A PAPER NOMENCLATURE OF THE PARTS OF THE HEAD INSECTS, (EEAD BEFORE THE ENTOMOLOGICAL SOCIETY OF LONDON, DECEMBER 2, 18 AND PUBLISHED, WITH EXPLANATORY PLATES, IN THE ENTOMOLOGICAL MAGAZINE). EDWARD NEWMAN, F.L.S. " I And it impossible to give, according to the present state of tlie science in England, any satis- factory description of insects without making some previous observations on their anatomical nomenclature." — Macleay. " Ce que personne n'avait encore tenti j'ai osi I'cntreprendre." . Savigny. " Dans ce travail je n'ai d'autre m^rite que d'avoir gen6ralis6." Marcel oe Serkes. LONDON: PIUNTLD FOR THE AUTHOR, BY R. CLAY, BBSAD-STBEET-IIILL, CIIEAPSIDE. 1834. §^^. SvJ, 4«.jr. 1^ i^ Ah^-v<- A PAPER, In addressing the following observations to the Entomo- logical Society of London, it seems needful to remark that they form part of an essay, now in the course of publication in the Entomological Magazine, under the title of " Osteology, or External Anatomy of Insects." In all probability very few of the members of this Society have even heard of that essay, or are in any way acquainted with its nature and objects ; permit me, then, to premise that it has in view the establish- ment of a uniform nomenclature for all the parts observable in Hexapod Insects. One portion only of the essay has been published; in which, adopting an idea previously broached, I have attempted to show that all Tetrapterous Hexapods are composed of thirteen segments or rings ; to these rings I have proposed the following names: — 1. Caput; 2. Pro- thorax ; 3. Mesoihorax ; 4. Metaihorax ; 5. Propodeon ; G.Podcon; 1 . Metapodeon ; S.Oetoon; d.Efinaton; \0. De- caton; 11. Protelum ; \2. Paratelum ; 13. Telum. I have further shewn that the legs are attached thus, — the first pair, which I propose calling Propedes, to the Prothorax ; the second pair, Mesopedes, to the Mesothorax ; the third pair, Metapedcs, to the Metatkorax : and that the wings are at- tached thus, — the first pair, to the Mesothorax, to be called Proalce. ; the second pair, to the Metathorax, to be called Metalee. As far as my knowledge extends, no technical term had been previously applied to nineteen out of these twenty- three parts ; whilst four, the Caput, Prothorax, Mesothorax, and Metathorax, had received, some years before, the names now retained. I propose, further, that the prefixes, pro, mcso, and meta, be applied to the individual articulations of each pair of legs, these never having, to my knowledge, received tech- nical appellations. 4 EXTERNAL ANATOMY OF INSECTS. The present paper, though but a portion of a larger work, and relating only to one segment out of the thirteen, is in itself complete, inasmuch as it contains all that will be said con- cerning the head. Permit me, further, to premise that the proposed nomenclature and descriptions have reference solely to the hexapods ; the organs described appear throughout the annulate kingdom of animals, but under widely different cir- cumstances and forms. I beg to thank the Society for permitting this paper to be read, after I had reserved the right of publication in another channel ; a degree of liberality which, if persevered in, will ensure an overflow of communications. It appears scarcely to admit of a doubt, that the head of an insect is composed of four distinct portions. That the por- tions of the head are merely sections, appears to me consistent with the general harmony of Nature." The second segment in the locust tribes, and the third segment in the bee tribes, present to the inquirer a quadruple division by far more mani- fest. You will however remark, and it is of no mean impor- tance, that, while the portions of the second, third, and following segments, are united by suture, those of the head have a freely moveable articulation. That the portions of the head are segments, is argued from the circumstance, that those organs which in one group are employed for manducation, in another serve solely for progression. When this is the case, the organs thus modified differ in no material characters from those of the second, third, and fourth segments. Consequently, it is said, that by their increase of importance to that of true organs of locomotion, they also raise the portions which bear them to an importance equal to that of those portions which uniformly bear such organs. These changes in the uses to which organs are applied we frequently detect in progress in intervening groups. They afford the most obvious distinguishing characters. A man is termed a biped ; a horse, a quadruped ; and not in- correctly : yet the number of limbs in each is the same. In man, the first pair of limbs is essential to feeding ; in « The segments of tlie head, which are sometimes three, but typically four, are therefore of course only to be considered as secondary. — MacLeay, EXTERNAL ANATOMY OF INSECTS. 5 the horse, these are purely organs of locomotion, and differ in no respect from the other organs destined to the same end; but in many animals we find them applied with per- fect ease to either purpose. ,^ The adaptation of the same organs to different purposes in the superior animals is obvious ; consequently, in the inferior, fairly to be inferred. Conclu- sions of this kind have been stigmatized as theoretical. Be it so : theory may be sound as well as unsound. When theory is a compound, of which facts are the ingredients, it is sound. In the present instance, facts are the ingredients. Whether the four portions of the head be primary or secondary parts, — in other words, whether they be segments or sections of segments, seems to hinge on another question ; vis. whether a single segment can bear four feet ; for it seems scarcely to admit of a doubt, that, in some annulate animals, the part which is analogous to the head of tetrapterous hexapods has four organs of progressive motion employed as feet. This circumstance appears to me by no means more remarkable, than that the third and fourth segment should each bear four organs of progressive motion, two of them adapted to walking, and two to flight. On these grounds I have considered the four parts of the head as so many sections of a segment, and consequently equivalent to the sections of succeeding segments. To give them the same names, however, while a doubt remains, would be objectionable ; more especially, as a nomenclature sufficiently definitive has been long established, although in its application confused and various. The parts of the head are the skull, the lips, the feeler-jaws, and the mandibles. These are the four sections of a segment. To simplify and conform to received ideas, the three last must be treated of as the mouth, of which, in tetrapterous hexapods, they constitute the com- ponent parts. The skull of insects is compact, solid, and osseous. It has a large opening in front, in which is situated the mouth; another behind, through which pass the oesophagus, spinal cord, blood-vessels, muscles of connexion with the prothorax, &c. ; and two smaller ones, generally in front, above that of the mouth, in which are placed the antenna;. There are two compound eyes, one on each side, so closely soldered into the skull, that, in case of fracture, the separation does not take place at the suture. Desvoidy well observed, that the eyes 6 EXTERNAL ANATOMY OF INSECTS. form the lateral regions of the scull. Besides these compound eyes, insects have generally two or three ocelli, or simple eyes. These, like the true eyes, are firmly fixed in the skull, and are alike incapable of being separated from it without fracture. The simple eyes are situated usually on the crown of the head; their number is generally, in Lepidoplera, two; in Diptera, three ; in Hymenoptera, three ; in Coleoptera, none ; •> in Orthoplera, three ; in Hemiptera, two. With the exception of the compound and simple eyes, the skull is a single, continuous, and undivided piece. Entomologists have endeavoured to assign names to the different regions of the skull, but have hitherto been unable to establish them. It cannot be too frequently or too emphatically repeated, that names of parts having unfixed limits are objectionable, as leading to confusion. An author might establish his nomen- clature from a single species, provided inquiry was directed to that species alone. The anatomy of a beetle's or locust's skull gives us scarcely any idea of that of a butterfly's. A nomenclature well adapted to the skull of a cockchafer would be useless for that of a dragon-fly. Fabricius describes no parts but the forehead, chjpeus, throat, and simple and compound eyes. Latreille, Burmeister, and many others, recapitulate the labours of preceding writers. Desvoidy is original, precise, and clear, but his nomenclature is adapted solely to Diptera.'' '' In the fourth number of Germar and Zincken Sommer's Magazine, it is affirmed, that they are discoverable in Gravenliorst's genus Omalium, but not in the kindred genera Mkropepius and Anthophagus. Upon examining the former genus, I find, that although Omalium planum and affinities, 0. Slriatulum, and some others, appear not to have them, yet with the aid of a good magnifier they may be discovered in most species of that genus, as likewise in Eveeslhetus. I find them also very conspicuous in A. Caraboides and other Anthophagi, but some species appear to want them. — Kirby. On a pr^tendu que les Anthophagus, les Omalium et les Paussus avaient de ces yeux simples ; mais j'avoue que je n'ai jamais pu les apercevoir. — Straus- Dnrchheim. " La tete off're six regions principales : le front ; la face ; la region inf^rieure; la rfcgion postiSricurc : les yeux ferment les deux regions lateralcs. 1. Le front (from-) ou la region frontale, s'itend de la partie posterieure de la (etc, 4 la base des antennes, et d'un (eil il I'autre ceil. II se divi.se en trois parties. La partie la plus postferieure, ct celle qui ordinairemcnt a le moins d'6tendue est situ^e derrifirc les stemmates, et porte le nom de vertex (vertex.) La partie stemma- tique, ou les stemmates (stemmata), plac6e entre le vertex et le vrai front, consiste en un petite pifice ordinairemcnt demi-circulaire, oil les yeux lisses sont im- plantes. Le front, le vrai front (frons) s'felend d'un ceil a I'autre et de la region EXTERNAL ANATOMY OF INSECTS. 7 Straus -Dijrckheim's description of the skull of a cock- chafer is beautifully simple ; and the only one yet pub- stemmatique & la base des atitciines. II ofire sur son milieu deux pieces ordi- nairement adoss^es et colorees assez r^gulifires : ce sont les frontaux (fronlalia.) A la partie anterieure du front, dans un triangle plus ou moins prononc6, vers I'origine des frontaux, on remarque deux pieces plus ou moins d6velopp6es, et qui parviennent meme a separer les frontaux, et a s'intercaler entre eux dans toute leur longueur : ce sont les inter-frontaux (interfrontaliu.) Les parties latdrales du front sont formC-es, ainsi que je le dirai, par le prolongcment des optiques. La region frontalc est ordinairement plus developpde sur les femelles que sur les males. 