The seven organs of the mouth above defined, viz. the Labrum, Labium, the two Mandibulæ, the two Maxillæ, and the Lingua, constitute what may be denominated a perfect mouth, peculiar to those insects that masticate their food[944]. In those that take it by suction, the Trophi, 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 representatives of the above organs have been detected by the elaborate researches of that learned and able zoologist, M. Savigny[945]. I shall next subjoin definitions of the principal kinds of suctorious mouths.
2. Promuscis (the Promuscis). The oral instrument of Hemiptera, in which the ordinary Trophi are replaced[946] by a jointed sheath, covered above at the base by the Labrum, without Labella (Liplets) at the end, and containing four long capillary lancets, and a short tongue[947]. It includes the Vagina, and Scalpella.
A Vagina (the Vagina). The jointed sheath of the Promuscis, representing the Labium in a perfect mouth[948].
B 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 Manidibulæ[949], and the lower the Maxillæ[950].
3. Proboscis (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[951]. It includes the Theca, and Haustellum.
A Theca (the Theca). The sheath or case of the Proboscis, representing the Labium in a perfect mouth[952]. It includes the Basis, and Labella.
a 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 Mentum?
b Labella (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[954]?
B Haustellum (the Haustellum). The instrument of suction contained in the Theca[955]. It includes the Valvula, Cultelli, and Scalpella.
a Valvula (the Valvule). A corneous piece which covers the instruments of suction above, representing the Labrum in a perfect mouth[956].
b Cultelli (the Knives). The upper pair of the instruments of suction, which probably make the first incision in the food of the insect; they represent the Mandibulæ of the perfect mouth[957].
c Scalpella (the Lancets). A pair of instruments, usually more slender than the Cultelli, which probably enter the veins or sap-vessels, and together with them form a tube for suction[958].
4. Antlia (the Antlia). The oral instrument of Lepidoptera, in which the ordinary Trophi are replaced by a spiral, bipartite, tubular machine for suction, with its appendages[959]. It includes the Solenaria, and Fistula.
A Solenaria (the Solenaria). The two lateral subcylindrical air-tubes of the Antlia[960].
B Fistula (the Fistula). The intermediate subquadrangular pipe, formed by the union of the two branches of the Antlia, which conveys the nectar to the Pharynx[961]. These two branches represent the Maxillæ of the perfect mouth.—N. B. M. Savigny discovered the rudiments of the remaining Trophi in this kind of mouth[962].
5. Rostrulum (the Rostrulum). The oral instrument 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[963]. It includes the Laminæ, Scalpella, and Ligula.
A Laminæ (the Laminæ). Two corneous plates which are laterally affixed to the mouth of a flea, probably representing the Mandibulæ of the perfect mouth, which somewhat resemble the beak of a bird[964].
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 represent the Maxillæ of the perfect mouth[965].
C Ligula (the Ligula). A capillary instrument between the lancets; probably representing the tongue of the perfect mouth[966].
6. Rostellum (the Rostellum). The oral instruments of Pediculus and some other Aptera, in which the ordinary Trophi are replaced by an exarticulate retractile tube, which exerts a retractile siphuncle. It includes the Tubulus and Siphunculus.
A Tubulus (the Tubulet). The tube or retractile base of the Rostellum.
B Siphunculus (the Siphuncle). The real instrument of suction, which when unemployed is retracted within the tubulet.
Besides the above variations from the type of what I call a Perfect Mouth, there are others in which the parts of the Trunk appear to aid in the conversion of the food, and become a kind of accessory Labium, Maxilla, &c. Thus in the Myriapods, the anterior pair of legs assume a Maxillary form and office[967]; the Prosternum those of a Labium[968]: in the Arachnida, also, the anterior Coxæ are accessory Maxillæ. In this Class, likewise, as has been more than once observed[969], the representatives of the interior pair of Antennæ of the Crustacea, are thought to assume the form and the functions of suctorious Mandibles[970].
ii. Facies (the Face). The upper surface of the head[971]. It includes all the parts that lie between its junction with the Prothorax and the Labrum: viz. Nasus, Postnasus, Frons, Vertex, Occiput, Genæ, Tempora, Oculi, Stemmata, and Antennæ.
1. Nasus (the Nose). That portion of the face, often elevated and remarkable, situated between the Labrum, Postnasus, and Genæ, and with which the Labrum articulates; called by Fabricius the Clypeus[972]. It includes the Rhinarium.
A Rhinarium (the Nostril-piece). The space between the anterior margin of the Nasus and the Labrum, in which, in vertebrate animals, the nostrils are often situated[973].—N. B. This is remarkable in some Lamellicorn beetles, as Anoplognathus Leach. In Necrophorus, and some others, it is membranous.
