Orders it is usually naked, but in some Neuropt™ the Myrmeleonina, &e it is hairy; and in the Libelli" it is fringed posteriorly with hairs. — J have om muss ome- 7. As to its relative proportions, the prothorazx is times rather wider than the rest of the trunk and $ : head, as in Onitis, Pasimachus, &e.; it isconsiderably?™ rower in Collyuris and Odacantha; and of the same W" 4 in those Scaritide with striated elytra <, Again, it y sometimes of the same width with the elytra, but wide? than the head, as in Hydrophilus, Dytiscus, &c.; N some instances it is of the same width with the head, and nar rower than the elytra, for instance in Anthia and Bro chinus. In most Coleoptera it is longer than the hea! and. shorter than the elytra; but in Manticora, the ve" catory beetles, &c., it is shorter than either. In Gnome longicollis“, it is nearly as long as the elytra; ‘in sai Staphylinide, Atractocerus; &c., longer; in. Phan@s call nifex, bellicosus, Xe., it is longer than the elytra and i rest of the body. With regard to itself, it is gometi”? 2 Prare VHI Fre. 10. b Jbid. © Linn. Trans. vi. t. xxi. f. 10. a bid, f. 8» - EXTERNAL ANATOMY OF INSECTS. very wide in proportion to its leneth—Dytiscus, Heleus ; t others very:long in proportion to its width—Colliuris, “entus, Mantis, &c. In Flata, and many other Ho- Nopterous Hemiptera, it is extremely short; extremely ng in Groma; in Sagra and Donacia its width about ®qQuals its length; in Elater, Dytiscus, and many Hete- topterous Hemiptera; it is narrowest before; in Langu- Ne it is every where of equal width; in Anthia, Carabus, 5 it is widest before; and, lastly, in the Scarabeide MacLeay it is usually widest in the middle. i. Antepectus?.—The antepectus, as was before ob- ‘erved b, in some tribes forms one piece, without any ind of separation, with the prothorav ; but very often 'S is not the case. In Carabus L. it occupies almost | S whole under-side of the manitrunk; but in Elater, “which the ora is very wide, the antepectus is merely he middle portion of that part. In Carabus F. &c. be- Ween the ora and the base of the arms is.a convex: tri- Mgular piece, distinguished from the rest of the ante- Pectus by a spurious suture; and: in Pentatoma and other eteropterous Hemiptera a similar piece is observable, "Rich . terminates cinsas convex: bilobed subtriangular à fath, receiving the base. of’ the clavicle*. This piece “eens a prop to that part, and analogous to the scapula of the medipectus and parapleura of the postpectus. I à all say no more upon the .antepectus, as it is. seldom “emarkable. In the mole-cricket, however, one peculia- ‘ty distinguishes it: it is in this of an elastic leathery ` Phare VIII. ò. b See above, p. 536. S Something of the kind is observable ‘at the base of the other Os + oes sae SS In this tribe. 544 EXTERNAL ANATOMY OF INSECTS. substance, while the prosternum is hard, resembling x bone. In other instances these parts are both of the same substance. 1. The sternum or breast-bone of insects COP mostly of three distinct pieces; in this resembling * : human sternum, which is described by anatomists n composed originally of three bones*. Each of thes? pieces is appropriated to a pair of legs, and each of them . > he at times has been called the sternum: thus in Elater : andin J y this gists prosternum, in the Cetoniad@ the mesosternum, drophilus the metasternum, have been distinguished b name. Our business is now with the first of these piece the sternum of the antepectus or prosternum®: thi middle longitudinal ridge of the,fore-breast, which pa between the arms, when elevated, extended, or other remarkable. It is most important in the Coleopter@ í der, to which my remarks upon it will be chiefly 0” fined. In these it is sometimes an elevation, and some times a horizontal process of the fore-breast. w examine the great Hydrophilus (H, piceus), at first J j will think that there is only a single sternum commo? sist i” all the legs; but if you look more closely, you will p° j a ceive between the head and the arms a triangular verti? process, with a longitudinal cavity on its posterio” ai which receives the point of the mesosternum that pass? between the arms °: this vertical piece is „the real P" sternum, and not the other, which really belongs to if alitrunk. In this case the elevation of thé prosternit i before the arms; in others it is between them, a5 s” a Monro On the Bones, 160. b PLATE vill. d- e Ibid. Fie. 7. d’. EXTERNAL ANATOMY OF INSECTS. May see in a Chinese chafer (Mimela K.), which imi- lates the external appearance of a quite different tribe? ; in Others again it is behind them, as in most of the Lamel- icorn SR In the common dung-chafer (Geotrupes s corarius), it is a hairy process, which, when the head 'S bent downwards, is received by a deep cavity of the Nesosternum. The Dynastide MacLeay may always € known by a columnar prosternum rising vertically be- Ween the arms and the medipectus. Lastly, in other Mibes there is a prosternal elevation both before and be- ind the arms, as in Cerambyx thoracicus, dimidiatus, and Minities. Of the second description, those that have a “8s elevated horizontal prosternum, the point in most is the anus, but in some to the head: thus in Carabus L. tis generally a subspathulate flat piece, the point of Which slides over the mesosternum, or covers it; but in “Apalus megacephalus Latr.”, one of this tribe, though “hilar ‘ly shaped, its point is to the head. ‘These hori- Onta] prosterna vary in their termination. In that of *rabus I. the apex is obtuse; in that of Elater, above “scribed €, and Dytiscus it is acute; in Prionus lineatus, Pencii K., &c., it is bilobed; and in Buprestis variabilis, Mtenuata, &c., obsoletely zrilobed. With regard to the er Orders no striking features of this part are observ- €, except in some Orthoptera. In Acrida viridissima ` (Locusta F.) it is represented by two long filiform ver- ‘eal Processes; and in Locusta Leach by a single coni- iv horn 4, mistaken by Lichtenstein for a process of the : Kirby in Linn. Trans. xiv. t. iii. fhi Yno t is doubtful whether M. Latreille’s Harpalus megacephalus is tu, p ous with Carabus megacephalus Fab. Comp. Gen. Crust. et 206. with Syst. Eleuth. i. 187. 95. x oL. HT. p. 317—. a Pyare VIII. Fie. 11. b, m, 2N 546 EXTERNAL ANATOMY OF INSECTS. a jong throat*. In one instance, Gryllotalpa, this part is a piece between the arms, shaped like the human thigh bone or`tibia, being more slender in the middle %9 widest at the ends, and which is of a much harder 84 g) the stance than the rest of the antepectus, and forme will þe- fore long be noticed. In many bugs (Cimicide), } i Ye i um a lower termination of a singular machine which of being elevated, the three portions of the ster” hollowed out into a longitudinal groove, in which © promuscis when unemployed reposes. The most conspicuous and remarkable appendages © the manitrunk, are the brachia or arms. I shall 2°” ~ however, enter into the full consideration of these, as the consist numerically of the same parts, till I treat of J slp legs in general. Here it will only be necessary toan : tio)” my reasons for calling them by a distinct denomina In this I think I am authorized, not only by the examp eS : š S3 of Linné, who occasionally found it necessary to do tH, that s egs" cion? and more particularly by the ancient notion pair of organs in insects were not to be reckoned 2 but likewise from their different position and fun They are so inserted in the antepectus as to point tow?” the head, whereas the other two pair point to the With regard to their functions, besides being am tory, and supporting the manitrunk in walking, theY but axe applied to many other purposes independent of that j - bi fice,—thus they are eminently the scansory oF clu i ; 3 ; Š a legs in almost all insects; im most Carabi L., bY m a Linn. Trans. iv. 58: b Syst. Nat. i. Cancer. Scor g c Moses, when he describe sinsects as going upon four leg ne dently considers the anterior pair as arms ;. Bochart does the 4 Levit. xi. 20—. Hieroxoic. ii. 497. EXTERNAL ANATOMY OF INSECTS. 547 Ë the notch and calear*, they are prehensory legs; in Writes belonging to that tribe, the Lamellicorn beetles, “nd the mole-cricket, they are fossorious legs, or proper y digging >; in Mantis, Nepa, and some Diptera, they ate raptorious, or fitted to seize and dispatch their prey°: °Y are used also by many insects to clean their head, Yes, and antennee, &c. For many of these purposes a" Cannot be fit without a structure different from that * the other legs, which renders it a matter of as great *BVenience in descriptions to speak of them and their tts under different names from those of the legs, as it Sof the arms of man; on this account it is that I propose ^ give to the fore-leg and its part the names by which | 4 analogous parts, or what are so esteemed, in the hu- N species are distinguished;—when spoken of in com- | N with the other legs, they may still be called the fore- Re ** Alitruncus. The alitrunk is the posterior segment. “the trunk, which below bears the four true legs, and p the organs for flight or their representatives. In ti "ating of this part we may consider its insertion or ar- n lation, its skape, composition, substance, motions, and "Pang. i With regard to its insertion, or articulation with the trunk and abdomen, it may be observed that it is z to both by its whole circumference by means of p in the Coleoptera, Orthoptera, and Heteropte- ts Homiptera being received by the posterior cavity of °° Prothoran, the shield of which in these Orders, espe- a , Puare XXVII. Fie. 31. d Prare XV. Fie. 5, 6. “amouelle Z. v. a 548 EXTERNAL ANATOMY OF INSECTS. ; in the cially the last, almost covers and conceals it; but 1 remaining ones it is merely suspended to it, In r former also, especially in the Coleoptera, it seems a separate and distinct from the manitrunk than ire i the abdomen, and more independent of its motio” a $ nor than of those of the latter part: but in the Lyme je from t piera and Diptera its greatest separation is 10" abdomen in both respects. In many insects, 35 wei Lamellicorn beetles, the mole-cricket, &c.s the trunk terminates posteriorly, drawing a line from r base of the prothorax to the antepectus, in an oblig man section; in other tribes, as in the Ceramby# Ls but in the alitrunk the anterior one is always ` he cal, while the posterior, by which it articulates a jei% abdomen, in the Orders with an ample thoracic sh sho? oblique, so that the pectoral portion is more ample the dorsal. cb ii. As to its composition, the alitrunk is usually ™” more complex than the manitrunk ; for, besides the struments of motion, it consists of numerous piece® may be regarded as formed of two greater segmen™ ihe first bearing “he elytra, or the primary wings, and ngs intermediate legs; and the second, the secondary 1 and the hind legs. . „he 1. Collare*. The first segment of the alitrunk * oo middle piece of the whole trunk, and therefore, © It spoken of per se, may be called the meditrun™ oy consists primarily of an upper and lower part, he in the table are denominated the mesothorax ™ a @ Prate IX. g. EXTERNAL ANATOMY OF INSECTS. 549 Nedipectus, The first piece in the former that requires Motice is the collar. I formerly regarded this piece, og is peculiar to the Hymenoptera, Diptera, and one € of the Neuroptera, as the representative of the pro- raw in the other Orders, and this opinion seems at this me very generally adopted, but subsequent observa- lons have caused me to entertain considerable doubts of ; eee : lts correctness. Many other Entomologists have Ought it improper to distinguish these parts by the N name*, Much, however, may be said on both “s of this question, and I shall now lay before you the Mincipal arguments that may be adduced in defence of ach opinion, beginning with those that seem to prove at the collar is the analogue of the prothorax. First, “n, the collar, like the prothorazx, is placed precisely ver the antepectus, and being placed in the same situa- tion, on that account seems entitled to the same denomina- lon; especially as in some genera, for instance Chlorion » It assumes the very semblance and magnitude of a thoracic shield, and is separated from the mesothorax by’ y “onsiderable incisure. Again, in some cases that have len under my own observation, the collar is endued With some degree of motion distinct from that of the trunk, since in Pompilus and Chrysis the animal can Make the former slide over the latter in a small degree. third and last argument is, that no prophragm is med from the collar : insects that have a thoracic shield 4 generally distinguished by having the anterior margin the dorsolum deflexed so as to forma septum, called in i a vi Latreille Organization &c., 199. Chabrier Sur le Vol des Ins. "412. c, iv, 54, &c. 550 EXTERNAL ANATOMY OF INSECTS. the table the prophragm, which enters the chest and s° parates the cavity of the mesothorax from that of the P pi thorax; now in Hymenoptera this septum is a proce of the piece behind the collar, and excludes it g having any share in that cavity. These arguments d first sight seem to prove satisfactorily the identity & ™ collar and prothorax. But audi alteram partem, eae e claims dips that think you will allow that the scale containing th of the collar to be considered as a piece sz generis much the lowest. And, first, I must observ though in Hymenoptera the collar seems to replace t a N, Sns E ae prothorax by its situation, yet it is in fact a part © : : : jat alitrunk ; for, if the manitrunk be separated from satel P : wt? ter, the collar remains, in most cases, attached © ir ; > : ; vi while the antepectus and arm, with the ligamentthat co i ; : , its cavity above, the real representative of the pr othor . fae oo RS - a are easily removed, and this in recent individuals: ji ine! neuter Mutilla; you will see that in this | not separated from the alitrunk in any respect, but fo ; ene piece with it, while the antepectus is distinct g capable of separate motion: further, the action © collar is upon the alitrunk, it being of essential jmp" 4 ance in flight, whereas the prothorax is of no othe pa portance than as a counterpoise to that part®. A furt argument to prove the distinction of these parts may is drawn from the case of Xylocopa, a kind of bee y of genus the collar forms a complete annulus or segment! 4 In Chlorion, Ammophila, &c., this part separates more real from the alitrunk. Baa » Chabrier Sur le Vol des Ins. c. i. 413—. c. iv, 54. This a seems to regard the collar as something peculiar to Hymenopt EXTERNAL ANATOMY OF INSECTS. 551 the body: now, if it really represented the prothorax, the under side of the segment, as in those Coleoptera in Which no suture separates the upper from the lower part of the manitrunk a, should represent the antepectus, and “ve the arms inserted in it; but in the case before Us there is a distinct antepectus bearing the arms received Y the socket formed by this annulus. But the most Powerful argument is the fact that some insects have both the prothorax and collar, a circumstance that com- Pletely does away every idea of their identity. If you. *Xamine the common hornet (Vespa Crabro), or any “ww-fly (Tenthredo L.), you will find, as was before inti- Rated, that the real covering of the cavity of the mani- - unk is a ligamentous membrane, which properly re- Presents the prothorax. In another genus of the same order (Xiphydria Latr.), the sides of the antepectus turn ‘Pwards and nearly form a horny covering distinct from the collar b, the ligamentous part being reduced to a Yery narrow line, and in Fcenus the dorsal fissure is quite filled up, so that in this the manitrunk is perfectly di- ‘tinet, and exhibits both prothorax and antepectus of the ‘sual substance. In Nomada likewise, N. Goodeniana K. Was the species I examined, there is a short minute pro- hora besides the collar. Next let us turn our attention to the Diptera; if you examine the common crane-fly Tipula oleracea), you will find, frst, a regular short Prothorax, to which the antepectus, with the arms, is at- tached; and behind this also is a short collar embracing the alitrunk anteriorly. ‘The next insects that I shall Mention, as exhibiting both prothoraw and collar, are the * See above, p. 536. v Prarr IX. Fie. 14. 552 EXTERNAL ANATOMY OF INSECTS. Libellulina. These are generally admitted to have the former of these parts*, but besides this they have also the latter, which is the most ample and conspicuous piece in the whole trunk’; intervening, as the collar should do, between the prothorax and those parts of the trunk to which the wings are attached. ‘There js one circumstance connected with the subject which shou not be overlooked. In the Hymenoptera, usually unde” a lateral process of the posterior part of the collar, is ? spiracle or respiratory apparatus; in the Diptera ther? is also one, though not covered by the part in questi in the same situation; now this you will find precisely sad ons situated with respect to the second piece in the thora* of Tipula oleracea, proving that this piece is the real 1” presentative of the collar. Enough, I think, has bee said to satisfy you that I have not changed my sentr ments on this subject upon slight grounds. Probably : : ; - he traces of the part in question might be detected 12 oh : ; : : e thoracic Orders in general, in connexion with gom vocal or respiratory organ‘; but having had no oppo” 2 Prate IX. Fie. 6. a. > Tbid. Fie. 7. g’. e M. Chabrier (Vol. des Ins.) supposes that the humming of ™S is produced by the exit of the superfluous air from their thora! spiracles, &c. ; in Melolontha he thinks they are in the metathora” g 4 der the wings (c. i. 457—. Prare XXII. Fre. 13, c. +. represents th operculum of one of those of Dytiscus marginalis): in the Hya ptera, in the mesothorax, near the posterior lobes of the collar a 459. c. iv. 50.); and in the Diptera, in the metathorax, near Í porer (c. i. 457.). I observed myself lately, that Elophilus tent if held by the anterior part of the body, when it hummed, alter nately opened and shut this spiracle. The wings during the gi e vibrated intensely. The hum ceased and was renewed, as they ge restrained from this motion cr released from restraint; Whe? a wing was moved towards the head, a different sound was emitted from that produced when it merely vibrated. ect® EXTERNAL ANATOMY OF INSECTS, 553 tunity, by an extended examination of living subjects, to verify or disprove this suspicion, I shall merely mention 't, and conclude this head by observing, that the collar Varies most in the Hymenoptera order, and that its most temarkable form is in V. espa, Cimbex, Dorylus, &c., in Which it bends into an ample sinus that receives the dorsolum®, | 2. Dorsolum®. Where there is no apparent collar, the dorsolum (dorslet) is the jirst piece of the mesothorax, “nd where there is one, the second; it bears the elytra r other primary organs of flight. It varies in the dif- ferent Orders, particularly with respect to its exposure. “2 Coleopterous insects it is most commonly, but not Nvariably*, covered entirely by the shield of the protho- "ae, the scutellum alone being visible; as it is also m the Orthoptera (with the exception of Mantis and P hasma, in the first of which it is partially, and in the latter intirely exposed), and the Heteropterous, and most of the Homopterous section of the Hemiptera. The scutellum is likewise covered in Gerris, Hydrome- tra, and Velia, and the whole of the back of the alitrunk Yy a process of the prothorax in Acrydium F., Centro- tus, &c, But in the remaining Orders, and the tribe of Tettigonia in the Homopterous Hemiptera, the dor- Solum is not hidden by the thoracic shield. It is usually less elevated than the scutellum; in Necrophorus, and Some other beetles, however, the latter is most depressed. ith regard to its substance, it is generally not so hard * Prave IX. Fie. 11. g’. b Prares VIII. IX. 7. . ° When the prothorax is separated from the elytra by a kind of is ; : : sthmus, as in Scarites, Passalus, &c., the dorsolum is more or less "eovered, 554 EXTERNAL ANATOMY OF INSECTS. and rigid as the scutellum, but in most Coleoptera harder than in the other Orders in which it is covered; ai the Hemiptera, except in Tettigonia, it approaches 4: membrane. As to shape and other circumstances» it varies in the different Orders. In the beetle tribes it has generally a sinus taken out of its anterior margi" and it approaches more or less to a trapezium 3 in Blatt it is transverse and somewhat arched; in Gryllotalp® . z an z ide is nearly square, and distinguished besides on each 3 by a minute aperture, fitted with a tense membran® which perhaps covers a respiratory apparatus. In the ages x $ sa A 7 nE locusts it is more or less triangular, and in Mantis % 2) yai ; s s . T Phasma long and slender. In the Hemiptera the dors? lum appears to consist of several pieces, variously cu $ ith cumstanced, separated by sutures, corresponding wit which are as many ridges on the inside of the crust™ In the Libellulina it is rhomboidal>; in Panorpa neat hexagonal; in the Liphemerina it is ample and oblong’ in Sialis and the Trichoptera this part is represented by x E T : 7 ing three subtriangular pieces, the scutellum constitutis fourth, with the vertices of the triangles meeting in the centret; in the Lepidoptera the part in question is Jarg” and receives the scutellum into its posterior sinus Ge [ums Hymenoptera usually exhibit a very ample dorso mostly subtriangular with the vertex rounded or E ad’ cated, and pointing in some (Vespa L.) to the ho tm and in others (Apis) to the anus; in the Diptera, excep Tipula, the parts of the mesothorax are not separated by any suture, but only indicated by impressed lines Of char a Prare VHI. Fre. 16. 20.7. b Prare IX. is. 49° c Ibid. Fic. 10.7. k. ahid Piel aa e Ibid: Fic. 11. T. EXTERNAL ANATOMY OF INSECTS. 555 Hels ; in the genus last mentioned, however, the dorso- lum is distinct, subrhomboidal, and received by an angu- lar sinus of the scutellum, which last, I think, is not the Part that has usually been regarded as entitled to that denomination ; for this opinion I shall soon assign my Teasons. 3. Scutellum’. Some writers on the anatomy of in- Sects, looking, it should seem, only at the Coleoptera and Orthoptera, have regarded the dorsolum and scutellum as forming only one piece, and others have affirmed that the Lepidoptera and subsequent Orders have no scutel- linc, But as we proceed in considering the scutellum in all the Orders, we shall see that both these opinions are founded on partial views of the subject, and that all Winged insects have a scutellum, more or less distinctly Marked out or separated from the dorsolum. In the Co- leoptera the scutellum is usually the viszble, mostly trian- Sular, piece that intervenes between the elytra at their base d and which terminates the dorsolum. Some Lamel- licorn beetles, &e. (Scarabeide MacLeay) are stated not to have the part in question (exscutellati): but this is not Strictly correct, for in these cases the sewtellwm exists as the Point of the dorsolum covered by the prothorax, though It does not intervene between the elytra: in others of this tribe, as Cetonia chinensis, bajula, &c., it separates these organs at their base, though it is covered by the Posterior lobe of the prothorax: in Meloe F., the elytra è Prarves VIH. IX. XXVIII. ¥. » Audoin, Chabrier, &c. _“ Olivier. He seems also to have thought that neither the Or- optera nor Homopterous Hemiptera have this part. VN. Dict. Vist. Nat. x. 112. ` Prave VIT. Fre. 3. X. 556 EXTERNAL ANATOMY OF INSECTS. e no of which are immoveable, there seems really to b scutellum. Generally speaking, as was lately observed, but not always, it is distinguished from the dorsolum by being more elevated: this is particularly conspicuous i the genus Elater, in which it is a flat plate elevated from the dorsolum by a pedicle; in Sagra the latter part is horizontal, while the scutellum is vertical: and eve? m cases where the distinction is not so striking, these parts are separated either by a line, or some difference in their sculpture and substance. In this Order this part varies greatly, and often in the same tribe or genus, bot in size and shape; being sometimes very large °, ane sometimes very minute; sometimes very long, and som®™ times very short; sometimes nearly round, at other square; now oval or ovate, heart-shaped, triangula acuminate, intire, bifid, &c. In the Orthoptera, thous less conspicuous, it still is present as a triangular elev" tion of the middle of the posterior part of the dorsolu™ with the vertex either pointing towards the head, a5 in Blatta, or towards the tail, as in Locusta Leach”. Jn the Heteropterous section of the Hemiptera (which, ip columns of Mandibulata and Haustellata, appear to beat the same reference to the Coleoptera, that the Hymen?” ptera do to the Diptera, and the Homopterous Hemi ptera to the Orthoptera‘) the part we are considering * mostly very large and conspicuous, quite distinct from the 2 In Macraspis MacLeay it is often half as big as an elytrum- b Pirate VIII. Fie. 12, X. ¢ Mr. W. S. MacLeay opposes the Hemiptera to the Orthopte™® the Homoptera to the Neuroptera, and the Aptera to the Coleopter? but if analogous structure be made the guide, I think my arrang®” ment will be found most correct. Hor. Entomolog. 367. EXTERNAL ANATOMY OF INSECTS. 557 dorsolum, and in some (Tetyra F.) covering the whole abdomen, as well as the Hemelytra and the wings; it is Most commonly, as in the Coleoptera, obtriangular*, but i the last-mentioned genus it often approaches to a pen- tagonal shape. Though usually so striking a feature in this tribe, in the aquatic bugs (Gerris &c.) it is covered by the prothorax. In some species of Reduvius F. (R. biguttatus, mutillarius, lugens, &c.) it is armed with one or more dorsal or terminal spines. In the Homopterous Section, where the dorsolum, as in Tettigonia F., is not Covered by the prothorax, the scutellum, which is merely a continuation of that part, bears some resemblance to a St. Andrew’s cross, and terminates in a fork>; in Ful- ora, in which it is partly covered, it is merely the trian- gular point of the dorsolum ; in the Cercopide, &c., whose dorsolum is wholly covered, the triangular scutellum is distinct from it; in Centrotus, Darnis, and Membracis, in Which the prothorax is producted, and covers the abdo- Men more or less, the scutellum is a short transverse di- Stinct piece. In the Lepidoptera, from the difficulty of abrading sufficiently the scales and hairs without injury, it is difficult to obtain a correct idea of the part in ques- tion; in the cabbage butterfly (Pieris Brassice) it ap- Pears to be triangular: in the humming-bird hawk- Moth (Macro-glossum Stellatarum) it approaches to a thomboidal shape °; and in the eggar-moth (Lasiocampa Quercus) it is completely rhomboidal. In the Libellu- lina, in the Neuroptera Order, it seems to be represented by the posterior point of the dorsolum, which terminates * Prare VIII. Fie. 20. #. b Jpid. Fre. 16. X. © Phare IX. Fic. 1. #. N.B: This is from Cossus F. 558 EXTERNAL ANATOMY OF INSECTS. in something like a St. Andrew’s cross*. In most of the other tribes of this Order the scutellum is a triang™ lar piece, with the vertex to the head, received betwee! two pieces of the dorsolum; in Psocus it is nearly like that of Tettigonia before described. In the Hymeno- ptera the scutellum is separated from the dorsolum, which it often embraces posteriorly, as the collar does in front, by a suture; it varies occasionally in shape in the diffe- rent tribes, most commonly it is crescent-shaped, put 12 many Ichneumonide and others it is triangular; in the hive bee, &c., it overhangs the succeeding piece of the alitrunk; in Melecta, Crocisa, &c., it is armed with a p% of sharp teeth €; in others (Oxybelus uniglumis, &c.) with one or more spines, and in some with a pair of long horns‘. Before I describe this part in the Dipter@ it will be proper to assign. my reasons for considering ® different piece as its representative, from what has usually been regarded as such, and which at first sight seems the analogue of what I admit to be the scutellum in the Hymenoptera. The dorsolum, and its concomitant th? scutellum, belong to the first pair of the organs of flight which are planted usually under the sides of the forme” and in the case of wings, by their Anal Area, connette! either mediately or immediately with the latter. Now» ' you trace the sides of the piece that I have considered 3° the part in question in Hymenoptera, you will find that they lead you not to the base of the Zower but to that of the upper wings *, and in the saw-flies ( Tenthredo L.) 4 Pratt IX. Fic. 7- > Ibid. Fre. 11, 15. k. ° Mon. Ap. Angl. i. t. vi. Apis. ** a. f, 2. aa. à Stoll Cigales t. xxviii. f. 164. * Prate 06, Big. 12%. EXTERNAL ANATOMY OF INSECTS. 559 You will see clearly that the Anal Area of these wings is Attached to a process of it, a proof that it belongs to the ®esothorax, or region of that pair. But in the Diptera, the part that has been usually called the scutellum is not at all connected, either by situation or as a point of at- tachment, with the wing itself, but with the lower valve of the alula, which is with reason thought to be the repre- Sentative of the secondary wing of the tetrapterous Orders. You may see this even in the common crane-fly ( Tipula), which there is areal alula, connected by means of a la- eral process, terminating in ligament, with this supposed Scutellum. If you examine further the same insect, you will easily find what I regard as the true one in the bi- obed piece which receives the dorsolum, situated be- tween the wings, and to the sides of which they are at- tached. In Asilus, Tabanus, &e., this part is transverse, “Nd only distinguished on each side by an oblique im- Pressed line ; inthe Muscid@ it is square, and marked by i Straight transverse one. 4. Freenum*. This appendage to the scutellum and dorsolum varies considerably in the different Orders, and in Many cases, as you will see, is a very important part, ing the process by which the former is mostly con- ected with the elytra or upper wings. In the Coleo- v tera, the elytra of which are nearly stationary in flight, "nd therefore less require any counteraction to prevent their dislocation, this part is commonly merely a process r inerassation of the under margin of the scutellum, Which towards the base of the dorsolum is dilated to orm the socket for the elytra. Its use as a countercheck a Prates VIII. IX. XXVII Z. 560 EXTERNAL ANATOMY OF INSECTS. in this Order is best exemplified in the common water” beetle (Dytiscus marginalis). This at the inner base of the elytra has a membranous fringed alula resembling those of Diptera; to the lower fold of this the extremity of the freenum is attached, which forms a right angle with the scutellum, and the upper fold is attached to the uo of the elytrum?. The object of this appendage is pe bably to prevent the dislocation of these organs, whic? seems to indicate that they are used more in flight than those of other beetles. The Blattæ also, in the next GF der, have a winglet attached to the anal area of the eS" mina. The freenum, as in the preceding Order, lies UW der the margin of the scutellum and dorsolum, but whic here forms one uninterrupted transverse line; it is nea ly vertical, and is attached to the ala. ‘The structu"? is not very different in the other Orthoptera ?, but thh : 0 frenum is surmounted or strengthened by one oF tw n ap” ridges; in Mantis it runs from the scutellum in a d im gular or zigzag direction—but in all it is attache mediately to the tegmen. In the Heteropterous Hem ptera it is represented by the narrow bead adjacent tO the scutellum on each side °, which dilates into a flat plate e it approaches the Hemelytrum, with the Anal Area of whic itis connected. Butthe Homopterous section of the orde in question furnishes examples of the most remarkab " structure ofthis countercheck, which proves that it is "°? j ly, what its name imports, a bridle. If you examine jj great lanthorn-fly ( Fulgora laternaria), or any species 0 Tettigonia, &c., you will find adjacent to the scutellu™ @ Prare XXIII. Fie. 6. e”. > Prare VIIL Fie. 12" e Ibid: Fre, 20. /. EXTERNAL ANATOMY OF INSECTS. 561 Parallel with it, on each side a flat plate ; and from the “gle of that part in the first case, and from one of its Processes in the last, you will further perceive a ridge or üervure which runs along this plate, in one forming an ngle, and in the other being nearly straight, to the base af the tegmen, where it becomes a marginal nervure to a Membrane that is attached to the posterior part ‘of the àse of the Anal and Costal Areas; and that this marginal ervure, like a trachea, consists of a spiral thread, or “ther of a number of cartilaginous rings connected by “astic membrane ĉ, and consequently is capable of con- ‘derable tension and relaxation, as the tegmen rises and ls in flight. In the Lepidoptera it appears to be a “rt piece overhung by the scutellum, which as it ap- "oaches the base of the wing is dilated. In the Libel- aina, to go to the Neuroptera, it has the same kind of astic nervure connected with the Anal Area of the wing ich I have just described in the Homopterous Hemi- terg , another nervure, in Æshna at least, appears to Verge upwards from the scutellar angle to the Interme- “ate Area: a structure little different distinguishes the Stof the Neuroptera, and even the Trichoptera. In the Imenoptera this part varies somewhat; in the majority “hans of the Order, as well as in the Diptera, it ap- ‘Nae to be merely the lateral termination of the scutel- ‘ny Where it joins the wing; but in some tribes, as in h redo L. (especially Perga Leach), Sirex L., and Ichneumonidae, a ridge, and sometimes two, runs ™ the scutellum to the wing; the upper one, where * Prare XXVII. Fic. 11.7. Yo b Chabrier Sur le Vol des Ins. c. iii. t. viii—v, B. i. = NT, oo 562 EXTERNAL ANATOMY OF INSECTS. there are two, as in Perga, being the stoutest, and con” necting with the Costal Area, and the lower one with the Anal. 5. Pnystega?. We learn from M. Chabrier; that the common dragon-fly, a space, consisting of three ; i s f triangles, which immediately succeeds the frenum * fords attachment to no muscles, but merely covers acne vesicles®, This is the part I have called the pnystege ` An analogous piece may be discovered in Phasm@ a Mantis in a similar situation; but I cannot trace it Locusta Leach, or in the other Orders. Having considered the parts that constitute the mes” thorax, we will next say something upon those, a far ® they require notice, that compose the medipectus OF ji i breast. But first I must observe in general of the ™ J dipectus and postpectus taken together, or the whole gi derside of the alitrunk, that though usually they are the same level: with the antepectus or under side °, manitrunk, yet in several instances, as the Scarab! s MacLeay, the Staphylinide, &e. they are much mo” elevated. than. that part; they are also usually lon i very remarkably. so in Atractocerus, but in Elate” ” í caius and many others they: are shorter. These P? 4 arẹ also commonly, rather more. elevated than the ab j men, —much so in some, as Molorchus; but scarcely ° i in others, as Buprestis, the Heteropterous Hemipter™ In some of the latter (Tetyra F.). the abdomen $% 5 the most prominent. Another observation relating he e Prate IX. Fie. 7. m. o Chabrier Sur le Vol des Ins. c. iii, 354, ¢ From wvéw to breathe and siyo to cover. EXTERNAL ANATOMY OF INSECTS. 563 this part must not be omitted, namely, that though in Many cases the medipectus and postpectus are perfectly istinct and may be separated, yet in othérs, as for in- ‘tance the Lamellicorm beetles, the Hymenoptera and ‘ptera, &e., no suture separates them; so that though © upper parts, the mesothorax and metathorax; are se- Parable, the lower ones just named are not so. ¢ 8. Peristethium*. The first piece of the medipectus is What I have called, after Knoch, the peristethium>. This “hnediately follows the antepectis; on éach side it is Mited by the scapulars, and behind by the mid-legs and "sosternum. Tts antagonist above is usually the dorso- “n In the Coleoptera Order it varies occasionally, ‘oth in form and magnitude, but not so as to merit pare cular notice, except that both are regulated by the séa- Pillars if these are small, the peristethium is ample; and, Vice versa, if they are large it is small. In all the fol- Wing Orders, except the Hymenoptera, it’ is equally “onspicuous, but in them it is often more remarkable. dave a Brazilian species of Cimbex (C. mammifera E Ms.) which appears undescribed, in which this part Wells into’ two! breast-like protuberances, terminating’ *Steriorly in membrane, as if it had separate motion: in 3 golden-wasps (Chrysis L:) it is anteriorly concave to “ceive the core of the mid‘legs; and in Stilbimn, of the , Peares VITT. IX. v. | ; Ri t first I had named this piece the antecosta, and the méesoste- tho ™the postcosta ; and there is certainly some analogy between the tha Of insects, consisting of several pieces that follow each other, € vertebral column; between their three sternums and the ster- ani’ and between their other pieces and the ribs of vertebrate Mals, Comp. Chabrier, ubi supr. c. iv. 49. note 1. 202 f 564 EXTERNAL ANATOMY OF INSECTS. x Pe r : se same tribe, it is armed with one or more conical obtt teeth. 7. Scapularia*. The scapulars are situated b cove of the mid-legs and the base or axis of the upp” organs of flight, and they seem to act as a fulcrum tO 8 In the Coleoptera Order they are most commonly gu drangular or subquadrangular, often divided diagonally , etweell the and sometimes transversely, by an impressed line; posterior part, which is usually the most elevated pi hich often has an uneven angular surface, is that w ; forme? tervenes between the coxee and elytra: where the are short, as in the Capricorn beetles, the scapulars are long; and where they are long, as in the Petalocero” ones, the latter are short. "The anterior part is n p which forms the lateral limit of the peristethium, © wi which it often encroaches: this part, in conjunction p Jow the dorsolum above, and the last-named part be forms the kind of rotula that plays in the posterior ace’ f bulum of the manitrunk, as the head does in the anter? one. In the flower-chafers (Cetonia F.) the scapula” are very thick and elevated, and interpose between t z posterior angles of the prothorax and the shoulder ° the elytra, which is one of the distinguishing charact® $ of that tribe : in this case the lower angle of the scapt* connects with the coxa of the mid-leg, and the upp? angle with the axis of the elytra; and the most elevat and thickest part of the scapular is about midway betwee t the two. This robust structure seems to indicate : the scapular has to counteract a powerful action bo a the leg and elytrum. In the Orthoptera.the scapw a Prates VIII IX.. EXTERNAL ANATOMY OF INSECTS. 