2. La face {fades) est la region qui s'6tend plus ou moins verticalement de la base des anteunes i I'tpistome et transversalement d'un ceil il I'autre ceil ; c'est -i. tort que les entomologistes Allemands la noniment hypostome (hyposloma). Cette region se compose de diverses parties distinctes qui meritent d'etre specialement caractcrises. La portion m^dianc offre deux fossettes (fovea) verticales ou obliques, qui servent de support aux antennes dans le repos : ees fossettes, faites de deux pieces souvent tris distinctes, forment quelquefois une cloison par I'adossement de leur cotfe internes; alors elles emittent une petite crete, plus ou moins aigue a leur point de jonction. Le long du cot^ externe de cliaque fossettc s'etend une pi^ce, plus ou moins d6velopp6e, plus ou moins cili- gSres, qui part de la base des antennes, longe le bord de la face, prend un peu plus de volume vers son angle ant(5rieur, et portc un gros cil avec une sorte de moustaclie, due il d'autrcs cils moins forts. Ces deux pieces qui portent le nom de faciaux (facialia) sont souvent ciligfires le long des bords du peristome. Les mfedianes (mediana) sont des pieces ordinairement triangulaires, souvent un peu colortes, et susceptibles d'acquerir un certain d6veloppement, qu'on remarque entre les faciaux et les pieces du pourtour de I'a'il un peu au-dessus des pieces lat^rales du peristome; ils ne raontent jamais jusqu'A la base des antennes. Je nomme optiques (optica) les piices plus ou moins bomb^es, qui entourent I'aMl sur la face, moment jusqu'4 la base des antennes, s'ctendent jusqu'au vertex, et jusque derrii^re I'ceil. Souvent ils forment vers les antennes la crete aigue ou Tangle qui s^parc le front d'avec la face. Ils sont ordinairement piligires surtout a la region frontale ; plusieurs observations tendent a me faire croire que, vers I'angle frontal, ces pieces optiques sont manifestement separfies. Si ce fait vient a se confirmer, on aura les optiques frontaux (aplica frontis) et les optiques de la face (optica faciei.) Ces optiques correspondent a une portion des joues (gence) des auteurs. 3. La r6gion inferieure situee entre la face et la region post^rieure, oftre un cavitt oft la base de la trompe et la plupart de ses muscles prennent leur attache, et oil la trompe se retirfie ordinairement pendant le repos. Cette cavity que je nomme peristome (peristoma) est form^e de deux pieces latferales qui se soudent en avant ct en arrifire. J'appelle 6pistome (epistoma) son bord antfericur, qui en haut se sonde avec les fossettes et se developpc souvent en bee. Cet 4pi- stome affecte diverses formes qu'il importe bcaucoup de remarquer : sur quelques genres, il est manifestement form^e par deux pieces. Les faciaux longent 11 lat(!ralement les pieces du peristome et souvent ils y sont ciliis. Les lateraux I ( (lateralia) sont de deux pieces ordinairement asse/, d6velop))ecs ct faciles A dis- I ( tinguer, que Ton voit sur les cotes inferieurs du p6ristome. lis s'itendent sur les medians, ct s'avancent jusque sous la partie un peu post^ricure des yeux. Dans plusieurs genres on voit, sous I'epistome une petite pii^ce semicirculairc, solide est bien detachee, qui recouvre la base anterieure de la trompe : c'est le chaperon (clypeus) des autres insectes. 4. La region post^ricure, fevidemment g EXTERNAL ANATOMY OF INSECTS. lished that is generally applicable.'' It will be of small sei'vice to name, with the greatest nicety, the parts visible in one genus or family. With exquisite talent Savigny has remarked, that naturalists multiply facts to admiration, but invariably decline generalizing them." It is this generalizing, this universal application, that we stand in need of. We want a nomenclature that can be applied to all. The only portion of the skull to which any general names can be attached, are these : — the Epicranlum, or upper portion of the skull, of which the Clypeus or shield, and Ocelli or simple eyes, are constituent parts ; the Gula or throat, which is the under portion of the skull, of which the Mentum or chin, is a constituent part;' and the Oculi or eyes, which are the lateral portions. The neck, of various authors, as applied to a part of the head, is nothing more than an elongation of the compos^e de deux pieces larges, inKrieurcs, et laterales, se trouve en contact avec la face ant^rieurc du prothorax. EUe est perc6e d'un trou pour le passage des nerfs, des trach^es et du tube digestif. A sa partie superieure, entre les yeux, ct au-dessus de ce trou, on doit distinguer le cerebral {cerebrate) ou la pifice qui fait suite au vertex et qui recouvre le cerveau. 5 et 6. Les yeux a reseau, ou les grands yeux forment les regions laterales de la tcte. lis offrent raremcnt quelque chose de remarquable et sont toujours entoures dans leur circonf^rence par les optiques, un peu moins dfiveloppees en arrifire qu'en devant. — Desvoidy. ^ Le crane du Melolontha est compose de six pieces soud^es entre elles, et qui je nomnie ia pi^ce Epicranienne, ou simplement I'Epicrane, le Chaperon, la Basilaire, la Pr^basilaire, et les deux Combes des yeux. 1. La piice Epicranienne comprend la majeure parti de la tete, dont elle occupe prinoipalement la region supferieure. 2. La Chaperon est une seconde piCcc impaire de la tcte, placfee transversalemeiit au devant du bord antero-supericur de I'Epicrane, avec lequel elle se sonde, et dont elle fait la continuation. 3. La pifice Basilaire, ^galement impaire, occupe la partie infcrieure et post^rieure de la tete : sur les cot^s, elle s'unit par suture avec I'Epicrane. 4. Je donne le nom de Prebasilaire 4 une quatridme pi&ce impaire du crane, placfie au-devant do la basilaire dont elle fait la continuation. 5 et 6. Les Corn^es des yeux forment les seules pieces paires qui entrent dans la composition du crane : ce sont deux calottes ovales, convexes, encliass^GS dans les deux grandes ouvertures laterales de I'epicrane. — Straus- Durckheim. ' Les entomologistes multipliaient h I'envi les observations ; mais ils se dis- pensent de les gfineraliser ; ils creaient chaque jour des genres nouvcaux, et les premiers fondemens de cet Edifice auquel ils travaillaient avec tant d'ardeur n'cxistaient point. — Savigny. ' ■ It will be seen by a reference to Latreille's last work, Cours d'Entomologie, that he finally decides the mentum to be a portion of the skull, and not of the lip; in fact, he declares that the part he means is the pribasHnire of Straus- Diirckheim. See Cours d'Entomologie, p. 204. Le menton ou ganache n'est que prolongement de cet cspace infErieur et gulaire de la tete que M. Straus nomme piice pribasilaire. — Latreille. EXTERNAL ANATOMY OF INSECTS. U skull posteriorly .I' If description requires more definite limits, parts may be intelligibly designated by their propinquity to other parts. The shield is that part of the skull which is immediately above the mouth, and whose office is to shield it from injury. It was considered by Fabricius a part of the mouth. It is described by him as a corneous porrected part of the head, covering the mouth above, horizontally. It is divided by him into two parts, the disk and the limb : the limb is the upper lip, the disk is the true shield.'' It is called by Straus-Uriickheim, &c., c/iaperon; by Kirby, nose. In Lei)idoiHera, the shield is little apparent; it is hidden by the scales. In Drptera, it is more readily distinguished. In Hijmenoj)lera, it is very distinct ; you will recognize it, in the large corneous piece embraced by the lower portion of the eyes in the hornet.' In Coleoptera, it is sometimes obscure, as in Hydrous;^ sometimes very conspicuous, as in Copris. In Ortkoptera, it is always distinct. In several orders of this class, the suture, uniting the shield with the upper part of the skull, is membranaceous; hence the lip and shield move simultaneously with the mandibles in mastication. This is a departure from a general law of nature, and its occurrence is well worth remarking ; as the motion of the shield might induce an observer to suppose it the lip, which would conse- quently become a new and supernumerary elementary part.' In Hemiptcra, it is frequently raised and conspicuous, but its limits are indistinct. In the central group, the dragon-flies, it is raised, conspicuous, distinct, and horizontally divided into two."' The Ejjicranium is the whole upper region of the skull, bounded in front by the shield when distinct; laterally, by the eyes ; and behind, by the junction of the head with the prothorax. Its extent is greatest in Coleoptera ;^^ least, in Diptera and Netiroptera." The Oculi, or eijes, are large lateral portions of the skull, known to every one. The Ocelli, or simple eyes, are small, highly convex lenses, soldered into < Necrophoriis . Head, with a distinct neck. — Stephens. ^ Clypeus. Hori/.ontalis capitis pais cornea porrecta os superne tegens. a. discus A. limbus. — Fabricitis. ' Plate V. fig. le. 3!. k Plate V. fig. 1, and 3. if. ' Je suis convaincuc lorsqu'on aura mieux examine la bouclie des insectes, proprement dits, on troUTera quelle forme qu'cUe affecte elle est toujours esseii- tiellement composee des mcmes Clemens. — Savigny. "> Plate V. fig. 15, X. ae. ■ Fig. 3. ^E. » Fig. 15. JE. 10 EXTERNAL ANATOMY OF INSECTS. the top or crown of the skull. The Gtila, or throat, is the portion immediately below the under lip, and extends to the union of the head with the protliorax. The fore-part of the throat is sometimes called the mentitm, but has no fixed limit. The meutmn of MacLeay is the labium of Fabricius. The parts of the skull are these : the crown, the two eyes, the throat. These are the four divisions of a section. I would propose these names for the — FIXED PARTS OF THE HEAD.P (^) EpicRANiUM, or upper part of the skull. (je) Clypeus, or shield of the mouth. ( oe ) Ocelli, or simple eyes. {M) GuLA, or throat. {ee) Mentum, or chin. (Q5) OcuLi, or eyes. MOVEABLE PARTS OP THE HEAD. (y) Antenn/E, or cranial feelers. ( j ) Os, or mouth. As before observed, the great development of one part necessarily requires the proportionate diminution of another part. A part increases or decreases in volume precisely as the organs it may bear require muscle for their guidance and government; on the (acknowledged) plan, that, for so much muscular exertion so much muscle must be provided, which muscle must occupy so much space. This is well illustrated by the head of insects. Professor Sang has prettily observed, that every instrument, whether it be for the generation or transference of power, has a best size and a best form. Nature, in