2. Postnasus (the Postnasus). That part of the Face immediately contiguous to the Antennæ, that lies behind the Nasus, when distinctly marked out.—Ex. Sagra, Prosopis.
3. Frons (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[974].
4. Vertex (the Vertex). The horizontal part of the Facies, next the front, that lies behind the eyes and between the temples[975]. This also is often the region of the Stemmata.
5. Occiput (the Occiput). The back part of the head when it is vertical, or nearly so, to its point of junction with the trunk[976].—Ex. Meloe, Ripiphorus, Hymenoptera, Diptera.
6. Genæ (the Cheeks). Those parts which lie on the outside of the anterior half of the eyes, and intervene also between them and the Mandibulæ[977].
7. Tempora (the Temples). Those parts which lie on the outside of the posterior half of the eyes, between which the Frons and Vertex intervene[978].
8. Oculi (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[979].
A Canthus (the Canthus). A process of the face, which enters the notch or sinus of the eye[980].—Ex. Scarabæus L., Cerambyx L.
9. Stemmata (the Eyelets). Two, or more commonly three, convex, crystalline, simple eyes, observable in the Frons or Vertex, or common to both[981].—Ex. Orthoptera, Hemiptera, Hymenoptera.
10. Antennæ (the Antennæ). Two moveable and jointed sensiferous organs, situated in the space between or before the eyes, but in no instance behind them[982]. They include the Torulus, Scapus, Pedicellus, and Clavola.
A Torulus (the Bed). The cavity or socket in which the base of the Antenna is planted[983].
B Scapus (the Scape). The first and in many cases the most conspicuous joint of the Antennæ[984]. It includes the Bulbus.
a Bulbus (the Bulb). The base of the Scapus, by which it inosculates in the Torulus, often subglobose, and looking like a distinct joint[985]. It acts the part of a Rotula, being the pivot upon which the Antenna turns.
C Pedicellus (the Pedicel). The second joint of the Antenna[986]: in some insects acting also the part of a Rotula in the socket of the Scapus, to give separate motion to the Clavola.
D Clavola (the Clavolet). The remaining joints of the Antenna taken together[987]. It includes the Capitulum.
a Capitulum (the Knob). The last joints of the Clavola when suddenly larger than the rest[988].
iii. Subfacies (the Subface). The lower surface or underside of the head[989]. It includes the Lora and Jugulum.
1. Lora (the Lora). A corneous angular machine observable in the mouth of some insects, upon the intermediate angle of which the Mentum sits, and on the lateral ones the Cardines of the Maxillæ; and by means of which the Trophi are pushed forth or retracted[990].—Ex. Hymenoptera.
2. Jugulum (the Throat). That part of the subface that lies between the temples[991].
iv. Collum (the Neck). The constricted posterior part of a pedunculate head, by which it inosculates in the trunk[992]. It includes the Nucha, Gula, and Myoglyphides.
1. Nucha (the Nape). The upper part of the neck[993]. It includes the Myoglyphides.
A Myoglyphides (the Muscle-notches). Notches in the posterior margin of the neck, usually two in number, observable in Coleopterous insects, to which the levator muscles are attached[994].
2. Gula (the Gula). The lower part of the neck[995].
v. Cephalophragma (the Cephalophragm). A Y-shaped partition that divides the head internally in Locusta Leach, into two chambers, an anterior and posterior.
II. TRUNCUS (The Trunk).
The Trunk is the intermediate section of the body, which lies between the Head and the Abdomen[996]. It includes the Manitruncus, and the Alitruncus[997].
i. Manitruncus (the Manitrunk). The anterior segment of the trunk, in which the head inosculates, or on which it turns[998]. It includes the Prothorax and Antepectus.
1. Prothorax (the Prothorax). The upper part or the shield of the manitrunk, in Coleoptera, Orthoptera, &c. called by way of eminence the Thorax[999]. It includes the Ora, Patagia, Umbones, and Phragma.
A Ora (the Ora). The inflexed or inferior lateral margin of the Prothorax, separated in many genera from the Antepectus by a suture[1000].
B Patagia (the Patagia). Two corneous scales observable in Lepidoptera, fixed on each side of the trunk, just behind the head, and covered with a long tuft of hair[1001].
C Umbones (the Bosses). Two moveable bosses surmounted by a spine, with which the Prothorax of the Coleopterous genus Macropus is armed.
D Phragma (the Phragm). The Septum that closes the posterior orifice of the Prothorax in Gryllotalpa Latr.