565 àre usually divided into two parallel pieces, corresponding Probably, though more distinct, with the two parts late- lY noticed of those of the Coleoptera: the upper side of the socket of the mid-leg is common to the base of both these pieces, but the articulation of the tegmen is chiefly With the anterior one. In the grasshoppers, locusts, &c. (Gryllus L.) in which tribe this leg is nearly opposite to that part, the scapular inclines but little from a vertical Position; but in the praying-insects (Mantis), spectres (P, hasma), and cockroaches (Blatta), in which the in- “ettion of the mid-legs is behind that of the tegmina, it is Nearly horizontal. In the Heteropterous Hemiptera the iNterior part of the scapular is covered by the antepectus, d separated ‘by a ridge, more or less pronounced, from € open part; the whole is of an irregular shape, and Marly parallel with the parapleura. In the Homopterous ‘ection it likewise consists of two pieces, and sometimes of more. Thus in Tettigonia F. it is bilobed, and be- Ween it and the coxa two small pieces are inserted®. In ‘ome others, Jassus Lanio F., &c., it is not very unlike he scapular in Coleoptera, being subquadrangular and divided diagonally. In the Neuroptera this part and the Parapleura are parallel, and placed obliquely °. In the “ommon dragon-fly (Zshna viatica) the former forms Nearly a parallelogram 4, which is not divided by any “dee or channel, but its lower half is separated into two Nhequal parts by a black longitudinal line, opposed to Which on the inside is a ridge. The mid-leg in these is “onnected with the scapular by the intervention of a ` Prare VIII Fie. 12.13.0.2. > Ibid, Fre. 17. o. Prare IX. Fic. 8,0. 2. a Ibid. o'. 566 EXTERNAL ANATOMY OF INSECTS. triangular transverse anterior piece, which in fact seems only marked by a black channel, to which also interiorlY a ridge is opposed ?. In the rest of the Order it is divided - longitudinally into ¢wo parallel pieces. In Panorpa the posterior piece is longer than the anterior and props the coxa behind; in Myrmeleon and Perla, XC» it apy pears to consist of three pieces. I haye not been able t obtain a clear idea of them in the Lepidoptera, excep! that they have more than one piece. Hymenoptero® and Dipterous insects for the most part have no scapula distinct from the peristethium; but in Cimbex, Pergh and other saw-flies, it seems represented by its posteri? depressed and sometimes membranous part: in Vesp™ &c, a small subtriangular piece, just below the base P: the upper wing, is probably its analogue”. 8. Mesosternum<. The central part of the medipect™ er that which passes between the mid-legs when ele vated, protended, or otherwise remarkable, is called the mesosternum or mid-breast-bone. In the Coleoptera Ol der it exhibits the most numerous variations, and ® usually the most strongly marked of any of the three portions of the sternum, affording often important cha racters for the discrimination. of genera and subgepel™ It may be said to be formed upon three principal typ, the first is, where it is a. process of the posterior part s the peristethium, and points towards the anus 9t tbe head ;—the second, where it is a process of the anterio part of the mesostethium, and points, only towards the head: in this case there is no suture to separate the @ Prats IX. Fie. 8. a. t Ibid. Fra. 12. © ° Prare VII. Fre. 3, 13, 7’. EXTERNAL ANATOMY OF INSECTS, 567 medipectus from the postpecius ;—the last type is where tis a ridge formed by a process both of the peristethium “Nd mesostethium meeting between the legs; an example of this you will see in the common dung-chafer (Geo- upes Latr.). Upon the two first of these cases I shall ofer a few remarks;—the last affording no variation need only be mentioned. If you examine the terrestrial Predaceous beetles (Cicindela and Carabus Ls) you will find that the periste- thium is usually flat, terminating towards the postpectus Ma kind of fork, the sinus of which receives the anterior Point of the mesostethium—this is the mesosternum; but "the aquatic insects of this tribe, at least in Dytiscus Nireinalis, &c. the structure at first sight séems diffe- "ent, for apparently the prosternum is received by the terior fork of the mesostethium ; but if you proceed to parate the manitrunk from the alitrank, you will find that the true mesosternum of the usual form is quite “Vered by this point; which curves towards the breast, 3 longitudinally concave to receive the point of the pro- termin, and permit its motion in the groove. In some &teromerous beetles, as the Helopide, &c. this part is “Hteriorly bilobed, so as to form a cavity which receives X point of the prosternum when the head is bent down: 3 Helops nitens (Tenebrio Oliv.) this sinus represents a escent; in Cistela Ceramboides it is shaped like the teek letter y; in the Lady-bird (Coccinella L.) it as- ‘Umes nearly the shape of a Saint Andrews cross; in Pheniscus K.? the mesosternum is wide, concave and “thkled, with an anterior and posterior sinus; while in a Linn. Trans. xii. t xxii. f. 4 568 EXTERNAL ANATOMY OF INSECTS. the analogous genus Hrotylus* it is convex anteriorly» and posteriorly more or less rounded ; in Doryphor@ i is a long, robust, subconical horn, often standing at a angle of about 45°, overhanging the prosternum. In the genus last named, though its mesosternum in its direction and appearance resembles that of many Ree” locerous beetles, yet it is separated by an evident _ from the mesostethium ; but in the last-mentioned tribe its representative is a process of the latter part: Y at the peristethium and mesostethium are separated hy #° suture, though in some cases a transverse channel, oft in others merely a coloured line, marks the point whet? they may be considered as soldered together, in thes? cases the mesosternum may perhaps be said tO common to both. In this great family, which include within its limits some of the most singular and wonder” ful in their structure and armour, as well as some of the most brilliant and beautiful of the beetle tribes, —the pa in question, in a vast number of cases, will enable Entomologist satisfactorily to trace its numerous group’ ; not only where it rises or stretches out into a hor? . ridge, but even often where it is merely a flat space ber tween the mid-legs. I shall notice some of its mo? striking -variations in this tribe. In Phaneus festiv and in Macraspis and Chasmodia MacLeay, it is elo?” gated horizontally, with the apex curving upwards; ? * A remarkable instance of analogy is afforded by this gents: Erotylus there are two groups ; one distinguished by gibbous ely? and the other by flatter ones. The same distinction is observal”® Spheniscus ; for to this genus belongs Helops fasciatus Oliv., whie presents the flat Erotylt, and even individually Erotylus trifoe Oliv., E. fasciatus F, jn z jats EXTERNAL ANATOMY OF INSECTS. 569 Anoplognathus it is horizontal, straight, and figures an isosceles triangle; in Cetonia suturalis, vitticollis, &c. t is very long, passing between the arms and nearly Teaching the head; in C. marmorea, Lanius, &c. it is a lofty, robust, conical prominence; and in many Rute- lide, especially those with striated elytra, it is pyramidal or four-sided; it varies also in its termination, particu- larly in the Cetoniade ; and even where there is little or No elevation of it, as in the Scarabeide MacLeay, it is Often terminated anteriorly by lines that vary in their angle or curvature, . The genus Copris, as restricted by Mr. W. S. MacLeay, may from an inspection of this Circumstance be divided into several families. Thus in C. Molossus and affinities its termination represents the letter A reversed, or a triangle surmounted by a mucro; u C. orientalis, &c., it ends in an acute-angled trian- gle; in C. lunaris, &c. in an obtuse-angled one; and in C. Iacchus, &c., in the segment of a circle. The part we are considering is not so important in the other Orders. Inthe Orthoptera, however, it is occa- Sionally remarkable. In Acrida viridissima (Locusta F.) attached to the anterior margin of the peristethium are two long triangular pieces which appear to represent this Part; in the kindred subgenus, Conocephalus, it is a Single piece bifid at the apex; in Gryllotalpa it is a very elevated hairy ridge; and in Locusta Leach, it is a flat anterior process of the mesostethium. In the Heteropte- “ous Hemiptera this part is often merely a portion of the channel in which the promuscis reposes ; but some- Umes, as in Edessa F., it is an elevated piece varying * I would restrict this name to the conical-headed Locusta E. 570 EXTERNAL ANATOMY OF INSECTS. in its termination. In the remaining Orders, as far as I have had an opportunity to examine them, it ©” scarcely be said to exist separately from the medipect™ except that in Tipula Latr. a bipartite subtriangulat membranous piece seems to be its analogue. We are now to consider the last segment of the ali- trunk, which, as a whole, may be denominated the et truncus; it bears the second pair of the organs of flight and the last pair of legs. The upper side of this is the metathorax, and its lower side the postpectus. 9, Postdorsolum*. The first external piece of the metathorax is the postdorsolum, which presents itselt under very different forms and circumstances in the dif- ferent Orders. In the Coleoptera it is intirely covet? by the dorsolum and scutellum ; it is generally more or Jes of a membranous substance, or partly membranous 4? partly corneous, which enables it to yield more to the action of the wings in flight; it is usually an ample transverse piece with tumid sides >; but in the Scarabaidé MacLeay, it is short though very wide; and in Cychri® and probably other apterous beetles, it is extremely mi- nute and almost obsolete. In the Orthoptera Order, observe once for all, the part in question, as well a the postscutellum and postfrenum are mere counterparts of the dorsolum, scutellum, and frenum, except that in ` some eases they are larger °. In the Heteropterous He- miptera at first sight it would appear that all the parts ° the metathorax were altogether wanting or absorbe a Prate VIIL. IX. €. Linn. Trans. xi. t. ix. f. 16. c d Prats VII. Frc. 3. t. e Tpid. Fic. 12. Comp. 7, Asi, with L, U, v’. EXTERNAL ANATOMY OF INSECTS., 571 in the ample scutellum; but if you remove this with care, Jou will find under it their representatives, its lower sur- face being hollowed out to receive them. The postdor- Solum appearsin these as a transverse obtusangular band; m the Nepide, Notonectide, &c. the three parts of the Netathorax seem united into a single plate, emerging laterally from under the scutellum below the frenum ; in Which, however, some traces of a distinction between them may be discovered. In the Homopterous section the Lulgoride exhibit these pieces very distinctly, cover- ed only at the base by the mesothorax : but in Tettigonia they are not so easily detected; they exist however as a Narrow strip or band, almost concealed by that part. As to the Lepidoptera Order, in Pieris Brassice at least, the postdorsolum is represented by a pair of nearly equi- ateral triangles whose vertexes meet. in the centre of the Metathorax, and. between which and the scutellum is a deep cavity; but in Macroglossum Stellatarum and La- Siocampa Quercus, there appears to be also a central transverse piece between them. In the Neuroptera there is no material or striking difference between the parts of the mesothorax and metathorar*. In the Hymenoptera Nore variety occurs in this part. In the saw-flies, &c. (Tenthredo E.) the postdorsolum is a transverse piece “evered by the scutellum; in the Ichneumonide it is Smaller, but not covered; in the Vespide it is apparent, transverse, and with the postscutellum obtusangular®; jn. Anis itis overhung by the scutellum The Diptera exhibit ‘ome variations in this part. In Tipula it consists of three pieces placed transversely, the central one qua- * Prare IX. Fic. ft > Thid. Fie 11. Z, 572 EXTERNAL ANATOMY OF INSECTS. drangular, and the lateral ones roundish ; in the Asilidé and most others of this Order, with the postscutellums p forms a segment of a circle?, sometimes armed with 2 pair of spines, as in Stratyomis F., and is what has bee? usually regarded as the real scutellum, though, as I have endeavoured to show, not correctly. 10. Postscutellum’. The postscutellum bears the same relation to the postdorsolum that the scutellum does tO the dorsolum, but it is seldom, if ever, a distinct piece. In the Coleoptera it is represented by the longitudinal narrow channel that terminates the postdorsolum towards the anus‘: this usually figures an isosceles triangle with the vertex truncated or open; but in Copris the triangle va equilateral. In the other Orders it is little more tha? the central posterior point of the postdorsolum °. , 11. Postfrenum'. The part now mentioned is much more important than the preceding one, and must not be passed over so cursorily. In the Coleoptera it usually presents itself under the form of two large and usually rather square pannels, the disk of which is convex, but the rest of their surface unequal, which are situated 08° on each side of the postscutellum 5; under the anterio” outer angle of these is the socket or principal attachment of the secondary wings, and their basal margin is at- tached to their outer side; posteriorly behind the yerte* of the postscutellum the postfrenum is crowned with ? ridge or bead, below which it descends vertically ° obliquely to the adomen ; this ridge often turns upwards a Prats IX. Fie. 19, 20. £. b See above, p. 558—- c Pares VIIL. IX. v. ‘ Prary VIIL. Fre. 3 “- © Ibid. VII. Fre. 12. wv. FLATE LA. 7. wv’. f Praves VILL IX. v. : Prave VII. Fie. 3. 0° EXTERNAL ANATOMY OF INSECTS. 573 aid proceeds towards the middle of the basal margin of the wing. In the Petalocerous beetles the part in ques- tion is usually more or less hairy; but in many others, as the rose-scented Capricorn (Callichroma moschatum), &ce. it is naked. At its side you will commonly observe Several plates and tendons (osselets Chabr.) connected inter se and with the base of the wing by elastic liga- Ments, which are calculated to facilitate the play of those Organs. In the Orthoptera, Neuroptera, and Homopte- tous Hemiptera, the postfrenum does not differ mate- tially from the frenum*. In the Heteropterous section of the last Order it is usually a transverse ridge termi- Nating the postdorsolum, with a bifurcation where it Unites with the wing; but in Tetyra F. (at least so it is in Tetyra signata,) itis a nearly vertical piece, marked in. the centre with an infinity of very minute folds, which Probably by their alternate tension and relaxation let Sut and pull in the wings. Amongst the Lepidoptera it ig not remarkable. In the Hymenoptera Order it. is Mostly represented, I think, by a double ridge or fork, Sometimes however obsolete, but very conspicuous in the Saw-flies, which laterally terminates the postdorsolum ; the upper branch, usually the thickest, going to the an- terior part of the base of the underwing, and the lower One to the posterior. You may observe something simi- lar in the crane-flies (Tipula Latr.) and Asilide. A tendon proceeding from the point of the postscutellum forms a fork near its end, the upper branch of which Connects with the anterior and the lower with the poste- rior valve of the winglet; the structure is a little, but not “ssentially, different in other Diptera. è Prats VIII. Fic. 12, 16.; and Prats IX. Fie. 7. v. 574 EXTERNAL ANATOMY OF INSECTS. 12. Pleura? By this name I would distinguish the part which laterally connects the metathorax and post pectus. It includes in it the socket of the secondary wings. In the Coleoptera this is a two-sided piece lying between the postfrenum and the parapleura, with the upper side horizontal and the lower vertical »—a tendon usually proceeds from its anterior extremity to the base °” thewing. Inthe Orthoptera, Neuroptera, and other Orders it is merely the longitudinal line of attachment of that part ; but in the genus Belostoma Latreille, related to the water-scorpion, it presents a peculiar structure, betig é deep channel or demitube, filled at its posterior extre™” ty by a spiracle and its appendages °. is 13. Metapnystega*. ‘This part, although in the table! have placed it.as an appendage of the pleura, is not alway? confined: to them,.as yow will soon see. It either covet? aérial vesicles, or is the seat of a spiracle. In the Ord Coleoptera itis of the former description. If you exi mine the metathorag of the common dung-chafer (60 trupes stercorarius), in the horizontal part of the pleut you will see:a sublanceolate or subelliptical rather me™ branous silky tense plate, with its point towards the head, —this is.the part we are considering ; something simila" yowwill find in most beetles; but insome, as Callichrom® moschatum, it is less: conspicuous: This part, as far 45* have observed, is not:so situated inany other Order, €% cept insome Heteropterous Hemiptera: in Belostoma the channel lately mentioned is filled up at its posterior €™ by a red organ with an anterior vertical fissure, tet” @ Prate VIIL Fie. 3. w. . > Prare XXII: Fre. 14w e Prare XXIX. Fic. 25. W. 4 Ibid. and Prater VIII. Fie. 12.; and Prang IX. Fre. 7. E- EXTERNAL ANATOMY OF INSECTS. 575 hating behind in a conical bag: in Notonecta the pleura has something of a plate like that of Coleoptera, but of a horny substance. In the Orthoptera and Neuroptera this part changes its situation, if it be indeed synony- Nous; and as the pnystega follows the frenum, so the Metapnystega succeeds the postfrenum. Inthe Libellulina M. Chabrier found that this as well as the other covered arial vesicles?, and it probably does the same in the Other cases in which it occurs. In Mantis and Phasma in the” Orthoptera it is very minute; but in Locusta each, it is more conspicuous under the form of a tense Membrane, the surface of which is depressed below that of the abdomen: in Acrida viridissima K. it fills. the Sinus: of the postfrenum, and is. vertical, as it is in ishna. It is worthy of remark that this piece bears Some analogy to that below the ridge of the part just famed in Coleoptera, which descends either vertical- ly or obliquely to the abdomen®. A similar space, though often nearly obsolete, may be seen in the Hemi- btera and Lepidoptera. But the Orders in which this Part is most conspicuous are the Hymenoptera and Dipte- ta, and in these its aérial vessels are connected with a Spiracle. In Tenthredo L. and: Sirex L., what Linné Named grana, from their situation, should be regarded as belonging to the pnystega, and whether there is any part tepresenting the metapnystega I am not quite satisfied ; Perhaps the membrane at the base.of the abdomen in Tenthredo, and the bipartite piece, apparently: its first Segment, in Sirex®, may beits analogues: butin the great Majority of the Order, the convex or flat. piece that in- ` Surle Vol des Ins. ec. ii. 354. b See above, p. 572. * Prag IX. Fie. 15. X’. 576 EXTERNAL ANATOMY OF INSECTS. tervenes between the postdorsolum and its adjuncts and the abdomen, and which bears a spiracle on each side, is the metapnystega*. ‘This part is often remarkable, not only for its size, but for the elevated ridges that traverse it, as in Ichneumon, Chlorion, &c. In the last genus it is of a pyramidal shape, with the anterior part horizontal and the posterior vertical; it is altogether vertical in Vespa, Apis, &c. Amongst the Diptera, in Tr- pula it is nearly horizontal, and shaped like a cushions but in general in this Order it is vertical, and conceale under the postdorsolum». We are now to consider the parts that constitute the postpectus or under-side of the metathorax, and which bears the posterior pair of legs. 14, Mesostethium*. This part in Coleoptera is termi- nated anteriorly by the peristethium, scapulars, and Me- sosternum, laterally by the parapleure4, and behind bY the core of the posterior legs €, which generally are in sérted transversely between it and the abdomen. It” commonly very wide; but in Dytiscus L., Carabus Ln &c., in which the cove and parapleure are dilated, it ® proportionally reduced : its length is regulated by the distance of the intermediate and posterior legs ; where these are far asunder, as in the rose-scented Caprico!™? (Callichroma moschatum), &c. it is long : but where they are near each other, as in the Scarabeide MacLeay: p is short; its width, however, generally exceeds its length. In shape it is generally subquadrangular f, though som” © Prats IX. Fic. 11. 2”. » Ibid. Fie, 20. £’. e Prares VIII IX. y. 4 Prare VILL Fre. 4.2- © Ibid. p”. f Ihid. y. EXTERNAL ANATOMY OF INSECTS. 577 times thomboidal, and other forms of it occur. Between the hind-legs it generally terminates in a notch or bifur- “ation distinct from the metasternum, as in Hydrophilus, ©; in Hister there is no notch, and in many Scara- fide it projects between the hind-legs in a truntated w rounded mucro; in the Vesicatory beetles, Meloe » it is more elevated than the medipectus, towards Which it descends almost vertically; in Dytiscus L., Ca- "abus L., &c., this part is usually divided into two by a "ansverse sinuous channel, and in Eater by a longitu- mal Straight one. In many Orthopterous genera, Gryl- alna, Acrida K., Locusta Leach, &c., the mesostethium “onsists of two pieces?. It is remarkable that in many of “se genera, in this part, as likewise in the medipectus and Nenectus, are one or more perforations which appear to “ter the chest, the use of which I shall explain hereafter. “the Libellulina, as I shall soon have occasion to shew, there is a peculiar arrangement of the legs and wings, in “sequence of which this part is placed behind the pos- “lor ones. In the remaining Orders, the mesostethium, . Ugh it exists, exhibits no peculiarities worthy of par- ular notice, except in some Aptera and Arachnida: ts, in Nirmus Anseris it is terminated posteriorly by _ Pair of transverse membranous appendages which “Over the base of the posterior core ; in Scorpio it con- “tg of two pieces, the pectines® being attached to the “Wes of the posterior one. l5, Parapleurat. The parapleura, speaking gene- » Ys is that piece of the postpectus which, intervening “Ween the pleura, mesostethium, and scapulars, is at- : PLarg VII. Fie. 13. y. a’ t. b Prate XXVII. Fic. 50. Yo lates VIII. IX. z. ` L, ur. 2 P EXTERNAL ANATOMY OF INSECTS. tached by its posterior extremity to the core of the hind- legs; by means of the pleura, from which it does not appear to be separated by any suture, it connects the secondary or under-wings with the hind-legs, as thes pular does the primary ones with the mid-legs; $° the the direction of the parapleura depends upon the rela tive situation of the legs and wings. In Coleoptero™ insects its direction is horizontal, it being generally anar row subquadrangular piece that runs straight from t° posterior coxs to the scapular*, and usually divided P two unequal portions by an elevated or impressed gill In the palm-weevil (Calandra Palmarum) this part j wider than usual; in Dytiscus marginalis, —in which g ple? nus, as likewise in Carabus L., the come are incap? 3 ata ; -pge separate motion,—it is nearly a right-angled triads” tio" . . 0 In the Orthoptera Order this part usually consists of a yh" and is divided longitudinally into two unequal po" equal portions, and its direction is sometimes nearly »° zontal, as in Mantis and Phasma ; sometimes forming r angle with the horizon, as in Blatta ; and somnei nearly vertical, as in Locusta Leach. In the two first cat? the wings are before the legs, and in the last theif 7 - sition is over them. In the Heteropterous Hemi" r it is parallel with the scapular, is divided into two © equal portions, and its direction is more or less jn oP tothe horizon>. As to the Homopterous section—™ p gora itis ofa very irregular shape with an angular gutta” and its direction from the leg to the wing is first new t vertical and then horizontal: in Tettigonia it is ana vertical, and consists of two nearly equal portions: a Prater VIIL Fre. 4. 2’. b PrLare XXIX. Fis: 15:7" EXTERNAL ANATOMY OF INSECTS. 579 Come to the Neuroptera—in the Libellulina it consists of wo pieces, like those of the scapulars, but smaller +, and tts inclination is towards the head: in Panorpa also it "esembles the scapulars both in form and other circum- Stances », In the remaining Orders it exhibits no very "markable features. l6. Metasternum®. The central part of the mesoste= ium when elevated or porrected, or otherwise remark- "ble, is called the metasternum. In the Coleoptera, in se cases, as we have seen above‘, in which the me- Pectus and postpectus form one piece, its anterior point “comes the mesosternum ; but in others, as the Preda- “ous and Capricorn-beetles, &c., it is received in a sinus “fork of that part, or meets it. It is usually neither © remarkable nor important as the mesosternum. In “lbocerus K, it is a rhomboidal elevation: in Gyrinus a dge; as also in many Hydrophili, in which it passes “tween the hind-legs to the abdomen, and terminates in 4 Sharp point’; and in Dyfiscus its two diverging lobes “Ver the base of the posterior trochanters*®. In the thoptera Order this part is not remarkable; but in "rida viridissima K. it consists of three triangular pieces, € lateral ones being erect, and the intermediate one ho- konta]; in Locusta Leach it resembles the mesosternum*, tthe Heteropterous Hemiptera the whole mesostethium ù elevated, and terminates at both ends in a fork, the K) : a ; 4 terior one receiving the point of the promuscis, and the terior one that of the epigastrium : in the Homopte- “Sus Section, the Tettigonie F. have usually a distinct me- | Priame IX. Fie. 8 2. b Prares VIIL IX. at. , See above, p. 565. a Prare VIN. Fic. 8. a F. © Geer iy. t.iv. f. 3, ddi ee. £ Prare VIIL. Fie. 13: a +. Z2PQ 580 EXTERNAL ANATOMY OF INSECTS. tasternal point between their hind-legs. In the remaining Orders there is no metasternum, or no remarkable OF except in one singular Hymenopterous genus, Evania, the parasite of the Blaite*, in which there is a forked oe points sh thos? > ; „ms plates, before largely described *, which cover the drum of male Tettigonie F.; and likewise those called als© by p many thos? ow the terior process of the mesostethium with recurved 17. Opercula’. By this term I distingul the same name by M. Chabrier ¢, which cover, 1 cases, the vocal apparatus of the trunk of insects: of Melolontha vulgaris he describes as situated bel wings, and between the two segments of the alitrunk pe and if you take this insect and remove the elytt a mesothorax and scapulars, under the latter and below wing you will find an oval convex plate, which is P” bably the part he is speaking of ;—but it is better exch” plified, I think, in the common Dytiscus marginalis * - which it is very distinct as a convex subtriangular pe connected with the metathorax by membranous ligame” covering a kind of pouch, and appearing to op? g shut at the vertex £. I must here observe, with regard to the Apier@ a Arachnida, that the trunk in them is much more simp than in those insects that are furnished with wings the hexapods, in the former Orders, though there ® a The history of this parasite has been traced by D alas! this learned and acute observer of nature did not live his discoveries to the world: it is hoped, however, they wi lost, being in most able hands. b Prare VIH. Fre. 18. and XXII. Fic. 13. c +. © Vor. I. p. 405. à Sur le Vol des Ins. ¢-1- 459. e Ibid. 457—, 3 £ Piare XXII, Fie. 18. et: EXTERNAL ANATOMY OF INSECTS. 581 ay three pedigerous s segments, there is no distinction °t dorsolum, scutellum, &c. In the Scolopendride and ~ tigera amongst the Myriapods, according to the acute 5 ‘ervations of M. Savigny*,—on which, however, some iy at present rests, —there is a remarkable formation, © whole thorax being represented by the single plate at follows the head, to the under-side of which are at- cheq the first and second pair of palpi or pedipalpi, Nd the first pair of legs, representing the three pairs of “Bs of hexapods. In the Julide the three segments that Mow the head, each bear a single pair of legs, while all “Test bear a double one: from whence it should seem å follow, that these segments and their legs represent ‘trunk and legs of Hexapods. In the Octopod Aptera >” the Arachnida the trunk consists of a single piece, N Separated from the head, and sometimes not distinct "Om the abdomen. w: Internal processes®. Perhaps you will think that $ head would be better considered when I treat of the “ternal Anatomy of Insects; but as the parts included er it are really processes of the external integument the trunk, it seemed to me best to treat of them under hat head. They are of two descriptions ; processes of the “thorax or upper part of the trunk, and processes of i reast or its under part. * Processes of the thorax*. These are the phragma, "Op hragma, mesophragma, and metaphragma. The first “longs to the prothoraz, the second to the mesothorar, b , Mem, sur les Anim. sans Vertébr. 45—. Hor. Entomolog:. 411—. \y tare VII. Fic. 3. 2’. IX. Fie. 2. s. and XXII. Fic. 5— c Prare XXII. Fie. 8—11. 582 EXTERNAL ANATOMY OF INSECTS. and the two last to the metathorax ; each forming a kind o chamber of the under-side of each segment of the thora® 1. Phragma. The phragm, or septum of the protho rax, is most conspicuous in the mole-cricket (Gryllol@ P pa), in which it is a hairy ligament attached to the insi of the upper and lateral margins of the base of that par inclining inwards, it forms the cavity which recel"? : : ar the mesothorax. tis not, however, without a represent king tivein many Coleoptera, though in these it is less stri tjo from its being smaller and taking a horizontal diree = PEF e In Elater, by means of some prominent pomts recel” ; ae ë by corresponding cavities of the vertical part of the pe ” of the elytrum, it forms a kind of ginglymous artic? 7 tion, which probably keeps them from dislocation 1, pose, and, by the sudden disengagement of these per from the cavities, assists the animal in jumping *- 2. Prophragma». This is a piece usually almos tical, but in Elater horizontal; of a substance bet? membrane and cartilage, descending anteriorly from dorsolum, and forming the first partition of the chest , the mesothorax; it is generally much shorter tha? d mesophragm. ‘Though very visible in Coleopter@ we the Heteropterous Hemiptera, in the other Order f less easily detected, and is sometimes obsolete. * f be observed here, that in the Hymenoptera, at lea the wasp, the hive-bee, the humble-bee, and the +” ra mostly, the interior of the upper-side of the alite” instead of two, seems at first to be divided into fou’ : sk bers, formed by septula: but as these ridges mer? y r out the internal limits of the dorsolum, scutellum, era t yer" a a Vor. I. p. 318. > Piare XXII. Fie. 8, 1HE he EXTERNAL ANATOMY OF INSECTS, 583 Solum, and metapnystega, the last but one of these being Usually less distinct, they seem not analogous to the three Partitions of the alitrunk in other Orders; so that in these the mesophragm at least seems to have no repre- ‘entative, and the prophragm and metaphragm include tween them only one ample chamber. In the Diptera, Wherever there is an external depression or suture there Sia, corresponding internal ridge or seam, so that the Parts seem more distinctly marked out on the inside than on the outside of the crust. 3. Mesophragma*. This piece also, which forms the Middle partition of the upper part of the cavity of the alitrunk, dividing it into two chambers, is most conspi- “uous in Coleoptera. It is usually in them a vertical Piece, resembling the prophragm in substance, but twice its height, of a quadrangular shape with a notch in the Middle; it fills the sinus of the postdorsolum, the sides of Which sometimes descend below it®. In this Order the Chamber that it forms with the prophragm is very small ¢, the motions of the elytra requiring no powerful apparatus of muscles; but that which it forms with the metaphragm, Which is appropriated to the muscles moving the wings, ig Very large’. In the Orthoptera the anterior chamber is larger than in the preceding Order, which proves that tegmina are more moved in flight than elytra. In the €teropterous Hemiptera a remarkable variation takes Place—the anterior being larger than the posterior Chamber; which last, in fact, consists of two, one for each Wing: in these the mesophragm towards the abdomen rms an angle, which in Pentatoma, &c., is acute; in * Prare XXII. Fic. 9, 11, s'. b Ibid. Fic. 9. aa. * Ibid, Fie. 11. a. d Ibid. b. 584 EXTERNAL ANATOMY OF INSECTS. x ; e Belostoma a right angle, and in Notonecia an pe one. In the two first the angle of the mesophragm sene : : ; n two short diverging ridges to the metaphragm ; and } the last only a single one: in this also the posteri® chambers together are nearly as large as the anterio" From this structure it should seem that in flight the Hemelytra are more important than the wings. Homopterous section the anterior chamber i smallest, at least in Fulgora candelaria; and the mes” phragm is lofty and bipartite. In the Lepidoptera í anterior chamber is the largest, and the part in que conspicuous*. In the Libeliulina and Hymenopter@ is merely represented by a low ridge, and in the Dipte” it seems evanescent. i 4! Metaphragma ?.. This, in many cases, is the larg? and most remarkable of the three partitions of the upp” portion of the cavity of the alitrunk, which separates from that of the abdomen; it is attached to the posteri" margin of the metathorax, and is nearly vertical : in 5U stance it may be stated as rather firmer than the t° preceding partitions. In the Coleoptera it is common) of the width of the posterior orifice of the alitrunk; ye its centre is cleft so as to form a deep sinus © fF tb transmission of the intestines,—a circumstance -W ‘ ; also, though less conspicuously, distinguishes the a” phragm ¢: from this sinus it slopes gradually towards t d sides, and is sometimes armed with an intermediate oe cess on each side*. This structure you will find exe™ a Prate IX. Fre. 2.5’. é b Prarm XXII. Fic. 10, 11. a. Comp. Linn. Trans. xk f 16g. © Prate XXH. Fic.10, 11. a Ibid. Fre,:9. c: © Ibid. Fic. 10. a. j$. EXTERNAL ANATOMY OF INSECTS. 585 plified in the common cock-chafer and many others of the Order. I have not, however, discovered traces of lt either in the Silphidæ, Staphylinidæ, or the vesicatory beetles (Meloe L.); or even in such species of Carabus . and Cicindela L. that I have examined; while in Dytiscus it is very visible. In the Orthoptera it is nearly Obsolete; but in Locusta Leach, under the metapnystega, Ohe on each side,.is a pair of seemingly pneumatic Pouches which may be mistaken for it. It is almost equally inconspicuous in both sections of the Hemiptera. As to the Lepidoptera,—in Pieris Brassice, it resembles in some degree, though in miniature, the metaphragm of the Coleoptera; but in Sphina Stellatarum and Lasio- campa Quercus ithas a sinus on each side, but no middle one. In Panorpa it nearly closes the posterior orifice Of the trunk, but in the Libellulina it is a mere ridge. Th some Hymenoptera, as Cimbex sericea, the drone-bee at least, &c., it is a large convex bifid piece. In the wasps, under the spiracle of the metapnystega on each side, as in the Locusta, is what I also take to be a pneumatic Pouch, which might easily be mistaken for a metaphragm. Th the Diptera Order this part is very conspicuous. If You remove the abdomen of any common Tipula, you will find that the posterior orifice of the trunk is closed above by a pair of oblong, vertical, convex, diverging Plates ;—do the same by any fly (Musca L.), and you will detect in the same situation a very large convex or gib- bous one notched below, which occupies almost the whole Orifice: this is the metaphragm. 5. Septula*. These are the smaller ridges of the inte- rior of the alitrunk, which afford a point of attachment to a bid. Fie. 9—11. 0". 586 EXTERNAL ANATOMY OF INSECTS. many muscles, and run in various directions both on the interior of the crust and of the metaphragm. These little seams are not to be found so generally in the other Or- ders; but very frequently, as has been before observed: where there is an exterior impression of the crust, oT * suture, one of these forms its internal base. ii. Processes of the pectus?» We are next to consider the internal processes of the breast of insects: these CO” sist for the most part of the endosternum, or internt sternum, and its branches. As the principal feature f this are the processes which rising from it serve as points of attachment to the muscles that move the legs, &¢s shall confine myself to them—they are, the antefurca, the medifurca, and the postfurca. 1. Antefurca’. The first portion of the endostern!™ or the internal prosternum, branches into the antefure® In the Coleoptera a plate varying in shape and direction” sends forth a pair of mostly vertical processes of a cal tilaginous substance“, differing in height in different genera. In Carabus L. there is neither this plate nor its processes; but in Dytiscus the latter are very visible. very singular and complex machine represents the part we are considering in that extraordinary insect the mole- cricket ( Gryllotalpa Latr.). When we look at its prodig” ous arms and consider their office*, we may imagine that the requisite apparatus for moving them must be very powerful and peculiar. Their Creator has according” ly provided them with a machine for this purpose more than usually complex, extending from the prothoraz to the a Prare XXII. Fic. 5—7, > Tbid. Fic. 7. e* [pid. & à Ibid, e. © See above, Vor I. p. 191. and IL. p. 257, 366- EXTERNAL ANATOMY OF INSECTS. 