the formation of her instruments, has always adopted that best size and best form. If her creatures wanted but to see, a globular eye floating in space might perhaps be the uniform character of the animal world. If to see and to eat, an eye and a mouth would be given. If to move swiftly in the air were desirable, wings must be supplied ; if, on the earth, legs must be added ; if in the water, fins. To carry all these organs, p In this table the parts marked with small diphthongs are variable and inconstant ; those with capital diphthongs are constant throughout the classes. The diphthongs and letters refer to figures in Plate V. EXTERNAL ANATOMY OF INSECTS. U and to contain muscle to guide and govern them, a body must be added. Each part of the body will be of best size, and best form, for the functions it has to perform. We have seen that insects, in the larva state, have a very uniform allowance of muscle to each segment. In the imago, the charge of support- ing the whole body in the air is entrusted sometimes to a single segment ; and, in order to supply sufficient strength for the pur- pose, nature robs the neighbouring segments of their muscle, and gives it the one which needs it. In the head, the mouth, feelers and eyes operate, in the same manner, one on another. Observe the dragon fly, the emperor of his tribe i"" his wings rustle as he hovers stationary and hawk-like in the air ; his appetite is insatiable ; his food, the active occupants of his own element, — it is given to him in charge to set bounds to the increase of the insect race ; he beholds his prey afar off; he darts on it with the rapidity of a lightning-flash. To devour it, ere life is departed, is the work of an instant. He sails round and round ; he soars up and up. When the sky is serene he seeks his prey, like the swallows, almost beyond the reach of human sight. What organs docs such an animal require? Are (hey not these; eyes, mouth, and wings ? How has Nature provided for his wants? Regard his head : below, it is all mouth ; above, it is one continuous eye. Contemplate his wings: their character is strength and lightness, power and activity. His body is slender and graceful ; like a rudder, it serves as an instrument wherewith to shape his course. Porrected feelers, whether cranial, labial, or maxillary, would be comparatively useless to an animal whose dependence for support is on the keenness of its vision and the velocity of its flight. We find them but little prominent ; his every organ of the required size. The same law obtains as certainly and unvaryingly in form. There is truly a best size and a best form, and nature always provides it. The fixed organs of the head, manifesting but slight variations, require no further comment. The antcnncc or cranial feelers, and the mouth, are the only moveable organs. The antenna; are too well known to dilate on. The mouth must be considered more at large. The union of the head witii X\\e protliorax is by an articu- lation much more free than that between either of the following 1 Ucnus Anax of Lcacli, 12 EXTERNAL ANATOMY OF INSECTS. segments. Its powei- of motion is principally dependent on its relative size as regards the jjrot/iorax ; sometimes it greatly exceeds tiiat segment in size, and it is then loosely suspended at its extremity ; sometimes it is mucii less than the jjrothorax, and received almost entirely within it, as a ball in a cup.'' The mouth of insects is essentially uniform. Its united parts work to the same end by different modes. Nature arrives at her object by the most direct means. Her plans are the perfection of simplicity. It may sometimes appear otherwise to us ; that it does so is attributable to our igno- rance, not her error. The construction of the mouth is peculiarly simple : even amid all the confused and laboured nomenclature with which descriptions of it have been loaded, its exquisite simplicity renders it intelligible to the meanest ca- pacity. A celebrated lecturer well said, in allusion to the rage of the day for theoretical ideas and metaphorical allusions, " A stomach, gentlemen, is a stomach." In like manner, a mouth is a mouth, not a jyroboscis, nor a haustellum, nor a trunk, nor an antUa, nor a j>romuscis, nor a tongue, nor a rostrum, nor a rostrulnm, nor a rostellum, but simply a mouth. The terms haiistellate and mandibulale , as applied to the mouth of ' Dans les insectes I'articHlation , comme dans quelqiies espices A' Altelabes, la tete se renverse en airif re par un tubercule arrondi, reyu dans une cavitfe cor- respondante du thorax; le bord de cette cavitfe est ^chancre et ne permit le mouvement de la tete que dans un scul sens. U n'y a guire que dans les insectes Orthoi)teres, et dans quehiues Neuropldres qu'on reinaniue rarticulation ligamenteuse : la tete, dans cette disposition articulaire, n'est gi!n6e que dans ses uiouvements vers le dos, par qu'clle est retenue par une avance du thorax, niais au-dcssous elle est absolument lihre. Les membranes ou les ligamens s'ctcndent du pourtour du trou occipital i celui de la partie antfirieure du corselet, ce qui doune une grande itcndue aux mouvemens.— Cttuier. EXTERNAL ANATOMY OF INSECTS. 13 insects, are unavailable as distinctive characters. To Clair- ville has been assigned the merit of distinguishing between these supposed different kinds of mouth. He does not de- serve it. Aristotle remarks, that some insects possessed teeth for devouring every thing, whilst others had only a tongue for sucking liquids.' Fabricius was well aware of the distinction; he placed together the four classes, Coleoptcra, Orthoj)tera, Neuroptera, and Ilymenoplera; and in a separate group, LejndojHera, Ilemiptera, and Dq)tera^ Lamarck applied the distinction to divisions. Clairville named those divisions. Savigny investigated more thoroughly, and proved the dif- ference to be rather apparent than real. Aristotle's was the observation of a true naturalist; that of Fabricius no less so ; Lamarck's was the application of a systematist ; Clairville's the clever and apt idea of a nomenclaturist ; Savigny's the discovery of a philosopher. I have not happened to meet with, in print, a distinctive character by which these supposed groups can be separated. It is a dichotomous one. Like all dicho- tomies, it consists of a positive and a negative. It is this: — in the mandibulate classes the mandibles do, in the haustellate classes the mandibles do not, move horizontally. It has no reference to the possession of mandibles : all insects possess mandibles. The food can never reach the a'S02)/iagiis without passing through an intermediate space. Its passage through this space is by suction ; the space is called the haustellum. The butterfly and the beetle alike possess this haustellum; it varies only in length. Any difficulty in obtaining food, which the bulk of the head and body may occasion, is provided for by nature by an elongation of this hausleUum. When, com- bined with this difficulty, the food is solid, the mouth is placed at the extremity of this haustellum, as in weevils. When the food is liquid, the parts of the mouth itself are elongated, and, united, form the luiustdlum, as in bees and butterflies. The caterpillar eats solid substances ; its mouth is necessarily hard for their mastication : the bulk of its head and body offer no obstruction to its obtaining an aifiple supply of food; the passage to the ossophagus is short. The butterfly subsists on • Tool' 8' fVTOfiwv Tti lifv ixovTo. oSoWos, iro^Kfaya €3-t(- ra Se 7AaiTTa>' ixovov toTs iyQoU TfiiipiTai, TtavToOtv (KxvKi^uvTa Tami). Jristalk. < Tliis apiitai-s lo Imvo been the liist ilivision of Uiis Uiml that is at all clearly defined. 11' EXTERNAL ANATOMY OF INSECTS. fluids ; its mouth requires no hardness ; the bulk of its head and body offers an obstruction to its obtaining a sufficient supply of its food, which is generally concealed in the nectary of flowers ; the passage to the ocsojj/tagu.i is lengthened, and the difficulty overcome. The caterpillar produces the butter- fly; one is haustellate, the other mandibulate : they cannot be placed in separate classes. The mouth sometimes varies as much and as abruptly in the same insect in its different stages, as in any two different insects in their final stage. In others it remains nearly the same, or gradually approaches its perfection with every change of skin. In Oithoplcra and Ilemiptera the latter is the case : in these classes, every ecdysis is a metamorphosis ; the food and economy undergo no change, the organs therefore require none. Nature never provides uselessly. Fabricius beautifully observes, that it is the part of the wise man to study these things ; to observe, record, and add them to the stores of science ; to weigh well the mysteries of Nature, and trace the hand of a Creator in the wonders of his creatures. Lamarck says, that each peculiar form has been acquired by degrees," and by striving to attain a particular object." He appears to have forgotten, that if honey had been denied to the bee until its little mouth had lengthened out into a thread-like tube, starvation and extinc- tion of its race must have been the consequence. Kirby, in reference to this, exclaims, It is grievous that this eminent zoologist, who in other respects stands at the head of his ° La nature, dans toufes ses opi5rations, ne pouvant proc6der que graduelle- ment, n'a pu pioduire tous les animaux i\la-fois : elle n'a d'abord forme que les plus simples ; et passant dc ceux-ci jnsqu'au plus compost's, elle a ctabli suc- cessivement en eux difierens systemes d'oi'ganes particulicrs, les a multiplies, en a augment^ de plus en plus I'^nergie, et, les cumulant dans les plus parfaits, elle a fait exister tous les animaux connus avec I'organisation et les facultfe que nous leur observons. — Lnmanlt. An. sans Vert. " Prcmifiremcnt, quantity de fails connus prouvent que I'emploi soutcnu d'un organc concourt ;\ son devcloppement, le fortifie, et I'agrandit meme j tandis qu'un defaut d'emploi, dcvenu liabituel a I'^gard d'un organe, nuit k ses develop- peraens, le deteriore, le r^duit graduellement, et finit par le faire disparoitrc, si ce defaut d'emploi subsiste, pendant une longue duree, dans tous les individus qui se succ^dent par la generation. On con9oit de 1.1 qu'un changement de circonstances foryant les individus d'unc race d'animauxa changer leur habitudes, les organcs moins employes d('perissent peu il pen, landis que ceux qui le sont davaiitage, se d6veloppent mieux et accpiiiircnt une vigucur et des dimensions proportionnelles 4 I'emploi que ces individus en font habiluellenieiit. — Laniard;. Phil. Zool. EXTERNAL ANATOMY OF INSECTS. 