2. Antepectus (the Forebreast). The underside or breastplate of the manitrunk, and the bed of the Arms[1002]. It includes the Spiracula Antepectoralia, Prosternum, Antefurca, and Brachia.
A Spiracula Antepectoralia (the Antepectoral Spiracles). A pair of breathing-pores fixed in the membrane that connects the Antepectus with the Medipectus[1003].
B Prosternum (the Forebreast-bone). A longitudinal or other elevation of the Antepectus between the Brachia[1004].
C Antefurca (the Antefurca). An internal vertical process of the Antepectus, consisting usually of two branches, which afford a point of attachment to muscles of the Brachia[1005].
D Brachia (the Arms). The first pair of legs of Hexapods, the direction of which is usually towards the head; when spoken of with the other legs, called the Forelegs[1006]. They include the Clavicula, Scapula, Humerus, Cubitus, and Manus.
a Clavicula (the Clavicle). The first joint of the Brachium, answering to the Coxa in the legs.
b Scapula (the Scapula). The second joint of the Brachium, answering to the Trochanter in the legs.
c Humerus (the Humerus). The third and elongated joint of the Brachium, answering to the Femur in the legs.
d Cubitus (the Cubitus). The fourth and elongated joint, answering to the Tibia in the legs. It includes the Coronula and Calcaria. . A Coronula (the Coronula). A coronet or semicoronet of spines, observable at the apex of the Cubitus or Tibia of some insects.—Ex. Dilophus Latr., Fulgora L.
B [Calcaria] (the Spurs). See the definition under Pedes Postici. They include the Velum.
a Velum (the Velum). A membrane attached to the inner side of the cubital spur in Apis L.[1007]
e Manus (the Hand). The terminal jointed portion of the Brachium, answering to the Tarsus in the legs[1008]. It includes the Pulvilli, Palma, and Digitus.
f [Pulvilli] (the Pulvilli). See definition under Pedes Postici.
g Palma (the Palm). The first joint of the Manus, when longer and broader than the subsequent ones, or otherwise remarkable; answering to the Planta in the legs[1009].
A [Digitus] (the Finger). See definition under Pedes Postici. It includes the Ungula.
a [Ungula] (the Claw-joint). See definition under Pedes Postici. It includes the Pollex, Unguiculi, and Palmula.
α Pollex (the Thumb). A small accessory joint, attached to the Ungula of the Manus in Mantis F.
β [Unguiculi] (the Claws). See definition under Pedes Postici.
γ Palmula (the Palmlet). A minute accessory joint between the claws, answering to the Plantula in the legs. It includes the Pseudonychia.
* [Pseudonychia] (the Spurious Claws). See definition under Pedes Postici.
ii. Alitruncus (the Alitrunk). The posterior segment of the trunk to which the abdomen is affixed, and which bears the legs and wings[1010]. It includes the Mesothorax and Medipectus, and the Metathorax and Postpectus.
1. Mesothorax (the Mesothorax). That segment of the alitrunk which bears the Elytra, or the anterior pair of wings, and the intermediate pair of legs[1011]. It includes the Collare, Prophragma, Dorsolum, Scutellum, Frænum, and Pnystega.
A Collare (the Collar). The first or anterior piece of the Mesothorax. In most insects that have a conspicuous Prothorax, as the Coleoptera, this piece appears scarcely to have a representative; but in the Libellulina it co-exists with it, and is more conspicuous[1012]. It is particularly remarkable in Hymenoptera and Diptera.
B Prophragma (the Prophragm). A partition of an elastic substance, rather horny, connected posteriorly with the Dorsolum, which passes down into the anterior cavity of the alitrunk, of which it forms the upper separation from that of the manitrunk. It affords a point of attachment to several muscles of the wings, &c.[1013]
C Dorsolum (the Dorslet). The piece which lies between the Collare and Scutellum, to which the prophragm is anteriorly attached, and which bears the upper or anterior organs of flight[1014]. It includes the Pteropega, Elytra, Tegmina, Hemelytra, Alæ Superiores, and Tegulæ.
a Pteropega (the Wing-socket). The space in which the organs for flight are planted. That for the secondary or under-wings is in the Metathorax[1015].
b Elytra (the Elytra). The upper organs for flight, when they are without nervures, and uniformly of a thicker harder substance than membrane whether corneous, or coriaceous; lined by a fine membrane; and when closed, united by the longitudinal suture[1016]. They include the Axis, Sutura, Epipleura, Alula, and Hypoderma, and are peculiar to the Coleoptera and Dermaptera.
A Axis (the Axis). A small, prominent, irregular process of the base of the Elytrum, upon which it turns, and by the intervention of which it is affixed to the Dorsolum, in the anterior wing-socket[1017].