587 Prosternum; the former being its base, and the latter its vertex. The cavity of the manitrunk is divided longi- tudinally by a double cartilaginous partition surmounted bya bony frame, with an anterior condyle or tuberosity, with which the inner part of the base of the clavicle of the arm appears to ginglymate; and the manitrunk is pre- served from the injury the powerful action of the arm Might occasion, by the counteraction of this machine, to describe which fully, would demand more space than I can afford?. Imentioned under the mesostethium, the aper- tures visible in the breast of Locusta Leach and Acrida K. Each of these apertures opens into an internal, tubular, horny, process, which arching off is attached at the other extremity to the sides of the trunk—a pair being appropriated to each segment; the first analogous to the antefurca, the second to the medifurca, and the last to the postfurca. In the medipectus and postpectus of Acrida viridissima there is only a single aperture, termi- nating in a single tube, which after rising vertically a little way sends off a branch on either hand to the sides of the trunk. Where there are three of these holes, as in the antepectus and medipectus of Locusta Dux, there are three of these processes, the intermediate one being vertical. In the subsequent Orders the processes of the endosternum are not sufficiently remarkable to require particular notice: my further observations upon them will therefore be confined to the Coleoptera Order. 2. Medifurca. This part, which belongs to the mid- legs, is inmany cases more conspicuousthan the antefurca. è This machine is described by Dr, Eschscholtz, Beiträge zur Naturkunde, &c. Heft, i, 24—. t. i, ii. > Prare XXII. Fic. 6. 588 EXTERNAL ANATOMY OF INSECTS. In Copris Molossus the endosternum of the medipectus 18 represented by a transverse zigzag ridge? between the sockets of the mid-coxee, from which proceeds a pair of branches wide at the base and growing gradually mor? slender to the extremity®, which is attached to the sides of the trunk; in Dytiscus marginalis a pair of slender, ve tical, straight processes, fitted with a broad cartilaginous plate at their apex, rises from the endosternum, and sends forth a lateral one to the side of the medipectus : and lastly; in Carabus the medifurca is represented by a pair of sub- triangular lamine attached to the sides of the trunk. 3. Postfurca®. ‘This, which belongs to the hind- legs, is the most remarkable of the pectoral processes and has been noticed by more than one writer. It is a kind of trident, the branches € of which are acute, and on their upper surface longitudinally concave, elevated on a footstalk * inclined towards the medifurca, consist- ing of two plates, a posterior one supporting the later al branches, and an anterior or interior one forming a right angle with the other, supporting the intermediate one. This footstalk rises from between the posterior cor which appear in the Lamellicorns to ginglymate with it at its base. The middle branch of the trident dips to the sinus of the medifurca. In Dytiscus marginalis the for® is different; for the intermediate branch consists of tw parallel pieces, and the lateral ones are dilated into broad vertical plates: the stalk of this is triquetrous, and a tri- ple cartilaginous partition appears to go from its base anteriorly, the lateral ones diverging to the sides of the a Pratre XXII. Fic. 6. a. b. Thid. b. © Ibid. Fre. 5. 5. T € MacLeay, Hore Entomolog. 9. Chabrier, Sur le Vol des Ins: c. 1.417. e Pirate XXII. Fic, 5. bbb. £ Ibid. c. EXTERNAL ANATOMY OF INSECTS. 589 trunk, and the intermediate one running straight to the base of the medifurca. , It may not be without interest to state here some of the several objects and uses of this structure of the trunk. When our Saviour says to his disciples, ‘ But even the very hairs of your head are all numbered” 2— he taught them that the attention and care of the Derry Were not confined to the mighty and the vast, but directed to every atom of his creation—that he not only decreed the number and magnitude of the planets and Planetary systems, and of their various inhabitants, but that the most minute and apparently insignificant part of each individual, both as to its number and form, was according to the law by him laid down; and whoever Studies them with attention will find that insects furnish a Very interesting homily upon this text; since in various stances I think I have made it clear, that parts seem- ingly of the least importance—as a hair, a pore, or a slight impression—have their appropriate use >. At first, it would seem that the various pieces of which we have Seen the second primary segment of the trunk of these animals to be composed, would be of little importance ; but when we reflect that this multiplicity of parts is Usually not to be found in those that have no wings, Whether they be apterous sexes or tribes °, a suspicion arises in the mind that they must be of more consequence than their prima facie appearance seems to warrant:—and this is really the case. The manztrunk, which is destined - Principally to incase the muscles that move the arms, did not require to be so complex as the part that had to Support the action of wings as well as legs. In those that * Luke xii. 7.» See above, p. 397—. © See above, p. 580. 590 EXTERNAL ANATOMY OF INSECTS. have a large prothorax, as the Coleoptera, it may; indeed, be useful in flight as a counterpoise to the abdomen: and since when the wings descend it rises, and vice vers” it may be of some service by its vibrations? ; but for this it required no complexity of structure. But not so the alitrunk + it consists of parts much more numerous, a” this number of parts is of great importance to the anima in its flight. All of them are so put together, being lined by a common elastic ligament”, as to be capable of a certain degree of tension and relaxation, which enables the animal to compress or dilate the trunk as its D& cessities require. To cause the elevation of the wing® it must be compressed or have its longitudinal diamet™ increased, and its vertical and transverse diminished: this compression is produced by the condensation © the internal air, which parts with some of its caloric, and by the action of the levator muscles. To cause the de pression of the wings, it must be dilated, or have its Zong! tudinal diameter diminished, and. its vertical and trans verse increased, which is effected by the rarefaction ° the internal air, and the action of the depressor muscles” In some Orders, the Coleoptera, &c., this effect is pr” moted. by the segments of the trunk, which are attache by loose ligamentous membranes, and. received, one oF more of them, into each other, which facilitates the above action 4. Thus much for the general use of thes? parts. Ishall further here mention a partial one ° two of them which seems indicated by a particular cit” Chabrier Sur le Vol des Ins. c. i. 418—., See above, p. 402. > Chabrier Sur le Vol des Ins. c. i. 446, 448, 451—. Ibid. 412, EXTERNAL ANATOMY OF INSECTS. 591 ‘umstance, and upon which a theory may be built. In Some insects the primary and secondary wings or their analogues are placed before the legs, in others over the legs, and in others behind the legs: but whatever their Position, the pieces which I have named the scapularia ‘nd parapleure invariably connect the one with the Other; the former, the primary wings with the mid-legs, and the latter, the secondary wings with the hind-legs. This circumstance seems to prove that the wings by the Mtervention of these pieces have an action upon the legs, and the legs upon the wings; and this is further proved in one case by an observation of M. Chabrier with re- Sard to Melolontha vulgaris,—that the levator muscles of the wings, by means of a long tendon, are attached to the lower part of the posterior coxze*. Now, more than one medical friend has suggested to me, that what are Called the core in insects are really analogous to the thighs of vertebrate animals ®: consequently these parts Must represent the core ; whence it would seem that the wings are really appendages of the legs. It must, how- “ver, be observed, that were this opinion admitted, in the Aptera, Hymenoptera, and Diptera, or even in the pro- . tħorag of other insects, there would scarcely be any ana- logue of the cove at all distinct from the trunk itself, of Which even in the other Orders these pieces are com- Ponent parts. An instance occurs in the Strepsiptera K., and in which the arms are furnished with an alary ap- Pendage, and the metathorax bas none °. ` * Ubi supr. c. ii. 333. According to. M. Chabrier, who agrees with him, M. Latreille also is of opinion, that the parapleura is the analogue of the poste- tior cone. Ubi supra, c. ti. 312, Note 2. “ M. Latreille has changed the denomination of this Order to 592 EXTERNAL ANATOMY OF INSECTS. those tru- hey VI. Organs of Motion. Weare next to consider organs attached to the trunk of insects which are ins mentsof motion. These are principally those by whicht are transported through the azr, and those by which they . move on the earth or in the water—their wings and the legs. I shall begin with the first, the wings °. These are not formed precisely after any type at present dis- covered in vertebrate animals: in some respects they have an analogy to those of birds’; in others, tO the dorsal fins of fishes: but, perhaps, altogether they 3P“ proach the nearest to those of the dragon or flying-liza? (Draco volans L.), which do not, as in birds, replace the fore-legs, are kept expanded by diverging bony ray and are connected with the hind-legs*. As the Divine Creator appears in his works to proceed gradually from one type of structure to another, it has been suppos? by a learned physiologist of our own country, that i2 winged insects, four of the legs of the Decapod Crustace@ Rhiphiptera, because at first he thought that these organs were not at all analogous to elytra or wings; but since, upon furthe® investigation, he appears to admit that they assist in flight (Awe nales Génér. des Scienc. Phys. VI. xviii. 8. Compare MacLeay, Hor Entom. 423. Note*), in common justice he-is bound to restore the name originally given to the Order. In the same place - the work here quoted, M. Latreille also speaks of these pseu elytra, as I would call them, as appendages of the mesothorax * ge whoever consults Mr. Bauer’s admirable figures of Xenos P echt (Linn. Trans. xi. t. ix.) and is aware of the unimpeached an minute accuracy of that admirable microscopic artist, will be cone vinced that they belong to the anterior legs, ‘and consequently ta the prothorax. a Prare X. and Prare XXVIII. Fre. 18-23. b Chabrier, Analyse, &c. 27. e N. Dict. d’ Hist. Nat. ix. 568. We have seen above (Pp: 578:) that the wings of insects are connected with their legs by the scapu™ and parapleura. EXTERNAL ANATOMY OF INSECTS. 593 are tepresented by the four wings?: this opinion, how- “Ver, is not yet fully proved; a remark which may also be "Pplied to a more recent one of. a celebrated French Writer, who seems to think their origin and structure ic that they are ae to the legs au bor- part from the respiratory organs>, Were I Sposed to enter into these subtile speculations, I might ‘te recall your attention to the analogy that, in their Metamorphoses, exists between the Saurian Reptiles or zard tribe and insects, and conjecture that the wings of : € Draco are really representatives of the mid-legs of *xapods, thus preparing to disappear altogether ; but Shall content myself with throwing out this hint, which You are welcome to pursue. The organs of flight in Shera] may be considered as to their number, kinds, and “Omposition. ne 1. Number. The most natural number is four, for this btains in the majority. In almost every Order, indeed, re occur instances of insects that have solely a single Pair or nonet; a : t ` MacLeay, Hor. Entomolog. 413—, Mr. MacLeay’s opinion seems ceive some confirmation from a circumstance overlooked when X larvee of insects were treated of above (p. 130—), and to which me ludes (411); namely, that in that state they consist of two seg- ts more than in the imago; these follow the three pedigerous Stents, have no pro-legs, and are supposed to belong to the trunk ‘er than to the abdomen. To make this circumstance bear upon © question, it must be proved that in the perfect insect these seg- pas in some manner become the back of the trunk and bear the Ags. This would not be more wonderful than many changes that te T 8 p Own to occur in insects. atreille, Organization extérieure des Ins. 1]3—, „Or instance Meloe, the female glow-worm, Lygæus brevipennis, Phemerq diptera, Cynips aptera, neuter ants, &c. &c. VOL. rir, 20 wow 594 EXTERNAL ANATOMY OF INSECTS, These, however, are only exceptions to the rule; but ™ the Diptera, unless we consider the alula, the represent tives of the secondary wings?, as a distinct pair, there are neyer more than two wings, and one instance ® known in which an insect of this Order has 7” ” Certain genera or individuals of the Tetrapterous Order are also furnished with alule: besides Dytiscus, Bia Phalena hexaptera, which have been before noticed” they may be detected in miniature in Ammophila K. a? affinities; these all may be regarded in some slight de- gree as insects with six wings. ; ii. Kinds. Under this head we may consider the Vor. II. p. 346—. LAaTES:-X, and XXVIII. 4. 4 Ibid.ec. © ° Ibid. d. 596 EXTERNAL ANATOMY OF INSECTS. in soft ones they also are soft. The most impenetrable ones that occur to my recollection are those of Mig? genus Doryphora, and the softest and most flexile thos? of Telephorus, Meloe and affinities. With regard to 10- dividuals, they are mostly as hard as the prothora*s a harder than the back of the abdomen. Elytra also, 2° far as my observation goes, are never diaphanous. 9. Articulation with the trunk. This is by me a process of the base of the elytrum which I call the or pivot, attached by elastic ligaments, and certain iit bony pieces (osselets Chabr.) in the socket under the S! of the anterior angle of the dorsolum®. You may easi remove the elytra attached to the mesothorax from Of” -trupes stercorarius, which will enable you to see the mr of articulation with little troubles. 3. Expansion. Itis by means of the bony pie mentioned that the organs in question are openet shut under the action of the antagonist muscles: opening for flight the two elytra recede from each © and are elevated so as not to retain their horizontal g sition, which would interfere probably with the play ; the wings, but form an angle with the body. When m return to a state of rest, the sutures usually m coincide longitudinally ; but in some cases when © as in Necydalis, &c., they diverge from each other a apex; and in Meloe, like the Orthoptera, to which ° genus approaches, one laps over the other. f 4. Parts. The parts to be considered in an ely all are the areas, the aris, the suture, the margins the 2 gris ; the a PLare XXVIII. Fie. 3—5. b”. b Chabrier Sur le Vol des Ins. c.i. 439. e Prare XXVIII. Fic. 10. a Chabrier ubi sup” EXTERNAL ANATOMY OF INSECTS. 597 Pleura, the base and apex, the angles, and the hypoderma. At first it should seem as if an elytrum was not like other Wings divided into areas; but I think upon examination \t will be found that, though often nearly obsolete, these e represented in it; for the epipleura? with the recurved Part of the external margin seems to me analogous to the Costal Area; the inflexed part adjoining the scutellum and often going beyond it to the Anal, and the rest of the organ ‘othe Intermediate. All this youmay see in the dung-cha- *t; Geotrupes stercorarius: The axis? or pivot by which the elytrum articulates with the trunk is generally placed about: the middle of its base, but nearer the scutellar than the humeral angle, and varies in length and shape the different tribes, but not so as to merit particular tice; it may be regarded as composed of three parallel Pieces, one belonging to each area, that of the costal be- » the longest. In many these pieces are marked by no Ne of distinction, but in Macropus, &c., they may bereadi- Y traced *.. The suture is the internal margin of the “lytrum from the point of the scutellum to the end. In tany beetles the right hand suture, looking from the aus to the head, has a lower ledge or margin, and the ther, one more elevated, which when they are closed "es upon the former; in some Dynastidæ there seems a = of ginglymous structure in this part, each suture “ing fitted with a kind of ridge which is received by à channel of the other; it these the suture is generally Marked out by an adjacent channel: but the most re- markable structure of this part distinguishes the genuine ‘Pecies of the genus Chlamys, in which both the sutures, ` Puare XXVII. Fic. 6--8. d”. b Ibid, eara 3". Prare XXVIII. Fie. 3. d Prare X. Fie. l. c”. 598 EXTERNAL ANATOMY OF INSECTS. except at their base, are armed with little teeth, alter- nating with eachother like the cogs of a mill-wheel. +” apterous beetles the elytra are often connate, OY a both sutures as it were soldered together. The margin’ or external edge of the elytra is generally formed bya bea or ridge, which, except in the case of the truncated on? in which it is straight, curves more or lessfrom the bas? si the apex; this ridge is often: recurved so as to form 4 jap of channel between it and the disk of the elytrum, 4 may be seen in the Dynastide ; in some there are two pat? j ridges, as in Copris; in Silpha the margin is dilated; ” Helæus and Cossyphus it is remarkably so and recurve ; so that, in conjunction with those of the prothorax whic’ are similarly circumstanced, they give the animal som? wi semblanceto a small model of abarge. Though the marg” of elytra is most commonly intire, yet in some beetles» ý R 3 SiE T a Gymnopleurus Illig., a sinus is taken out of it; in Cetom it often projects at the base, and in Cryptocephalus int ; middle, into a lobe; in Phoberus MacLeay it is dentiow” lated, and in many Buprestes more or less serrulate’’ sometimes it terminates before it reaches the apex of elytrum in a tooth, as in many Carabi Latr. The gr pleura® or side-cover is that part of the organ in quer tion, below the margin, with which it usually forms angle, being more or less inflexed, that covers the s # of the body. It varies in different tribes, being | times obsolete, as in the weevils (Curculio L.); Capricorn beetles it is very narrow; in Carabus, dilated at the base; in many Heteromerous peetles» P Blaps, Pimelia, &e., it is very wide and conspicuous’ ph t * Prate X, Fic. Tec. > Prare XXVIII, Fic. 6—8 ; EXTERNAL ANATOMY OF INSECTS. 599 Cossyphus it stands out a little from the abdomen, so as to form a kind of fence round it. Its shape generally ap- Proaches thatofa scythe, beingincurved and growing more Slender towards the apex *; but it is sometimes straighter ‘nd shorter. In Geotrupes and many other Lamelli- corns, the base of the elytrum is nearly vertical, forming a right angle with the rest ofit; it is usually transverse and Straight ; but in Calandra Palmarum and many Casside it Slants to the scutellum; in Chlamys it is sinuate, and U Elater it has a deep cavity above the axis which re- “tives the points of the phragma mentioned before». The apex of elytra is usually acute, the angle being formed by the confluence of a curving and straight line: “ut there are many exceptions ; for instance, in Mylabris t is rounded; in Hister obliquely, and in Necrophorus transversely, truncated; in many Capricorns it is emar- SMate; in others, as Macropus longimanus, it is biden- tate; in some Prioni, P. cinnamomeus, &c., it termi- Rates in a mucro at the internal angle; and in Ceram- ® Batus, horridus, &c., at the external; and, to name no more, in some species of Necydalis it ends in a long cumen. The scutellar angle in insects that have a large Scutellum, as Macruspis MacLeay, is obliquely trun- “ated to admit it, but where it is small it is generally rect- Ngular, with the angle rounded ; in Buprestis vittata it is obtusangular; and in Dytiscus marginalis, &c., it is “Marginate. In Cassida spinifex, perforata, &c., the hu- “eral angle is producted into an acute lobe that stretches Yond the head, and in C. bicornis and Taurus it forms “horn at right angles with the elytrum. In general it * Prare XXVIII. Fic. 8. t See above, p. 582, 600 EXTERNAL ANATOMY OF INSECTS. Pease. i + f is either rectangular or rounded, with a prommence 9 the elytrum within it. The sutural and anal angles exist only where the elytra are truncated at the apex. In e and case the sutural is generally rectangular, and th s the rather obtusangular or rounded. The Hypoderma i fine soft membrane before noticed è that lines the under- side of the elytra, the use of which is probably to prevent “injury to the wings from friction with their usually har substance; this membrane is commonly of either * pallid or brownish colour ; but in some insects, as Sta- phylinus hybridus, murinus, &c., Buprestis Gigas, it is © a beautiful green or blue; and it exhibits the puncles strie, and other modes of sculpture of the elytra very - distinctly, the pores of which usually perforate this me™™ brane’. Just under the shoulders of these organs you may observe an:oblong and sometimes roundish spol occasioned by the hypoderma in that part being part cularly tense, and covering a cavity or pocket which ap” pears to be connected with the axis by the hollow part which I regard as representing the Costal Area; this pocket is evidently the analogue of a part in the wing noticed by M. Chabrier *, and named by me the phi alum: from its connexion with the axis by a chann?” this part in elytra should also seem destined to receive 2 fluid to add to the weight of the margin and its means j resistance. l 5. Shape. The shape of elytra is various; taken t0” gether, in which case, in describing insects, they are de- nominated coleoptra, their most common form is more or less oblong, or forming more or less a considerable a See above, p. 402—. r Ibid. 399. © Sur le Vol des Ins. i. c. AZ8--. c. ii. 325. EXTERNAL ANATOMY OF INSECTS. 601 Portion of an ellipse; taken separately, it inclines to that of an isosceles triangle, with the exterior side curvilinear: truncated elytra are generally quadrangular, sometimes Presenting a trapezium, at others nearly a parallelo- Sram, and at others a square. With regard to their Proportions they vary considerably, but the most general law seems to be that the length shall exceed twice the Width; in some, as Buprestis Gigas, it is more than thrice ; in many Staphylinide they are as wide as they are long and sometimes wider ; they are generally nar- ‘ower at the apex than at the base, but in some species of Lycus, as L. fasciatus, &c., the reverse takes place ; in- Lelephorus they are nearly of the same width every Where: with regard to their surface they are sometimes. very convex, as in Moluris; at others very flat, as in Eurychora, Akis, &c. 6. Appendages. These, though not so remarkable as those of the head and prothorax of beetles, ought not to be overlooked. In many Capricorns, as Lamia Tri- bulus, speculifera, &c., the disk and sides are armed with Short sharp spines; in others (Stenocorus, &c.) the sutu- ‘al and anal angles or one of them terminate in a spine X tooth; sometimes the whole surface, as in Hispa atra; Ac, is covered, like a porcupine, with a host of slender Spines, or its sides defended by spinose lobes, as in Heri- naceq : the humeral prominence is armed with a spine Pointing to the head in Macropus longimanus, and form- ing a right angle with the elytrum in some Curculionida, a Eea. spinifex; but the most remarkable ap- Pendage of this kind is exhibited by Cassida. bidens and s affinities, —from the centre of the sutures of the elytrum "Ise perpendicularly a pair of long, slender, sharp pro- -602 — EXTERNAL ANATOMY OF INSECTS. cesses internally concave, which both apply exactly t0 each other, so as together to form a single horn which rises, like a mast from a ship, from the body of the ami- malè. Besides the appendages here mentioned, the elytra exhibit a variety of tubercles and other elevations of various form and size, which it would be endless © particularize. 7. Sculpture. The sculpture of the organs in ques is very various and often very ornamental: but as al- most every kind of it will be noticed in the orismolog* cal tables, it will not be necessary to enlarge upo” it here, especially since I have endeavoured upon a forme! occasion to explain how it may be useful and important as well as ornamental to the animal’. I shall therefor? only notice a few instances, amongst many, in whic a particular kind of sculpture distinguishes particula" tribes. Amongst those that are Predaceous the Cicin- delidæ have elytra without striæ or furrows, while the majority of the subsequent terrestrial tribes of this sec" tion are distinguished by them: the Dynastide in the Lamellicorn section are remarkable for a single ¢& nated furrow next the suture; in the weevil tribes the _ numerous species of the genus Apion are ornamented by furrowed elytra with pores in the furrows, which giv? them the appearance of neat stitching ; in many of thos? beetles that have soft elytra, as the glow-worms (Law pyris), the blister-beetles (Cantharis, Mylabris), and stil more in Gidemera, two or three slight ridges generally run longitudinally from the base to the apex, and are visible also on the under-side; as the furrows probably tion a Oliv. Ins. No. 97. Cassida, t. i, f. 10. e See above, p. 397—-. EXTERNAL ANATOMY OF 1NSECTS. 603 lighten a hard elytrum, these ridges may serve to Strengthen a soft one, and it is by these that the first ap- Proach is made to the reticular structure of tegmina or the wing-covers of Orthoptera: Lycus palliatus, &c., in tts elytra exhibits a direct resemblance of the reticula- tions of nervures. 8. Clothing. To what I have before said on this Subject in general? I shall here add a few remarks, Which, though they more properly belong to elytra, may in many cases be extended to the whole body of a beetle. Tn various instances it happens that the beautiful mark- ings of these organs, as in Macropus longimanus, whose elytra when denuded are black, are produced by short de- cumbent hairs; in some these variegations are the effect of scales resembling those of Lepidoptera, often of a Metallic lustre; from these scales is derived all the bril- liancy of the diamond-beetle (Entimus imperialis, Germ.); in some the scales are so minute as to resemble the Pollen of flowers, as the white marks observable on the green elytra of the rose-chafer (Cetonia aurata). 9. Colour. The organs of flight in the majority of the Orders with respect to colour are usually the most: gaily decorated part of insects; I therefore deferred the ‘Notice of that subject till I came to treat of them. In general the colour of insects is either inherent in the substance of their crust, orproduced by the hairs or scales that either partially or totally cover it. To confine my- self to the Coleoptera, of whose elytra we are treating, it May be observed, I think, in general, that the majority of those that feed upon putrescent substances, the sapro- Phagous tribes of Mr. W. S. MacLeay, are commonly of a a See above, p. 399--. 604 — EXTERNAL ANATOMY OF INSECTS. more dark and dismal aspect and colour than those which feed upon such as are living and fresh, denominated thale- rophagous by the same learned author; this you may pe exemplified in his Scarabeide and Cetoniade. Again, in the Predaceous beetles a smilar contrast of colours is ofe” observable. Howbrilliant and gay arethe fierce Cicindel@! those tigers of insects, as Linné calls them; how black as to colour, how horrible in aspect is their near relation the Manticora : what difference exists in the economy ° these animals is not known, except, as I learn from Mr. Burchell, that the latter is subterraneous, whereas the former seek the sunbeam and fly rapidly. I shall now point out a few instances in which the colours of the” elytra distinguish tribes or families. Amongst the Pre daceous beetles a large family of the Cicindelide are distinguished by a middle angular white band, and or veral white dots on their green or brown elytra, as " C. sylvatica; afamily of Brachinus, and the majority of Mylabris, Lamia capensis and fasciatus, &c.s by black elytra, with yellow or red bands; Carabus violate and affinities by the violet margin of these organs ; Cal- liochroma Latreille by their sericeous, and Eumolpus by their metallic, lustre. These instances will be sufficient to turn your attention to this subject, which though not of primary importance in discriminating genera &¢-s © not without its use in a secondary view. 10. Uses. I must not quit this subject without say8 something upon the ends which elytra seem designed al serve. Their first and most obvious use is the protection of the wings when unemployed, that they may not be lacerated or soiled, and rendered unfit for flight in the various retreats to which these animals betake themselves EXTERNAL ANATOMY. OF INSECTS. 605 either for food, repose, or to lay their eggs; to promote this purpose more effectually, the wings are usually cu- Yiously folded and laid up under them; and where the elytra are very short, as in the Staphylinide, these folds are very numerous and complex. In some instances, however, as in Molorchus F., Atractocerus, &c., the wings are only partially protected by the elytra and not folded under them; probably they are less in danger of laceration from their peculiar habits than the generality. Another Use is to protect the upper-side of the alitrunk, which for reasons before assigned is usually softer than the under- Side, and also of the abdomen, often above nearly mem- branous, from the injury to which they would otherwise be exposed ; in. the latter part also the spiracles in Co- leoptera are not covered hy the inosculations of the seg- Ments, as is the case in most other Orders, and therefore probably require some covering when the insect is not flying. In the Apterous beetles this appears to be their, Principal use ; where these organs are connate, or as it Were soldered together, the back of the abdomen is a thin membrane; the appearance _of two elytra in these Cases is given, doubtless, for the sake of symmetry and — beauty, a subordinate attention to which may be traced / in all the works of creation. If we consider the bulk and Weight of many flying beetles, we may imagine that they Want some assistance, more than the extent and dimen- Sion of their wings seem to promise, to support them in the air, and to enable them to move more readily in it; and although it seems clear from the state of their mus- Cular apparatus that elytra do not move much in flight, _ Yet by giving a broad and concave surface to the air, for then they are usually nearly vertical, they may assist in 606 EXTERNAL ANATOMY OF INSECTS. some measure as sails, and help them in flying r% versely and before the wind *. ii. Zegmina”. By this name the learned Illiger has distinguished the upper organs of flight of the Ortho ptera and Heteropterous Hemiptera ©. They may be considered under the same heads nearly as elytra. 1. Substance. Tegmina differ very materially from elytra in their substance, being generally more or less diaphanous, though in Blatta Petiveriana the dark parts are as opaque as elytra, and those of the Mantes that resemble dry leaves are only semidiaphanous. These organs are also of a less dense substance than ely! something between coriaceous and membranous, which I shall express by the term pergameneous, as somewhat Fe sembling parchment or vellum. Another circumstant? relativeto this head also distinguishes them,—they are not lined with membrane.. In some instances, as in B. Petiv@~ riana just named, they approach nearly to the substanc? of elytra, and in B. viridis, some Mantes, and Tettigon™® &c., they are little different from wings in their substance but this does not diminish their right to be considered as tegmina, since their structure is altogether the same. 2. Articulation with the trunk. Tobserved above that the axis of elytra may be regarded as formed of thre? parts, one appertaining to each of the areas or their 1e- presentatives!; in ¢egmina, and indeed in wings in gene a M. Chabrier says that the are described by the wings of Melo- lontha vulgaris to that of the elytra, is as 200 to less than 50. Su” le Vol des Ins. c. i. 440. » Prare X. Fic. 2. and XXVIII. Fic. 18—20. € Magas, 1806. Terminologie der Insekt. 18. 1675. 1 Prats X. Fre. 2. is the tegmen of a Blatia divided into areas: EXTERNAL ANATOMY OF INSECTS. 607 ral, these parts are separate and may be more distinctly traced, the axis of the Costal Area being generally the longest, and that of the Intermediate often the shortest; these axes are suspended in the wing-socket by elas- tic ligaments, intermixed with hard bony plates, the Principal one of which, called by M. Chabrier the žu» merus, is connected both with the tfegmen and the — trunk, and in some a little resembles the head and neck ofa swan. This structure permits the animal to move the lateral areas in some degree separately, so that each, specially the anal, shall form an angle with the inter- Mediate; as the motion of the latter is not wanted, its axis often falls short of the base, or is obsolete, as in - Blatta, 3. Composition. The three areas, traces of which we had discovered in elyéra, are particularly visible in teg- mina. If you take any cockroach (Blatta), you will at first sight see that in it they are divided into three larger Portions by stronger nervures or folds; and if you also take a Mantis, or Locusta Leach, a Fulgora or Tettigo- nia, the same circumstance will strike you, only you will See that in these the intermediate portion terminates also in an axis; these are what I call the three areas. The external one or Costal is usually the longest and nar- Towest>; the Intermediate one is commonly triangu- lar, with its inner side curvilinear; and the interior One, or Anal area, in the Orthoptera is rather oblong ; in Fulgora angular, and in Tettigonia it presents an - lsosceles triangle; with its vertex to the apex of the Wing‘, The first of these may be defined as that por- ` Sur le Vol des Ins. e.ii. 327—. b Prats X. Fie. 2. &. ° Thid. e. d Thid. d. 608 EXTERNAL ANATOMY OF INSECTS. tion of the wing that lies between the costal and post costal nervures; and perhaps, in some cases, asin Mantis, for there is the fold of the tegmen, the mediastinal may be regarded as its limit; the Intermediate Area is that which lies between the postcostal or mediastinal nervuré and the anal fold of the wing; and the Anal Area is the remainder. ‘These areas may perhaps best be made out by tracing each to its axis. To study them carefully ” tegmina and hemelytra is of considerable importance? for in them we find the first outline of the general pla” upon which the wings of insects are constructed, 4 which, as we shall see hetéafter, more or less enters i the composition of them all, 4. Position, and folding in repose. With regard d their position when not expanded, tegmina vary some” what in the different tribes. In the Coleoptera we hav? seen that, except in a few instances, the elytra unite ê their suture. Something like this takes place in Fulgor” Cercopis and affinities, in the Homopterous Hemipter™ in these, though the union is not near so exact, yet the tegmina do not lap over each other; they are usually more or less deflexed, with scarcely any portion in a ha rizontal position: in Tettigonia F., Chermes, Aphis, S00 the middle part only of these organs meets, from whic point they diverge both towards their base and ap°* is In the Orthoptera the position is quite different, for onf tegmen more or less lies over the other. In Blatta, ™ which the ¢egmina are nearly horizontal, the left han one covers almost half the other®: in the other tribes g the Order, with little variation, the Anal Area of the tes” nto 2 Stoll, Cigales, f. Vill. ¥ 39. b PLATE a Fie. 2. EXTERNAL ANATOMY OF INSECTS, 609 men is horizontal, and covers the back of the animal, and the Intermediate and Costal are vertical and cover its sides; the former, however, in some cases, only forms the angle between them. Sometimes in these the right-hand Ne is laid upon the left, as in Acheta; and sometimes the “everse of this takes place, asin Acrida K. With regard to the folding of thezegmina, the most remarkable instance that occurs is that of Acheta monstrosa, in which the ends of both these organs and the wings, in repose, are folded like a fan, and then rolled up like a serpent ?. 5. Shape. The shape of tegmina is various. In the Platte and some Mantes they are more or less oblong ; u Mantis precaria, strumaria”, and others, they incline to elliptical ; in Phasma Gigas and Acheta monstrosa they are rather panduriform®“; in M. gongyloides they are semi-cordated; in Pterophylla trapeziformis they are *homboidal® ; in. Conocephalus erosus they are sinuated ; in Locusta Leach they are usually linear or linear-obe Sng’; in Pterophylla K. they generally terminate in a Short mucro®; and in some of those Mantide whose tomina simulate arid leaves, in a recurved one, In d © Homopterous Hemiptera the shape of these organs “less various. In the Tulgorelle Latr. they incline to i trapezium, sometimes to a pentagon'; in the Tet- wont F. they approach to an obtuse-angled_trian- * Stoll Grillons t.1. c.f. 2. b Ibid. Spectres t. xxv, ha te nd Xl. f, 42, - © Ibid. z. ii. f. 5. Grillons t.i. CJ " Ibid, Spectres t. xvi. f. 58. ° Ibid. Sauterelles à Sabr. t iii. By this name (Pterophylla) 1 distinguish those Locuste F A “thont a conical head that are veined like leaves, e Stoll Tid. t. vi, a. f. 18. and Prate XXVII. Fro. 19. - Stoll Sauterel. à Sabr. t, i—iii. n Ibid. Spectres t. iv. f. 14, Thid. Cigales t. i.f. 1, 3——5. and t, vi. f. 31. Beni.. QR 610 EXTERNAL ANATOMY OF INSECTS. gle; and in others of the tribe they are nearly wedge- shaped °. 