15 science, should patronize notions so evidently absurd and childish. Cuvier wisely remarks, that there is no proof that the differences which at the present day distinguish animals from each other can have been produced by circumstances. Thirty years ago, in this country, we were so bound by the fetters of the Linnaean system, that the mouth of insects was never resorted to as likely to afford distinctive characters. Our great writers in their generic descriptions make no allu- sion to it. Marsham's^ C'o/eo/j/era, and Haworth's'- Lejyi- doptera, at this day the only continuous descriptive lists of the species of whole classes that we possess, are dependent for their principal characters on the antennae alone. At the present time it is far otherwise. The value of the mouth, in furnishing characters, is well known : its anatomy, therefore, cannot be a matter devoid of interest. The mouth of insects I have already traced to three sections; the lips, the maxillae, and the mandibles. I am now about to consider it in another light, as consisting of seven primary pai'ts, as under ; — No. 1. (a) LAnauM, or u^per-///), bearing inferiorly the (a) Epipha- iiYNX, or valve. ' 2. (m) Labium, or lower-Up, bearing the (ii) Labipalpi, or labial-feelers, and, moreover, divided into : — (u 1.) Insertio, or insertion, (stipes of MacLeay). (« 2.) Labium, or true lip, (mentum of MacLeay). (u 3.) Palpioeb, or feeler-bearer. (w 4.) LiGULA, or limb, {labium of MacLeay). 3&4. («') MAi^BiBVLjE, or mandibles. 5 & C. (o) Maxill/e, ot feeler-jaws, bearing the {6) Maxipalpi, or maxillary-feeler, and the (o) Galea, or helmet, and divided into : — (o 1.) Insertio, or insertion. (o 2.) Maxilla, or true feeler-jaw,^ . , , (o 3.) P ALPiTER, or maxillary feeler- > ,. dr- ^ , \ stipes 01 K\rhy. bearer J (o 4.) Lacinia, or blade. 7. (e) Lingua, or tongue, (Jtypopliarynx of Savigny). The whole of these parts are not equally developed. The 1 Scarabceus. Antenna.' clavatsD, capitulo fissili. — Marshaiii. ' Papilio. Antennic versus apicera clavato-capitatoe, in sectione ultima plus ininusvc uncinala". — Ilauiorlh. 16 EXTERNA!. ANATOMY OF INSECTS. mode of their development affords cliaracters by which classes are distinguished; the degree of their development, and the variation of their form, those for subordinate divisions. The diminution of a part until it escapes our notice is no proof of its non-existence ; otherwise, the discovery of a part by a highly-magnifying power might be termed its creation. In the foregoing table, it will be seen that there are some parts originating in, and totally dependent on, the others. These are the feelers and galea; which may be termed secondary parts. Now secondary parts cannot exist without the pri- mary parts which bear them. The presence of labial-feelers ensures a labium ; the presence of maxillary-feelers ensures a maxilla. I feel considerable hesitation in considering the tongue, or hi/pop/iarj/nx of Savigny, a primary part. It is, however, of little moment what nominal value we may set on it. Its importance is precisely that of the tongue in the human mouth. It originates at the pharynx in common with the two lips, and is a portion of the same section. The situation of the mouth is commonly in the lower part of the head, a little forward, calculated for feeding readily while the liead is naturally inclined ; it is bounded above by that part of the skull called the clypeus, and below by that part termed the mentum, from both of which it is per- fectly distinct. I will now endeavour to trace the variations of its parts. The first part of the mouth is the Labrum, or upper lip. Fabricius, in describing this part, is very inaccurate. He has confounded it with the clypeus. He describes its variations in different genera. He alludes in one genus to the clypeus, in another to the labrum ; in a third he unites the two. You will remark, it is never sutured to the skull ; it is always free, move- able, and distinct. It unites with the lower-lip, and forms with it a distinct section. It bears on its under side the Epipharynx. It is usually an osseous piece, freely articulated to the clypeus, and originating below and within it. It is of variable shape ; never palpigerous ; and it serves as a cover to the other parts of the mouth. In LepidojHera, the upper-lip is an unimportant part, and appears to have escaped the notice of naturalists, until detected by the accurate Savigny.* It is a thin flat scale- • On voit d'abord que la livre sup6rieure doit etre trds petite et trte peu apparente ; elle est mince, membrancusc, quelquefois dcmicirculaire, mais le plus EXTERNAI, ANATOMY OF INSECTS. 1( like piece, projecting but little beyond the clypeus. It is generally pointed ; and its under surface or epipharynx is formed to fit exactly the aperture at the base of the feeler-jaws. It has thus partially tlie power of a piston, and assists in draw- ing fluids through the tube formed by the united feeler-jaws. In Diptera, the parts of the mouth are generally very obscure ; but when a peculiar mode of feeding requires active exercise, you will find they are called into very obvious existence, and each becomes fully developed. The Diptera, like the Lejn- doptcra, live principally by suction ; but unlike them, have frequently to pierce the cuticle of the object, the juices of which they seek to extract. This operation calls into action organs which were dormant in the honey-sucking butterflies. The blood-suckers among Diptera offer the best examples of a developed mouth. The upper-lip is large, long and sharp- pointed in Tabami.s.^ In Cidex, it is longer still, and more slender. If equal development of the primary parts constitutes perfection in the mouth of insects, then Tabanus and Ctilex may be said to possess perfect mouths. In these the primary parts are equally developed. In Sphccromias, and other nearly allied genera, you will find the upper-lip deeply grooved be- neath, and partially receiving the other organs, as in llemip- tera. In Khyphus, it has a tendency to the same form. In the Asilites, it is plain, stiff", and but half the length of the other organs. In the Empiles it is long, and forms the outer cover of the beak of these insects. In Medeterus, if I have not mistaken, it is palmate ; the central lobe being longest, the next to it next in length, and the external ones shortest. In Qistrus, the labrum and whole mouth have disappeared. Clark, in his valuable Essay on the Bots of Horses, speaks of the mouth of Oistrus as a simple aperture ;' thus implying the existence of a. 2}/iarynx ; I confess I have not found it. Des- voidy appears to have a new theory regarding the mouths of Diptera. If it prove correct, nearly all the received nomen- clature must fall.'' In Hymenoptera the upper-lip is short, souvent allongce en pointe, appliqu^e contre la base de la trompe et refue dans la suture moyenne de maniire il fermer exactement le leger ^cartement qui se trouve cntre ses deux filets. — Savigmj. '' In Plate VI. is represented the mouth of Tabanm bovinus. " Os, apertura simplex, neque ullo modo exertum. — C/ori. ■* La trompe (proboscis) des Dipt^res, scion moi, n'est point forniee par la 18 EXTERNAL ANATOMY OF INSECTS. solid, bony, and somewhat quadrate. Unlike the same part in Diptera, it cannot be bent without injury. It either retains" the bend or it breaks. It is not always visible externally. In the bee it is conspicuous : in the wasp it is hidden by the clypeus. In Coleoptera it retains a similar character. It varies much in development. The Scarabceites have the upper- lip small. I cannot consider, with Olivier, that it is in any case absolutely wanting," although the great stag-beetle is almost without it. In these orders*' the clypeus supplies its place : whence the error of Fabricius in confounding the two. In the rapacious beetles it is large. In Anthia and Cicindela it is very conspicuous. In all water-beetles it is fully developed ; the difference in their economy does not affect \t.* In Oitliop- iera its character continues the same, its relative size larger. In Hemiptera it has changed. It continues rigid, and is injured by bending : but it is longer and more pointed than in the three preceding classes. It is grooved to receive the labium, and is the only part of the mouth that is detached. In Jssus it is sharper than a needle. In the other Cicadites it is more obtuse. In the Cimicites, again, it is sharp ; and the same in the Nepiles. The mouth in Neuroptera has no com- mon character. Neuropterous orders, with the exception of the central one, Libellulites,^' assimilate in all their characters to the classes to which they approach. I cannot, therefore, detail livre inferieurc, commc celle des Hymenopt^res, mais par les machoires. Dans les Myodaires, elle est ordinairement membraneuse, quelquefois solides et triardculee. La base est enveloppee par la base de la I^vre inKrieure, dont ks deux palpes sont toujours d6veloppC'es, et qui se prolonge en deux supports lateraux et ordinairement solides. Le corps de la trompe se prolonge en une gaine, termin^e par des Idvres membraneuses dues 4 des trach^es trfis developp^es, et par des palpes qui peuvent etre solides. Elle renferme deux filets allonges qui forinent le sucoir et qui representent les mandibules. La pifice plus ou moins solides qui se prolonge sur la rainure de la trompe est le labre ou la Ifivre sup^rieure. — Desvoidy. ' Les Scarahies qui ont des mandibules, et qui n'ont point de ISvre sup6- rieure. — Olivier. ' Scarabesites and Lucmiites. t In water beetles the clypeus is never distinct. >■ La labre demi-circulaire vout6 ; deux mandibules 6cailleuses, trds fortes et tr^s dentfees ; des machoires termin^es par une piice de la meme consistance dent^e, epineuse et ciliee au cott interieur, avec une paipe d'un seul article, applique sur le dos, et imitant la gal6le des Orthoptires, une l^vre grande, voutie, i trois feuillets, et dont les lateraux sont des palpes ; une sorte d'dpiglotte ou de langue vesiculaire et longitudinale dans I'interieur de leur bouche.—Latreilte. EXTERNAL ANATOMY OF INSECTS. 