B Sutura (the Suture). The conflux of the sutural or inner margins of the two Elytra, where when closed they unite longitudinally[1018].
C Epipleura (the Epipleura). The inflexed accessory margin observable underneath in many Elytra, which covers the sides of the alitrunk and abdomen[1019].
D Alula (the Winglet). A small, membranous, wing-like appendage, attached to the Elytrum on one side and the Frænum on the other; which probably serves to prevent the dislocation of the former[1020].—Ex. Dytiscus. N. B. A similar organ for a similar purpose is to be found in Blatta and the Diptera.
E Hypoderma (the Hypoderma). The skin, in some species beautifully coloured, that lines the Elytra[1021]. N. B. This skin is also found in some Hemelytra, but not in Tegmina.
c Tegmina (the Tegmina). The upper organs of flight, when of a uniform coriaceous or pergameneous texture, veined with nervures, and lapping over each other[1022]. Ex. Orthoptera[1023].
d Hemelytra (the Hemelytra). The upper organs of flight, when they are corneous or coriaceous at the base and membranous at the apex[1024].—Ex. The heteropterous Hemiptera. They include the Corium and Membrana.
A Corium (the Corium). The corneous or coriaceous part of the Hemelytrum[1025].
B Membrana (the Membrane). The membranous part of the same[1026].
e Alæ Superiores vel Primariæ (the Upper or Primary Wings). The upper or anterior organs of flight when formed of membrane, or of the same substance with the under-wings[1027]. They include the Axes, Areæ, Areolæ, Neuræ, Stigma, Parastigma, and Lobuli.
A Axes (the Axes). Several osseous or horny pieces, by which the wing is connected with the Dorsolum[1028]. One usually to each area.
B Areæ (the Areas). The larger longitudinal spaces into which the wing may be divided[1029]. They include the Area Costalis, Intermedia, and Analis.
a Area Costalis (the Costal Area). That part of the wing lying between the anterior margin and the post-costal nervure[1030]. In Hymenoptera and Diptera it includes all the space bounded by the nervures that spring from the postcostal.
b Area Intermedia (the Intermediate Area). That part of the wing lying between the costal area and the interno-medial nervure, in Diptera; or the Anal in Orthoptera, Hemiptera, Hymenoptera, &c.[1031]
c Area Analis (the Anal Area). All that part of the wing which in Diptera lies between the internomedial nervure; or in Orthoptera, &c. between the anal nervure and the posterior margin[1032].
C Areolæ (the Areolets). The smaller spaces into which the wing is divided by the nervures. They include the Areolæ Basilares, Mediæ, and Apicales.
a Areolæ Basilares (the Basal Areolets). The parallel areolets of the base of the wing[1033].
b Areolæ Mediæ (the Middle Areolets). The areolets of the wing that lie between the basal areolets and the apical[1034].
c Areolæ Apicales (the Apical Areolets). Those areolets of the wing that terminate in or very near the apex[1035].
D Neuræ (the Nervures). Corneous tubes, for expanding the wing and keeping it tense, and to afford protection to the air-vessels—commonly called the Nerves. They include the Neura Costalis, Postcostalis, Mediastina, Externo-media, Interno-media, Analis, Axillaris, and Spuria.
a Neura Costalis (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 Tegmina[1036]. It includes the Phialum and Hamus.
α Phialum (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[1037].
β Hamus (the Hook). A Hook fixed to the Costal Nervure, near its base on the under-side, in the wings of some Lepidoptera, in which the tendon runs[1038].
b Neura Postcostalis (the Postcostal Nervure). The second principal, and often strongest, nervure of the wing[1039]. It includes the Neuræ Subcostales.
α Neuræ Subcostales (the Subcostal Nervures). Nervures springing from the under-side of the postcostal nervure, or from each other; called the first, second, third, &c. in the order of their occurrence[1040].
c Neura Mediastina (Mediastinal Nervure). A usually slender nervure, springing from near the base of the postcostal; between which and the costal it intervenes. In the Lepidoptera Diurna, however, it is often a strong nervure[1041].
d Neura Externo-media (the Externo-medial Nervure). The third principal nervure of the wing[1042]. It includes the Neura Subexterno-media.
α Neura Subexterno-media (the Subexterno-medial Nervure). A nervure that in some cases intervenes between the externo-medial and interno-medial[1043].
e Neura Interno-media (the Interno-medial Nervure). The fourth principal nervure[1044]. It includes the Neura Subinterno-media.