6. Neuration. The circumstance that most strikingly distinguishes tegmina from elytra is their newration O veining ; which adds much to their strength, without in- creasing their weight so much as to render them unapt for flight. To look at these organs in Blatta Petiveriam™ you would imagine them at first to be deprived of this distinction ; but if you observe them attentively, partici- larly their white spots, you will soon detect their 2° vures; and if you further examine their lower surfac® you will find them very visible. The gibbous Blatt also, Blatta picta and affinities, the analogues of Eroty! amongst the Coleoptera, have tegmina which, except j their apex, exhibit but faint traces of the nervures of the tribe, and approach to elytra besides by the innumera i minute impressed points that cover them. In the Ortho ptera and some Homopterous Hemiptera thenervures ay fem ne be divided into longitudinal ones more or less rami and traversing ones. In the Blatte the traversing vures cut the longitudinal ones nearly at right angles; be not at regular intervals, so as to cover the tegmeP be quadrangular areolets; in Mantis precaria and affiniti@ the longitudinal nervures of the Anal Area diverge p the base, and are traversed nearly as in Blatta, Y™ those of the Costal diverge from the mediastinal nervu” i but the traversing ones form innumerable irregula” ticulations; in Mantis sinuata K.? the whole tegm®™ such reticulations but less numerous; in Locusta Lea it is regularly reticulated at the base, but the areolets ° a Stoll Cigales t. iii. f. 12—15. and ¢, xvii. f 92. bd Linn. Trans. xii. 449, no. 96. EXTERNAL ANATOMY OF INSECTS, 611 the apex are quadrangular; in the Mantes, with oblong Wings, all are quadrangular; in Pterophylla K. the Cngitudinal diverging nervures are not numerous, and the traversing ones cut them into quadrangular and tri- angular areolets, besides which they are covered by in- üumerable impressed points, so as altogether to exhibit a most exact resemblance of the leaf of some evergreen : in Gryllotalpa the longitudinal nervures of the Anal Area “ather converge towards the apex, are traversed by few transverse nervures, and those of the Costal Area which diverge from the mediastinal nervure by still fewer; the Neuration of Acheta F. has been before described? ; I shal] only observe here, that the constructors of stringed Mstrumenté of music might, perhaps, from the teginina of the male, the nervures of which probably modulate the sounds which it produces, take a hint for giving the Strings in them a serpentine or convolute direction, and ‘© might produce something new in that department, “orresponding with the serpents and French-horns in Wind instruments. Of the Homopterous Hemiptera in the Fulgorellé Latr., which are most analogous to the Or thoptera of all that tribe, the longitudinal nervures are More numerous and branching, more especially toward the apex of the ¢egmen, and are traversed as much by Ransverse ones, sometimes reticulating the wing with “oundish areolets, as in F. laternaria, and at others with Wadrangular ones, as in F. candelaria; in some of these Wever, as Otiocerus K., Flata F., &c.°, there are no “aversing nervures; and these lead to the Cercopide anq others in which the longitudinal nervures become a , Vor. T. p. 395— inn. Trans. xiii. t.i. f.14. Flata should come before this genus. Phas e 612 EXTERNAL ANATOMY OF INSECTS. few, and some are without any *, and these terminate those of this section of the Order in which the nervure? in question are continued to the margin of the wing. next come to those, Darnis, Centrotus, Membracis, X0” in which they are circumscribed a little within the ap by a traversing nervure, so that the tegmen ends in a marg” of pure membrane, and thus some approach seems to made to the Hemelytra, from Tettigonia, the most sane spicuous genus of this tribe, in which the areolets, fe¥ 1 number, like those of Lepidoptera, are not formed, exc°P the terminal ones, by traversing nervures, but by Fy e 10- termediate Area, which is connected with the base of the S apy ramifications of the longitudinal ones; in Chermes th wing by a single nervure, is the only part that ha areolets °. 7. Colour. Orthopterous insects are seldom re able for tegmina of brilliant colours; there is in them P© of that gilding or metallic lustre which so often dist marks pone guishes elytra: they are alsofrequently less ornamented? for® this respect than the wings, with which they usually ress an agreeable contrast. Their reticulations and nervl : š : g which are sometimes of a different colour from the re of the tegmen, decorate them considerably: a remark” pla¢ ble circumstance belonging to this head attends the = tS, pe tegmina of Blatta Petiveriana ; one has four white 5 and the other only three; but as one laps over the othe! the symmetry of the arrangement is preserved : the P? mopterous Hemiptera are more distinguished in this g spect, and some of the Fulgoride imitate the Lepidop! s both by their ocelli and spots : Fulgora laternaria, a Of this kind is one of Stoll’s Cigales, t. xxv. f- 141. b Prare XXVIII. Fie. 18. EXTERNAL ANATOMY OF INSECTS. 613 delaria, serrata, and Diadema, sufficiently exemplify this remark, as do several Flate likewise ?. We may observe here—that ¢egmina are more calcu- lated for flight than elytra, both from their thinner sub- Stance, and from the angle that their Anal Area, and often the Costal, forms with the rest of the tegmen; a circum- Stance which, in wings, M. Chabrier thinks presents some facilities in that kind of motion. iii, Hemelytra». The next species of wing-covers, Which though varying in the substance of their base, ter- inate in a part distinct from the three areas, consisting n almost every case of mere membrane, peculiar to the eteropterous Hemiptera, are called hemelytra, or half- Elytra :—this term was also formerly employed, but cer- tainly incorrectly, to denote tegmina. I shall consider fhem with respect to such of the particulars noticed under the former heads as apply to them, but without repeating them formally. 108 L. Astotheir substance, they must beseparately consider- “dwith regard to their baseand apex. In various instances the base, or part consisting of the three areas, is almost “orneous, asin Cydnus Morio and bicolor, bugs not uncom- ton with us, and many others °; in these cases it is lined With a hypoderma like elytra; and in many the points, Which are impressed upon it, also perforate the hemely- trum, and seem to act as pores: but in Lygæus, Reduvius, Capsus, Miris, and the majority of the Heteropterous He- Mibtera, the organs in question being soft and flexible, a ii ~ &c. b Prate X. Fic. 3. 3 In Latreille’s whole genus Pentatoma, including several Fabrician . the Hemelytra are more substantial than in the subsequent toll Cigales t.i. f. 1. t.x. f. 46. t. xxix. f. 170. t. v. f. 22. t iv. ce 614 EXTERNAL ANATOMY OF INSECTS. may be stated as rather resembling leather than horn ese this account this part of a hemelytrum is denominated the corium. In Scutellera the portion covered by the 500 tellum is membranous; and in Acanthia paradoxa, an the cucullated species of Tingis, the wing-covers are ul tirely so. The apex of these organs is almost universally either membranous or coriaceo-membranous, on whic account it is called the membrana. I say almost, pecaus? in Aradus and the Hydrocorise Latr., this part, thoug rather thinner than the rest of the Hemelytrum, iS als? coriaceous; in the latter tribe usually with a very narrow membranous edge; and in many Reduvii and Zeli ther? is scarcely any difference in the substance of the base 4” apex. 2. As to the articulation of Hemelytra with the trunk" seems not strikingly different from that of tegmina : the point or base of the Intermediate Area, which falls short of that of the lateral areas, seems connected by a slendef ligamentous piece, with its axis, which is thick; and j do not discern Chabrier’s humerus shaped like a swan’s he and neck 4 3. The composition of these organs differs from that of tegmina in more respects than one: in the first place, they consist, as was lately observed, of four instead of hare? areas; in the next, they appear to have, at least sevet? of them, a part, which I suspect to be analogous to #2? above described in Coleoptera, supposed to represent the phialum of wings”. I shall first speak of the areas. some apterous species related to the bed-bug, Tyga brevicollis Latr.*, &c., there is no trace of the usual areas, a See above, p. 607. o Ibid. p. 600. © My insect, which nearly resembles the Coleopterous genus Cery- EXTERNAL ANATOMY OF INSECTS. GIS and the membrana is a very narrow strip; in L. apterus ; p the former are very faintly traced out, but they are pre- sent in all those that are furnished with wings; whence We may conjecture that they are of the same importance Inflight with the folds observable in those organs*. The three basal areas may be said most commonly to present three isosceles triangles, the Costal one being narrow and curvilinear >, the Intermediate the most ample °, and the Anal one the narrowest and shortest 4, with its vertex to- Wards the apex of the Hemelytrum, while in the twoformer it is at its base. In Lygeus compressipes (Rhinuchus K.MS.) the Anal Area is cultriform; and in most of the Hydrocorise it has an angle in the middle of its posterior Margin. The proportion that the membrana or apical area bears to the rest of the wing varies in the different tribes. Ih some, as before stated, it is obsolete, in others nearly So; in the majority, perhaps, it occupies about a third of the hemelytrum ; in Lyg@us compressipes, cruciatus, &c., full hal If; in Alydus calcaratus, two-thirds; in Reduvius, Nearly three-quarters* ; and in Aradus depressus the cori- um,—divided, however, though indistinctly, into the three areas,—is driven to the base of the wing: two ends are answered by this structure—as this insect lives under bark, its thin hemelytra take less room; and as it flies, though it has only rudiments of wings, they are more fit to supply their place: the part we are speaking of usually lon Latr., agrees with Latreille’s description in all respects, except ee it une be said to be membrana nulla apicali. * Chabrier Analyse, &c. 24. b PLATE X. Fig. 3, b°. * hid, e 4 Ibid. d. © Prate XXVIIL Fie. 23. f” is the corium and g”' the membrana fa species of Reduvius F, 616 EXTERNAL ANATOMY OF INSECTS. | he runs obliquely from the vertex of the Anal Area to t base of the Costal. 4, Astotheir position and folding inrepose, Hemelytr@ are usually nearly or altogether horizontal; but in Notonecta and Plea they are deflexed and cover thesides of the body; and the apical area of one wing precisely covers that of the other; where the scutellum does not intervene, 4° in Scutellera, Pentatoma, &c., the vertical angles of the Ana Area meet in the middle of the back, so as to exhibit the appearance of a cross. In Notonecta, in which the hemelytra are deflexed, at the apex of the membrana is a fissure which permits the two sides to form an angle with each other, and to apply exactly to the body. Jn Plea, in which there is no. apical area, the posterio® margins of the tegmina, as they ought rather to be ter” ed, unite, but do not lap over each other. With rega!" to the appearance of something like a phialum, if you ex amine the hemelytra of most species of bugs on the w derside, you will see that the costal nervure at the bas? is inflexed and covers a kind of channel ; if you next take one of Belostoma grandis, where the structure is most CO” spicuous, or even the common Nepa cinerea, you will £2 in the same situation, adjacent to the inflexed costal ne" vure, a hollow tube running from the base of the wings and terminating, after proceeding about one-fourth of its length, in a hollow cavity, which, as it is covered by j membrane, appears to me to be a collapsed pouch. Ths circumstance is worthy of further and more general in- vestigation. i 5. In their shape, with few exceptions, hemelytra more p less represent a wedge, being wider at their apex, where EXTERNAL ANATOMY OF INSECTS. 617 they are usually obliquely truncated, than at the base; but in Plea Leach they are obtusangular, with the angle in the sutural margin ; in Notonecta, on the contrary, an obtusangular sinus distinguishes that part; in Naucoris they are curvilinear and every where of equal width; in Ranatra they are linear and straight; in Aradus they äre oblong, usually with an external lobe or dilatation at their ands a remarkable instance of the intention of this iS observable in a nondescript Brazilian species, in which the head, prothorax, and abdomen, are edged with a Number of broad foliaceous appendages; if the base of the hemelytrum had not been furnished with a similar *Ppendage, the symmetry of the whole body would have been destroyed by the hiatus between the prothorax and abdomen, as may be seen by removing the hemelytra ; but by this compensating contrivance of Providence, the gap is filled, the above lobe fitting exactly into it. 6. The neurationof these organs will not occupyus long, Since the corium or harder part, though in some species there are traces of nervures, is often without them. Those the cucullated species of Tingis resemble many tegmina in being ornamented by them with a kind of network, Which looks like the finest lace; in several Lygei, Edessa, and some Reduvii, there are afew diverging longitudinal Nervures which occasionally by a ramification here and there form an areolet?, but there are seldom any tra- Yersing nervures. ‘The Apical Area is usually most di- ‘tinguished by nervures, in some forming several areolets, as in Aradus, in others running parallel to each other, Nearly to the end of this area, as in Belostoma grandis, a Prate XXVIII. Fie. 23. 618 EXTERNAL ANATOMY OF INSECTS. bject . where they are met by a traversing nervure ; the o of this is doubtless to strengthen the membrane. 7. Both tegmina and hemelytra are most commonly naked, yet very short hairs are found on those of some species of Cercopis, and in many more instances in thos? of the latter description, as in Notonecta, several Lysh and Reduvii, &c. 8. Colours in hemelytra are very various, and in instances are peculiar to families; in certain Lyge! ( Hyoscyami, &c.) black and red; in Lygeus compresstp a and affinities a dingy black; in some Reduvii black wit a large white spot ;—but it is needless to enlarge farthe many on this subject. 9. That hemelytra are used in flight is evident not oY from the large space allowed for their muscles *, but like- wise from a circumstance noticed by M. Chabrier, that in flight, in the Pentatome Latr., the corium of the he melytrum is fixed to the wing*; in which case both mu describe the same arc. iv. Wings. We are next to consider organs which a° exclusively appropriated to flight, and therefore are pe perly denominated wings. These in the Orders that have elytra, tegmina, or hemelytra, are the pair that corresp with the secondary wings of the other Orders. It may be said, indeed, that in severa! instances both tegmina an hemelytra do not differ at allin substance or use from tP? wings that they cover. This is true; but as their strut ture in other respects is the same with that of those that are more solid and less apt for flight, it was convenient 1° consider them under the same name. a Chabrier Analyse, &c. 23. EXTERNAL ANATOMY OF INSECTS. 619 1. To begin with the articulation of these organs with the trunk ; in general it may be stated that this, as in tegmina and hemelytra, is usually by the intervention of three axes, formed by the conflux of the nervures of the three areas at the base of the wing, which either imme- diately or by other pieces are implanted in the trunk, so as to receive from it the aérial and other fluids, neces- Sary for its expansion and motions*. Having given this general statement, I shall next apply it to ‘the wings in Some of the different Orders. If you carefully extract one from the stag-beetle (Lucanus Cervus) or any large species ofthe Dynastida, in the Coleoptera; the first thing that Will strike you, upon examining the base, will be the plate before mentioned called by Chabrier the humerus, which ls a stout transverse corneous piece, with a deep sinus to- Wards the wing, filled with ligament: if you again follow the costal, mediastinal, and postcostal nervures, you will find them unite to form an axis, consisting of three pa- Tallel pieces, which connects by its intermediate internal Piece with one end of this plate. The nervures of the In- termediate Area terminate also in a corneous axis at a Steater distance from the base than the other two, which Connects with Chabrier’s humerus by means of the liga- ment of the sinus just named. Those of the Anal Area re received by a ligament attached to a transverse plate, Widest at its anterior end, which connects with the poste- tior part of the said humerus; and at its posterior end is United to the postfranum”, with which it forms a right gle. In the Orthoptera: Order the structure is not very different, but the axes and other plates of the base of the © Chabrier Sur le Vol des Ins. c. ii. 325—. and 326. Note 1. » See above, p. 572—. 620 EXTERNAL ANATOMY OF INSECTS. wing are less distinct and rather cartilaginous; the ner- vures of the Anal Area often terminate in a transverse 01e that there forms the segment of a circle; the inner base of this circle is ligament connected with the postfræenum”. In the Homopterous Hemiptera the three axes may be readily traced, but the humeral plate, with which they all are connected, is more irregular in shape, and in Fuge" A longitudinal, with an angular surface; in this Order the nervure, in some cases consisting of cartilaginous rings”? in which the frenum and postfrenum terminate in the tegmina and wings, is attached posteriorly to the ligament of the Anal Area. In the Heteropterous section the thre? axes are evident, but the humeral plate is not easily made out. In the Libellulina the axes of the Costal and Inte™ mediate Areas are the coloured broad plates at their bas formed by the dilatation of their nervures ; that, howeve” of the Anal is not dilated, but forms one nervure, in the primary wing, with the frenum, and in the secondary wit? the postfrenum. Having given you this clue to trace the axes in those tribes in which they are most conspicuous» it will assist you in searching for them in the remain- ing Orders, in all of which they may be traced, except perhaps in those minute Hymenoptera whose wings hav? solely the costal nervures; probably in these there is only one axis. In the Lepidoptera and Hymenoptera a cit” cumstance connected with the present head is observable, which is not to be discovered in the other Orders: thes . are the zegul@ or base-covers, which appear intended t° defend the base of the anterior wings. They are coP- cavo-convex scales, which in the Lepidoptera are larg® a Prate XXVIII. Frc. 9, a. e See above, p. 572. © Ibid. p. 560. and Prate XXVIII. Fie. 11. a. EXTERNAL ANATOMY OF INSECTS. 621 and of an irregular shape *, but in the Hymenoptera are Smaller and semicircular». 2. Wings, with regard to their substance, may generally be termed membranous; but they vary in this respect, some being much thicker than others, either partially or total- ly: in spotted wings, as in those of many Libellulina, Tettivonia F., &c., the dark opaque parts are denser than those that are transparent: in several Orthopterous in- Sects, as in Phasma, some Mantes, &c., the Costal Area or covering part of the wing is of a substance equally firm with that of the ¢egmen. ‘This is a compensating Contrivance, that where the latter is shorter and smaller than the former, its membranous part, when folded, may be protected from injury. Another similar contrivance of Divine Wispom is exhibited by those Prerophylle K. (Locusta F.) whose tegmina resemble the leaves of Plants (Pz. laurifolia, &e.); in these the tip of the wings When folded being longer, is not covered by the tegmzna, and therefore exposed to injury; to prevent which this Small piece, while the whole wing, as far as covered by those organs, is membranous, is of the same substance With them’. The wings of most Coleoptera, Orthoptera, Hemiptera, and Thereva coleoptrata, in the Diptera, &c., are of a firmer substance than those of the other Orders; in many Locust@ Leach, Fulgore, &c., they are nearly as firm as the tegmina; and in Ascalaphus italicus, except at their base, the secondary wings are less membranous than the primary. M. Chabrier has observed? that the Wings of insects in general diminish in thickness from their i Pracre IXe Fress. b Ibid. Fie. 11. 12. g”. © Stoll Sauterelles à Sabr. t. iv. f. 12. t.vi. f. 21. &e. € Sur le Vol des Ins. c. i. 424. 622 EXTERNAL ANATOMY OF INSECTS. base to their apex, and from their anterior to their pos- terior margin. 3. I should have had, it is probable, but little origin! matter to communicate under the head of the composition and neuration of wings, had M. Jurine, who has written so ably on those of Hymenoptera, undertaken a survey of the organs of flight in every Order of insects: but as his views were confined to only żwo of the Linnean Order it is not wonderful that his system and set of terms should fail where a generalization is necessary; and I may stand acquitted of presumption and conceit if I attempt to sub- stitute a system and body of terms more universally aP“ plicable. Had the plan of this able Entomologist led him to pay attention to zegmina and hemelytra, the division into three longitudinal areas would have imme diately struck him; and having acquired this outline 9 the greater natural divisions, he would have applied it t° the Orders that have wings only, and having discovere that it is to be traced in all, the result would have pro“ bably superseded my labors. Had his life been longe" spared, perhaps something of this kind would have bee” effected by him; but as he, alas! is gone, and no able hand seems to have undertaken the task, I will do what I can to give you satisfaction on this subject?, You a The idea of dividing the wing of an insect into larger areas seems first to have been acted upon in Monogr. Apum Angl. (1801), in which those of Hymenoptera were stated to consist of three portions, Y” Basis, Medium, Apex (i. 211.); which mode of dividing them was at first adopted by M. Latreille (Gen. Crust. et Ins. iii. 226. Note l} The same learned author (Ibid. iv. 239.), with regard to the Dipter® made a near approximation to the plan of dividing wings into Jong’ tudinal areas, but by the addition of a basal area, which interrupt the attention to the communication of the areas with their aves, P? has rendered his system less perfect. Two of his terms—Costal Aret EXTERNAL ANATOMY OF INSECTS. 623 have already got a tolerably good idea of these areas from What has been said upon the subject under tegmina and hemelytra; but I shall now more particularly state to you Ow they are circumstanced in wings. I shall first ex- Plain the general law as to their limits. The Costal Area? is all that longitudinal portion of the wing that lies between the anterior margin and the postcostal nervure; the Intermediate Area” is all that longitudinal portion of the wing that lies between the postcostal and the anal nervures; and the Anal Area® is all that longitudinal Portion of the wing that lies between the anal nervure and the posterior margin. But there are other helps to enable you to distinguish the areas in the different Orders. The Anal Area in all Orders forms the posterior fold of the wing; in Coleoptera turned underwhen in repose ; in Orthoptera folded like a fan; in Lepidoptera, in some Papilionide, forming an arch over the abdomen. Again, in Blatta, the Costal Area is distinguished chiefly by Zongi- tudinal nervures ; the Intermediate by oblique ones; and the Anal by radiating ones; and in both this tribe and the Mantide this last Area is marked out from the Inter- Mediate by a marginal notch, which is not present in Phasma, but is found in both sections of the Hemiptera. In Locusta Leach the notch is between the Costal and Intermediate Areas: in Phasma the nervures of the In- termediate Area are branches of the externo-medial, while those of the Anal, as they do in all the Orthoptera, diverge and Intermediate Area, are here adopted ; but his Internal is changed to the Anal Area, for the term internal belongs rather to the base of the wing. M. Latreille afterwards relinquished both these plans, N. Dict. d’ Hist. Nat. i. 248--. * Prare X. and XXVIII. b. i. is the Postcostal Nervure. è Ibid. c. m, is the Anal Nervure. © Ibid. d. 624 EXTERNAL ANATOMY OF INSECTS. from the base of the wing: in many, as in Pterophylla K. the part of the wing lately alluded to, that is longer than the zegmen, and of the same substance, points out the limit of the Costal Area; and in others this part terminates A a segment of a circle and is differently reticulated at the apex from the Intermediate: in the Homopterous Hemi- ptera and the Libellulina, in which the areas at first see™ indistinct, they may generally be easily traced by follow- ing them from the axes. The separation of the Costal from the Intermediate in the remaining Orders seems less easy on account of the branching of the nervures : in the rest of the Neuroptera and the Lepidoptera, if the poste- rior branches of the postcostal nervure are not include you will have a narrow Postcostal Area, which in mo% cases forms an angle more or less prominent, in Corydalis almost a right angle, with the Intermediate: in Hemerobi’ and affinities this part is distinguished by areolets form- ed by ¢ransverse nervures, while those of the rest of the wing are longitudinal*: but if the posterior branches a° included, the Costal Area will be more ample: a spnilat observation applies to the Hymenoptera and Diptera; ® these, in all cases, the areolets adjoining the anterior ma!” gin, which follow the stigma, should be regarded as be longing to the Area in question. In those tribes of thé former Order, whose wings are without nervures, the areas are often marked by folds. M. Chabrier has observed that in Coleoptera the sp cific weight of the margin of the wing, and its meas $ resistance, are augmented by a liquid which is introduced at the wili of the animal, into a long pocket under the * PLATE X. LIC V 2°. 2°. &. b Ibid. Fia/8. 9. 12.4 °° EXTERNAL ANATOMY OF INSECTS, 625 br achial, here called the costal and mediastinal nervures, “overed by a supple membrane, which in a state of repose becomes flaccid? : it is easily detected, being of a paler Colour than the nervures between which it lies ; this is What I call the Phialum ; we have before seen that it exists also in Elytra and some Hemelytra®; but I have Not detected it in any other wings. ~ I have before given you a sufficiently full account of the alule or winglets of Diptera‘; and shall here only °bserve that they are not confined to one particular tribe, àS has been usually imagined; but though sometimes “Xtremely minute, simple, and not easily detected, arean Universal distinction of the Order. Having thus endeavoured to elucidate the Jarger Areas to which wings appear to be divided; I shall next Say something on the smaller ones produced by the in- tersection or ramification of the nervures; these had “en named areolets (areol@) several years before M. “Urine’s work, in which he calls them, I think improper- Y; cellules (cellulæ), was published; I therefore retain “prior term. The general structure of the nervures f the wings of insects having been before explained4, I ‘hall nothere repeat what I thensaid; but there is a curious “ircumstance connected with it, particularly visible in the Wings of certain Hymenoptera, that I must not pass with- Nt notice. If you examine attentively with a microscope Wainst the light the wing of any Nomada or Andrena, You will discover little transparent points in some of the ‘maller transverse nervures that form the middle areolets, “which: the! nervure becomes white and looks as if it 3 Sur le Vol. des Ins. ¢. i. 428. » See above, p. 600, 616. Vor. II. p.358—. See above, p. 559. 4 Vor. II. p. 346—: L. ur, 25 Yo 626 EXTERNAL ANATOMY OF INSECTS. tinued: ix bub- these little points, somewhat resembling minute al bles detained in the tubes, are what M: Jurine, who first hich was interrupted, though in substance it seems Con discovered them, has, on that account, named bullæ, W he thus further describes: ~“ When the tube (of the ne" vure) arrives at the spot where a bulla is to be formed, i extends itself on all sides in minute threads in the uppe” rut- ture, which it resumes immediately after the formatio” of the bulla?” But if you look closely at them you i find that there is always a slight fold of the wing that cuts the nervure exactly at the bullæ, and if the fold membrane of the wing, losing its colour and tubular st changes its direction they accompany it; their objec therefore, is clearly to relax the tension so as to admit # little motion where the fold is; consequently, rather tha? bulla (bubbles), they should be denominated articulation A similar construction, but on a larger scale, may be 9 served in the wings of Coleoptera” and some others ” Psocus, where thefolds traverse the nervures. I shall než ; Se t makeafew observations on the principalnervures; and iil? a word upon their names. M. Jurine, being of opini” that a striking analogy exists between the wings of insel and those of birds, in which M. Chabrier seems to agre? with him, has named the nervures in the anterior marg” of the wings of the former, radius and cubitus, as corte” sponding with the bones so named in the fore-arm of latter, and the plate which often terminates these or vures in Hymenoptera, he names the carpus pit may g like presumption to differ from two such weighty aith” rities, but as their observations seem to have bee t Jurine Hymenopt. 19. and ż. v. b Prare X. Fie. 4, EXTERNAL ANATOMY OF INSECTS, 627 limited, in one case to the Hymenoptera and Diptera on- Y; and in various Orders there is nothing analogous to the stigma or carpus, and all the other nervures of an in- Sect’s wing have no analogue in that of a bird, but more “specially as M. Latreille seems to think with me on this Subject *, I have retained Linné’s term for the marginal Nervure, and for most of the others have adopted those of the great French Entomologist just mentioned, I Shall here only further observe,—and it seems to me an €rvation of prime importance, in the determination of the question of the analogy of the wings of insects,—that SY are not, as in birds, the Jore-leg converted into an rgan of flight, but, like the wing of the Draco, an organ Uperadded to the legs; and, further, that the connection 'S not with the fore-legs, but, as has been before ob- “tved*, with the two posterior pairs. The Costa® is usually the strongest of the nervures, Md that upon which the wing seems to be built ; but in * Some cases, as in Blatta, Scutellera, Cynips, &c., it is re- Presented by the mere membrane of the anterior margin; some Coleoptera, as in Geotrupes, Dytiscus, &c., its struc- ure, except at the base, appears to be annular or nearly 50, at least a vast number of corrugations, running trans- Yersely, are observable on its upper and lower surfaces ; t is thus capable of greater tension and relaxation; and Nore flexile, The stigma or carpus 4, though most conspi- “tous in the Alymenoptera Order, may be traced in some leoptera, Heteropterous Hemiptera, the Libellulina, %3 but it has no representative in the Orthoptera, Le- 'doptera, Trichoptera, &c. The mediastinal is usually a o N. Dict. d’ Hist. Nati: 251. © b See above, p. 564, 578, 591. Prate X, pe d Ibid, Fre. 4, 11, m”. 2s2 628 EXTERNAL ANATOMY OF INSECTS. very slender nervure, placed between the costa and costa, sometimes terminating in the former?, and at 0 in the latter? ; in the Orthoptera, Lepidoptera, &¢-» ben ever, and some others, it isa very conspicuous and pr ging cipal one; in the Hlymenoptera it is obsolete, mer in those nervures®. The Postcosta is the principal ath vure of the wing in Scutellera, but in Staphylinus it # wanting; in Chalcis sespes it is the only true nervure 7 that organ, the others being represented by spuriov? ‘onest. The externomedial and internomedial are 50% times distinct at their origin, but more frequently branches from a common stem. - Having made these general remarks, I shall now p sider particularly the neuration of the wings in the di- ferent Orders; beginning with the Coleoptera. thing that strikes the physiologist in surveying longing toan insect of this Order, is the general ment of the nervures °; which are so placed that ag required degree of tension may be given to every. part’ this organ: thus some are nearly straight‘; others ee pra? a serpentine direction £; others areforked with one : j recurrent and another proceeding onwards*; others ag? ee yng are insulated, or donot originate from the base of the wer e or fromother nervures, butare merely placed to strengt an open space: of it: these nervures are also us” broader and more substantial than those of the wing? ‘ the subsequent Orders.. Another striking circumst™? ; ; F po with regard to them is that the nervures form few ° a Prate X. Fie. 14%. » Ibid. Fic: 12. k. ' Ibid. Fie. 8. 9. 4 Jurine Hymenopt. t. e. PLATE X. Fie. 4. f Ibid: a. n, 0°. UST 2. i Ibid. a. zj Gen: 41. ; « jbid.” EXTERNAL ANATOMY OF INSECTS. 629° Closed areolets, except in the Costal Area, where they are inconspicuous; in Dytiscus marginalis, indeed, and Tenebrio Molitor one or two may be found, but in ge- neral there are none. In many of this tribe the post- costa, which terminates at the joint of the wing, becomes recurrent, so as to form a hook, which perhaps repre- Sents the stigma, as in Dynastes*; in Creophilus K., a fovesbeetle, there is no hook but a broad plate adja- Cent to the costa. In the Strepsiptera Order the neu- Tation is extremely simple, the nervures, except one insulated one, diverging from the base of the wing”: in this respect, as well as in the form of that organ, an approach is made to the Orthoptera. In the Derma- Piera this approach is still more evident; in the common _ farwig °, the diverging nervures become numerous; be- tween each is an insulated one, taking its origin in the Middle of the wing, and running to the margin; a little Nearer to the latter all the nervures are dilated into a Plate; those of the anal area are angular‘, and the ex- Posed part of the costal is as hard as the elytra. The Neuration in the Orthoptera Order may be called radiate, the longitudinal nervures for the most part diverging from the base of the wing like rays: in some few instances °, but not often, I believe, an insulated nervure intervenes between each; traversing or connecting nervures, cutting the longitudinal ones in Various directions, ornament these Wings with an infinity of areolets, causing them to resem- ble fine gauze or beautiful lace or net-work ; very often these areolets are quadrangular, sometimes rhomboidal, * Ibid. 0”. b PLATE Il, Fic. 1. Comp. Linn. Trans. xi. fix. fl. © Pirate X. Fie. 5, 4 Ibid. n, 0, p. “ Stoll Spectres, t. xviii. f. 65. 630 EXTERNAL ANATOMY OF INSECTS. frequently nearly circular, and differing occasionally, 4 has been before observed ?, in the different areas: it some- times occurs that there are no traversing nervures”, when the wing of course is without areolets. In the Hetero pterous Hemiptera the type of neuration, as to the wing seems borrowed from the Coleoptera, a further proof that these are the analogues of that Order amongst the Hat stellata Clairv. In these the nervures usually are few and dispersed, and seldom form any closed areolets. J you examine any Scutellera, Pentatoma, or Lygaus, you may trace the uncinated, forked, serpentine, and inst lated nervures of Coleopterous insects; in Gerris and Velia there is an approach to the neuration of som? Homopterous species, and in Belostoma &c. the wing ® reticulated by spurious nervures. In the Homoptero¥® section there are several types of neuration ; thus the Full gore resemble the Orthoptera in this respect; while the Tettigonie F., &c., approach nearer to the Hymenopter@ and Diptera, and have their apical areolets cireumscribé within the margin by a traversing nervure; in Flath &c., the areolets are mostly formed, not by traversi¥8 nervures, but by the branching of the longitudinal ones’ in this respect they are not unlike the Lepidoptera. In this last-named Order there are some variations with sd gard to their neuration—thus, amongst the butter fires a Urania, &c., there is no closed areolet in any of the wings, and almost all thenervures diverge from the base in Morpho, &c., there is only one in the primary wing’ in Heliconia, &c., there is one in both wings; amongst >, ‘al ; oe it * See above, p. 624. > Stoll figures Empusa as withov them, t. ix. f. 35. but? Ihave a nondesc. Phasma? without the™ e Jones in Linn. Trans. ii, t viii. f. 2. à Thid. f. 0 & EXTERNAL ANATOMY OF INSECTS. : 631 the moths, in the Bombyces L., this is divided into two, and m Cossus labyrinthicus Don. into three areolets: in some butterflies (Lycena) there is one insulated nervure*, and m others (Hesperia) there are two>; in these two last, and Heliconia, Urania, &c., the end of the Costal Area is divided into several areolets by oblique nervures $, Which gives them some analogy to the wings of many Neuroptera ; and at the base of this Area, in Morpho, is a roundish areolet*’. In this Order the externo-medial and interno-medial nervures coalesce into one, and are Only represented separately by their first: and third branches‘. In the Neuroptera Order the general type of Reuration is borrowed from the Orthoptera; but in Os- mylus, Termes, &c., there is an approach to that of Hata in the Homopterous Hemiptera, and in Psocus to others of that section; in the second of these genera the ner- Vures, except those of the costal margin, are spurious. I now come to the Order in which M. Jurine has la- boured with so much success, I mean the Hymenoptera ; and I only regret that his labours were directed to so Small a portion of the Class Insecta, and in that portion Only to a part of the upper wing; I say only a part, be- Cause all those areolets of the posterior part of the wing, in some cases amounting to jive’, that lie behind his cu- bital cellules, are not employed by him as diagnostics, and are left without a name. By dividing the areolets of the a Jones in Linn. Trans. ii. t. vill. f. 7. > Ibid. f. 9. © Ibid. f. 2, 3,6—9. 