19 their peculiarities. To describe a single order would be merely to mislead ; to describe all would be extending my letter to an unreasonable length. The LABIUM or lower lip corresponds with the upper lip. It occupies the same situation below the jaws that the upper lip holds above them. The upper and lower lips therefore close the mouth vertically. There is no part of the mouth con- cerning which writers are so little agreed as this. The difficulty has arisen in two ways ; — first, from the number of its parts ; secondly, from the propinquity of similar parts. The lower lip is a compound and somewhat complicated organ. Every one has seen this ; and every one has been desirous of applying some name to each of its parts. The next organ above it is the tongue ; the next part below it is the menttim. It is not much to be wondered at that entomologists finding these three names— finding three very distinct parts in the lip — and moreover, very frequently finding no distinct tongue or mentum, should have applied the three names, tongue, lip, and mentum to the three most conspicuous and manifest divisions of the lip. The name mentum was given by Reaumur. Now the names of Reaumur impose no law : did they, half our present nomencla- ture must be abandoned. Latreille has, however, decided on retaining the name, and has applied it to the part of the throat immediately adjoining the mouth. The lower lip is divisible into four portions : — the Insertio or insertion ; the Labium of Fabricius, or true lip ; the Palpiger or feeler-hearer ; and the Ligula of Fabricius, or limb. Of these, the palpiger appears to be now noticed for the first time. The insertion is precisely what the name implies ; it is, in fact, the root by which the lip holds. It is always, in a greater or less degree, concealed by the mentum. Savigny has called it support and inser- tion. MacLeay, it will be seen, has named it stipes; — a name not inapplicable to the particular instances in which he figures it. The true labium is the second part : it is thus named bv Fabricius, and has since been erroneously termed the mentum by most modern entomologists. The palpiger, or feeler-bearer, is situated above the disk, and is very often confounded with it. It seems generally to be a mere fleshy fold, between the lip and the ligula, but is occasionally thrust out far beyond the lip, and assumes the appearance of a ligula. In these instances it is easily detected by the feelers which it bears on its summit. 20 KXTERNAL ANATOMY OF INSECTS. The feeler-bearer is seldom elongated witliout a similar elonga- tion of the Ugula. The ligiila, or limb, is the fourth and ter-- minal portion of the lip ; its names have been most numerous. Its variations in form are very striking, and afford excellent generic characters. The two lips are united at their base. The nearer we can approacli to a perfect tetrapterous hexapod, the more clearly will this be demonstrated. The type' of a tetrapterous hexapod we may yet be unacquainted with. Such a type must exhibit each organ fully developed. Our large dragon-flies are the nearest approach we know of to full and equal development of principal primary organs ; in these we clearly perceive that the two lips are but a single piece, of vtfhich the central portion is flexible and fleshy, and perforated by a circular aperture, known as the pharynx. Let us now trace the variations of the lower lip. In Lepidoptera, the lower lip is usually a triangular piece, the base of which is closely united to the inferior region of the skull.'' Its surface is uniform, and its divisions obscure. Its apex is generally acute, and terminated by a single point : yet sometimes, as in Amarysstis,^ it is bidentate. The labial- feelers arise from it in nearly an erect position, one on each side of the feeler-jaws, which form a small ring between them. Although obscure, the divisions of the lip are manifest under a good glass. The genus Ino, of Leacli, exhibits very evident lines across it, which show with sufficient accuracy the limits of each division. The margin of the insertion rises to a level with the anterior margin of the mentum. The labium is a narrow arcuate piece, situated above this, and bordering the insertion of the feelers. The feeler-hearer is another narrow piece, whose margins, centrally, are nearly connate, late- rally dilated for the reception of the feeler. The Ugula is very considerably larger than the other divisions of the lip : it is triangular, with a very acute apex. The feelers in this genus, as figured by Savigny, exhibit a basal joint, in addition ' By the word type I would imply the perfection of a peculiar kind. Hex- apods, approaching spiders, or Ametobola, for instance, would be departures from types. I" Je dirai peu de choses de la l6vre inf^rieure : elle consiste en un simple plaque triaiigulairc, ordinairement ecaillcuse, unie par uiie membrane aux deux tiges des machoircs, et supportant H sa base les deux palpes que tout le monde connait.— .yoDi^Hj/. ' Papilio Machaon. — Lin. EXTERNAL ANATOMY OF INSECTS. 21 to the two usually described. The apex of the ligida, and the form of the articulations of the feeler, seem to be the only por- tions of the lip in this class that are likely to be available for generic distinctions. In Diptera, the lower lip is the largest and most conspi- cuous portion of the mouth. It is the organ known to every one, with which the busy house-fly attacks our sweets. It is not unfrequently termed the proboscis of the fly, a term, however, applied by Meigen to the united mouth of Citlex."' Desvoidy, as already stated, has another idea about the ana- tomy of this organ. Tiie ligida of Hymenoplera, shortly to be noticed, appears to have a precise analogue in the incrassated bilobed termination of the lip oi Diptera. Immediately below this, in the genus Tabumis and some neighbouring groups, may be seen on each side of the lip a pilose excrescence. Savigny considers this the labial-feeler. It is the very situation in which analogy will lead us to look for this organ ; and the idea that it is such is, consequently, far from improbable. I have, with great pains, sought for some character, whereby I might with confidence confirm Savigny 's opinion, but have been un- successful : there appears no trace of articulation. By a careful examination, and frequently turning the object in the light while the eye is fixed on it, a nearly direct line will be seen crossing the lip immediately below these excrescences, thus separating, as I conjecture, the feeler - bearer from the true labium. The insertion is distinct ; it has been noticed and figured by Savigny and others. The divisions of the lip are more prominent in Empis, Stomyxis, Rhingia. &c. than in Tabaniis ; yet still sufficiently indistinct, and scarcely to be recorded with certainty. The conspicuous presence of four divisions in the lip of Ilymenoptera, Coleoptera, Orthoptera, and Hemiptera, led me to expect them in Lepidoptera and Diptera. Let me not influence the judgment of others. I have satisfied myself by patient investigation : I hope my fellow-labourers will do the same. With the exception of the ligida, the lip of Diptera affords but few characters for generic descriptions. We now arrive at the Ilymenoptera. Here the lower lip reaches its maximum. Let us examine the mouth oi Bombus, the humble-bee. This mouth, if neatly spread out, presents " Culcx. Proboscis porrectu, loiigitudinc thoracis. — lUcigen. 22 EXTERNAL ANATOMY OF INSECTS. US witli the branching appearance of a little tree. Let us part off the outer branches, right and left : these branches are the feeler-jaws, to be noticed presently. After the removal of these, we find a long stalk or stem. At its base is a portion, very distinct, of a triangular form, with the apex pointing downwards. To the interior of this triangle the feeler-jaws are very firmly attached, and are with difficulty removed without carrying it with them. From the base of this triangle, which you will recollect is looking upwards, rises the true lip, a long slender piece with nearly parallel sides : near its summit a distinct and tolerably direct line crosses it ; this line terminates the true lip : above it is the feeler-bearer. From each side of the feeler-bearer spring the feelers ; throughout this order very elongate and conspicuous. From the summit of the feeler-bearer rises the Ugiila," trilobed ; each lobe is distinct to the very base ; the lateral ones are called paraglossce, a name that appears redundant, unless it could be carried through all the orders of this and the two following classes. In Nomadu the lip is broad, the central lobe of the Ugula large and moderately long ; the lateral lobes small, and very acute. The labial-feelers are distinctly quadriarticulate, and longer than the central lobe of the Ugula. In Saropoda the lip is similar, the feelers indistinctly articulated ; and these, together with the central lobe of the Ugula, much more elon- gate. In Bomhus the central lobe of the Ugula is much longer than the feelers. In Melecta the lip is longer than the Ugula. In CoiUoxys rufescens" the Ugula, in its central lobe, is much shorter than the feelers ; its lateral lobes are rudimental. In Osmia the central lobe of the Ugula is nearly three times the length of the lip, and twice the length of the feelers ; still the lateral lobes are very minute. In Anlhidium manicalum the central lobe of the Ugula and the feelers are exactly of a length ; the lateral lobes of the Ugula are thin, short, and scale-like. In Andrena, Halictus, Dasypoda, Colletes, Hylceus, and Sp/tecodes,v the Ugula is not a quarter of the length of the lip. " Ligvla. This is the part considered by many authors as the lower lip. — Samouelle. ' An insect common in the south of England, but one which I think has not found its way into our British lists. I" Sphecodes monilicornis excepted ; which will probably form a new genus, or be removed from this. EXTERTJAL ANATOMY OF INSECTS. 23 In these instances it is quadrifid. Leaving the bees, we shall find tjie ligvla in Odynerus, Eumenes, and Epipone, elongate and quadrifid ; the feelers also differ essentially from those of the bees, in being situated considerably below the union of the lobes of the ligula. The lips of fossorial Hijmenoplera are shorter than those of the foregoing ; the ligula is usually short, obtuse, and bifid ; the feeler-bearer variously developed, and the feelers much longer in proportion. The lehneumonites, and other pa- rasites, are very similar ; the tongue being generally bifid and much shorter than the feelers. Lastly, in the Tenlhredinites, we find distinctly trilobed ligulce, short lip, and long feelers. ^ In Coleoptera the lip is reduced in length, but in all 'i other respects it is very close to that of Hipnenoptera. N. Latreille gives the name of labium to the whole lower lip in ) Colcojitera. MacLeay calls the same part mentum; but, >K^ reluctant to relinquish the Fabrician term, labium, has ap- v plied it to the ligula. Kirbyi calls the whole lip, labium, ' i but follows MacLeay in the nomenclature of its parts. J Curtis, whose beautiful work, entitled " British Entomology," j is known to every entomologist in this country, follows the ^ nomenclature' of MacLeay. TJie labial feelers of Coleop- S tera arejbur-jointed. The basal joint is very various in its S development. This circumstance is a fruitful source of con- fusion. The ligula originates at or near the pharynx. It extends along the inner surface of the lip, to which it is closely attached, and stretches beyond it. The produced portion being in the nomenclature of Fabricius, the limb of the lip, and sometimes the ligula, is the only part available for cha- racters. The feeler-bearer in the lip of Coleoptera is soft and fleshy, and is remarkable for the variety of its development; and the feelers are attached to it by a loose and flexible arti- culation. Now, this being the case, you will observe, that the elongation of the ligula is very likely to affect the position of organs so situated. Let us examine this. In Cicindela the lip has three lobes; the central acute, the lateral ones obtuse. In the spaces between these are situated the feelers; there is no produced feeler-bearer, nor ligula. We will next 1 III the Coleoptera only I speak of. The labium o( Coleoptera is, in Kirby's nomKnc\atuie, the lingiin of If yvienoptera. In Orlhoptera ani Neuroptera I am not competent to offer any explanation of this author's nomenclature of tliese parts. ' In the majority of the Coleoptera. In the other classes there is but little uniformity in the nomenclature of parts. 