4 I wonder Mr. Jones’s plan of ascer taining the divisions or subgenera of butterflies by the neuration of their wings has never been E aea up; it would J think furnish an easy clue for the extrication of the tribes of all the Lepidoptera. Mean as subsidiary to more important characters. * Prare X. Fic. 6. Bami. f Ibid- Fre. 8, 632 EXTERNAL ANATOMY OF INSECTS. Intermediate Area of these wings into three portions, the basal, médial, and apical*, I have endeavoured to as medy this defect, and by naming each set of areolets ™ the middle portion, as you will see in the Orismological Definitions, under the term Areolets, you will find 1t easy to describe any given areolet and its place in the wing; those of the base may be called the anterior, in- termediate, and posterior, where three occur; and the first and last of these terms will suffice where there are only two ; the apical areolets, or those that are open to the margin, may be called, jirst, second, and third in the order of their occurrence, reckoning from the anterior OF gE ETS eee ree ee eae ee SS ET os costal margin. In this Order it is curious to trace the progress of ve ration in the wings of different genera. 'Thus in Psiltt only the costal nervure and the st7gma are to be traced”; in Chalcis the postcostal and stigma ©; in Codrus and Le’ cospis the costal, postcostal, stigma, and a nervure repre senting the externo-medial and interno-medial coalescing into one’; in Omalus the basilar areolets appear °“; in Crabro both basilar and medialf; in Cynips basilan medial, and apical®; and in Hylotoma the wing is filled with its greatest complement of areolets'. The medial areolets of the Intermediate Area, as you will see in the definitions, form three distinct series; these may be calle the protomesal, deuteromesal, and tritomesal, reckoning from the postcostal areolets; the first of these corresponds with the cubital cellules of Jurine. These series may Pê a Prate X. Fie. 8. basal e+, medial f', apical g’. Jurine Hymenopt. t. v. Gen. 48. © Tbid. Gen. 47° Ibid. Gen. 45, 46. Comp. Prater X. Fic. 11. Jurine Ibid. Gen. 43. £ Ibid. t. iv. Gen. 47. Ibid. t. v. Gen. 40. h Ibid, t i. Gen. 2. EXTERNAL ANATOMY OF INSECTS. 633 expressed, according to the number of their areolets; by figures, the protomesal standing first. They vary much in this respect in the different genera. Thus in Cyclo- Stoma K.*, reckoning the didymous areolet as two, the Numbers will stand 4:2:1; in Hlylotoma, &c., 3:2:1°; in Aulacus, &c., 2:2:1°; in Bracon, &c., 2:1:14; in Chelonus, 2:0:1°; in Cynips erythrocephalus Jur., 2:0:0'; in Formica, 1:1:18; in Oxybelus, 1:0:15; in Chrysis, 0:21:11; and in Cynips Rubi K.,1:0:0*. The most Natural number is 3:2:1.. The next in importance to _the medial areolets of the Intermediate Area are the ical, or those open to the margin ; the most usual num- ber of them, excluding the postcostal areolets which be- long to the Costal Area, is three ; but in Sirex there is an approach to four! ; in Evania there are only two™ ; and in Philanthus there are none”; in many, as Proso- pis, Nomada, Andrena®, though there is the usual num- ber, they are incomplete and do not reach the margin. The basal areas are of little importance in assisting to determine genera; they are most commonly /wo in num- ber, but in Cynips, &c., there is only one?. The shape and other circumstances of the areolets vary consider- a This is a remarkable insect belonging to Vespa L., related to the Ornets (V. Crabro), distinguished by having a semicircular piece taken _ Out of the internal margin of each mandible, so that when these or- Sans are closed there is a circular orifice,—whence the name Cyclo- oma, t Jurine Hymenopt. t. ii. Gen. 2. c Ibid. Ord. ii. Gen. 2. ` Ibid. t. iii, Gen. 3. © Ibid. i. v. Gen. 41. * Ibid. t. xii. Gen. 40. € {bid. t. v. Gen. 39. ^ Ibid. t.iv. Gen. 29. i Ibid. t.v. Gen. 42. * This Cynips inhabits a long polythalamous gall of the bramble, Jurine Ibid. t. ii. Gen. 11. ™ Ibid. Ord, ii. Gen. 1. 3 Ibid. t.iv. Gen. 23. ° Ibid. Gen. 30—32. Ibid. t. v. Gen. 40 634 ' EXTERNAL ANATOMY OF INSECTS. ably in different genera and species: upon these however I shall not enlarge further, but proceed in the next place - to consider very briefly the wings of the Diptera Order as to their neuration. These are not so easily made sub- servient to a general plan. The basilar areolets are 2” reduced considerably in length, occupying merely the bam of the wing*; the medial are become less numerous an important’; and the apical, in a variety of instances, pe the most conspicuous®; in some wings, as in those g Penthetria, the Intermediate Area has no nervures a areolets, or only spurious ones; in Psychoda the nervures diverge from the base almost without branching, so 4° e form no closed areolets¢; in many, the lower media areolets are very long, resembling the basilar in Hymne” optera®; these are often crowned by a single small 09% as in the Stratyomide, Tipula, &c., from which num?” rous branches proceed to the margin‘; but in Musca w? large ones approach the margin, the anterior one havi0s an angle open to it; in the Hippoboscide almost whole of the wing is occupied by the apical areole# though in some cases they are incomplete’. 4. I am next to consider the position of wings in 7 epos? and their folding. The most important object of this ® that when unemployed they may occupy less spac® less in the way of the insect, and be most effectually pe. tected from injury. Another end is also served by owe structure,—that wings can thus be very ample, and pr?” a Pratt X. Fre. 12, 15, e. b Ibid. Fie. 15. f- © Ibid. Fre. 12. g'. v Ibid. Fre. 13. e Ibid. Fic. 15. c. f Ibid. d. € Ibid. Fre. 14. e. è Leach on Eproboscideous Mem. Wern. Soc. 1817. t. xxv. f. 3, 5, 8, &c. i Ibid. t. xxvi. f. 7, 10, 13. Insect EXTERNAL ANATOMY OF INSECTS, 635 Sent a large surface to the action of the atmosphere with- Sut incommoding the insect when it has not occasion to Use them. With respect to this head, insects may be divided into two classes—namely, those whose wings in repose are Covered by wing-cases harder than the wings themselves, and those that have no such protection. In the former the wings, though the rule admits several exceptions, have More folds than in the latter. As the different mode of folding the wings has been assumed for a characteristic of the earlier Orders, I shall explain to you with as much brevity as possible how each is circumstanced in this re- Spect, beginning as usual with the Coleoptera. There are two principal folds of the wing in this Order, Which may be named the anal and the apical: the Jor- meris when the Anal Area or part of it is folded on the ünder surface of the base of the wing; this fold is always More or less longitudinal: the latter, the apical fold, is by means of the commissura or joint of the postcosta lately Mentioned: which in Hister, Staphylinus, &c., for obvious reasons * is nearer the base of the wing; in Necropho- us in the middle; in Dynastes Aloeus beyond the mid- dle; in Tenebrio Molitor near the apex; and in Dytiscus marginalis there appears to be no joint at all; but the fact is, that in this insect the postcosta,—the termination of which really forms the joint, the costa itself being only flexible at that point,—stands at a greater distance from the latter at its end. Well, at this joint the above fold 's made, the apex of the wing, being first folded longi- ‘udinally, turning under and inwards, and forming an ` Insects with short elytra of course must fold their wings nearer the base than those with Jong ones. b Pratz X. Fic. 4. 0”. 636 EXTERNAL ANATOMY OF INSECTS. angle, more or less acute, with the joint or costal margin so. that the fold is not quite but nearly transverse: this at least is the case in Geotrupes stercorarius and other Lamellicorns: in Staphylinus, &c., there are several transverse and longitudinal folds, and thus the wing ® more easily packed under the short elytra; in Molorchus Necydalis, &ec., in which it is left uncovered, except at its base, the anal fold takes place, and the apical in some degree;'a short portion near the apex forming an obtus? angle with the margin ; in Atractocerus the wing appeal? to be only longitudinally folded; and in Buprestis vittatð only the anal fold is to be detected. Besides these tra™* verse and longitudinal folds these organs, in many ash tles, have an infinity of fine corrugations, which ramiby like the nervures of the tegmzna of Ilata*, &c., proceediné from the Costal Area or the disk of the wing to the per terior margin; the object of these plicatures is doubtles to present a more ample surface to the action of the a” mosphere in flight®, When all these folds have bee? P . its made ina Coleopterous wing, the apex of the one at? posterior margin crosses or rests upon that of the other“: In the Dermaptera, at least the common earwig there is a triple transverse fold of the wing, and besides this it has numerous longitudinal ones like those of 2 fad: each of the diverging nervures representing one of the sticks. In the Strepsiptera the folds are only longitud nal; a circumstance which, besides the form and neur? ‘tion of the wing, sufficiently attests that its station is more near the Orthoptera and Coleoptera than the Dipter i : gi * See above, p. 611. è See above, p. 613, and Chabrie Analyse, &c, 24. * Prate XXIII. Fie. 5. a Prate X. Fic. 5. EXTERNAL ANATOMY OF INSECTS. 637 We next come to the Orthoptera*; in these the folds in general are longitudinal ; and those of the Anal Area in particular, either in whole or in part, exact counterparts of a fan: wherever there is a straight nervure, there is usually a fold or a tendency to it; this is the case even with the short oblique ones observable in the Interme- diate Area of Blatta: in this tribe the Anal Area, or a considerable portion of it, is folded under the rest of the wing, and the whole lies on the back of the animal, so that in this wing there are only two primary folds; but in those with a narrower body, as Phasma, &c., there are more, and the Anal Area, folded like a fan, lies hori- zontally on the back; the Costal is vertically applied to the sides, and the Intermediate is between both, asin the tegmina®. In Gryllus Latr., Gryllotalpa, &c., when the wings are folded, the end of the Anal Area projects so as to present the appearance of two tails °; and in that re- markable Chinese animal Gryllus monstrosus, in which these tails are very long, they are convolute like those of some quadrupeds*. It is to be observed that in the secondary folds of these wings the angles of the folds are surmounted by a nervure. In both sections of the Hemiptera Order, as in the Co- leopiera, the Anal Area is turned under the wing and lies over the back of the insect; this is the only primary fold, but besides there are several longitudinal semifolds or secondary ones, in which one part of the surface forms an obtuse angle with another; and in Tettigonia, &c., these folds ramify in the wings as well asin the tegmina at the * Prats XXVII. Fic. 22. b See above, p. 608—. © Stoll Grivlons, t. iii. c. f. 11—13. a Thid. t:i. ¢. f. 1, 2. 638 EXTERNAL ANATOMY OF INSECTS. margin: a number of semifolds also, sometimes trans- verse and sometimes oblique, run in pairs from each side of every nervure of the disk of both tegmina and wings 12 the genus last named, the use of which has been before mentioned ®, We now come to those Orders that have four mem- branous wings: first, I shall consider the Lepidopter@ With respect to the position of their wings in repose some variations take place. In the majority of the day-/lers (Papilio L.), when the animal reposes the wings are 4)" plied to each other by their upper surface so as to be vertical; but in the skippers (Hesperia), the secondaty wings assume a horizontal position, while the primary atè vertical but applied to each other. In the Crepusculat tribes (Sphinx L.) the upper wings are incumbent on thé lower, and deflexed. In the night-fliers (Phalena L) the types of position are various. In some Attacus; SY turnia, Noctua, &c., the wings cover each other, and até a little inclined from a horizontal position; in Gastro- pacha, Odenesis, and some other Bombycide, they are de- flexed, and the anterior margin of the under wing pro” jects beyond that of the upper: in some of the Tinee Ls as Crambus, the wings are convoluted, and in others Galleria, they are applied close to the sides of the bodys and being elevated at the apex, terminate, to use a French term—en queue de cog: in Noctua, Geometra, &c., thé wings usually cover the abdomen, and are nearly hor zontal, With regard to the folds of their wings, the Anal Area of the secondary is the only part that has ay striking one; in Papilio Hector and affinities it turr’ * See above, p. 636. EXTERNAL ANATOMY OF INSECTS, 639 Up so as to defend the sides and part of the back of the abdomen; in Morpho Teucer it turns down, and meeting that of the opposite wing, forms a semitube which re- Ceives and shelters that part below. In the Crepuscular and Nocturnal Lepidoptera this fold, especially in the former, is very slight. With respect to semifolds in the Diurnal, there is oneoriginating in the disk, between each of the nervures, that goes to the margin of the wing; like- Wise the under wings, particularly of many Noctue, Arc- tie, &c.f have many longitudinal semifolds. In the Neuroptera Order several variations take place With regard to the position of these organs in repose: thus, in Æshna, Libellula, &c., they continue expand- ed; in Argion they are applied to the body; in Myrme- leon the upper are horizontally incumbent on the lower ; in Hemerobius they incline to the horizon. With regard to their folds in Æshna, &c., the longitudinal nervures alternately form the summit or the bottom of a semifold, as do those branches that terminate in the posterior mar- gin; this kind of plicature may be observed, but in a less degree, in Ascalaphus, Myrmeleon, &c.; in Panorpa every hervure is the ridge of a slight fold; in Termes, on the Contrary, it forms its bottom. In the 7richoptera, the under wing being much more ample than the upper, the Anal Area forms a fold under the wing, and there seem longitudinal secondary folds besides. We now come to the Hymenoptera. In this Order the wings, as to their position in repose, are usually in- cumbent upon each other, and cover the abdomen; in the Vespide, however, they are placed parallel to the body, but do not cover it. Before I notice the plicature of these wings, I must recall your attention to what I lately 640 EXTERNAL ANATOMY OF INSECTS. observed* with regard to Jurine’s bulle (bubbles), but which are really the joints of the nervures, as they ar? to be found only where the folds pass; and where they exist they are an index by which the folds, or rather sê- mifolds, may be traced. I counted eleven of these little joints in the upper wing of Andrena cineraria; sometimes, however, instead of a bulla, a nervure stops short to ad- mit the fold. Wings in this Order have often three longitudinal semifolds more or less conspicuous ; these you may trace in the saw-flies (Tenthredo L.), whos wings Linné terms zwmide, by which term he would in- dicate the elevation of the whole surface produced by this structure; in the under wings of these, and Scolia, Bem bex, &ce., the Anal Area is turned under the wing, as in many preceding tribes?» in Sirer, &c., that Area of the upper wing turns upwards, forming an acute angle with the rest of the organ; the same circumstance distinguishes the under wing in the Ichneumonidae. Several api semifolds, marked by a pellucid streak, distinguish Tiphia F., and in Bombus, Bembex, &c., an infinity of branching ones, like those before described in Coleopter® corrugate the apical margin. In the Vespide the upp wings are folded longitudinally into three nearly equ% portions, but in the under ones the Anal Area only forms the fold. : In the Diptera Order, as to their position when atr est, j the wings are mostly incumbent one on the other; but in Psychoda they are deflexed, so‘as to form a kind of pent- house. With regard to their plication, in some, Tipul oleracea, &c.; a slight oblique semifold runs from the * See above, p. 625. > Ibid, p. 635, 637, &¢-_ EXTERNAL ANATOMY OF INSECTS. 641 stioma tothe apical margin, and the Anal Areahas two, as it has in many Muscida, itself forming nearly a right angle With the rest of the wing; besides these it is corrugated with minute transverse semifolds, which are observable also in several other Dipterous insects; in many Stratyomide they are oblique, and run from the disk to the posterior Margin; and in Asilus, Bombylius, &c., they are wavy. ` 5. Wearenexttosay something upon the shape of wings: this, though apparently extremely various in the different Orders and tribes, may I think be traced in every wing to one original prototype, a triangle with the largest angle rounded and subtended by the anterior or costal margin: m some, as the Coleoptera, Orthoptera, &c., this type of formation is a right-angled triangle*; and in others, as in the Hymenoptera, Diptera, &c., the majority of the Neuro- Piera, &c., it is an obtusangled one; it may be further Observed, that in receding from these forms wings very often assume that of the half or quadrant of some regular figure, as we shall see when we consider those of the diffe- tent Orders. Another general observation I shall first men- tion,—that these organs are universally narrowest at their base and widest at the apex, provided we consider as the apex the termination outwards of thethree Areas; otherwise We might say that wings in the Coleoptera, Orthoptera, &c., were wider at the base than at the apex*®. The wings in the former Order, and in several of the Heteropterous Hemiptera, as Gerris, Velia, Xc., may in general, as to their shape, be termed semicordate or semiovate 4; in the ermaptera they incline to an oval figure€; in the Stre- * Prate X. Fic. 4, 5. and XXVIII, Fic. 21, 22. è Phare X. Fre. 6—14. c Ibid. Fre. 4, 5. and XXVII. Pre, 21, 22. 4 Pirate X, Frc, 4. * Ibid, Fre. 5 VOL, II. aah SAZIN i Og I lg AE T OD Re eR Sree ee Fe Lie Ee Aan paws i l —— >E eet = See es LIBEL MET PG LITE TART Bet TF 642 EXTERNAL ANATOMY OF INSECTS, psiptera, Orthoptera, most Homopterous and many He- teropterous Hemiptera, they approach to the quadrant of a circle; in a considerable portion of the Lepidoptera the two under wings, if united at their posterior margin, aP- proach a circular form; the upper ones vary a little from the prototype of the under ones, forming an obtusangled triangle*; in many Neuroptera the primary wings may g, while the secondary betray more evidently the right-angled or obtusangled triangle; in the Hymenoptera this latter form is every where conspicuous, with little deviation, except in the rounding of the angles ”; and, finally, in the Diptera this form shades off again into an oblong, ovate, or linea! be called oblong or linear-oblon shape, the wing being most commonly attenuated at thé base into a kind of footstalk °. Some singular variations with respect to the termination or marginal processes © the wings are exhibited by many Lepidoptera; thus # Attacus Atlas, &c., the primary wings are falcated p hooked at their apex t; and in great numbers both wing? are there scolloped into alternate bays and capes, if, may so speak, varying in depth and length €. There ® usually a sinus between every pair of nervures, each which terminates in the adjoining prominence, as 4 fol does in thè sinusf. Where present, in the primary wing? there are eight of these sinuses, and in the secondary where they are most usual, seven; some are remarkable for the long żails which distinguish their secondary wings’ those in Papilio are usuallyan elongation of the fifth, from + Pate X. Fic. 6. b Ibid. Fic. 8—11. * Ibid. Fic. 12—15. ¢ Prare XIV. Fie.4. e Ibid. Fic. 2. In Gastropacha quercifolits Bes amongst the Nocturnal Lepidoptera, these sinuses exist, in the upp wing ten, and in the lower nine, but without the folds. EXTERNAL ANATOMY OF INSECTS. 643 the anterior margin, of the prominences before mentioned, into a spathula-shaped diverging process, varying in length and width®: but in P. Ulysses it does not diverge ; and in P. Podalirius it is linear. They are found also in other subgenera; thus in Urania Patroclus there are two; in U. Riphæus three; in Erycina Cupido jive; and in X. Endymion six of these tails; in some, as in E. Dorylas, the whole wing seems to form the tail; in others again, as in Hesperia Proteus and Bombyx Luna, it is an elongation of the anal angle. Other wings in this Order are divided into lobes resembling feathers, as you may see in Prero- Phorus hexadactylus, &c.” 6. We are next to consider the clothing of wings: these, in the Orders in which they are covered by elytra, teg- mina, or hemelytra, are generally naked, except that the Spots in those of Fidgora laternaria, serrata, &c., and the whole wing in Flata, Aleyrodes, and others, are covered With a kind of farinaceous powder; but in all the remain- ing Orders, hairs or scales are more or less implanted in these organs: as the Lepidoptera are the most remarkable for the clothing of their wings, I shall leave them till the last, and begin with the Neuroptera. If you lightly Pass your finger over the wing of any dragon-fly ( Libel- lula F., Æshna F.), from the apex towards the base, you will find that the longitudinal nervures are, as it were, Serrulated with very minute bristles, which point towards the extremity; if you next move the finger across the Wing, from the posterior to the anterior margin, a simi- ar circumstance will strike you. M. Chabrier conjec- tures that, amongst other uses‘, these hairs may contri- * Prater XIV. Fie. 1. s. , > Ibid. Fre: 3. € For some uses of hairs, see above, p. 399—-. 27.2 644 EXTERNAL ANATOMY OF INSECTS. bute to fix the atmospheric fluid when the wings até depressed in flight, while it glides over them as they rise?; in Ascalaphus, Myrmeleon, Nemoptera, Hemero- bius, &c., the nervures are more visibly bristled ; the bristles diverging on each side from the longitudinal ones, but all pointing towards the apex from the connecti transverse ones; in Panorpa, besides these bristles, hairs, pointing the same way, are thickly planted in membrane of the wing; and in Hemerobius the margins of the wing are fringed; in the FEphemerina, Corydalis &c., the wings are naked. In the Trichoptera Order; pe their name imports, they are covered with minute decu®® bent hairs, less easily seen but still existing in the s© condary pair. In the Hymenoptera in general the wings are covered with minute hairs or bristles; but in Tiphia Scolia—with the exception of S. Radula and affinities 1” which they are hairy—and others, the wings are nearly naked; in Pompilus, Pepsis, &c., the hairs are infinite- ly numerous and very short; in the Sphecide, Mutilla, &c., they are more distinct, longer, and less numerous? in the humble-bee ( Bombus) and many others the ape* of the wing is darkened by a large number of more co?” spicuous hairs, each of which seems to spring from a mi- nute tubercle: as these tubercles are in a part of the wing, that is strengthened by few nervures, they may probably be intended to supply their place, in giving firmness 4? tension to this part. The wings of Diptera, under the present head, may be viewed with regard to the hairs that are implanted in the membrane of the wing, iN its nervures, and in its margin. In the first view, in Sire ng oF short the —— EE = = renee S : =: e e p a= Hi oe Hi bh a Analyse, 24. He seems to think that certain crooked hairs, m some wings, supply the place of folds. dia. EXTERNAL ANATOMY OF INSECTS. 645 tyomis and immediate affinities the wing is nearly naked; but in Xylophagus, Beris, and the great majority of the Or- der, the membrane of the wings is thickly planted with in- humerable very minute bristles, not to be seen but under à powerful lens, often black, and seemingly crowning a little prominence, and giving the wing an appearance of the finest net-work. As to the clothing of the nervures, the costal, in Anthrax, Bombylius, &c., is often remark- ably bristly at the base, with hairs intermixed; in ŒÆstrus Ovis, in the inner margin or edge of this nervure, is a Single series of bristles, or rather short spines, like so Many black points; in Œ. Equi the whole costa is co- vered with short decumbent hairs or bristles; in Musca Pagana F., just at the apex of the costal arcolet, that ner- Yure is armed with a spur or diverging bristle larger than the rest, which is also to be found in many others ofthe Muscide, some of which have two and others more of these spurs. The little moth-like midges (Psychoda Latr., Hirtza F.) at first appear to have the whole sur- face of their wings covered with hairs; but upon a closer ®xamination it will be seen that they are planted in the nervures, from each of which they diverge, so as under a lens to give it a very elegant appearance*. This fly has its wings beautifully fringed with fine hairs, the third circumstance to be attended to under this head; in the Tipulidans, and many others of this Order, the apex and posterior margin are also finely fringed with short airs. Some Dipterous insects make a near approach to the Lepidoptera in the covering of their wings: in the “ommon gnat, when the wings are not rubbed, the ner- Yures are adorned by a double series of scales, and the 4 Pirate X. Fig. 13. 646 EXTERNAL ANATOMY OF INSECTS. marginal fringe also consists of them?; and ina Georgia genus, which appears in some degree to connect Culet with Anthrax &c., there are scales scattered upor the membrane as well as upon the nervures; besides, its ave tennze” and abdomen are also covered with them. The Order, the clothing of whose organs of flight excites the admiration of the most incurious beholdet j that to which the excursive butterfly belongs, the Lepr doptera. The gorgeous wings of these universal favour” ites, as well as those of the hawk-moths and moths, o¥f all their beauty, not to the substance of which they are composed, but to an infinite number of little plumes of scales so thickly planted in their upper and under su face, as in the great majority entirely to conceal that substance. Whether these are really most analogous W plumes or scales has been thought doubtful. De Geet is inclined to think, from their terminating at the lower end in little quills and other circumstances, that they resemble feathers as much as scales“; Reaumut 9” the contrary suspects that they come nearer to scales * Their substance, approaching to membrane, seems make further for the former opinion, and their shap© aps the indentations that often occur in their extremity; fur? ‘nish an additional argument for the latter. Their nun bers are infinite ; Leeuwenhoek found more than 4.00309 on the wings of the silk-worm moth (Bombyx Mori)" and in those of some of the larger moths and butterth® the number must greatly exceed this.. You will observ? @ Reaum. iv. t. xxxix. famil » A portion of the a” tenna of the insect here mentioned is figured Prase XU. Fre. =" ° De Geer i. 63—. € Reaum. i. 200. e Hoole’s Leeuwenhoek. i, 63—~. EXTERNAL ANATOMY OF INSECTS. 64.7 however that in man y Lepidoptera the wings are partially, and in some instances generally, transparent: thus in Hesperia Proteus, a butterfly before noticed for the long tail that distinguishes its secondary wings, there are many transparent spots; in Attacus Atlas, one of the largest of moths, and its affinities, there is as it were a window in each wing formed by a transparent triangular space ; in 4, Polyphemus, Paphia, &c., the pupil of the ocellus is transparent, which in the former is divided by a ner- vure. In several of the Heliconian butterflies, and in Zygæna F., &c., the greater part of both wings is trans- Parent, with scales only upon their nervures, round their Margin, or forming certain bands or spots upon them; in Parnassius Apollo, Mnemosyne, &c., the scales are so arranged as not wholly to cover the wings, which renders them semidiaphanous; and in some (Nudaria) the wings are intirely denuded. With regard to size, the scales vary often considerably in different tribes; in Heliconia they &ppear to be more minute than in the rest; and in Cas- ‘nia they are the largestand coarsest; the extremity of the wings of Lepidopterous insects in general is fringed with longer scales than their surfaces, and even thoseof the last in the same wing sometimes vary in magnitude. The little seeming tooth that projects from the middle of the pos- terior margin in the upper wings of Notodonta, a subgenus of Bombyx L., is merely produced by some longer di- verging hairs. The shape and figure also of scales are Very various—some being long and slender; others short and broad; some nearly round; others oval, ovate, or oblong; others spathulate; others panduriform or para- bolical ; some again almost square or rhomboidal ; many triangular ; some representing an isosceles triangle, and et oe SSS ee aed SS TT So appease = 648 EXTERNAL ANATOMY OF INSECTS, others an equilateral one; lastly, some are janceolate and others linear; again, some have a very short pedicle and others a very long one: with regard to their extremity; some are intire, without projecting points or incisions, while others are furnished with them: of these some ter- minate in a single long mucro, others have several shortet ones; some are armed with teeth, varying in number from two to thirteen in different species?.. Many other forms might be enumerated, but these are sufficient to give you a general notion of the infinite variety. of this part of the works of the Creator. I must next say i word or two upon their arrangement on the wing. Jn most instances this is in transverse lines, which som®- times vary a little from a rectilinear course, and the €% tremity of the scales of one row reposes on the base ° those of the succeeding one, so that in this respect their arrangement is like that of tiles in a roof: in some cas?’ it is not so regular: thus the minute scales on the wings of Parnassius Apollo, and others with subdiaph® nous wings, are arranged without order; in Pieris 2 other Diurnal Lepidoptera, and many of the Crepusc™” lar and Nocturnal, there appears to be a double laye p scales on both sides of the wing ; the under layer usually consisting of white ones. If you denude the wings of any butterfly, which you may easily do by scraping it lightly on both sides with a penknife, you will be amused t° trace the lines in which the scales were planted, consist ing of innumerable minute dots: the lines of the unde” side, in some cases, so cut those of the upper side, 825 by a De Geer has given 34 figures of different scales (i. t. iii. f- 28); and in PLATE XXII. Fre. 6. a—w. 22 others, collected from Reaumt” are given. EXTERNAL ANATOMY OF INSECTS, 649 their intersection to form lozenges. With regard to the Position of the scales on the wing, they usually lie flat, but sometimes their extremity is Matec : In the beau- tiful Argynnis Vanille a very singular appearance of nu- Merous transverse ridges is produced by the extremity of those scales that cover the longitudinal nervures of the primary wings, except at the base, being recurved, But though the general clothing of the wings of Le- pidoptera consists of these little scales, yet in some cases they are either replaced by airs or mixed with them. Thus, in the clear parts of the wings of Heliconians, 4t- taci, &c., short inconspicuous hairs are planted; in a large number of the Orders the upper side of the Anal Area of the secondary wings is hairy; in several Crepus- culars (Sphinx Phenix, &c.), where there is. a double layer as before mentioned, the upper one consists of dense hairs, except at the apex, and the lower one of scales; and in most of them the scales of the primary wings are piliform, and the secondary are covered by what ap- proach very near to real hairs; many of the Attdci- are similarly circumstanced: the four wings of 4. Cytherea are also covered externally with hair. 7. Before I conclude this long diatribe on the organs of flight of insects, I must not omit some notice of the infi- nite diversity of colours with which their wings are often Variegated and adorned by the Creator, who loves to delight us by the beauty, as well as to astonish and awe _ Us by the immensity and grandeur of his works. Though the wings in every Order exhibit instances of brilliant and beautiful colouring, yet those of the Lepidoptera in this respect infinitely excel them all, and to these, under this head, after noticing a few in the less privileged Or- 650 EXTERNAL ANATOMY OF INSECTS. ders, my observations will be confined. Although in the Coleoptera the wings are seldom distinguished by their splendour; yet those of some Cetoniade, as Cetonia africana, are extremely brilliant, and resemble those of many Xylocopæ in the lovely violet hue that adorns them: amongst the Orthoptera some Pterophylle, and in the Homopterous Hemiptera some Fulgora, emulate the Le- pidoptera in the ocelli that give a kind of life to these organs; and a vast number of the destructive tribe 0 locusts (Locusta Leach) are remarkable for the fine colours and gaiety of their wings?; in the Neuroptera DU merous Libelluline emulate the Heliconian butterflies bY their maculation; and in the genus Ascalaphus, which represents the Lepidoptera by its clubbed antennæ €, many also have the resemblance increased by the painting ° their wings, so that some Entomologists have actually considered some of them as belonging to that Order‘; the wings of the Xylocope, before alluded to, sometim® ° add to the deep tints of the violet-—which also prevail i" the wings of several Diptera—towards their extremity ne Sess eRe ance cn Bn eS a Fale Ban Oe me eS TEREE E ie AAT E ae rere DE ae ere AE BEBA DE EE DEA meme EE EIEEE te Pip Seas See a ee ee Se the most brilliant metallic green or copper varying, “ As the site varies in the gazer’s hand,” and even those wings that consist of clear colourless membrane are often rendered extremely beautiful from the reflection of the prismatic colours. I should undertake #” endless task did Lattempt to specify all the modes of mark- ing, clouding, and spotting, that variegate a wing, and all the shades of colour that paint it, amongst the Lepidopt®- / 2 Stoll Sauterelles à Sabre. Pterophylla ocellata t, i. ii., Cigales, Ful- gora laternaria t. i. f. i, and F. serrata t. xxix. J-170. -~ b Ibid. Sauter. de Passage, Locusta Dux t.i. 5. L. carinata t. V- b. F-16. L. cristata t.ix. b. f. 30. &e. &e. © Phare XXV. Fie. 30- 4 Scopoli, Hubner. EXTERNAL ANATOMY OF INSECTS. 651 rous tribes; I shall therefore confine myself to a few of the principal, especially those that distinguish particular tribes and families. Of whole coloured wings—I know none that dazzle the eye of the beholder so much as the upper sur- face of those of Morpho Menelaus and Telemachus: Linné justly observes that there is scarcely any thing in nature that for brightness and splendour can be paralleled with this colour; it is a kind of rich ultramarine that vies with the deepest and purest azure of the sky; and what must cause a striking contrast in flight, the prone surface of the wings is as dull and dark as the supine is brilliant, so that one can conceive this animal to appear like a planet in full radiance, and under eclipse, as its wings open and shut in the blaze of a tropical sun: another butterfly, Papilio Ulysses, by its radiating cerulean disk, ` surrounded on every side by a margin intensely black, gives the idea of light first emerging from primeval ob- scurity; it was probably this idea of light shining in dark- ness that induced Linné to give it the name of the wisest of the Greeks in a dark and barbarous age. I know no Insect upon which the sight rests with such untired plea- sure, as upon the lovely butterfly that bears the name of the unhappy Trojan king (P. Priamus); the contrast of the rich green and black of the velvet of its wings with each other, and with the orange of its abdomen, is beyond expression regal and magnificent. But peculiar beauties of colour sometimes distinguish whole ¢r7zdes as well as individuals. ‘What can be more lovely than that tribe of little butterflies that flit around us every where in our summer rambles, which are called blues, and which exhibit the various tints of the sky? Lycæna Adonis of this tribe scarcely yields to any exotic butterfly in the 652 EXTERNAL ANATOMY OF INSECTS. celestial purity of its azure wings: our native coppers also, Lycena dispar*, Virgauree, &c., are remarkable fot the fulgid colour of these organs; in Argynnis the uppet side of their wings is tawny, spotted with black, while the under side of the secondary ones is very often adorned by the appearance of silver spots. How this remarkable effect of metallic lustre, so often reflected by spots in the wings of butterflies, is produced, seems not to have occupied the attention of Entomologists. M. Audebert is of op nion that the similar lustre of the plumes of the humming birds ( Trochilus) is owing to their density, to the polish of their surface, and to the great number of little minute concave mirrors which are observable on their little beards?. But these observations will not apply to the scales of the wings of butterflies, which are always very thin and generally very flat: in some instances, as i! Morpho Menelaus, there appears more than one very slight channel upon a scale; but this takes place also in others that reflect no lustre. Their metallic hues must there- fore principally be occasioned by the high polish of theif surface and the richness of their tints. It is the purity of the white, in conjunction with their shining surface contrasted with the dull opaque colour of the under side of the secondary wings, that causes the spots that decorate those of the Fritillaries (Argynnis) to emulate the lustre of silver. In Papilio the Trojans are distinguished by the black wings with sanguine spots, and the Greeks by the same with yellow spots; but these have proved in some instances only sexual distinctions®. In the Danat candidi L. the colour of the tribe may be described aS @ Prate I. Fic. 1. > N. Dict. d Hist. Nat. viii. 257- ° See above, p. 303. EXTERNAL ANATOMY OF INSECTS. 653 Sacred to the day, since every shade, from white or the Palest yellow to full orange, is exhibited by them. The yellows prevail also in those Noctuc, the trivial names of Which Linné made to end in ago, as N. Fulvago, Citrago, Xc. I must not conclude this part of my subject with- out noticing one of the most striking ornaments of the Wings of Lepidoptera, the many-coloured eyes which de- Corate so large a number of them. Some few birds, as the Peacock and Argus Pheasant, have been decked by. their Crearor very conspicuously with this almost | dazzling glory; but in the insects just named it meets us every where. Some, as one of our most beautiful but- terflies, Vanessa Io*, have them both on the primary and Secondary wings; others, as Noctua Bubo’, only on the Primary; others again, as Smerinthus ocellata c, only on the secondary: in some also they are on both sides of the Wing, as in Hipparchia Aigeria*, and in others only on the upper side, as in Vanessa Io; in others again only on the under side, as in Morpho Teucer®: in some likewise they are very large, as in the secondary wings of the same butterfly: and in others very small, as in those in the Wings of the blues (Lycena). Once more, in some they Consist only of ¿rís and pupil, as in Hipparchia Semele, and in others of many concentric circles besides; as in Morpho Teucer, &c. ` v. Legs'. We are next to consider those organs of Motion affixed to the trunk, by which insects transport themselves from one place to another on the earth or in * Sepp. L i. £ vii. f. 6. t Ræmer Genera t. xxii, f. 2. * Sepp. T. iii. 4. ii. f 7. è Thid, ict vi. f 7. ° Reemer ubi supr. t. xiv. f. 1. êE Prates f°, 7, dt, 654: EXTERNAL ANATOMY OF INSECTS. the water, and by which also they perform various op€- rations connected with their economy*. In treating of them we should consider their number ; kind; substance; articulation with the trunk ; position; proportions; cloth- ing; composition; folding; and motions. 1. Number. Having before very fully explained to yo" the number and kind of the legs of insects in their p°- paratory states”, I shall now confine myself to the co? sideration of these organs in their perfect or last state beginning with their number. Insects, properly so call- ed, as I formerly obsérveđ®, in this state, including thé anterior pair or arms, have only six legs, none exceeding or falling short of this number; but in several of thé Diurnal Lepidoptera (Vanessa, &é.) the anterior pair are spurious, or at least not used as legs, the tarsi having neither joints nor claws‘; this in some cases is said to P? only a sexual distinction®. In Onitis, Phaneus, and som other Scarabeide M‘L., the arm has either none or a Sp" rious tarsus or manus‘; which in the first of these gener? is also a sexual character. From both these instance we see that walking is only a secondary use of fore- legs in the insect tribes. Besides insects proper, a whole tribe of mites (Caris Latr., Leptus Latr., Astoma Latt» Ocypete Leach) have only six legs; the rest, and the Arachnida in general, have eight; in the Myriapot Pollyxenus has twelve pairs; Scutigera has fifteen: the terrestrial Glomerides (G. Armadillo, &c.) sixteen; W4 the oceanic (G. ovalis) twenty; the oriental Scolopendr@ Leach, twenty-one; Polydesmus has usually about thirty t See above, p. 546--. b Ibid. 131. e VoL. IT. p. 307. t De Geer i t.xx. fe `* Règne Animal, iii, 546, £ Prare XXVI Fro! 44,4? EXTERNAL ANATOMY OF INSECTS. 665 Pairs; Craspedosoma, fifty; Geophilus electricus at least sixty; in Tulus terrestris there are more than seventy ; in T. sabulosus nearly one hundred; in I. fuscus; 124; and in T. maximus 134 pairs or 268 single legs. But with respect to the Geophili, Iuli, &c., it is to be observed, that the Number of pairs varies in different individuals; and the Circumstance that has been before mentioned?, that these animals keep acquiring legs in their progress to the pet- fect state, instead of losing them, renders it difficult to ascertain what is the natural number of pairs in any / Species. 2. Kinds. Upon a former occasion I gave you a suff- ciently full account of the kinds of legs?, and I have alsé assigned my reasons for giving a different denomina- tion to the anterior legs under certain circumstances?; I ‘Shall not therefore enlarge further upon this head. 3. Substance. The substance of the legs is generally tegulated more or less by that of the rest of the body, only in soft-bodied insects they seem usually more firm and unbending. Each joint is a tube, including the mov- ing muscles, nerves, and air vessels. 4. Articulation with the Trunk. M. Cuvier has ob- Served that the hip (coxa), which is the joint that unites the leg with the body, rather inosculates, in its acetabu= lum, than articulates in any precise manner‘; but this observation, though true of a great many, will not apply Universally, for the legs of Orthopterous insects, and of Most of the subsequent Orders, are suspended rather than Inosculating. Even in many Coleoptera a difference is ob: Servable in this respect. I have before mentioned that a VoL. I. p. 312, 363, 365. b See above, p. 546—. © Anatom, Compar. i. 453. 656 EXTERNAL ANATOMY OF INSECTS. whatare called the puncta ordinaria, which distinguish the sides of the prothorax of many Scarabeide and Geotrt- pide, form a base for an elevation of the interior surface with which the extremity of the base of the clavicle, which plunges deep into the breast, ginglymates °; thi structure may also be found in other Lamellicorns, as the stag-beetle (Lucanus) and Dynastes, that have not those excavations; im these last it is an elevated ridge forming a segment of a circle with, it should seem, 4 por terior channel, receiving a corresponding cavity and p? tuberance of the clavicle. With regard to the mid-legs in Copris, the cova is emboxed in a nearly longitudin? cavity of the medipectus, and the coxa of the hind-leg & teriorly is suspended to a transverse cavity of the post pectus, but posteriorly it is received by a cavity of the first segment of the abdomen; so that it may be regard- ed as suspended anteriorly, and inosculating posteriorly In some tribes of this Order, as the Weevils (Curculio L.) and Capricorns (Cerambyx), the coxee of the four an- terior legs are subglobose® and extremely lubricous, and are received each by a socket that fits it, and is equally lubricous. In the bottom of this externally, and in thé head of the coxa, is an orifice for the transmission ° muscles, nerves, and bronchi; but the coxa is sU& pended by ligament in the socket. This structure 4P proaches as near the ball and socket as the nature of the insect skeleton will permit; the high polish of the. arti- culations acts the part of synovia, and the motion 1s in some degree rotatory or versatile, whereas in Copris, Xe» lately mentioned, it seems to be more limited, and is pr” 2 See above, p. 308. > Prarr XXVII Fre. 18,19 EXTERNAL ANATOMY OF INSECTS. 657 bably, at least in the mid- and hind-legs, only in two di- rections; in the middle pair, probably, from the core being in a position parallel with the breast, opposite to that of the hind pair. In Dytiscus L., Carabus L., and Some other beetles, the coxæ, especially the posterior pair, appear to be fixed and incapable of motion. In many insects these coxæ seem to belong as much to the abdo- Men as to the trunk. We have just seen this to be the Case in Copris, &c.; and in the Lepidoptera, if the former be separated from the latter, the legs will be detached with it. 4. Location. We are now to consider the location and Position of the legs, both in general and with respect to each other. And first, as has been before stated, we may Observe that, in the hexapods with wings, the arms belong to the manitrunk, and are attached to the antepectus on fach side the prosternum; and the two pair of legs to the alitrunk, the mid-legs being attached to the medipec- tus, between the scapularia and mesosternum; and the hind-legs to the postpectus, between the parapleura and the posternum; and further, that the arms are opposed to the prothorax: the mid-legs to the mesothorax and the Primary organs of flight; and the Aind-legs to the me- ‘athorax and the secondary organs of flight; though in Some cases the wings appear to be behind the legs and in others before them: thus, in Panorpa, the former are Nearer the head than the latter; but in the Libellulina the reverse of this takes place, the legs being much nearer the head than the wings: in both cases, however, the Scapularia and parapleure run from the legs to the ' wings, but in an oblique direction; and in Panorpa these Pieces assume the appearance of articulations of the legs. VOL, HI, aoe 658 EXTERNAL ANATOMY OF INSECTS. In most of the apterous hexapods they appear to be attached laterally between the thorax and the pectus* ; but in the flea (Pulex) they are ventral. In this tribe the arms are usually stated to be inserted in the head”: but I once succeeded in separating the head of a flea from the trunk, and these organs remained attached to the latter Astothe Octopods and Arachnida, in the mites (Acarus L.) they are lateral, and in their analogues, the spidets (Aranea L.), they emerge between the thorax and the breast, which last they nearly surround; in the Phala™ gid@ the bases of the coxæ approach near to each othe! being separated only by a narrow sternum; in their aP“ tagonists, Chelifer and Scorpio, they apply to each othe the anterior ones acting as mazillz. In the myriapods the legs of the Chilopoda Latr., and some Chilognathó as Glomeris, are inserted laterally, a single pair in a seg ment; but in Julus L. their attachment is ventral, the coxæ seem to spring from a common base, and there are two pair to each segment‘, except the three first, which bear each a single pair. . I shall next consider how the legs are located with 1° spect to each other. ‘Torender this clear to you I shal represent each of the variations, which amount in all t° a Mr. Montague describes the legs of Nycteribia, as dorsal (Zant Trans. xi. 13); but Dr. Leach calls them lateral (Samouelle, 303). > N. Dict, d Hist. Nat. xxviii. 247. © Prane XXII. Fis-* à Prare XXVII. Fre. 58. M. Savigny affirms that these insect? cannot have, and really have not, but one pair to each segment ; omy that the segments are alternately membranous and shelly, and t a the former are concealed under the latter (Anim. sans Vertebr. 1. 1.447" but, pace tanti viri, I cannot discover that any suture separates t on portions from each other: so that, admitting his theory, they mu’ be regarded as two segments soldered together. EXTERNAL ANATOMY OF INSECTS. 659 twelve in the hexapods that have fallen under my notice, by six dots. 1. : In this arrangement the legs are all planted Near to each other, there being little or no interval be- tween the pairs, and between de legs of each pair.. It is exemplified in the Lepidoptera, Blatta, and many Diptera. 2. :; Similar to the preceding, but the anterior pair are distant from the two posterior ; exemplified in the bees (Apis) and most Hymenoptera; Chironomus; Scu- tellera; Pachysoma K.? 3. i Like the last, but the posterior pair is distant from the two anterior. HLixamples: Silpha, Necrophorus, Telephorus, &c. 4, .*, Similar to the last, but the legs of the posterior pair are more distant from each other than the four an- terior. Hx. Curculio L. 5. ~ The legs of each pair near each other, but the pairs distant. Ex. Gibbium. 6. :: Both the legs ofeach pair and the pairs distant. Ex. Blaps, &c. 7... Anterior pair distant from the two posterior, and the legs of the middle pair rather more distant from each other than those of the other pairs. Lx. Sca- rabæus M°L. 8. "°. Like the preceding, only the legs of the mid- dle pair are at a much greater distance from each other. Ex. Copris MeL 9. :: Legs of the two posterior pairs distant. Zz. Hister, Scaphidium. * It is by this arrangement of the legs that Pachysoma is princi- Pally distinguished, as a subgenus, from Scarabæus M'L. ee 660 EXTERNAL ANATOMY OF INSECTS. 10. = Like the preceding, but the posterior legs more distant than those of the middle pair. Ex. Lyg@ 11. <^ Like the last, but the legs of the anterior pair also distant. Lz. Velia. 12. <". The arms distant, intermediate legs mo stant, posterior legs close together. Ex. Byrrhus L. 5. Proportions. In general the legs of some insects as in Phalat- those &e- Te di- are disproportionally long and slender, gium Opilio and some species of Gonyleptes*: of others are disproportionally short, as in Elater, With regard to their relative proportions, the most ge neral rule is, in Hexapods, that the anterior pair sha be the shortest and most slender, and the posterior the longest and thickest; but there are many exceptions * - thus, in Macropus longimanus, Clytra longimana, XC» ip the male the arms are the longest; again, a thing t very rarely occurs, in the same sex of Podalirius retust hat the intermediate legs are the longest?; but in Rhzna bar in Sa birostris and many weevils they are the shortest : perda hirtipes Oliv.* the hind-legs are disproportional! long: with regard to thickness, they arein general extreme ly slender in Cicindela, and in the Scaraberde very thick. In Goliathus Cacicus the arms are more robust than th? four legst; in Gyrinus the latter are more dilated than the former; in many Rutelide, and particularly in the cele “brated Kanguroo beetle (Scarabeus Macropus Franc.) th? hind-legs are much the thickest; in a new genus of wee vils from Brazil (Plectropus K.), the intermediate pair are more slender than either the arms or the posterior par a See above, p. 37- b Monogr. Ap. Angl. i. t. xi. Apis* *, d. 2. æ. f. 18. ii. 296—- © Oliv. Ins, 68. t. i. f. 8. - a Thid. n. 6. t. iv. f- 2 EXTERNAL ANATOMY OF INSECTS. 661 6. Clothing. ‘The hairs on the legs of insects, though at first sight they may seem unimportant, in many cases are of great use to them, both in their ordinary avocations and motions: but as most of these were sufficiently no ticed when I treated of the sexes of insects 2, I shall not here repeat my observations, but confine myself to cases hot then adverted to. Some insects have all their legs very hairy, as many spiders, the diamond beetle (Entimus im- Perzalis), or at least a species very near it and common in Brazil’, &c.: in others they are nearly naked, as in the stag-beetle. In the Crepuscular Lepidoptera (Sphinx L.) and some of the Nocturnal ones (Bombyx L.) the thighs are much more hairy than the rest of the legs: and in Lucanus, Geotrupes, and many other Lamellicorns, _&c., the anterior ones have a yellow or golden spot at their base, composed of decumbent hairs, which prevent them from suffering by the violent friction to which they are exposed in burrowing. In most Petalocerous beetles the tibiæ are set with scattered bristles, and sometimes the thighs. The Tiger beetles (Cicindela) are similarly circumstanced: but the bristles, which are white, are ge- Nerally arranged in rows. In Dytiscus, Hydrophilus, &c., the four posterior tarsi; and in Notonecta the posterior Pair, and also the tibize—are fringed on each side with a dense series of hairs, which structure assists them in Swimming °. The tarsi, especially the anterior pair, in a Certain family of Lamia F. (L. papulosa, &c.‘), are simi- larly fringed, only the hairs curl inwards; and the hand * See above, p. 305—. > This variety appears to differ Very little from the Curculio imperialis of Fabricius and Olivier, ex- “ept in the remarkable hairiness of its legs. e Vou. II. p. 563. * Oliv. Ins. n. 67. t. xx. f. 156. eg a ne ee See one OT 662 EXTERNAL ANATOMY OF INSECTS. in Sphex and Ammophila, but not in Pelopæus and Chlo- rion, is fringed externally with long bristles. 7. Composition. With regard to their compositions both arms and legs generally consist of five pieces, which Entomologists have denominated—the cova or hip—the trochanter—the femur or thigh—the tibia or shank—and the tarsus or foot. Where the structure and use of the fore-leg is different from that of the four hind-legs, I pr pose calling these pieces by names corresponding with those which anatomists have.appropriated to the arm in the higher vertebrate animals: thus, as you will see ™ the table, 1 call the whole fore-leg the brachium or arm 5 and the coga becomes the clavicula or collar-bone; th® trochanter, the scapula or shoulder-blade; the femur, the humerus or shoulder; the tibia, the cubitus or arm; the - tarsus, the manus or hand. But let me not lead you to suppose that the pieces, either in the arms or legs of in- sects, which are there named after certain others in verte- brate animals, precisely correspond with them—by po means—since that is a very doubtful point; and some © them, as the trochanter, clearly do not. Many gentleme? skilled in anatomy, as I have before observed, hav? thought that what is regarded as the coza in insects really represents the femur: but there are considerable dificul- ties in the way of this supposition, several of which I ther stated. I shall not however enter further into the s19- ject, and take the above names; since this application “ them is so general and so well understood, except with à See above p. 591. Some physiologists have been of opinio” that in birds, what is called the thigh should properly be denominate the tibia, and that this last is really the tarsus. Illiger, Terminolog 184. § 185. n, 1246, EXTERNAL ANATOMY OF INSECTS. 663 regard to the fore-leg, under certain circumstances, as I find them. I shall now consider them in the order in which I have named them, | a. Coxa or Clavicula*. The coxa, ìs the joint that connects the leg with the trunk of the insect. With re- gard to their shape, the most general form of the four anterior is more or less that of a truncated cone: in the Staphylinide, however, they tend to a pyramidal or four- sided figure; as do the whole six in the Trichoptera: in numbers of the weevils and capricorns they are subglo- bose; in the Lamellicorns they are mostly oblong, and hot prominent: the posterior pair in the Coleoptera are generally flat and placed in a transverse position, and more or less oblong and quadrangular : in Elater, &c., they are Cuneiform : in Haliplus Latr. they are dilated, and cover the thigh °: in Buprestis, Copris, &c., they have a cavity that partly receives it: the corresponding part, the cla- vicle, in the arm of Gryllotalpa, is very large and re- markable; viewed underneath it is triangular, and trifid where the trochanter articulates with it: in that of Me- gachile Willughbiella the clavicle is armed with a spine‘. As to their proportions, the most general law seems to be, that theanterior pair shall bethe shortest and smallest, and the posterior the longest and largest. In some instances, as in Buprestis, the two anterior pair are nearly equal ; in others (Mantis, Eurhinus K.), the anterior are the longest, in the former as long as the thigh, and the four Posterior the shortest: in the Trichoptera, Lepidoptera, &c., all are nearly equal; in Mantis the two posterior, and in Phengodes the intermediate pair are the largest; but * Prares XIV. XV. XXVII. p. b Prare XV. Fre. 1. p”, r”. © Prare XAVI Fic. 27. 664 EXTERNAL ANATOMY OF INSECTS. in Necrophorus they are the smallest :—though almost universally without articulations, in Galeodes the clavicle | consists of żwo and the coxa of three?. b. Trochanter or Scapula®, This is the second joint of the leg: and if the coxa is regarded as the analogue of the thigh in vertebrate animals, this should seem to 7& present the patella or rotula, vulgarly called the kne® pan. Latreille and Dr. Virey consider this articula- tion as merely a joint of the coxa t; but if closely e3% mined, especially in Coleopterous insects, you will fin it so fixed to the thigh as scarcely to have separate MO tion from it, and in many cases it seems to be merely its fulcrum; but [am not aware that any instance occurs in which it has not motion separate from that of the forme! joint. As to its articulation with the cora, —in the Cok- optera it appears to be of a mixed kind; for it inos¢™” lates in that joint, is suspended by ligament to its 0" fice, and its protuberances are received by correspond- ing cavities in it; and its cavities receive protuberance” which belongs to a ginglymous articulation. I have observed two variations in this Order, in one of which the motion of the thigh and trochanter is only in we di- rections, and in the other it is nearly versatile or rotato- ry. The Lamellicorns afford an example of the first, 2” the Rhyncophorous beetles or weevils of the second. you extract from the coxa the thigh with the trochantet of the larger species of Dynastes M° L., you will find that the head of the latter is divided into two obtuse incur” 2 L. Dufour, Descr. des six Arachn. &c.: Annales Generales, KC 1820. 19. £. Ixix. f. 7. d. > Prare XIV. XV. XXVII. g” © N. Dict. d’ Hist. Nat. xvi. 195. xxvi. 157. EXTERNAL ANATOMY OF INSECTS. 665 ing lobes or condyles; that on the inner side being the Smallest and shortest, and constricted just below its apex; and that under this is a shallow or glenoid cavity, ter- minating posteriorly in a lubricous flat curvilinear ridge. If you next examine the trochanter in articulation with the coxa, you will perceive that the head of the former inosculates in it, that the lower condyle is received by a sinus of the coxa, which also has a lubricous very shallow cavity corresponding with the ridge, in which it turns ; and in the head of the coxa, on the lower side, is an ex- ternal condyle, which is received by a sinus common to both, of the head of the thigh and of the exterior side of the trochanter*, in which it likewise turns: this last con- dyle has also an internal protuberance, which appears to ginglymate with a cavity of the trochanter: from this structure the Jeg is limited chiefly to a motion up and down upon two pivots, or to fold and extend itself. You will find an articulation very near this, but on a smaller scale, in the stag-beetle. In the other kind of articula- tion, which admits of freer motion, the head of the tro- chanter is prolonged, and the process terminates in a short interior condyle, which appears to work in a cor- responding cavity of the interior of the coxa; and the base of the process is encompassed by a ridge with a cavity behind. it, which is received by another of the lower part of that piece, and admits a corresponding ridge—a structure that allows a rotatory motion. In the hind-legs of this tribe the motion is chiefly limited to folding and extending; in Carabus, &c., also the head of the trochanter is nearly hemispherical, and the articula- a Prare XXVII Fie. 12, b. = = iene Sees SE E A A a S Save oe >: ore eee re Sens E q i E it | i 666 EXTERNAL ANATOMY OF INSECTS. tion approaches ball and socket. In most of the other Orders, the Hymenoptera excepted, there is little or BO inosculation, the trochanter being simply suspended by ligament to the coxa as well as to the thigh; its connec tion with the latter is similar in Coleoptera; but in C% cindela, &c., it inosculates in it. The part we are con- sidering varies in its position with respect to the thigh : in the hind-legs of Carabus, &c., it forms a lateral ful- crum on the inner side of that part, and does not inte! vene between its base and the coxa; the muscles fro™ the latter entering the former, not at the bottom of the base, but at its side: but in the four anterior legs it forms their base, as it does in all the legs in Apion, and in all the Orders except the Coleoptera, cutting them €97 tirely off from contact with the coxa: in the Lamellicor"™ they cut off part of the base obliquely, but so as to pe” mit their coming in contact with the condyle of the coa as before mentioned. In the Ichneumonide and some other Hymenoptera the trochanter appears to consist 9 żwo joints particularly visible in the posterior legs*. As to size in general,—the part in question is smaller than the coxa; but in Notonecta it is larger, and in the dog-tick (Ixodes Ricinus) longer than that joint. It ex- hibits few variations in its shape or appendages worthy of particular notice. In general, in the Coleoptera it is triangular or trigonal; but in Carabus L., in the hind- leg it is oblong or rather kidney-shaped; in that of Bs crophorus” it terminates in one or two teeth or spines varying in length in the different species: in the othet Orders it is not remarkable in this respect. a Prats XXVIL Fie, 20. 7’. » Ibid. Fre. 28. EXTERNAL ANATOMY OF INSECTS. 667 c. Femur or Humerus*. The femur or thigh is the third, and usually the largest and most conspicuous joint of the leg. In the hypothesis before alluded to? it is Considered as the analogue of the tibia of vertebrate animals. With regard to the articulation of this part with the trochanter, it has been sufficiently explained ‘under that head, and that with the ¢zbza I shall treat of when I come to that joint. Asto the szze of the thighs, and their relative proportions to each other and to the remaining joints of the leg, the most general law is, that the anterior pair shall be the shortest and smallest, and the posterior the longest and largest. With respect to the remaining articulations, most commonly thezhighis longer and larger than the ¢zbza, and the fzbza than the tarsus. But there are numerous exceptions to both these rules. With respect to the first, we may begin by observing that the increase of the magnitude of the thigh, from the an- terior to the posterior pair, is usually gradual: but in mahy jumping insects, and likewise many that do not jump, the posterior pair are suddenly and dispropor- tionally thicker than the rest®. Again, in many insects the anterior pair are the longest and thickest, as in Mas cropus longimanus, Bibio, Nabis, &c.: in others, the zn- termediate exceed the rest in magnitude, as in Onitis Aygulus, cupreus ; Sicus flavipes, &e.; in many Lamelli- corns all the thighs are incrassated and nearly equal in size: but in some, as Ryssonotus nebulosus M°L.4, the intermediate pair are rather smaller than the rest. With respect to the second rule—in some, as in the male of Macropus longimanus, the ‘anterior tibia, though more e Phare XIV. AV. XXVII 7. > See above, p. 591, 662. e Vor, IH. p. 314—. å Linn, Trans. xi, t. xxi. f. 12. 668 EXTERNAL ANATOMY OF INSECTS. slender, is longer than the thigh ; in Hololepta maxil- losa it is longer and more dilated; in Lamia marmorata, or one related to it from Brazil, the intermediate pair are longer; in Ateuchus gibbus and others of that tribe thé posterior thighs are smaller than the żibiæ: and, to men- tion no-more; in Callichroma latipes the posterior tibia is wider than the part last named. Again, the tarsi are as long as either ¢ibéa or thigh in many of the larger DY- nastide, as Megasoma Acteéon, &c.; longer than either in Melolontha subspinosa F.; and in Tiphia, Scolia and affinities, often as long, or longer than both together. As to shape, —the thigh, especially in the fore-leg, varies considerably : most generally it is flat, linear, and a little thicker where it is united to the zdbia, on the oute! - side convex, and concave next the body ; but in many it is gradually thicker from the base to the apex: in some Cerambyces (C. thoracicus) it is clavate; in others of this genus and Molorchus they may be called capitate; iP Pterostichus they are rather lanceolate; in Onitis Sphin# the humerus is triangular, and the intermediate thigh rhomboidal; in Bruchus Bactris it is bent like a bow; and in some Brazilian Haltice it is nearly semicircular. The humerus in Phasma is attenuated at the base; I” Empusa gongyloides it is at first ovato-lanceolate, and tet” minates below in a kind of footstalk*; in Phasma fie belliforme it is dolabriform; in Mantis often semioval or semielliptical, and thickest at the inner edge, which affords space for two rows of spines-with which it ÍS planted. In Phyllium siccifolium all the thighs are fur- nished on both sides with a foliaceous appendage nearly à Stoll Spectres t. xvi. f. 58, 59. b Ibid. ¢. xviii. f. 65. EXTERNAL ANATOMY OF INSECTS. 669 from base to apex?: ina species of Empusa (E. macro- ptera), the four posterior ones are so distinguished only on their posterior side’: others of this last genus, as E. gongyloides, have an alary appendage on both sides at the apex of these thighs*; and another family, as E. pauperata, have only one on the posterior side‘, The thighs of no insect are more remarkable for their elegant shape,—tapering gradually from the base to the apex, where they swell again into a kind of knee,—than the pos- | terior ones of the locusts (Locusta Leach); each side of these thighs is strengthened with three longitudinal nearly parallel ridges, and the upper and under sides are adorn- ed by a double series, in some coalescing as they ap- proach the tibia, of oblique quadrangular elevations re- sembling scales °. I shall next say a few words upon the spines and other processes which arm the thigh. Those moveable ones of Mantis which help to form a fearful instrument of de- struction, have just been mentioned, and similar ones, but less conspicuous, arm the intermediate thighs of Sicus fla- vipes: other appendages of this kind are for a less de- structive purpose—to keep the tibia when folded in its place. This seems to be the use of the serratures and spine that arm the thigh of Bruchus Bactris, or the Hymenopterous genera Leucospis, Chalcis, &e.; in Onitzs Aygulus a short filiform horn arms the humerus, and a longer crooked one that of many species of Scaurus f. In many Stenocor? the thighs terminate in two spines, and * Stoll Spectres t. vii. f. 25. bd Ibid. t. viii. f. 30. © Ibid. ubi supr. a Thid. t. x. f 40. © Ptarr XIV. Fre. 5. This appearance of scales on the thighs is principally confined to this tribe. £ Prarr XXVU. Fie. 23. 670 EXTERNAL ANATOMY OF INSECTS. in Gonyleptes K. the posterior ones are armed internally with very strong ones; with which, as the legs converge at their knee*, they may probably detain their prey- The knee-pan (Gonytheca) of the thigh, or the cavity at its end, which receives the head of the #ibia, is very conspi- cuous in the weevils; but in no insects more than in Locusta*, in which tribe it deserves your particular at- tention. | d. Tibia or Cubitus*. The tibia or shank is the fourth joint of the leg, which according to the hypothesis lately alluded to is the analogue, in the anterior leg of the cat” pus or carpal bones, and in the four posterior ones of the tarsus or tarsal bones of vertebrate animals. This may be called the most conspicuous of the articulations of thé leg; for though it is generally more slender and ofte? shorter than the thigh, it falls more under the eye of the observer, that joint being more or less concealed by thé body: it consists in general of a single joint; but 1 the Araneide and Phalangide it has an accessory 00 often incrassated at its base, which I have named thé Epicnemis 4. | With respect to the articulation of the tibia with the thigh—we may observe that in general it is by means of three processes or condyles, two lateral and one interm™ diate, of the head of the former joint®: the lateral on are usually received by a cavity or sinus of the gonythec@ * Linn. Trans. xii. t. xxii. f. 16. b Pilare XIV. Frc- 5, and XXVII. Fre. 15. 7”. © Phares XIV. XV. XXVII. s” a Prate XXVII. Fie. 21. s”. M. Savigny (Anim. sans Vertebr. ™ i. 46. Note b.) seems to think that this structure obtains in all his Apiropods ; viz. the Octopod Aptera, Arachnida, and Myriapoda: but it seems to me evident only in the two tribes mentioned in the tex * Prater XXVII Fic: 6, 16,17. £”. H EXTERNAL ANATOMY OF INSECTS. 671 of the thigh”; and upon these the ¢ibia turns, with a Semirotatory motion up and down as upon a pairof pivots: at the same time the mola or head of the latter joint, Which has often a flexure so as to form an elbow with the rest of it, inosculates in the gonytheca, and is also sus- Pended by ligament to the orifice through which the muscles, nerves, and bronchize are transmitted: so that in fact the articulation, strictly speaking, belongs exclu- Sively to none of the kinds observable in vertebrate ani- mals, but partakes of several, and may properly be de- Nominated a mixed articulation,—a term applicable in nu- merous instances also to the other articulations of the legs of insects. In the different Orders some variations in this respect take place,—I will notice some of the most re- markable. In no Coleopterous insects is the structure More distinctly visible than in the larger Lamellicorns. In Copris bucephalus, for instance, if you divide the thigh longitudinally, you will find on each side, at the head, that it is farnished with a nearly hemispherical protube- rance, perforated in the centre for the transmission of muscles, and surrounded externally by aridge, leaving a semicircular cavity between them: if you next examine the tibia, after having extracted it, you will find on each Side, at the base, a cavity corresponding with the protu- berance of the thigh which it receives, having likewise a central orifice, and surrounded by a semicircular ridge Corresponding with the cavity in the thigh in which it acts: below this ridge another cavity, forming a small Segment of a circle, receives the ridge of the thigh®. You will observe that the ridge of the żibia represents the * Prate XXVII. Fie. 15, 7”. b Thid. Bie 11, 7”. Abid. Fre. IO rS 672 EXTERNAL ANATOMY OF INSECTS. lateral condyle lately noticed: in the Dynastidæ this 15 more prominent, and often forms a smaller segment of a circle. In these also the protuberance of the thigh 15 more minute, and its ridge is received by a cavity of the tibia nearly semicircular?; in Geotrupes Latr. the articu- lation is not very different, though on a reduced scale; Calandra Palmarum the lateral condyles of the tibiæ at? flatter and broader »; and the articulatiou not being quite so complex, this joint is kept steady by an intermediate process observable in the gonytheca®. From the above description it appears that the dislocation of the ¢ibz@ 1° effectually prevented in the Lamellicorns by the protube- rance and ridge of the thigh working n their correspond- ing cavities, while the condyle of that part turns with # rotatory motion in the cavity of the thigh. In the Or- thoptera Order the tibia is suspended by a ligament, in the gonytheca the lateral condyles, which are very pr minent, working in a sinus of that part‘. The subse quent Orders exhibit no very striking variations fro™ these types of articulation, I shall therefore not detain you longer upon this head. With regard to the proportions and magnitude of the joint we are considering,—the most general law is, that the anterior pair should be shorter and more slender tha? the intermediate ; and the intermediate than the posterior; and that all the ¢7i¢ should be shorter and more slende” _* Prare XXVII. Fic. 8. Thigh. a. Protuberance. b. Semicir cular cavity. c. Ridge. Fic.9. Tibia. a. Central cavity. b. Ridge. c. Exte- rior cavity. > Ibid. Fic. 6. a. © Ibid. Fie. 7. a (Ibid. Fic. 15. Thigh of Locusta Leach, a. Sinus in which the co- dyle of the tibia works. Fre. 16. Tibia of Do. aa. Lateral condyle b. Intermediate one. EXTERNAL ANATOMY OF INSEC'ts. 673 than the thighs, and longer and thicker than the tarsi Various exceptions, however, to this rule in all these cases might be produced ; but I shall only observe that in all those insects in which the fore-legs are calculated for dig- ging or seizing their prey, as in the Petalocerous beetles, the Gryllotalpa, Mantis, &c., this joint of the leg is Usually much enlarged and more conspicuous than the others. | As to its figure and shape—most commonly the zibia Srows thicker from the base to the apex, as in. the majority of Coleoptera, Hymenoptera, &c.; in the Orthoptera, Neu- řoptera, &c., it is generally equally thick every where. Another peculiarity relating to this head observable in it, is its tendency to a trigonal figure: this, however, though very general, is not universal ;— thus, in some Orthoptera, as Pterophylla K., its horizontal section is quadrangular; in others, as Locusta Leach and many other insects, it is nearly a circle; in some scorpions it is almost a hexagon. The superficial shape also of this joint in numerous instances is more or less triangu- lar, but it sometimes recedes from this form :—thus, in Callichroma latipes it is a segment of a circle; in some Limpides it is clavate; in Onitis Sphinx, dolabriform ; in the Orthoptera, Neuroptera, &c., it is usually linear ; in Some Lygei it is angular?: but the most remarkable “bie in this respect are those of such species of this last Stnus as have the posterior ones winged or foliaceous, So that they resemble the leaf of some plant—the tibia being the rachis, and the wing (which in some species 'S veined) representing the leaf itself. This structure is ® Stoll Punaises, t. x. f. 67. t. xvi. f. 114, VOL, ON 2x 674 EXTERNAL ANATOMY OF INSECTS. exemplified in Lygeus compressipes, phyllopus, foliaceus; ge.2 Under this head 1 must say a few words upo? the flexure of this joint, which in some cases merits n0- tice. I have before mentioned its bend at the knee” oF base: the apex also is sometimes incurved—in the ante- rior one of the male of Macropus longimanus so as almost to form a hook¢: in Lygeus Pharaonis the posterior pair are flexuose 4; in Bruchus Bactris, Leucospis, and several species of Chalcis, these tiie curve so as to adapt them selves to the bend of the thigh when folded. The notch on the inside of the anterior pair, in a large majority ° Carabus L., armed above by a spur °, a structure which probably assists them in seizing and detaining their prey? may also here be introduced : in the generality it is 4 lit tle removed from the apex of the joint in question; but in Pamborus it is very near to it, and in Cychrus, Car bus, &c., it becomes obsolete. I may mention here also a singular character which distinguishes the-cubit of both sexes of Gryllus campestris, domesticus, &c. At the bas? there is an aperture which passes through the joimt—2" teriorly it is oval, and posteriorly elliptical and mu larger, and on both sides is closed by a tense membran? The most striking peculiarities as to the clothing P his joint have been chiefly noticed under the sexual cha racters of insects‘, but some appear not to be of that de scription. In Spheridium Leach, while the thighs aP tarsi are naked, the posterior źibie are remarkably beset a Stoll Punaises, t ii. f. 14. t vii. f 54. t xxviii, f. 201. PEAT XV. Fic. 2. b See above, p. 671. © Oliv. Ins: n. 66. Lii A 12. Compare Scarabaeus longimant®? Ibid.n. 3. t. iv. f. 27. d. Stoll Punaises, t. Bud AT e Phare XXVI Fic. 31. f See above p. 306— EXTERNAL ANATOMY OF INSECTS. 