24 EXTERNAL ANATOMY OF INSECTS. examine Ci^chrus. The middle lobe of the lip seems to be completely cut away ; and the feeler-bearer appears in its place, with a pair of closely-approximating feelers rising from its summit. Turn the other surface of the lip, and apply a good lens : you will find the trilobed ligula, minute indeed, but beautifully distinct ; the lateral lobes being rather longer than the central lobe, and termed by Latreille paiaglossa-. Blethisa and Nebiia present a very similar structure, except in the central lobe of the ligula, which in these is large and somewhat rounded. In Helobia the central lobe has a central tooth. In the Harpalida; and Scaritido!, the ligula is generally more produced ; and the feeler-bearer and feelers are carried with it. In JJcinus, the lip and its appendages are similar to those of Cychrus. You will find the same similarity in the feeler-jaw and its appendages. In the Dy- tiscites no great difference appears ; the lateral lobes of the ligula are however mostly obsolete. In the HijdrophiUtes the lip is less indented than in predaceous beetles ; the ligula is frequently bilobed, and the feelers appear to lose one joint by the second being received into a cup formed by the first. In Hydrous, the feeler-bearer appears obsolete ; and the insertion of the feelers behind the lip actually swells out the portions of its margin, behind which it enters. In Parnus, supposed to be nearly related to Tlydroils, the feeler-bearer and feelers project far beyond the lip. In Tetratoma, and Cis, the feeler-bearer is raised, but the ligula is concealed. In Leiodes all the four parts are distinctly developed. In Trox, the insertion is peculiarly prominent; and still more remarkably so in Acant/iocerus." In the vast order, Cwculionites, I find the feeler-bearer very prominent and elongate ; yet the ligula is mostly obsolete or concealed. In Curtis's figure of Mono- nyclms there appears to be a distinct ligula; — I have never investigated the mouth of this genus. It seems a general character of the order, that the feeler-bearer should be promi- nent and elongate, the feelers approximate, placed at its summit, and occupying the usual situation of the ligula. In the Cerambicitcs, the four parts of the lip are very distinct : in Saperda, and Hematicherus, particularly so. The remaining " Mentum quasi e dupHci parte formatum, alia apiculi cordata ad basin, truncata, carinata, margine antico emarginato, lateribus rotundatis, elevatis ; altera prioris stipite transversa, concava, margine antico recto, lineari. — MacLeay. EXTtRNAL ANATOMY Ol' INSECTS. 25 orders of Coleoptera exhibit many variations in tlie parts of this organ, but mostly analogous to those described. In Orthoptcra, the lip has the same development as in Cole- optera, but the ligiila is much more produced. It is divided into four lobes, somewhat palpiform. The common cock-roach presents an instance of this. The feelers are four-jointed ; the 'I basal joint occasionally amalgamating with the feeler-bearer. ' ' In Hemiptera the lower lip wraps itself round the mandi- bles, &c., forming a sheath for them. It is four - jointed. Savigny considers the basal joint to be the true lip,' if I com- prehend rightly his meaning. Latreille, in his last work, still treats of the lower lip as a quadri-articulate sucker, assigning no names to the articulations. I suppose the four joints to be analogous to the insertion, labium, feeler - bearer, and limb, observable in Ilipnenopteia, Coleoptera, and Orlhop- tera. Savigny has figured what he considers the feelers of Hemiptera, on the part which I have called the feelor-bearer. Willing as I must be to prove the correctness of this idea, I am compelled in fairness to admit that I have never made them out to my own satisfaction. The lower lip in Hemiptera varies scarcely at all, except in length. In the Linnacan genus, Aphis, several instances occur of its being twice as long as the body, passing beneath it, and projecting beyond it, like a tail. In the larvae of the LihelluUles the lower lip has a most wonderful development, and all its parts are very conspicuous ; the insertion is short, but distinct; the labium is long, stout, and incrassated externally ; the feeler-bearer is still more deve- loped, in /Esclina, it is full half an inch in length, and divided into two lobes ; the feelers are prehensile and mandibuliform ; in fact, much resembling the mandibles of Ciciiidela; the Ugida is a thin plate spread over the interior surface of the feeler-bearer, and filling up the space which occurs between its lobes. The most remarkable character of this extraor- dinary lip is its articulation. The labium is so freely articu- lated to the insertion that it is capable of being bent under the body of the insect reaching to the metacoxa:. The articu- lation of the feeler-bearer to the labium is of the same kind ; while the latter is bent below the insect, the former is directed forwards, and reaches to the front of the mout'i ; • Elle (la levrc iiiKrieure) est compos6e ilc quatrc articulations, dont la prcniicio lejii^^sente la ganache des Cotioptires et dcs Orlhoptircs, — Savigni/. 2a EXTERNAL ANATOMY OF INSECTS. tlie two joints thus reposing in parallel lines. The lower lip is the organ with which this ferocious larva seizes its prey. The perfect dragon-fly has also a singular development of the labial feelers : the lip itself is however little different from that of Lepidoptera; but the broad mandibuliform feelers are evidently used as organs of prehension and detention of their living prey, as I have often observed on feeding these in- satiable creatures with flies whilst holding them by the wings. Raphidia displays the three lower parts of the lip in equal development; the ligiila is concealed behind the feeler-bearer. Next in order come the Maxillae, ov feeler-jaws ; they are situated in the lower part of the mouth, one on each side, immediately above the lower lip, and below the mandibles, from which they may be instantly distinguislied by constantly bearing the maxipalpi, or maxillary feelers. This distinction is so evident and unvarying, that I hope I shall be pardoned for applying to them the term, feeler-jaws ; a term rather uncouth, I admit, yet I think also very distinctive and descrip- tive. The word maxillce appears to offer no other translation than simply jaws, which would not sufficiently distinguish these organs from the mandibles. The feeler-jaws are less liable to variation than any other part of the mouth." Their variations are therefore most important. Fabricius, Latreille, MacLeay, &c., have borne testimony to their value in aflfording distinguishing characters. Each feeler-jaw is divisible into four parts, the insertio, maxilla or disk, palpifer,^ and lacinia. Straus-Diirckheim has the merit of first distinguishing these." • Maxillam constantissimum invenimus, vix in congeneribus aberrat. — Fabricius. Piice palpi/ire of Straus-Diirckheim. » Chez les Melolontim le corps tie la mfichoire est form6 de quatre pieces, mobiles les unes sur les autres, mais qui n'ont point encore it& dicrites. L'une d'entre elles fixe la machoire sur la basilaire : c'est une piice 4 peu pr^s trapezoVde, portant h son petit cot6 parall^le un condyle articulaire, qui pfeniitre dans la cavitc cotyloide interne qu'on remarque sur I'apophyse ant6rieure dc la basilaire. De ce point d'articulation cette premii^re piice se porte transversalc- inent en dehors, et va s'unir par son bord oppose aux autres pieces du corps de la machoire, d'ott je lui donne le nom de Branche transverse.— La pidce Dorsale des machoires est chcz tous les colioptfires une plaque presque plane, en triangle isocile i elle est unie par son petit cote Ix la branche transverse, et de cette arti- culation elle se porte en avant et determine la direction de la partie principale du corps de la machoire, dont elle occupe la face externc. Par son bord interne cette seconde piice s'articulc linfeairenient avec une troisiime, placec i la face inC6rieure de la machoire, et que je nomme Y Intermaxillaire, et son bord extcrne EXTERNAL ANATOMY OF INSECTS. 2^ The insertion is almost invariably concealed. Savigny has called it also support. Kirby, if I understand him rightly, has denominated it the cardo, or hinge.^ The disk anA feeler- bearer arc commonly two pieces running nearly parallel with each other ; the former occupying the front, the latter the back of the jaws. It has unfortunately happened, that Straus- Diirckheim has selected for his dissections an insect, in which the situation and proportions of these two parts are very unusual, whence, in different formations, his names appear rather defective. The palpifer bears on its back the maxipalpus, or maxillary feeler. The fourth part is the lacinia, or blade. It is called by Savigny, lame ; by Straus- Diirckheim, intermaxillaire ; by Latreille, internal lobe; by MacLeay, lacinia. It is certainly the lacinia of Fabricius, as applied to a butterfly. United to the back of the blade, is the galea or lobe, a part exceedingly variable ; sometimes bearing the appearance of a true feeler, and sometimes being wholly obsolete. It has been called, in the Carabites, the internal feeler; in the Scarahceites, the outer lobe of the feeler-jaw.'' The name galea was given to it by Fabricius. This writer also treated of it as an inner maxipalpus. In Le23idoptera, the insertion of the feeler-jaws offers nothing s'articule avec la quatri^me, que j'appelle la pii^cc Palpijire. h' hitcrmaxUlaire occupe comme nous vcnons de le dire la face inf^rieure de la machoire, et forme en meme temps son bord interne : elle se prolongc peu au-deli de la piice dorsale, et forme en dessous une large plaque allongue, qui s'^tend vers le milieu de son bord interne en une longue apophyse dentiforine, dirig^e obliquement en avant et en dedans. L'intermaxillaire s'articule en dehors avec la dorsale ; a c6t6 de son apophyse, avec Tangle interne de la piSce palpif^re ; k son bord interne elle est liee par un espece membraneux avec la galea ; enfin, son bord postcrieur se continue avec le pharynx. La pidce Palpi/tire occupe la face sup^- rieure de la machoire, et se trouve contigue 4 la mandibule. C'est une grande plaque, 4 peu prds triangulaire, articulee par son bord externe avec la piece dorsale ; par I'ant^rieur avec la galea ; par Tangle interne avec Tintermaxillairc; et enfin son bord posterieur se continue avec le pharynx. Cette piiice forme ainsi avec la dorsale et l'intermaxillaire une chanibre ouverte, d'une part, du cot6 de la branche transverse, par ofi elle communique avec la cavity de la tete, et, d'une autre, avec le galea. Sur Tangle antSro-exlerne de cette pi^ce est arti- cul6 le palpe, qui forme le principal appendice de la machoire. — Strmts-Diircklieim. ? At their base they articulate with a piece more or less triangular, which I call the hinge (cardo.) 