675 with stiff bristles; in Empis pennipes they are thickly fringed on both sides; in Scarabeus MeL. only exter- nally, and in Dytiscus serricornis internally ; in Necydalis barpipes K. this fringe is longer at the apex; and in Sa- Perda hirtipes Ol. the same tibia at that part are adorned With a large brush, like that observable in the antenne of some Lamia*. I must next call your attention to the teeth, spines, and Spurs with which the zbz@ of insects are sometimes armed. With regard to teeth, you have doubtless often observed those that distinguish the cubitus of the arm of most La- mellicorn beetles: these vary in number from one, as in Trox suberosus, to seven, as in Geotrupes autumnalis; but the most universal number is ¢hree: in some species of Geotrupes, as G. stercorarius, &c., the third tooth from the apex, and those that follow it, may be called double. These teeth, in their cubit or anterior shank, doubtless assist these insects in burrowing. The four posterior tibie in this tribe are also distinguished by a kind of teeth Which occupy their whole diameter, and resemble so many steps. I have before noticed the remarkable cubit of the Gryllotalpa, and likewise that of Scarites, Pasi- machus, &c., in which some of the teeth are prolonged into spines», which are the next description of tibial arms that I mentioned. Spines are of two kinds-—those which are merely processes of the crust of the żibia, and thosethat re implanted in it, and seem to have a gomphosis or per- haps an amphiarthrosis articulation*. An instance of the Jirst kind may be seen in the hind-legs of some grasshop- * Oliv. Ins. n. 68. t.i. f. 8. comp. n. 67. £. xii. f. 83, and PLATE XIL. Fie. 25. a. b Vor. II. p. 365. and Prats XV. Fie. 5. 6. ° See above, p. 433, Note b. and 404, Note a. Se 676 EXTERNAL ANATOMY OF INSECTS. pers? (Locusta Leach), the Rutelide, &e. though in others they are implanted :—of the second, in the cubitus of the Mantide, and of ali the t7bi@ of the dragon-flies (Libelladin® M¢L.)°;—and of both kinds inthe hind-legs of Acrida Ky those which arm the upper angles of the tibiæ being 77 cesses, and those of the lower being implanted. The term spine I think ought to be restricted to the first kind; the second ought rather to be denominated spurs (calcar ia) and may perhaps be regarded as in some degree synony” mous with those most important appendages of the joint in question, that are implanted in or near their apex which have been hitherto distinguished by this last den mination, and which Iam next to consider. But thoug! I have not altered a term generally adopted, I must h express my opinion that they oughtrather to be considere as minute foes or fingers, and that the denomination best agreeing with their functions, as accessories to the mai? toe, would be digituli: this is proved particularly by% character peculiar to those of many species of the genus Cimbex amongst the saw-flies, in which these organs are furnished with a sucker or pulvillus (as they are also “és (Enas a kind of blister beetle), as well as the joints of the tarsi °; which makes it evident that they are applied by the animal to surfaces, and assist it in walking or climb- ing; and in general it may be observed that in most 1° jons ere sects their principal use is connected with these mot . . . ° re. and with burrowing. This circumstance tends to pr a Pirate XIV, Fic. 5. » It is remarkable that in th tribe all the legs may be called raptorious, though the thighs 2° _ incrassated, for they are armed with a double series or more © aS long spurs, which enable them to catch and retain their prey- 9 © Piare XXVII: Fre. 35. o”. Philos, Trans. 1816. t. xix. fi 9” See above, vol. ii. p. 331. EXTERNAL ANATOMY OF INSECTS. 677 that the generality of insects (for all have not these *rgans) have really a didactyle or tridactyle hand or foot; and the hypothesis so often alluded to—that the cubitus or tibia, &c., is really analogous to the carpus or tarsus in vertebrate animals*—seems to receive no small Confirmation from it; since, if the spurs be really ana- logous to fingers or toes, the part they articulate with Cannot be the zibia, &c. Though the parts in ques- tion did not escape the notice of Reaumur, Linné, De Geer, Latreille, &c., yet they have not been employed in the determination of tribes, genera, &c., except by the “uthor last named, but perhaps adopted. from Bonelli, In the subgenera Zabrus and Pelorus: in many instances, however, they afford excellent subsidiary characters, Sometimes common to a whole Order, and at others di- ‘tinguishing its various subdivisions. With regard to their number—I havenoticed many variations which ĮI will Now state to you, first observing that I shall express them by three figures, the first representing the number of spurs n the anterior leg, the second that of those on the inter- Mediate, and the third on the posterior; and where there Wwe spurs, as in the Trichoptera and Lepidoptera, on the middle as well as at the end of the tibia, I shall express it byone figure over another, the upper one representing the Number of the middle spurs. If you make an examina- tion yourself, it will be proper to remind you that these ttle organs are extremely liable to be broken off, but the Socket in which they were planted is usually very visible. he most natural number is represented by 2 2:2; this * See above, p. 591, 667,&c. ° Règne Animal, iii. 191. I have n % . A r "ver had an opportunity to consult Bonelli’s Observ. Entomolog. on, € genus Carabus L. in the Memoirs of the Turin Academy. 678 EXTERNAL ANATOMY OF INSECTS. you will find very prevalent in the Coleoptera Order, as in the Predaceous and numerous other beetles: I the Orthoptera and Hemiptera Orders, however, I bav? not discovered an instance of it; but in all the gest it more or less occurs: next to this number—zibié with obsolete or no spurs seem most prevalent, particularly in the Hemiptera; not a single instance of an insect fur- nished with them occurring to me in the Heteropte? ous section; and it is doubtful whether there are any 12 the Homopterous.—Having stated the most universal struc ture in this respect, I will next consider the Orders 5% riatim. Amongst the Coleoptera though the numbe 2:2:2 are most frequent in occurrence, yet there a! numerous exceptions. ~ Thus, in the Lamellicorns, t: 1:3 represents the calcaria of one tribe of the mentite M° formed of the genus Scarabæus M‘L.; 1:2:1 represen! those of another tribe of that family, tnt the sub” genera Ateuchus, Copris, Phaneus, &c.3 1:2:2 agoi forms the character in this respect of Sae and the great majority of the Lamellicorns; while 2:2:2 is ©” fined in this section to salus F. and Melolontha chrys” meloides Schranck (Psephus M'L. MS.). In the othe tribes of Coleoptera other numbers occur. Thus, 0: a characterizes Hyleceius; 0:1:2 Mordella; 0:2:2 cropus; 4:2:2 Harpalus, and all those Carabi Ly” cept Zabrus, that have a notch in their anterior zibidi 4:2:2 Zabrus. In the Orthoptera Order it is not easy to distinguish the real spurs from the implanted spine that ANEN arm the legs: these in Blatta are o tremely numerous, even at the apex of the tibie; ÞYt cannot distinguish any that can be regarded as true ae logues of the former: the most natural number of spur EXTERNAL ANATOMY OF INSECTS. 679 in this Order is represented by 0:0:4; this you will see in all the Locusts; in Acrida, Conocephala, Pterophylla; and in Truxalis, Pneumora, &c.; in Phasma there are None. In Mantis, if the terminal process of the cubitus is excluded,. it will be 0:2:2; in Gryllotalpa, admitting the terminal teeth of that part* as analogues of spurs, the number is 4:4:4; in Tridactylus Latr.0:0:5>; in Gryllus Latr. 3:3:5; in Gryllus monstrosus, 4:4:6. In the whole Hemiptera Order I have discovered no instance of an insect furnished with the real spurs: for though in Tettigonia F., Cercopis, &c., there are implanted spines in the posterior żżibia, and several at the apex, there are none of them clearly analogous to real spurs. In the Lepido- ptera the most general arrangement appears to be 4: 2:43 and next to this, 4:2:2. In this Order most commonly there is no spur at the end of the cubit, but one resem- bling a thumb* arms its middle; in Pieris, &c., this thumb is not present, so that the number is 0:2:2; in Agarista Leach, Erebus, &c. you will find 4:2:4, the posterior calcaria being all terminal; and in Attacus Atlas, all these organs are obsolete except the thumb. In the Neuroptera the most general arrangement is 2:2:2; but in the Libellulina, although the legs are very spinose, there are no spurs. In the Trichoptera K., in Phryganea rhombica and affinities, the number of them is expressed by $:4:45 and in those with long antennz, P. atra, &c by $3314 In the Hymenoptera the number 1:2:2 is most prevalent and next to this, asin Apis L., 1:1:2. In the Ichneumones minuti L. the spurs are a Prare XV. Fic. 6, 0”. b Coquebert Illustr. Ic. ii. t. xxi. f. 3. D. © Pare XXVIL. Fic. 29. v”. epee ae “eee = 680 EXTERNAL ANATOMY OF INSECTS. 1:1:1; in Atta Latreille, a kind of ant, 1:0:0. In the Diptera it is often difficult to distinguish the spurs from the spines; but the number most universal is, I think, 2:2:2; in Tipula it is 1:2:2; in the Tabanide 0:2:0; and in Culex, Limonia, &c., there are none. Amongst the insects with more than six legs, most commonly the tibiae have no spurs; but in the Araneide each is armed with ¢wo, a circumstance which also distinguishes the corresponding joint of the pedipalpi. These little organs inosculate each in an appropriate socket of the end, or in many cases of the middle of the tibia; and that part of their head or base that is received by it, is often constricted for the purpose: from hence it follows that they are capable of some degree of motion but in some insects, as those on the four posterior legs of Scarabæus sacer and its more immediate affinities, and those at the end of the cubit of Gryllotalpa, they are im- moveable, and appear almost processes of the joint t? which they belong. They are commonly sharp, of 2 subtriquetrous figure, with the lower side flat: where there are two, the outer one is usually the longest ; and in general the spurs on the hind legs are longer than those on the four anterior: but there are exceptions— thus, in Acanthopus Latr. the intermediate spurs are the longest; and in Cicindela the anterior are longer than the former; in Blaps mortisaga those on all the legs are nearly equal in length. They vary sometimes in shapé— those on the middle of the cubit of many Lepidopter% a Most of Latreille’s genera of ants are confirmed by differences in their spurs. Thus Formica is 1:1:] ; Ponera 1:2:2 with the internal intermediate one pectinated : Myrmica 1;2:2 with all sy™ metrical, &c, EXTERNAL ANATOMY OF INSECTS, 681 which may be regarded as a kind of thumb’, are of a lanceolate shape; in Meloe the external posterior one is flat and obtuse; in Ginas Latr. it is obconical, concave at the extremity, and apparently furnished with a sucker; in Ateuchus smaragdulus the anterior, and in Copris Ca- rolina the posterior is forked and emarginate; in Sirex the former is hooked and winged; in Lamprima it is trian- gular and dilated; in Aphodius analis it is dolabriform ; In Dynastes retusus and Juvencus the spurs are bent like a bow. In many Hymenoptera, as the Sphecide, they are pectinated”, with a series of minute parallel spines—a Structure which assists the animal in burrowing‘; in Acanthopus Latr. they are armed with little teeth or Spines#; in the hive bee the spur of the cubitis furnished with a membranous appendage which I have called the velum®; and in a subgenus related to Saropoda Latr. (Ctenoplectra K. MS.), the interior spur of the posterior leg is crescent-shaped, fixed transversely, and fitted on the inner side with a membrane, the edge of which is finally pectinated. . e. Tarsus or Manus‘. This is the last portion of the leg, usually supposed to be analogous to the hand or foot of vertebrate animals; but, according to the hypo- thesis so often alluded to, rather the representative of their jointed finger or toe. In treating of this part I Shall consider its articulation with the tibia, and of its joints inter se; the number of those joints; their propor- tion and shape; their parts and appendages. 2 PLATE XXVII Fic. 29. v”. b Ibid. Fic. 33. v. € Linn. Trans. iv. 200. Note a. 4 Prats XXVIL. Fic, 32.0”. © ThidFic. 36.2% f Prares XLV. XV. XXVI. XXVII. a’, t 682 EXTERNAL ANATOMY OF INSECTS. I seem to have observed three kinds of tarsal articula- tion. The first isaspecies of enarthrosis or ball and socket, the joints terminating in a globular head, perforated in- deed for the transmission of muscles, &c., and which is received by a corresponding cavity of the tibia or pre ceding joint, as may be seen in many weevils (Curculio L.*). This admits of some rotatory motion.—The second is a mixed articulation between enarthrosis and gingly- mus, when at the base of the ball a deep transversè channel receives a corresponding ridge of the żzibiæ oF preceding joint: this may be found in Rutele and pro bably many other Lamellicorn beetles; and something very similar in the Predaceous ones.—The third kind is where there is little or no inosculation, and the joints are scarcely more than suspended: this takes place in the Orthoptera, Neuroptera, &c.; but in Blatta and the hind legs of Mantis there is some approach to the foregoing kinds. | We are now to consider the number of joints of the tarsus, which varies considerably in the different Orders» and in one has been assumed as a clue for a subdivisio” of it into sections”, which, though not perfectly natural, is very convenient, and has been adopted by most moder? Entomologists. In treating of this head, I shall us¢ those denominations that have been employed by M. La- treille and others to express the variations of the nus” ber of the tarsal joints in the Coleoptera, but shall apply. them to insects in general. Insects in this view, ther fore, may be called pentamerous; heteromerous ; tetra- merous; trimerous ; dimerous; oY monomerous. a PLATE XXVI. Fic. 44, 46, 47. a. b By Gecflroy— Hist. Ins. i. 58. EXTERNAL ANATOMY OF INSECTS. 683 Pentamerous insects are those which have five joints in all their tarsi. This is the most universal, and may be called the natural number of these joints. More than half the Coleoptera belong to this section; in the Orthoptera —the Blattide, Mantide, and Phasmide ; all the Lepi- doptera except those butterflies called tetrapi (Vanessa, &e.); all the Trichoptera, Hymenoptera, and Diptera; in the Neuroptera—Ascalaphus, Myrmeleon, Hemerobius, Corydalis, &c. ; and in the Aptera—Pulex*. Heteromerous insects are those in which the number of these joints varies in the different pairs of legs”. These variations, like the spurs, may be expressed by three figures, the first representing the anterior tarsus, the second the intermediate, and the third the posterior. I begin with 5¢5:4. This number represents those beetles that have been exclusively regarded as heteromerous by modern Entomologists—of this description is the Lin- nean Tenebrio, Meloe, XC., now subdivided into nume- rous genera; they have , five joints in the two anterior pair, and four in the posterior. ‘The tarsal joints of the aquatic genus Hydroporus (a singular anomaly in the Order to which they belong) are expressed by 4:4:5, a The Cleride, which M. Latreille has placed in the pentamerous section, vary considerably in the number of their tarsal joints. ‘Thus in general in Thanasimus the tarsi are pentamerous ; but in T, for- micarius they appear to be heteromerous ; and in Enoplium, Opilo, Clerus and Necrobia they are tetramerous. M. Latreille’s expression, (N. Dict. d Hist. Nat. vii. 172.) “ le premier article etant fort court et caché sous le second,” seems to indicate that there is a fifth joint in some of these, the first being concealed under the second ; but I have never been able to discover it. Perhaps he reckoned the pulvillus as a joint ? bd The term heteromerous properly belongs to all insects in which the different pairs of tarsi vary inter se in the number of their joints, and it is here used in that large sense. 654 EXTERNAL ANATOMY OF INSECTS. thus reversing the number in the preceding tribe: other Heteromerous genera are to be found — the He- miptera. Thus, in Ranatra the numbers are 2.1.1.3 iÐ Sigara and Nauceris 1:2:2; in a new ers between Belostoma and Naucoris (Xiphostoma K. MS.), brought by Dr. Bigsby from Canada, 3:2:2: in the Lepidoptera the butterflies called tetrapi (Vanessa, &c.) may be ex- pressed by 1:5:5. Amongst the Aptera and Arachnida there are three remarkable genera, which if their pedi- palps are included may. be deemed Heteromerous. . I mean Phrynus, Thelyphena, and Galeodes ;—in the for- mer the numbers will be *:4:4:4, the asterisk denoting more than ten; in the second, 8:4:4:4,; and in Gale- odes) in which the first pair of pedipalps are not chelate; - the mandibles performing their office) the numbers are belsS: Ses? Tetramerous insects are those in which all the ¢arsz consist of four joints; these in the Coleoptera are next in number to the pentamerous—indeed a very large propor- tion of them strictly speaking are really of the latter description, since in Linné’s four great genera, Curculio, Cerambyx, Chrysomela, and Cassida and some others, the clawyoint (ungula) consists of two articulations, one very short, forming merely the ball at its base’, which inosculates in the socket of the preceding joint, and the other constituting the remainder: if you carefully sepa- rate these two pieces, you will find that the last inoscu- * These three genera appear really to have only six legs, since the pedipalps or maxillary legs are not armed with claws, while the real representatives of the legs, or three last pair, are so distin- guished. In Phrynus and Thelyphona the anterior pair are chelate ; but in Galeodes they are pediform, as in the Araneida, and the great chele are the mandibles. b Prate XXVI. Fie. 47, 48. d *. EXTERNAL ANATOMY OF INSECTS. 685 lates in the summit of the ball, and is moved by appre- priate muscles*. This structure probably permits the readier elevation and depression of this joint. In the Orthoptera the tetramerous genera are those which Linné called Tettigonia amongst his Grylli (Locusta F.); Acheta monstrosa also, and in the Neuroptera, Raphidia belong to this section. Š Trimerous insects are those whose tarsi consist of only three joints. Amongst beetles the Lady-birds (Cocci- nella L.) ave remarkable for this structure, but in them the claw-joint is also biarticulate, so that strictly speak- ing they are tetramerous; in the Orthopterous Order the migratory locusts (Locusta Leach) belong to this sec- tion, as likewise Gryllus Latr. and Gryllotalpa Latr. : in the first of these genera is an appearance of there be- ing more joints in the tarsus, because there is more than one cushion below the first>. To this section also belong _ the great majority of the Hemiptera, excluding only those tribes that connect the two sections of the Order consti- tuting the two Linnean genera Nepa and Notonecta; the Libellulina likewise belong here, as do also the Scor- pionide and Scolopendride. Dimerous insects are those that have żwo joints in all their zarsi. Such are the Pselaphide in the Co- leoptera Order‘; in the Hemiptera—Belostoma and No- tonecta; in the hexapod Aptera—Pediculus ; in the octo- pod—the Acari of Linné; in the myriapod—ZJulus; and in the Arachnida—the Araneide. 2 Prats XXVI. Fie. 49. s. a. b Vor. II. p. 330. e Dr, Leach says there are three joints in this tribe. Nat. Misc. hi, 80. 686 | EXTERNAL ANATOMY-OF INSECTS. Monomerous insects are those which have only a single tarsal joint. Only one Coleopterous and also one He- mipterous genus is so distinguished : the first is Der- mestes Armadillus De Geer*, and the second the common water-scorpion, Nepa Latr. Among the Aptera we find Nirmus, Podura, Sminthurus; &c., that belong to this section. To the above sections another may be added for those insects whose tars? have more than five joints, which may be denominated Polymerous, Here belong the gener Gonyleptes K., Phalangium and Scutigera Latr. In the first the number of joints varies from six to eleven, and in the two last they far exceed that number, amounting in some species of Phalangium to more than fifty, and becoming convolute like the antennæ of Ichneumons?. I am next to notice the proportions and shape of the tarsus and its joints. The most general law is, that it shall be shorter and more slender than the ¢ibia; but it admits of several exceptions—thus, in Megasoma K. ¢, in all the legs; in Agrostiphila MeL. MS.¢ in the inter- mediate, and in Amphicoma lineata in the posterior pait the żarsi are the longest; in Trichius Delta these last are longer than the thigh and tibia together. In some insects the ¢arsi are disproportionally short, as in Cas sida, the Pselaphide, Locusta Leach, &c. Though ge- nerally more slender than the tibia, in several instances * From De Geer’s description this insect seems related to Agathi= dium (iv. 221—., t. viii. f. 21— 23). M. Leclerck de Laval discovered it to be monomerous. Règne Animal, iii. 365. b Pirate XXVI. Fic. 22. € See above, p. 311. Note a- * Melolontha sericea and aurulenta. Linn. Trans. xii, 463, 400. be- long to this subgenus. EXTERNAL. ANATOMY OF INSECTS. 687 they are as thick or thicker, or more dilated, as in most of the tetramerous beetles, which being climbers require a dilated tarsus. Again, comparing the three pairs of this joint with each other, the most general rule is, that the anterior should be the shortest, and the posterior the longest: but in some, as the Capricorn beetles, &c., they are nearly equal in length; in others, as Lytta marginata, the anterior pair, and in Rhipiphorus the intermediate, are the longest; in Trichius Delta these last are the shortest. With respect to thickness, the anterior tarsi, except in many males?, are not very strikingly different from the rest. With regard to the proportion of the joints of the tarsus toeach other,—according to the most general law, the first is the longest, the last next in length, then the second and third, and the fourth is the shortest. In Gony- leptes K. and other Phalangide the first is almost thrice the length of all the rest taken together; but there are numerous exceptions to the rule. In the female Carabi the first joint is not longer than the last, and in the males not so long; and in Hydrophilus, &c., itis the shortest of all. Again, the second joint is longer than the three fol- lowing onesin Dasytes ater®; and than the last in Cicindela sylvatica: the third joint is shorter than the fourth in Lam- pyris ignita : it is longer than the first in Donacia, many Melolonthide, &c. Once more, the fourth joint, usually the shortest of all, is longer than the second and third in Anthia, &c. Lastly, the claw-joint, usually the second in length, in the Eproboscidea Latr. (Hippobosca L.) is very long and large, while the four first joints are so a See above. p. d35—. b Prats XXVII. Fie. 25. 688 EXTERNAL ANATOMY OF INSECTS. extremely short as to be scarcely distinguishable from each other: it is the shortest of all in Colymbetes, &¢-; it is of the length of the third in Cicindela sylvatica, of the fourth in C. sexguttata. Though commonly the slen- derest joint of all, particularly so in Raphidia, in many Heteromerous and Lamellicorn beetles it is the largest conspicuously so in Mellinus tricinctus. Sometimes, 4 in Buprestis chrysis, &c., all the tarsal joints are nearly equal in length and thickness. We are next to say something upon the shape of the tarsi and their joints. In general we may first observe that their upper surface is commonly more or less cor- vex, and the lower flat or concave: in insects that are swift runners, as the terrestrial Predaceous beetles, they are usually slender and filiform?; in those that swim, 45 Dytiscus, the two posterior pair taper nearly to a point from the base to the apex; in some that climb, as Bu- prestis, they are rather flat and linear; and in others (the Weevils, Curculio L.) they grow gradually wider towards the claw-joint*; sometimes, as in Mordella Latr., the four anterior tarsi are of this shape, and the posterior pair setaceous. In Gyrinus the four posterior are flat and triangular; and in that extraordinary insect Gryllus mon- strosus the tarsi are foliaceous and lobed‘. In many males and some others the anterior pair or hands are of a different shape from the two posterior: thus, in several Carabi they are lanceolate; in Staphylinus, Creophiluss &c. in both sexes they are often nearly circular, like those of male Dytisci*. With regard to the shape of 2 Prats XIV. Fic. 7. 2’. b Ibid. Fic. 6. £’. * Prare XXVI. Fic. 47. 4 Prare XXVII, Fic. 41. £ Prate XV, Frc. 9. EXTERNAL ANATOMY OF INSECTS. 689 individual joints it may be said in general that they are rather triangular, with an anterior sinus for the reception of the succeeding joint: the first joint usually departs most from this form; in the bees it is commonly much larger than the rest, especially in the last pair of legs, and nearly forming a parallelogram *; in Euglossa it is trapezoidal; in the majority nearly linear or filiform. With regard to their termination—in Brachycerus and some ants (Ponera, Myrmica, &c., Latr.) the three first joints; in Dascillus, Lycus reticulatus and affinities, the third and fourth; and in the great majority of the Tetramerous insects the penultimate joint is bilobed; although in most Predaceous beetles this joint is entire or simply emarginate, yet in Colliuris it terminates in a single oblique lobe; and in Lebia, Drypta, &c., it is nearly bipartite. I must now advert to the Ungula or claw-joint: it is usually clavate or thickest at the end and curved; but in the Asilide it is shaped like a vase or cup; in Phaneus, in the four posterior farsz, in which the claws are obsolete, it is thickest at the base and sharpest at the extremity >; it usually forms an angle with the rest of the tarsus, rising upwards, which enables the insect to move more easily without hindrance from the claws, and also more readily to lay hold of any object it meets with; but in the La- mellicorn beetles and many other insects it is in the same line with it. As in the beetles last mentioned this joint is often inserted in the extremity of the preceding one; but in Gidemera it articulates with the middle of its upper surface; and in Lycus and a numerous host of » Mon. Ap. Angl. i. t. xii. neut. f. 20. b Prare XXVII. Fic. 44. s, VOL, II. ies ee Aa A SH nine S sf a fk y 4 i a E H A i pi hi i4 a ti fh ae Ni A j hig E af i a ii R i i} i fie ; ia hi , a tf a yn i St aes E EA Spee A a ee con Sot SS re eae ae 690 EXTERNAL ANATOMY OF INSECTS. Tetramerous beetles it springs from its base, just behind where it diverges into two lobes. I shall next call your attention to the different kinds of appendages with which the tarsi are furnished. They are seldom armed, like the ¢idie, with teeth, or spines or horns; but something of the kind occasionally distin- guishes them. In Phileurus, Oryctes, and several othe Dynastida, the first joint is armed at the apex externally with a considerable mucro; in the fore-leg of Dasytes ater a similar process is prolonged into a crooked horn” But the most important, appendages of the tarsi are the claws which almost universally arm their extremity, and which appear clearly analogous to those of birds, qua drupeds, &c.; though probably differing as to their sub- stance’. Some few, however, are without them; this, 2° I lately observed, is the case with Phaneus with respect to the four posterior legs ; the anterior ones of Vanesst amongst the Lepidoptera, and all. those of Stylops and many Acari L., are also without them: this is likewise - the case with the first pair of legs, or the second of the - pedipalps of Galeodes. _ In this genus these organs con- sist of two joints®. With respect to number they vary in different tribes, but not so much as the calcari@* these variations may likewise be represented by thre? numbers. The most natural is zwo in all the ¢arsi, exhi- bited by the Predaceous beetles and the great majority’ 2.2.1. are to be found in Hoplia, Anisonyz, Sic. t; 1.2.2. in Belostoma ; three in all the legs in the Ara- 4 Prare XXVII. Fre. 26. w”. ? See above, p. 396. ¢ L. Dufour Descr. de six Arachnides. Annales, &c. 1820. 19- a Prare XXVII. Fic. 51. is the posterior claw of Hoplia. EXTERNAL ANATOMY OF INSECTS. 691 nerde@* ; in Meloe”, Elater, &e., each claw is double or Consisting of two, which makes four in each leg; and in Many EHippoboscide there are six*; in Nepa and the Myriapods there is only one. In most insects, perhaps, the claws are simple or undivided*; but in Galeruca, Melolontha subspinosa®, &c., they are bifid at the apex; as” is the exterior claw of the four posterior legs in Chasmo-- dia and Macraspis * M'L., and of all in Melolontha hor- ticola; in Serica brunnea M°L. the claws are all cleft at the extremity, but the internal tooth is broad, flat, and’ obtuse’; in Melolontha vulgaris and Pelidnota punctata McL..4, the claws are armed with an internal tooth near | the basei. In the Araneid@, which have three claws, the two external ones are furnished with several parallel teeth, which the animal uses to keep separate the threads | ofits web, and probably for other purposes‘; and some Predaceous beetles, as Lebia and Cymindis; have ‘both their claws similarly furnished !. These organs vary in their relative proportions: thus, in Anoplognathus the inner claw is much smaller than the other™; and in Elater sulcatus, fuscipes, &c., it is represented by a mere bristle ; in Hoplia, in the anterior tarsus it is not half the length of the outer one”; in Areoda and Pelidnota M‘L. this last is the smallest. They vary also in length—in Ryn- chenus, Ascalaphus, &e., they are very short; in the La- mellicorns, Galeodes, &c., very long; and in Myrmeleon a Prare XXIII. Fie, 14. b Prate XXVII. Fie. 52, © Ibid. Fre. 46. @ Ibid. Fre. 53, 54. © Tbid. Fic. 49. f Ibid. Fie. 38. = Ibid. Fie. 39. h This structure is not general in this genus. i Prare XXVII. Fie. 40. k Prare XXII. Fre. 14. ? Prats XXVII. Fie. 43. ™ Ibid. Fre. 47. i " Ibid. Fic. 48. Z¥2 692 EXTERNAL ANATOMY OF INSECTS. longer than the claw-joint. With regard to their curva- ture they generally form the segment of a circle ; in many Asilide they are crooked like the claws of the eagle *s and the posterior one of the Hopiie is bent like a hook”; they most commonly diverge from each other; but in the Rutelidæ, Anoplognathidæ, &c., they are perfectly parallel, and in the former often inflexed ©. With regard to other appendages of the part we are treating of, if you examine the stag-beetle and many other Lamellicorns, you will find between the claws a minute but conspicuous joint terminated by two bristles which seem to mimic the wngula and its claws; these parts are what are den minated in the table the palmula, plantula, and pseudony- chia: in the stag-beetle these are long‘; in the Melolon- thide short; and in many Cetoniadæ they resemble a” intermediate claw. The most remarkable of the appendages of the tarsi 2° to be looked for on their under side or sole (solea), and are the means by which numbers of insects can overcom? atmospheric pressure and walk against gravity. Many of these have been fully described in a former let ter f£; but much that relates to them was there omitted, which I shall now detail to you. Four kinds of pulvillis as I would call these appendages, are found in the sole of insects, upon each of which I shall make a few remarks: The frst is a cushion or brush composed of very thickly set hairs or short bristles: examples of this you will find in the majority of Tetramerous and Trimerous beetles. Jn Chrysomela, Timarcha, &c., there is one of these cushion’ a Prare XXVII. Fie. 53. b Ibid. Fic. 51. c Ibid. Frc. 47. 4 Ibid. Fre. 56. awd, f*- / © Ibid, Fra, 49. ad, f*. f Vou. I. p.326—- EXTERNAL ANATOMY OF INSECTS. 693 on each of the three first joints; in Prionus, Liparus, &c., there is a pair; and in Coccinella on the two first; in others (Balaninus Nucum, &c.) a pair only on the penul- timate joint ; in Calandra Palmarum, Rhina barbirostris, &c., that joint has an intire cushion ; in Eurynotus mu- ricatus K.* the three first joints of the four anterior tarsi are similarly circumstanced, but the cushions resemble sponge, . | The second kind of cushion is a vesicular membrane capable of being inflated. This distinguishes the tarsi of Thrips’, and many Acari L.4; likewise those of Xenos®; and also of many Orthoptera fully described on a former occasionf, though the fact of their capacity of inflation has not been ascertained, belong to this sec- tion. The third kind of covering of the sole is when the three or four first joints of the żarsus each terminate in one or two membranous lobes or appendages : of the first description is Priocera K., in which the lobes are invo- lute’; and of the second Rhipicera Latr.*, in which there is a pair on each joint, in the Brazil species set with very fine hairs. The fourth and last kind are what may with the utmost propriety be denominated suckers, since their use as such is clearly ascertained. These are not only to be found in a large proportion of the Diptera, in some of which there are two of them, as in the Aszlide'; and in others a Linn. Trans. xii. t. xxi. f.l. > For other instances of this structure, see above, p. 336. © De Geer, ii. 7. 4 Ibid. vii, 84. Pirate XXVII. Fre. 60, 63. l e Ibid. Fie. 61. f Vor. II. p. 327—. ® Prars XXVII. Fie. 59. » Linn. Trans. xii. t. xxi. f. 3. i Prare XXVII Fie. 53. 694 EXTERNAL ANATOMY OF INSECTS. three, as the Tabanide? ; but also in many of the subse- quent Orders: thus, in the Heteropterous Hemiptera, 10 Scutellera and Pentatoma; but not the Reduviada, and in the Neuropterous genus Nymphes Leach there is a mi- nute one under each claw. It is discoverable between the claws in many Hymenoptera, as Apis, Vespa, &c. But the genus that exhibits to the curious Entomologist the most singular and elaborate apparatus of this kind is Dytiscus Latr. ; and the examination of the under side of the hand of any male of this genus will almost compel the most inattentive observer to glorify the wisdom and skill of the ALLFATHER so conspicuously manifested in the structure of these complex organs. For this part in these instead. of two or three pedunculate cups as in the in- sects just mentioned, is composed of a vast number, some large and some small. If you take a male specimen of the common D. marginalis, you will find that the three first joints of the hand are very much dilated, so as t0 form a plate or shield nearly circular, fringed all round with stiffish hairs; if you next examine the under side of this plate with a good magnifier, you will discover at the base, where it is united to the cubit, two circular cup% the external one more than three times the size of the other, with an umbilicated centre‘; besides these tw? larger cups the rest of the shield is covered by a vast number of minute ones of a similar construction4: the larger cups are nearly sessile, but the smaller are elevated upon a tubular footstalk € ; the three first joints of the intermediate tarsi are also dilated, but not into 2? a PLATE XXVII. Fie. 54. Philos. Trans. 1816. t. xviii. f. 9—11. b Prate X.XVIL Fie. 55. £ © Prate XV. Fre. 9. a. 1 Tid, b, © Philos. Trans. 1816. t: xx. f. 9, 12—15. EXTE RNAL ANATOMY OF INSECTS. 695 orbicular shield, and thickly set with minute peduncu- lated suckers*. The structure varies however in dif- ferent species. ‘Thus in D. limbatus the shield is trian- gular with the smaller suckers at the base, and two rows of larger oblong ones, concave but not umbilicated, at the apex; in another Brazilian undescribed species (D. ob- ovatus K. MS.) the shield is oblong and quite covered with suckers like those last mentioned; in D. sulcatus ( Aci- lius Leach) almost the whole plate is occupied by a very large sucker, above which, at some distance in the inner side, are two smaller ones, while the extremity of the | shield is covered by minute ones elevated on long foot- stalks: the central umbilicated elevation of the large one, which nearly fills its cavity, is in this species beautifully radiated. The male of Colymbetes transversalis has also an orbicular shield, but the suckers are much less strongly marked. ‘The use of this organ has been before suffi- ciently explained °. . A few words will be necessary upon the folding of the legs in repose. When insects walk, the thigh is usually in an ascending position, rising above the horizontal line, the zibia forming with it rather an obtuse angle, and the tarsus nearly a right one with the ¢zzbia; but in the My- riapods, as far as I can unravel their swift many-footed motions, these angles in walking do not take place; in repose however, in many insects, the coza forms an angle with the thigh below the horizontal line and with the tibia above it, and the tibia and tarsus continue in the same line, and point downwards nearly vertically ; in. others, as in the Tetramerous beetlés, the last-mentioned joints a Philos. Trans. 1816. t. xx. f.4, 11. © See above, p. 305—.- 696 EXTERNAL ANATOMY OF INSECTS. form an angle with each other and turn upwards, the tibia having an external oblique cavity to permit this ; but the insects most remarkable for packing close their legs are those carnivorous genera Dermestes, Anthrenus, Byrrhus, &c. In the last-mentioned genus there are cavities in the under side of the trunk, in each division of the breast, and at the base of the abdomen, to receive the legs when folded; the core have also a cavity to receive the base of the thigh. - In the anterior legs this last part has a longitudinal one on its upper side, and in the four posterior on the under, which receives the tibia; which at the inner edge are straight, and at the outer curvilinear, and the ¢arsz are turned up and received by the concave part, on the anterior side of the first pait and the posterior side of the two last of the tibia, so as to lie between it and the body: when the legs are close packed, the animal looks almost as if it had none. | have observed that when Dytisci repose on the water, the posterior legs are turned up and laid over the elytra, and curved towards the head. vi. Pectines. I must next say a few words upon a re~ markable organ, which seems in some degree supplemen- tary to the legs, by which the Creator has distinguished the genus Scorpio, ¢alled from its parallel teeth, set in 2 back, their pecten or comb*. This back consists of tw or more articulations, is attached by its anterior extremity to the sides of the posterior piece of the mesostethiums and is marked by a longitudinal furrow or channel. The teeth, which vary in number in the different species, and * Prate XXVII. Fic. 50. EXTERNAL ANATOMY OF INSECTS. 697 in the same species at different periods of its growth, are usually ovato-lanceolate, or obtusangular, furnished on their exterior edge with what appears to be a longitudi- nal sucker, and supported between their bases, or at the base, both within and without, by triangular, conical, or subglobose props. With regard to the use of these organs, it has not been clearly ascertained. Amouroux states that he has seen the animals use them as feet, and he con- jectures that by them they may fix themselves and turn — upon them as on a pivot, when they have to make a re- trograde movement*. M. Latreille, from their having br eba pouches immediately under them, seems to think that they are connected with respiration’. This may be true; but from the suckers just described, I am inclined to think with Amouroux, that they are useful to the animal in its motions, and that like the suckers of the Gecko, flies, &c., they enable it to support itself against gravity and to climb perpendicular surfaces. Whether the five obtriangular plates, elevated on a pedicle, which are found arranged in a series on the un- der side of each of the jointed cove of the posterior legs in Galeodes, are at all analogous: to the pectens of scor- pions, has not been ascertained’. M. Leon Dufour watched them very attentively in one species (G. intrepi- dus), but he could observe no motion in them4. a Amouroux Insectes Venimeux, 44. > Observations Nouvelles, &c. Mém. du Mus. viii. “77. © N. Dict. d Hist. Nat. xii. 370. à Descr. de six Arachnides, &c. Annales Gen. des Scienc. Phys. 1820. 19. é. Ixix. f. 7.d. LETTER XXXVI. EXTERNAL ANATOMY OF INSECTS |. CONTINUED. THE ABDOMEN, AND ITS PARTS. Tue 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; ar- ticulation with the trunk; composition; shape and pro- portions; its appendages; and its clothing. i. Substance. Under this head I may observe in ge- neral, that where the abdomen is protected by hard elytra or tegmina, as in most Coleoptera, and many Heteropte- rous 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 Dynastide 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 Sta- phylinus ; or only its anal extremity, as in Melolontha; ot its sides, as in Lygeus, &c., is not covered by the elytra EXTERNAL ANATOMY OF INSECTS. 699 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 Araneide, 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 promi- nent metaphragm?, the trunk may with more pro- priety be said to inosculate in the abdomen. With re- gard 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 ab- domen 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 Ti- pulide, Asilide, &c., belong rather to the first section— and the Aranezde; the abdomen, however, inall is merely suspended, without any inosculation. To the second subdivision belong all the Hymenoptera, except the Ten- è Anatom, Compar: i. 450. 700 EXTERNAL ANATOMY OF INSECTS. thredinide and Siricide, 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 Jong 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 Araneid@ in the same tribe with such Hymenoptera as have a petio- late abdomen?; but as the manner in which the latter articulates with the trunk is widely different from that of the Diptera &c., Í 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 Hymeno- ptera are wholly without it. This learned author thus de- scribes the articulation where the abdomen is connected by a pedicle. ‘ They have,” says he, “ a real solid arti- culation, 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 ren- dered: 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 ex- tent of its movement?.” But this passage by no means conveys an adequate idea of the singular mechanism by which the Divine Artijicer has enabled these little crea- tures to impart the necessary movements to an organ sO ` bulky compared with its very diminutive point of attach- ment. As no author that has fallen in my way has ex- amined the articulation of the abdomen with the trunk in these Hymenoptera with the attention which it merits”, * Anatom. Compar.i. 451. » De Geer notices something of the kind in Cimbex femorata, ii.947. EXTERNAL ANATOMY OF INSECTS. TOL 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 meta- thorax 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 re- moved, 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 trans- mitted a flat and sometimes broadish ligament or rather tendon, in which the levator muscles of the abdomen, at- tached by their other end to the metaphragm *, terminate: another minute orifice above the base of the pedicle af- fords 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), the tendon is the rope ( funiculus)’, 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 a It was omitted to be observed, when the supposed pneumatic pouches in the genus Vespa were mentioned (see above, p. 585), that l they have also a very conspicuous metaphragm, as probably have most Hymenoptera, to which the muscles that move the wings are attached. ' b Prare IX. Frc. 13. F'is the tendon, G’ the aperture in the abdomen C, and a, the aperture in the trunk B. 702 EXTERNAL ANATOMY OF INSECTS. Formicidae, Scoliade, &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 abdo- men, varies in different genera: thus, in the bee it is tri- angular, with the vertex reversed; and in the wasp the upper one is circular, and the lower one transversely ob- long ; 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 me- tathorax, 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 sus- pended, 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 Phalangide (Gonyleptes K.) it appears almost re- tracted within it*. iii. Composition. I shall next consider the segments into which the abdomen is usually divided, their num- ber, and other circumstances connected with them, In the Hippoboscide, Acaride, Phalangide, and Araneid@, the part we are considering is not divided into segments, though in some instances, as in Gonyleptes and the can- criform Epeiræ?, 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 @ Prare XV. Fie. 11. Linn. Trans. xii. t. xxii. f. 16. » Surely these Epeire, of so different a habit from the rest, form a distinct genus? EXTERNAL ANATOMY OF INSECTS. _ 7038 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 com- monly 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 seg- ments, as has been before observed*. I shall express the variations in question by two figures, the frst repre- senting the number of dorsal segments, and the second the ventral—they usually only express the apparent seg- ments: perhaps a very general examination and dissec- tion, might bring many of them nearer to a common type. 1:1. Chelonus. 6:5. Nepa. Chrysid@”. 6:6. bees g. (Belostoma. Syrphus. ag. Curculio L. Halictus 2. Cerambyx Le ls 3. :2. Leucospis °. 5. 6. a See above, p. 339. b There is reason to suppose that in Chelonus and the Chryside 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 theepigastrium 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 excava- tions that look like holes. In some species of Stilbum this segment consists as it were of three ridges or steps. _ e In this genus the ventral segments are replaced by a long narrow central plate, sueceeded by a minute one. 704 EXTERNAL ANATOMY OF INSECTS. 7:6. Dytiscus 9. 9:7. Perga Leach. ¢. 7:7. Ammophila, &c. 9:8. Perga 3. Dytiscus 3. 10:7. Locusta Leach ?- aba &c. 10:8. g. 8:7. Geotrupes Latr. 10:10. Æshna. 8:8. Pimpla. 11:7. Phasma. 8:10. Euchlora M¢L.?? 11:9. Chelifer. 8:13. Scutigera. | 12:11. Thelyphonus. 9:5. Carabus Latr. Many: Myriapoda.: 9:6. Gymnopleurus Ill. 8:6. 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 re- spect to the former, that each ring is suspended by liga- ment 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 znosculation ; 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, oY inosculates. The first kind here mentioned you will find exemplified in Melolontha, Geotrupes, Musca, &c.5 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 2 In this genus the bed of the posterior coxze appears to consist of two segments, which are beautifully fringed with parallel short bristles. EXTERNAL ANATOMY OF INSECTS. 705 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?. We see the reason of this structure when we consider the calls they have for greater powers of movement in this part in lay- ing their eggs, and annoying their enemies and assail- ants; and also in the Staphylinide 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 Julus 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 be- longing to the other Hemipterous section; but. in the Test 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 a Anatom. Compar. i. 451, Fd VOL, TH 2H 706 EXTERNAL ANATOMY OF INSECTS. of the ends of the ventral, uncovered. The Lamelli- - corn 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 betwee? 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 Gryllo- talpa, which must permit a vast extension of the abdo- men. In this membrane, in some cases, as in Dynastes MEL., Melolontha, &c., the two or three first spiracles are fixed*. 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”. I shall next notice the segments seriatim, in the order of their occurrence, beginning with the dorsal ones. The most remarkable circumstan@ with respect to these that occurs to my recollection takes place in the Cancroid spiders (Epeira cancriformis, a” leata, &c.), in which the back of the abdomen is formed by a plate, in some extended in a transverse directio”? (E. cancriformis), in others in a longitudinal one (E aculeata), of a mùch harder substance than the unde” side and quite flat, set with strong sharp spines, in the former species apparently moveable, and terminating be- 2 Prare VIII. Fre. 9. A’, B. b Ibid, Frc. 5. A”. EXTERNAL ANATOMY OF INSECTS. 707 hind in a piece resembling in some measure the scutellum of the Stratyomide and similarly armed with a pair of Spines?: in Æ. aculeata the sides of the abdomen, un- der the plate, have a number of longitudinal folds like those of Phrynus. In Cryptocerus, a genus of ants pecu- liar 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 distin- guishable. Nothing very remarkable is exhibited by the other segments, except that in Trichius the penultimate is the largest; in some Staphylinide (S. splendens) and Brachini ( B. melanocephalus) it is emarginate, and in the former tribe also often terminating in a white membrane. The dorsal segmentmost 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 con- spicuous 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 oviposi- tor in repose’. 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®, many Muscide, and Thelyphonus. As to its termination the podex is sometimes bifid, Blatta ; bipartite, Ranatra ; * Prare XV. Fie. 10. b Reaum. v. é. xvii. f. 14. a. a. © Linn. Trans. v. t. xii. f. 15. 222 708 EXTERNAL ANATOMY OF INSECTS, mucropate, Sirex; acuminate, Melolontha vulgaris, Tri- chius hemipterus. Generally this part is flat; but the disk is elevated or gibbous in Oryctes and some other La- mellicorns. 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. In some in- sects 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 tri- angular 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». We are now to turn our atte?” tion to the ventral segments of the abdomen. The first of them is what is called the epigastrium® in the table. This part, according to M. Chabrier, is of considerable importance to the animal in flight, as, by its pressu? against the trunk, not only regulating the movements ° the abdomen, but as, in his opinion, contributing to push forward the trunk‘ in the descent of the animal. It # remarkable only in the Coleoptera and Heteroptero™ Hemiptera, to which my observations upon it will be confined. - It may be stated as usually consisting of tW° articulations, that nearest the trunk being narrow, and if the Predaceous beetles‘, as also in Scutellera, Pentatom% * Daldorf (Asiatic Society’s Trans. vii.) has divided Geotrupes int two families, one with the podex covered (G. vernalis, &c.) which ies calls modesti, the other with it uncovered (G. stercorarius, &c-) whieh he calls obsceeni. > Pirate VIL. Z’. e Ibid. D’. à Sur le Vol des Ins. c. i. Addend. 299- ° In Dytiscus marginalis the upper side of the margin of the Hy- pochondria is curiously cut into transverse corrugations. ; Py EXTERNAL ANATOMY OF INSECTS. 709 &c., interrupted in the middle*. In many Lamellicorns this joint is concealed under the posterior core, 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», and which is received by a sinus of the metasternum; this point is generally minute and tri~- angular, but in Sagra it is large and rounded at the €xtremity, 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 Cetoniada, &c., the Hypochondria unite beforethis mucro, and form a ridge which articulates with it, and dips towards the abdominal cavity; in Scolytus the epigas- ‘rium is much elevated from the rest of the ventral seg- ments, 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 * Piare VHL Fre. 6. C’. t Thid p 710 EXTERNAL ANATOMY OF INSECTS. remarkable peculiarities, I shall pass them without fur- ther notice, and call your attention to the last, which 15 opposed to the podex, and which I have named the hy- popygium?. Though usually a single small piece, in Edessa and many Pentatome it consists of several plates; and in Trichius it is very large: it is mostly znézre, but in the male Dytisci it is cleft; in Lamia ocellata trilobed s in Edessa tripartite; in Centrotus Taurus it is boat- shaped and hollowed out to receive the stalk of the ovi- positor. It is also generally in the same line with the body, but in Xenos it is turned up and bent inwards”. iv. Shape. With regard to shape, in some Orders the abdomen varies considerably; but the most general for™ is one that approaches to trigonal, so that a transver® section will be a triangle, with the vertex more or Jess obtuse, and the base more or less convex; some tendency to this form will often be found even in those insects whos? abdomen appears almost as flat as a leaf, as in mavy Aradi. In the hive-bee the transverse section is almost an equilateral triangle; in Belostoma grandis the disk ° the under side of the part in question is longitudinally elevated into a trigonal ridge, the section of which is o equilateral triangle, the sides being quite flat. In ge?” ral, in the vertical section of an abdomen, the vertex © the triangle points downwards, but in Libellula F. r points upwards. In Blatta this section is nearly lance” late; in Staphylinus olens it is a segment of a circle with the convex side downwards; in Zishna F. with that side upwards; and in dgrion the section is circular. Jo Copris, Ateuchus, &c., the abdomen is very short 4 @ Prare VHL I. b Linn. Trans. xi. t. ix. f. 15 & EXTERNAL ANATOMY OF INSECTS. 711 thick; in Staphylinus slender and long; in Aradus, Nepa, &c., depressed and flat; compressed in Ophion and Evania; conical in Cælyoxis; rhomboidal in many Mantes; boat-shaped in many Lyga ; fusiform in various Papilionde ; lanceolate in some Zchneumonida, falcate in others; nearly round in Diapria purpurascens; ovate in Lyrops ; elliptical in Andrena; oblong in many Xylo- cope ; heart-shaped in the naked Euglosse ; triangular in Dytiscus; gibbous in Fata; 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 Andrenide and Apide ; long in the Sphecide; thick in the Formicidae; slender in Evania; fusiform in Pelecinus; clavate in Ammophila; campanu- late in many Vespide; nodose in Myrmica* ; squami- gerous in Formica? : it sometimes also consists of two joints, as in Ammophila and many Vespide. 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 Nepide; in Staphylinus, XC. it is distin- guishable 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 pa- radoxa, 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 re- markable degree in some Agrionide from South America, @ Puare IX. Fic. 18. J’. b Ibid. Fic. 17. H’. 712 EXTERNAL ANATOMY OF INSECTS. as A. lineare, &c.*; 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, &e.; dis- proportionably so in Staphylinus: though usually of the same width with the trunk, in many Mantide it is much wider®; and more slender in the Libellulina, Myrme- leon, &c. vi. Arms and Appendages*. 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 promi- nences 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; 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®; in S. pygmeeus (I. multistriatus Marsh.) the same segment is armed by a flat horizontal tooth or horn; in an Aradus from Brazil, before alluded tof (A. lami natus K. MS.), the margin of the abdomen is surrounded by eight flat subquadrangular laminae; in another species figured by Stoll’, it is cut out into bays by a number of * Roemer. Genera, &c. t. xxiv. f. 4. b Stoll Spectr. t. vii. e PLAte KV. Fic. 10—23. d See above, p,339—- e This tubercle I find only ina specimen from Sweden, sent to me by Major Gyllenhal, but not in any British one I possess. In this spe cimen the declivity before mentioned (see above, p. 709.) is observa ble in the first segment, but in the others it is formed by the second: i See above, p. 617. € Punaises, t. xiii. f. 84- EXTERNAL ANATOMY OF INSECTS. 713 denticulated teeth; and in Acanthia paradoxa by long spinose lobes% In Edessa F., another genus of bugs, the abdomen usually terminates in four strong sharp dentiform spines, the intermediate ones being the short- est, and: in some the margin is also armed with. spines?; occasionally the anal spines are very long‘. In addition to the ventral horns before mentioned that distinguish the sexes of Some insects t; 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 €. 2. Organs of respiration’. 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 appear- ances in some insects, which at first sight seem to par- take of the same character, but which being really inde- pendent of that vital function, may here have their place. If you examine the abdomen of the mole-cricket (Gryllo- talpa 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 chan- a Stoll Punaises, t xiii. f. 101. b Ibid. t. xvii. f. 117. © Ibid. t.xxxvi. f. 253. d See above, p. 339—. © De Geer, vi. 260. Ł. xv. f. 8. d. £ Phare XXIX, 714 EXTERNAL ANATOMY OF INSECTS. nels, 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 interme- diate dorsal segments, four or six elevated points resem- bling spiracles, but not perforated, connected often by - corrugations in the skin or crust?; in the larvee also ot some Reduvit 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 sec tion 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 # white round callus, with a dark point resembling # perforation on its exterior side, and terminating inter- nally in a channel covered by membrane leading to the disk of the segment, so that the whole in shape resem- bles a tobacco-pipe®. A number of similar callosities with a central impression, but without any channel, va- riously disposed, are also to be found in another bug; Rhinuchus compressipes K.¢ In the Homopterous sec- tion 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 Centrots in which the real spiracles are quite concealed. In spiders, as we learn from Treviranus, the open ven- tral spiracles of the scorpion are replaced by pseudo- a Prare XXIX. Fie. 22. is part of the back of the abdomen of the pupa of a Pentatoma. a the pseudo-spiracle, b the connecting Corru- gations. b Thid. Fie. 24, a. © Ibid, Fre. 27. 4 “EXTERNAL ANATOMY OF INSECTS. Tie, spiracles; these in Hpezra 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 żwo?: the most re- markable, however, are exhibited by the cancriform spi- ders before noticed”: in Epeira cancriformis, in the plate. which covers the abdomen, they are dark red spots with an elevated rim and centre" 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’. 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 €. 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’. Machilis to the anal fork adds eight pair of ventral linear springs (Elastes), which are covered with hair or scales, and ter- minate in a bristle or two. I have on a former occasion mentioned the natatorious laminæ with which the anus 2 Treviranus. Arachnid. 23—. » See above, p. 702, 706. c Phare XXIX. Fie. 26. represents one of them. a Vor. II p. 319—. e Prare XV. Fic. 14. M”. De Geer, vii. t.i1. f. 5, 10,21. f Ibid. $, i. J. 4, 14. 716 EXTERNAL ANATOMY OF INSECTS. of the larva of Agrion and of some Diptera is furnished*; the same part in that of Dytiscus ends in a pair of taper-. ing organs, fringed on each side like the hind-legs of the imago, which doubtless assist it in swimming; those respiratory foliaceous laminee which so singularly di- stinguish the abdomen of the larvae of Ephemera, like the legs of the Branchiopod Crustacea, are probably used in some degree as fins, and aid their motions in the water €- Under this head may also be mentioned the many-jointed bristles that form the long tails‘ of the fly that proceeds from these larvae, 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‘, 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‘. 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 or- a See above, p. 154. > Pratre XVIII Fre. 5 ° Prate XXIX. Fie. 3, 4. De Geer, ii. #. xvii. f. 12. aid xviii. Pa t Tbid. A xvi. f. 8—13. ~ Prater XV, Fic. 16, 8”. f Ibid. Fie. 12. ZL”. i EXTERNAL ANATOMY OF INSECTS. yay gans 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 tre- mendous 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?, the mandi- bule of spiders’, the second pair of pedipalps, or the fangs of the Scolopendride*, and the organ in question‘; but the last possesses this peculiarity, that it is placed at the opposite extremity of the body, where it is preceded bya 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 ©. 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 se- cond, 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 in- cluding 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 down- 2 Philos. Trans. 1818. t. xxii. N. Dict. @ Hist. Nat.ii. 275—. Hoole’s Leeuwenh. i. t. u.f. 19.1. © Leeuwenh. Epist. 17. Octobr. 1687. f. 10. C. Hoole’s Leeuwenh. i. t. v. f. 12,13. * Treviranus, Arach. 4. 718 EXTERNAL ANATOMY OF INSECTS. wards, and has an orifice in a channel at the end on each side. Treviranus could not discover these orifices in the sting of Scorpio europeus* ; 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 consist- ing in some specimens of more than fwenty joints, the first being very much larger than the rest”. 6. Appendages*. 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 Staphylinide ; the leaflets { foliola) of the Libellulina ; the floret ( flosculus) of the Fulgore; the cerci of the Blattide and Gryllina; and the threads (fila) of Ma- chilis: but having nothing important to add concerning them, the definitions of those terms will give you a suf- ficiently clear idea of themi. As they are common to both sexes, if their use is connected with the sexual in- tercourse, it must be similar to that which Treviranus ascribes to the pectens of scorpions, they must be in- struments 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 a Treviranus, ubi supr. 14, b In my specimen including the first joint there are twenty, and some seem to have been broken off. In Ræmers figure (Genera, t. xxix. f. 11.) there are only ex. Perhaps they vary in number ac- cording to the age of the animal. ¢ Pirate XV. Fie. 13, 16, 17. 4 See above, p. 391—. EXTERNAL ANATOMY OF INSECTS, 719 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 €xamination, 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 Crearor in this department, that it would require a long life, and fill volumes upon yolumes, to discover and give a de- Scription of all the peculiarities of structure of the insects that are already known; and could all that exist è 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 re- quired to receive the results. But “ who is sufficient for these things®?” This is a question that the most able and most experienced physiologist must often feel dis- posed to put to himself when, lost in the intricate laby- rinth of the works of his Maker, he sees all things ar- ranged, “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 him fragments of the truth of things, and such vestiges * 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! > 2 Cor. ii, 16. ; 720 EXTERNAL ANATOMY OF INSECTS. of the grand system. of the Derry, as enable him in some degree to appreciate, and dispose him humbly to adore that Wispom, Power, and Goopness, 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. > = = Asi À nd y N Ss x AS N yw iw) ns ~ iii WMA EXPLANATION OF THE PLATES:. ene PLATE VI.” FIG. 1. Head of Mylabris. Upper side, or face. 2, Under side, or subface. 3. Trophi of Dytiscus. Sis 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 VIIL? 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’, 7. Head of Oxypterum. Face. * Recourse must be had to the synoptical table of the nomencla. ture of the parts of the external crust of Insects (Vor. IIT. p. 354) for the explanation of the reference letters not here given. > VoL. I. p. 394—. III. p. 355—, 394—. IV. p. 305—. c Ibid: * Probably e' is resolvable into two pieces. VOL. III, 3A EXPLANATION OF THE PLATES. . Head of Pulex, with its antennz and trophi, or rostrulum. Side view. _——- Araneide@, with the trunk. . Trophi of ditto. . Head of Scolopendra morsitans. Subface. Front view, to show the mouth. . Trophi of ditto. . Pharynx of Pentatoma. (Savigny.) PLATE VII.. . Prothorax of Lucanus. a. Apex. b. Base. cd. Sides. a. Disk. . Antepectus of ditto. . Alitrunk of ditto. Upper side. a. A piece between the metathorax and metaphragm, Under side. . Abdomen. Upper side, or tergum. - Under side, or venter. . Antepectus of Hydrophilus piceus. . Alitrunk of ditto. Under side, to show the metasternum. , Abdomen of Dynastes Aloeus, to show the dorsal and ventral spiracles. . Prothorax of Locusta, a. Apex. b. Base. cc, Sides. 12. 13. 14. 15. 16. 17. 18. . Antepectus of ditto, to show the prosternum. Alitrunk of ditto. Upper side. Under side. Lateral view. VoL. III. p. 48. Abdomen of ditto. Lateral view. Alitrunk of Cicada Latr. Upper side. Under side. a. The piece in the Ọ corresponding to the drum-covers of the ĝ, Abdomen, and part of postpectus of ¢ ditto, Under side, to show the drums, Vot. II, p. 405—. : * Vor. II. p. 367—, 529—. IV. p. 326—. EXPLANATION OF THE PLATES. 723 FIG. 19. Abdomen, and part of postpectus of g. Lateral view, with the covers removed to show the machinery. 20. Alitrunk. Upper side. Pentatoma. PLATE IX,? . Alitrunk of Cossus ligniperda. Upper side. . Part of ditto, to show the mesophragm. , — Under side. . Patagia of Lepidoptera. Upper and under sides, Vol. III. p. 268, 539. - Tegulz of ditto. Two species. Vot. IIL. p. 378. . Prothorax of Eshna. a. The base elevated and forming an obtuse angle with the rest. 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, Lateral view. a. A piece by which the mid-leg is connected with the scapular. Vox. III. p. 48, 565. . Part of the abdomen of Libellula. . Trunk of Semblis F. Upper side. . Alitrunk of Vespa Crabro. Upper side. a. Aperture in the trunk for the passage of the ligament that elevates the abdomen. . Lateral view of ditto. posterior part of ditto, and of the base of the abdomen, to show the above apparatus. a, The aperture, Vot. III. p. 701. . Head and part of the manitrunk of Tenthredo L. to show the membrane a. representing the prothorax. VoL. III. p. 550—. * Vou. II. p. 367—, 529—. IV. p. 326—. 342 724 EXPLANATION OF THE PLATES. FIG. 4g. 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 no- dus. Vou. III. p. 389. 4. 19. Alitrunk of Musca. Upper side. a. Alula or winglet. 20. Metathorax of ditto. i 91. Alitrunk of ditto. Lateral view. 22, Abdomen of ditto. Venter. PLATE. X.? N.B. In this plate the red points out the costal, and the yellow the anal areas, the intermediate being unco- loured. . Elytra, a. Base. b. Shoulder. c. Lateral margin. d. Apex. Tegmina. Blatta. . Hemelytra. Pentatoma. . Wing. Coleoptera. a. An insulated nervure, VoL. III. p. 625. ; . ——- Dermaptera. . —- Lepidoptera. . ——- Neuroptera. . ——- Hymenoptera. Tenthredo L. A Bombus. Under wing. Hymenoptera. Proctotrupes. _———— Diptera. Tipula. - Psychoda. Vou. III. p. 645. Musca. ab. Two areolets be- tween the costal and mediastinal nervures. c. Areolet between the mediastinal and postcostal nervures. * Vor. II. p. 347—. II. p. 372—, 595—. EXPLANATION OF THE PLATES. 725 FIG. d. Areolet between the postcostal and subcostal ner- vures. e. Open areolet. Vor. IIL. p. 634. 15, Under wing. Diptera. Stratyomis. ab. The two areo- lets between the costal and postcostal nervures ; the mediastinal being nearly obsolete. c. Middle areolets crowned by a small one, d. PLATE XI.* Antenne. FIG. FIG. 1. Setaceous. 13. Distichous. 2, Capillary. 14. Pectinate. 3. Filiform. 15, Duplicato-pectinate. 4, Incrassate. 16. Ciliate. 5. Fusiform, 17. Flabellate. 6. Prismatic. 18. Ramose. 7. Ensiform. 19. Furcate. 8. Falciform. . 20. Auriculate. a. The auricle. . Moniliform, 21. Palmate. . Dentate. 22. Irregular. . Serrate. 23. Perfoliate. . Imbricate. PLATE XII. Antenne. FIG. FIG, Capillaceous., 9. Capitate with a solid . Mucronate, ~ knob. - Uncinate. 10. Capitate with a perfo- . Clavate. liate knob, - Nodose, or Biclavate. 11. Filiform. . Convolute. 12. Globiferous. . Geniculate. 13. Connate. . Capitate with a tunicate knob, O~IA A SP wpe 14. ; i } Setigerous. * Vor. III p. 366, 510—. IV. p- 316—. 726 EXPLANATION OF THE PLATES. FIG. FIG. 16. Subulate. 23. Stupeous. Vor. II. p. 646. 24, Plumose. 19. Filate, compound. 25. Scopiferous. a. Brush. a. Joints. 26. Barbate. 90. Filate. 27. Verticillate. . Aristate. Setarious. 28. Inflated. a. Bristle. 29, Auriculate. a. Auricle. . Aristate. Plumate. a. Bristle. zé } Filate, simple. PLATE XIII. . Unguiculate feeler. Gonyleptes. a. Claw. _ Securiform ditto. Cychrus. a. Terminal joint. _ Inflated ditto. Araneide ĝ. a. ditto. _ Lunulate ditto. Oxyporus. a. ditto. . Dentate mandible. Megachile. _ Suctorious ditto. Larva of Dytiscus. a. Aperture. _ Prosthecate ditto. Staphylinus. Vor. IMI. pp. 356, 439- . Trophi of Curculio L. - Pedunculate eyes. Diopsis. a. Footstalk. . Compound ditto. Muscide. Vor. III. p. 494. 3. . Conglomerate ditto. Tulus. Ibid. p. 494. 2. . Rostrate head. Balaninus. . Capistrate ditto. Nitidula. . Clypeate ditto. Copris. . Lychnidiate ditto. Fulgora. . Buccate ditto. Myops. a. The inflated part. . Cruciate prothorax. Locusta. _ Cucullate and alate ditto. Tingis. _ Subulate elytra. Sitaris. . Ampliate ditto. Lycus. 1 2 3 4: 5 6 7 8 9 a Vor. IV. p. 307. iii. iv. 309. b. 310. d. 313. viii. 328, 334. EXPLANATION OF THE PLATES. PLATE XIV. FIG. 1. Ideal wing, to exemplify painting. Vox. 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 Jascia, or band. 6. Macular ditto. cd. Sesquialterous ditto. de. Sesquitertious ditto. f. Dimidiate ditto. g. Abbreviate ditto. h. Pyramidate ditto. z. Super- cilium. &. Hastate pupil. ¿ Compound eyelet or ocellus. m. Nictitant ditto. n, Simple ditto. o. An- nulet. p. Bipupillate eyelet. g. Sesquialterous ditto, r. Double ditto, s. Caudate wing. ¢. Pupil. wu, Iris. v. Atmosphere. . Reversed wings. Gastrophaca. . Digitate ditto, Pterodactylus. . Faleate ditto. Attacus. . Saltatorious leg, with loricate thigh. Locusta. - Natatorious ditto. Dytiscus. . Ambulatorious ditto. Lucanus. - Prehensorious ditto. Gonyleptes. PLATE XV.’ . Laminate coxa. Haliplus. 2. Alate tibia. Lygæus phyllopus. a. The appendage. - Clypeate ditto. Crabro g. a. The clypeus. Vor. III. p. 334. - Dolabriform ditto. Curculio maritimus E.B. - Fossorious leg, with palmate tibia. Clivina. Vox II. p. 365. with digitate ditto. Gryllotalpa. Ibid, p. 366. Chelate feeler. Scorpio. . Scutate tarsus. Hydrophilus piceus 8. Vou. Ill. p- 336. - Patellate ditto. Dytiscus marginalis 8. a. Cups. Ibid. p. 336, 694—, * Vou. IV. p. 286—, 338, 345—. * Ibid. p. 345—, 350—. EXPLANATION OF THE PLATES. . Obumbrate abdomen. Epeira cancriformis. . Retracted ditto. Gonyleptes. , Cheliferous tail. Panorpa ĝ. . Flosculiferous ditto. Fulgora. . Saltatorious ditto. Podura. . Folioliferous ditto. Æshna. . Cauduliferous, and filiferous ditto. Machilis. . Styliferous ditto. Staphylinus. . Unciferous ovipositor. Locusta. . Ensate ditto. Acrida. . Navicular ditto. Cicada. . Serrulate ditto. Tenthredo L. . Telescopiform ditto. Chrysis. . Anal apparatus of Blatta. PLATE XVL* _ Extricated ovipositor. Pimpla. Two pieces. . Telescopiform ditto, Stomoxys calcitrans? (Reaum.) : Œstrus. (Ibid.) Vor. I. p. 150. . Semicomplete pupa. Cicada. , Subsemicomplete ditto. Libellula. a. Mask. Vox. III. p. 125—. . Incomplete ditto. Hydrophilus. (Lyonnet.) —- Myrmeleon emerging from its cocoon. (Reaum.) Vespa vulgaris. Chironomus plumosus. (Reaum. ) ab. Respiratory plumes. ; Obtected pupa. Apatura Iris. - Vanessa Urtice. a. Head-case with two points. Gonepteryx Rhamni. 4. Head-case-with one point. * Vou. IV, p. 351, ii. III. LETTER XXXII. Vor. I. p. 65—. ` EXPLANATION OF THE PLATES. 729 FIG. 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, Vou. III. p. 249—. . Hairy obtected pupa of Laria Jascelina. PLATE XVII. . Coarctate pupa. Cistrus hemorrhoidalis. (Reaum.) Stratyomis chameleon. (tbid.) a. The _ pupa as formed within the skin of the larva. . Oviform body which many pupæ of Diptera at first as- sume under the skin of the larva. (Ibid.) Vow, IH. p. 235. . The same when the parts begin to show themselves. (Ibid.) . Cocoon of Saturnia pavonia; a. Pupa. b. Threads that close the orifice. Vor. III. p. 217, 279. . Loose and irregular ditto, of Arctia villica. Ibid. p. 220. . Boatshaped ditto, of Tortrix prasinana. Ibid. p. 221. . Network ditto, attached to the stalk of a plant. . Ditto, imitating the scales of fish. (Reaum.) Vou, I. p. 462. ; . Spiral case of Trichopterous larva, formed of pieces of leaf. (De Geer.) , Grate spun by these larvæ to prevent ingress. (Ibid.) Vou. II. p. 264. , Chilopodimorphous larva of Melolontha vulgaris. VoL. ILL. p. 163. . Araneidiform? ditto of Cicindela campestris. Ibid. 152, 163. : PLATE XVIII.” . Anoplurimorphous larva. Chrysomela Populi. a. Osma- teria, or scent organs. VoL., II. p. 245. II. p. 163, 166. * Ubi supr, » Vor. ILL, Lerter XXXI. VOL. III. 3B 730 EXPLANATION OF THE PLATES. FIG. 2. Anoplurimorphous larva. Cassida, a. The fecifork co- vered with excrement. Vor. IV. p. 353, 5. 3. Helminthimorphous or vermiform ditto of Balaninus Nu- cum. Vou. III. p. 163. 4. Chilognathimorphous ditto of Elater Segetum. a.a. Spi- racles, . Decapodimorphous ditto of Dytiscus marginalis. Vou. iil. p. 165. . Chilopodimorphous ditto of Staphylinus? a. Anal pro- leg. È . Amphipodimorphous ditto of Acrida. Vou. HI. p. 165. . Larva of Zelus. . Helminthimorphous ditto. Apis mellifica. (Reaum.) . Larva of Sirex. — Tenthredo L, (Reaum.) a. 6 legs. 6. 16 pro- legs. -= — Sphinx. a.6 legs. 6, 10 prolegs. c. Anal horn. . Spinose ditto of Vanessa Io, PLATE XIX.* . Larva of Papilio Machaon. a. Its retractile osmaterium emerging from its neck. Vou. I. p. 244—~. Ill. p. 148. l . Larva of Cerura Vinula. a. Its anal mastigia. Vor. III. p. 151. . Onisciform ditto of Thecla Rubi. . Larva of Stauropus Fagi. (Rösel.) Vow. Ill. p. 133. note 4%, ~ Notodonta ziczac. (Reaum.) — Laria fascelina. a. Pencil of hairs, 6. Ver- ricules of ditto. c, Fascicule of ditto. Vor. IV. p. 277. 9, Sects , ———- of one of the Geometers in their attitude of surveying. ) 2 Vor. IH, Lerrer XXXI. X EXPLANATION OF THE PLATES. FIG, 8. Araneidiform larva of Myrmeleon, (Reaum.) 9, Larva of Culex pipiens, (Reaum.). a. Tail. b. Respi- ratory apparatus. 10, ——~ of Chironomus plumosus. (Reaum.) a. Respira- tory 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 Chameleon. (Swamm.) a, Plumes of respiratory orifice. PLATE XX.: - Larva of a Musca. — an Gstrus. - Egg of Vanessa Urticæ. (Sepp.) Hipparchia Pilosellæ. (Tbid.) —— EHyperanthus. (Ibid.) Geometra Crategata. (Ibid.) ——— Pieris Brassica. (Ibid.) Iipparchia Ægeria. (Tbid.) ~ Ourapteryx Sambucaria. (Ibid. ) -——— Noctua nupta. (Ibid. ) Frazini, (Ibid. ) Geometra prunaria. (Ibid. ) armillata. ( Ibid.) Lasiocampa neustria. (Reaum.) Hipparchia Jurtina. ( Sepp.) Pentatoma. a. Bow-shaped spring, by which the operculum is thrown off. Voz, III. p. 104. Apis mellifica. (Reaum.) -————— Culex pipiens. (Ibid.) a. Summit. Scatophaga. (Ibid.) aa. Auricles, NO = a 4, 5. 6. rf 8. Y. * Ubi supr. and Lerter XXX, 732 EXPLANATION OF THE PLATES. FIG. 20. Necklace of eggs. Vox. III. p. 67. 21. Egg of Tipula oleracea. (Reaum.) 22. Ophion luteum. (De Geer.) Vou. IV. p. 213—-. 23. Nepa cinerea. (Swamm.) 94. Jelly, with a necklace of eggs running in a spiral direc- tion from end to end, taken out of the water. 25. Jelly of more consistence, enveloping the eggs of Phry- ganea atrata. Vou. III. p. 68. Printed by Richard Taylor, Shoe-Lane, London. A OE A EON OGLE TALENT ENE IO NLL AE TOTO NIT OI TOE srera tree aaa a a RG “ors S _—— i = E ~ a — + è