'I'his, on its inner side, is often elongated towards the interior of the base of the labium, to which it is probably attached. This elongate process of the hinge in yipis, Bombus, Sic, appears a separate articulation ; and the two together form an angle upon which the mentum sits, and by this the maxilla acts upon the labial ap)(aratus. — Kirbtj. ' C'est une/ rossc pidce mobile qui termine la machoire. — SlraHs-Diirckheim. 28 EXTERN AL ANATOMY OF INSECTS. worthy of remaik. The disk and feeler-beaver are closely connected, tiie suture uniting them being obliquely longitu- dinal. In treating of these parts, I believe it will be better to consider them but as one. Their distinctness is more clearly to be discerned from actual examination of the objects them- selves, and from the accurate plates of Straus-Diirckhcim, Savigny, &c., than from any verbal description. The blade is long, slender, pliable, and capable of rolling up like an Ionic volute, or the main-spring of a watch. This is a principal cha- racter of the class. When at rest, the blade appears to be a small ring, and is situated between the labial feelers. Each blade, when examined, is found to be externally convex, internally concave ; so that the two, united together in front, form a tube. Through this tube, the honey of flowers is drawn. Each blade is also in itself a tube. The organ formed by the union of the two is very elastic ; and, if artificially drawn out to its full length, will, on being loosed, instantly return to its natural position. The maxillary feelers are by no means a prominent portion in the mouths of Lefiidoptcra. They are situated one on the feeler - bearer of each feeler -jaw. Reaumur, a hundred years ago, noticed the maxillary feelers of Lepidoptera ,"■ and figured them very accurately ; but Savigny appears to have been the first scientifically to ascertain their identity. Though not prominent, they afford the best charac- ters for dividing this class that we at present possess. The galea, or helmet, is still undiscovered. In the Spliingitcn I find no feeler: I conclude, tlierefore, it is nearly obsolete. In Zygeena, Ino, Glaucopi.s, Pijrausta, and all the PuraUtes and Crambites, it is distinctly visible, generally without a glass, and appears to be typically three-jointed. In the Tortiiciles and Tineiles the maxillary feelers are less distinct, but always present. In the Nochnlcs they are small and two-jointed. In the Gcometrites they are still less conspicuous. In the PajdUonites, less still : in Amaryssus Machaov, obsolete.'' ° Dnns la figure on ]H'ut rcmarqucr deux barbes plus ecartees Tune de Tautre que ne le sont commun^ment celles des autros papilluns : deux filets places eiitre les barbes, et diriges dans un sens contraire it celui oil les barbes Ic sont — R((iumur. '' Savigny's figure of tbe maxillary feeler in /Inmrysstis Maclmon represents ratbcr the site of tlie feeler, tlian tlic feeler itself I liave hunted for it in vain in tlie specimens I have dissected. EXTERNAL ANATOMY OF INSECTS. 29 Tlie blade of tlie feeler-jaw, in the class Lepidoptera, appears to vary only in length. InDiptcra, the fecler-jaws are generally of about equal length with the upper lip and mandibles, but are shorter than the lower lip. They are straight, sharp-pointed, and lancet-like. It does not appear that they are generally tubular. The insertion of the feeler-jaws in Dijjtera presents little worthy of notice. The disk and feeler-bearer are two small pieces, placed above each other; from the latter proceeds a feeler with from two to five articulations. The blade is the long sharp-pointed part. The helmet is apparently obsolete. The feeler-jaws fluctuate greatly in their development in the various orders and families of Diplera. Curtis, in the work already alluded to, denies their existence in many genera, yet figures the maxillary feelers. This is not reconcilable with the idea of the leclers being secondary parts, or with their njime, maxillary. The existence of the hand presupposes the existence of the arm. The existence of the feeler presupposes the existence of the part that bears it. I refer you to the genera Oxijcera," Scato- •jilidga, Drapetis, llclcomy&a, Sepsis, Ti/ropliaga, Mede- ieriis, &c. &c. In two of these genera, Scatopliaga and Helcoiin;sa, I find that the feeler springs from a short and nearly quadrate piece, on which it is not placed quite perpen- dicularly, but leans a little outwai'ds, and lo which it is joined by a very evident suture. Is not this smaller basal joint of the feeler the true feeler-jaw? The blade of the feeler-jaws varies little excepting in length. The feelers vary in many particu- lars: the variation in the number of their joints is worthy of notice. In the Culicitcs they are long and five-jointed, the central joint being the longest. In the Tipulites they are short, and have five joints, all the joints being nearly equal in length. In liibio, and its congeners, nearly the same. In the Tabaniles, Asilites, Miiscitcs, &c., they appear to be three- jointed ; the basal joint short and indistinct ; the second more slender, and rather longer ; the third stouter and longer than either. In Hymeno'ptern we find a considerable change takes place in the feeler-jaws. The bees appear to be the nearest " Oxtjcera. Maxillae and mandil)Ies none. Palpi short, linear, mcnibianous and I'omiircsscd i thickened, oiiaque and imbcsccut at the apex. — Curtis. 30 EXTERNAL ANATOMY OF INSECTS. approach to Diptera ; and on this account the examination of their mouth is not unimportant. The insertion is a small triangular piece, on which the disk and feeler-bearer are seated. Their union is usually by a distinct longitudinal suture. The feeler is slender, five or six-jointed, and situated close to the base of the blade. The blade is long, slender, flexible, and elastic ; it unites with the Ugiila, and labial- feelers in forming a honey -sucking tube. In all these re- spects, excepting the union with the ligula, the feeler-jaws of the bees very closely resemble those of Lepidoptera. In NoTiiada the feeler and the blade are of equal length. In Sarojjoda the feeler is about one-fifth as long as the blade. In Bombus it is scarcely one-fifteenth the length. In Melecla the disk and blade are of nearly equal length : the feeler is about one-third their length. In Andrena, Halictus, Dasy- poda, Colletes, Hylcetis, and Sp/iecodes,'^ the length of tlie blade is much diminished. The division of the other parts is in these genera much more manifest. Vespa, Odijnerus, &c. display a greater change : in these the feeler is much longer than the blade. In Hedycriim the feeler-bearer is longer than the insertion and stalk together : the galea, or helmet, also reappears in a large oval form ; the blade is short ; the feeler is long.'' Passing through the Fossores, the Pujiivora, and the Tenthredinites , we arrive very nearly at the mouth of Coleoptera. In all these the helmet of the feeler-jaw is present under some of its various modifications : it is the terminal portion, and its variations are of the greatest importance as distinguishing characters. In Coleoptera, the feeler-jaws have assumed much more the appearance of the mandibles, than in any class through which we have traced them. Still it is far from certain whether they are, even in this class, employed for mastication. Kirby has ex- cellently suggested that, under their present form, they are the holders or retainers of the food, while the mandibles are em- ployed in masticating it. Their form and situation certainly favour this idea. Dumeril supposes they also assist in masti- cation, f The insertion of the feeler-jaw in this class is but '' With the exception of S. monilicomis, before noticed. ' The description is from the dissections of Hedychrum in Curtis's British Enlomology. C'est avec les mandibulcs que I'insccte coupe, arraclic ou retient les atimens ; EXTEKNAL ANATOMY OF INSECTS. 31 little conspicuous : the disk is an important and considerable part; the feeler-bearer, usually a small lobe, something resem- bling a basal joint ; and the blade long and large, frequently with a sharp-pointed incurved apex, and a ciliated internal margin. The maxillary feelers in this class are constant and conspicuous. » They are usually composed of four distinct joints,'' and possess great freedom of motion. Geoffroy not unaptly compares the feelers to hands.' The helmet is also present; and in some of the carnivorous beetles is many-jointed, and wears completely the appearance of a true feeler.'' Fabri- cius considered it a true feeler in the carnivorous beetles. Latreille, even in his latest work, disapproves of the general ap- plication now made of the term to the same part, however different its form. ' It seems strange that one who theorises so boldly and successfully as Latreille has done, should hesitate in acknowledging the obvious identity of the part in question.'" In the Cichidelites the feelers are long, four-jointed, and placed on a round compact feeler-bearer, which precisely resembles a fifth joint. The helmet is two-jointed, and longer than the blade, which is incurved and very sharp. In the Carabites, the helmet is usually shorter than the blade. In the Dijtis- cites there is no essential difference. In Parmis, the helmet taiulis que les machoires recoupent, broient ou ^crascnt la partie qui se frouve comprise entre leur eftbrts.— DumciiV. ' Les palpes paioissent destinies .1 palper, A tiitonner I'alimcnt, A le toucher en tous sens, pour reconnaitre ses qualit^s; aussi les voit-on continuellement en action lorsque I'insecte mange. Dans beaucoup d'csptees ils servent 6videmnicnt a rcdresser I'aliment, afin qu'il soient mieux saisi par les mandibules, dont Tofficc est d'agir comme les dents incisives et laniaires chez les mammifires. — Dumeril. •> There is, in all probability, a uniform number of articulations in the feelers of the insects of every class. It is worthy of remark, that every new discovery in natural history tends to harmonize phenomena previously at variance ; and adds to, rather than subtracts from, the symmetry of the wliole. ' Leur usage paroit etre de servir comme d'espi^ce dc mains, pour retenir les mati^res que mange I'insecte et qu'il tient 4 sa bouche. — Geoffroy. ^ La galea prend quelquefois la forme des palpes, ce qui a fait dire que certains Coliopteres, tels que les Cicindeta, avaient six palpes il la bouche : dans ce memo genre il est (ormt de deux articles arrondis et fort allongts ; dans d'autres il n'en a qu'un seul ; il est souvent termini par une grosse masse membraneuse, converts de poils toufFus, et quelquefois il est entidrement nu ; enfin les Cetonia sont enti^re- ment depourvus. — Straus- Durckheim. ' Je ne saurais apjirouver M. Straus qui n'ayant pas ^gard A ces modifica- tions, donne au galea une acception trop g^nSrale. — Latreille. '" See Plate V., and trace the helmet («) in Hymenopterous, Coleopterous, and Orthopterous insects. 32 EXTERNAL ANATOMY OF INSECTS. is a large, obtuse, exarticulate terminal lobe. In the Hi/drop/d- liles, the maxillary feelers are used as antenncc ; they are consequently very long : the helmet is a distinct obtuse lobe. In the ScarabeeiU's, the feeler-jaws are soft, membranaceous, and hairy ; the helmet is extremely pilose and indistinct. In Lucanus the helmet is remarkable ; it is employed to draw up sap into the mouth, and thus performs the office of a tongue. In the Ccramh y cites, Curciiiionites, &c. all the parts are obvious ; their variations are very valuable in generic descrip- tions. In Orthuptera, the parts and appendages of the feeler- jaws are very fully developed. The helmet in this class appears to have reached its maxinmm ; it is frequently, as in Acridium, three-jointed : in Achela, the common cricket, it consists of two joints, the basal being the shorter. In Hemijdera,'^ the feeler-jaws undergo a complete change. Their appendages are obsolete. Tlreir blade is a slender hair, encased in the under lip, already described ; » the pair being united, serrated, and linguiform. The mandibuL/T: or »««« Tous les auteurs out 6crit que le bee des llemiptferes contenait un sucoir forme par trois soies. Le fait n'est pas exact ; le sucoir des Hernipteres se compose toujours de (juatie soies, bien distinctes, c'cst-il-dire, de deux man- dibules et de deux machoires. Ces quatres piiSces sont cornfies, renflces 4 la base, comprimfies et armies do cils ou de dents trds aiguijs, lorsquc les espiccs sont carnassiircs. — Suvignij. EXTERNAL ANATOMY OF INSECTS. SH the outlines occasionally given to illustrate genera, iVeqiiently differed from my own dissections. Latreille, and several other entomologists, have been fully aware of this discrepancy, which is occasionally so great, that a figure, however accurate, of a single mandible, will by no means characterise a genus. Every description, therefore, taken from a single mandible, is faulty. I am aware this will be found a sweeping censure ; but it ap- pears to me nevertheless a sound one. The mandibles in all these classes have denticulations or teeth more or less deve- loped on their interior margins. It is to be observed, that the mandibles are the maxillce by Linnaeus.'' In Lepidojdera the mandibles are of a substance and size corresponding with tliat of the upper lip.i It does not appear that they perform any office, or are possessed of any motion.' In Diptera the mandibles are elongate, pointed and lancet-like, and in most respects, excepting the want of feelers, resemble the feeler-jaws. They are now possessed of a decided motion, essentially difTe- rent however from that of the mandibles of masticating insects. Their motion is more of a vertical jerk, by which the insect stabs them into the skin of the object which it attacks. The precise character of the motion has not, however, been satis- factorily ascertained. The variations of the mandibles in Diptera are chiefly in size. In Hijmenoptera the mandibles are abbreviated, osseous, and masticatory. They now have a distinct, free, and powerful horizontal motion, and, with the feeler-jaws, close the mouth laterally. They are subject to little variation throughout the class. In Coleoptera, the mandibles are still more developed, forming by far the most conspicuous part of the mouth. They do not so completely P Lucanus scutellatus ; maxillis exsertis apice bifurcaiis lateia unidcnialis. — Linnaus. 1 Les mandibules sont d'une exiguetfi propoitionfe ilcelle de la Idvre supc- rieurc. Dans la plupart des espices elles paraisscnt \ la loupe beaucoiip nioins grandes que les ^cailles qui couvrent le chaperon : elles sent appuyees sur Its deux cotes de la trompe, et trop ecart^es pour pourvoir se toucher par leur sommet. Leur mouvemcnt est assez obscur et dans certains genres, coninie dans les Sphinx elles paroissent plutot soudfees au chaperon qu'articulfcs ; d'autrefois elles font corps avec la base de la I^vre supferieure : elles sont d'ailleurs cornees, tris lisses dessus et dessous, vides au dedans, tantot applaties, tantot renflees, plus ou nioins coniques; divergentes, paralliles ouconvergento!^; pointucs ou obtuscs, suivant les genres, mais dans tons borders do cils irfs-cpiiis sur leur tranchant interieur. — Saingnij. • See Plate VI. figs 1, 2, 3, 4, /. E 34 EXTERNAL ANATOMY OF INSECTS. close the mouth as in Hymenoptcra ; in some instances not even uniting, except in defence." In others, as the beautiful Cicindelites, the mandibles cross each other in front of the mouth. In others, the mandibles are at their edges soft and flexible. This is particularly the case with those beetles whose food is the pollen of flowers, as the CetoniidceJ Another family, AjihodUdce," whose food is the recent excrement of cattle, has a similar peculiarity. In Orthoptera, particularly the locust tribes, the mandibles are osseous, large, and power- ful. Marcel de Serres discovers, as he imagines, an analogy between the teeth which arm the mandibles of Orthoptera, and those possessed by the mammiferous animals. He accord- ingly names them incisive, canine and molary. Your readers will be pleased by a reference to his paper.^ Though specu- lative in ideas, it is rigidly accurate in facts. I am not disposed to apply to annulose animals the anatomical terms employed for the vertebrates, unless their propriety be at once manifest.)' In the present instance, moreover, the nomenclature of these parts is not applicable to generic or other characters, and therefore comes not within the compass of this essay. In Hemiptera, they undergo a complete alteration ; and here, as in Diptera, they are elongate, pointed, flexible, lancet-like, and without the horizontal motion. Lingua, or tofigue. The tongue of insects is an organ but little known. This arises, in some measure, from its being gene- rally inconspicuous : and partly from the application of the names Ligula, Lingua,' Langtietfe,Langue, Tongue, &c. to apart,which ' In Lucanus, the great Stag Beetle, more particularly ; this insect also em- ploys his immense mandibles to pierce the tender bark of young trees. He applies his antenna to the wound he has made, and if he finds that the sap flows, he inserts the helmets of his feeler-jaws in the wound. He sucks up the sap as it flows. ' Mandibula' compressae, tenues, lanceolatae, membrana subquadrata intus auctae, hujus latere externo producto et basi vix cornels vel cornels. — MacLeay. " MandibulcE clypeo obtutse, ad basin cornea,-, deinde in laminam brevem, compressam, dilatatam, coriaceam aut vix membranaceam producta;. — MacLeay. ' Annales du Museum, No. XIV. p. 56. Les dents des ulonates peuvent se diviser comme celle des quadrupides en incisives, en laniaires ou canines, et en molaires. — Marcel de Serres. ? Such terms as nose, ears, and hands have been applied to beetles ; do they not tend rather to excite a smile, than convey a scientific idea ? I do not men- tion this out of disrespect to the authors of such names, but to shew how very widely fancy may lead us, if we determine on providing analogies. EXTERNAL ANATOMY OF INSECTS. 35 is in reality nothing more than the Hmb, or elongate process of the under lip. Tiie true tongue is the hypopharynx or lingua of Savigny. I cannot find it mentioned by Fabricius, except as a seta in the mouth of Diptera. Cuvier first notices it as a tongue in Orthoptera. Savigny clearly points it out in Diptera, Hymenoptera, Orthoptera and Hemiptera. Our illustrious countryman, Kirby, applies the term lingua to the right part in Orthoptera, Hemiptera, and Neuroptei-a : but in Hymenoptera and Coleoptera, he has given this name to the process of the lower lip, already described as the ligula. In Diptera he has declined naming it.'- Latreille, in his earlier woi'ks, calls this part by various names; but in hisCours d'Entomologie, he clearly points out the true tongue, and laudably proposes that the last name should be restricted to it. My ideas on the subject have somewhat altered since I gave a cursory sketch of the mouth on a former occasion. I am happy in being able thus to point out my own error before the unthankful task has devolved on another. Beautifully has De Geer observed, that the evil is not very great, if further observation prove our old ideas to be untenable ; we have then merely to remodel those ideas by the result of the later observation." It ever has been, and may it still continue to be, my endeavour to amend an error as soon as I am aware of it. In Lepidoptera the tongue has never yet been noticed. Latreille fancied, if I comprehend him rightly, that it existed in the suture, uniting the feeler-jaws."" I have observed, very near the pharynx, but a little below it in Sphinx Ligiistri, a small mammiform protuberance. This is so exactly the site of the tongue in bees, that it seems wonderful that the accurate Savigny should have overlooked it. 1 can » See Plate VII. fig. 5, in the Introduction to Entomology. * Le mal n'est pas meme fort grand si par des nouvelles observations on trouvc s'4tre trompfe dans ses id^es ; il n'y a lorsqu'4 les changer selon le resultat de ces ob.servations ulterieurs. — De Geer. " Amongst these parts (of the mouth in Lepidoptera), there seems at first sight no representative of the tongue ; hut M. Latreille has advanced some very ingenious, and, I think, satisfactory arguments, which go to prove that this part, at least the tongue, in Hiimenoplera, has its analogue in the intermediate tube or fistula formed by the union of the two maj-illee, and which conveys the fluid aliment of this order to the pharynx. As in Diptera the maxill