α Neura Subinterno-media (the Subinterno-medial Nervure). A nervure that sometimes intervenes between the externo-medial and the anal[1045].
f Neura Analis (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 Hemelytra by several[1046]. 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.
g Neura Axillaris (the Axillary Nervure). The short nervure, where there is only one, intervening between the anal nervure and the interior margin; replaced in some Muscidæ by a spurious nervure[1047].
h Neuræ Spuriæ (the Spurious Nervures). Very obsolete nervures, sometimes found in addition to those usually occurring; as in Syrphus[1048].
E Stigma (the Stigma). A corneous spot or plate, supposed to contain fluid, in the anterior margin of the upper wings; often produced by the conflux of the costal and postcostal nervures[1049].
F Parastigma (the Parastigma). A corneous spot between the costal and postcostal nervures, distinct from the Stigma observable in the Libellulina.
G Lobuli (Lobuli). One or more rounded portions of the base of the wing, separated from the rest by fissures peculiar to the Muscidæ, and the under-wings of some Hymenoptera[1050].
f Tegulæ (the Tegulæ). Small corneous concavo-convex scales, which in many Orders, particularly Hymenoptera, cover and defend the base of the Upper-Wings[1051].
D Scutellum (the Scutellum). A piece, usually triangular, which follows the Dorsolum; and in Coleoptera is often only a continuation of it—placed between the base of the Elytra or upper-wings[1052].
E Frænum (the Frænum). A piece that lies under the lateral margin of the Scutellum and Dorsolum, or is adjacent to it; and which in many cases connects with the base of the upper organs of flight, so as to prevent their dislocation, by being pushed too far outwards[1053].
F Pnystega (the Pnystega). A corneous scale or plate, which covers certain pneumatic vessels, usually supported by the Scapularia, in Libellulina, &c. becoming dorsal[1054].
2. Medipectus (the Mid-breast). The underside of the first segment of the alitrunk[1055]. It includes the Peristethium, Scapularia, Mesosternum, Medifurca, and Pedes Intermedii.
A Peristethium (the Peristethium). The anterior piece of the Medipectus, which intervenes between the Brachia and mid-legs[1056].
B Scapularia (the Scapulars). Two pieces, one on each side the Medipectus, which succeed the Peristethium, and lie between the midlegs and the Pteropega or wing-socket[1057]. It includes the Spiracula Scapularia.
a. Spiracula Scapularia (the Scapular Spiracles). Two spiracles observable, one in each scapular, in Acrida laurifolia, &c.
C Mesosternum (the Mid-breastbone). The elevated and central part of the Medipectus, between the midlegs, often terminating anteriorly in a mucro; sometimes, as in Elater, in a cavity, receiving the mucro of the Prosternum[1058].
D Medifurca (the Medifurca). A branching vertical process of the Endosternum, which serves as the point of attachment to the muscles that move the midlegs[1059].
E Pedes Intermedii (the Mid-legs). The intermediate pair of legs, consisting of the same parts as the posterior legs[1060].
3. Metathorax (the Metathorax). The posterior segment of the Alitruncus[1061]. It includes the Mesophragma, Postdorsolum, Postscutellum, Postfrænum, Pleuræ, and Metaphragma.
a Mesophragma (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 attachment to several of the muscles that move the wings[1062]. This, with the prophragm, forms the anterior cavity of the alitrunk, and with the metaphragm it forms the posterior cavity.
b Postdorsolum (the Postdorsolum). The middle-piece between the mesophragm and the Postscutellum. In Coleoptera it consists of a tense elastic membrane, which is quite covered by the Mesothorax[1063].
c Postscutellum (the Postscutellum). A narrow channel running from the Dorsolum to the Abdomen in 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[1064].
d Postfrænum (the Postfrænum). In Coleoptera the part of the Metathorax in which the Postscutellum lies, at first nearly horizontal, but posteriorly it takes a vertical direction towards the abdomen. In general it may be defined, the part that intervenes between the Postscutellum and the Abdomen; and which in many cases is connected with the posterior basal margin of the under-wings, and prevents their being pushed too far forwards[1065].
e Pleuræ (the Pleuræ). The space behind the scapulars, on which the lower organs of flight are fixed[1066]. They include the Alæ Inferiores.
A Alæ Inferiores (the Under-wings). The lower or secondary pair of organs for flight[1067]. They include the Commissura, Tendo, Hamuli, Pterygium, Alula, and Halteres.
a Commissura (the Commissura). A joint in the costal nervure of the wings of Coleoptera, where they bend to take a transverse fold[1068].
b Tendo (the Tendon). A strong bristle, or bristles observable at the base underneath in the under-wings of many Lepidoptera, which plays in the Hamus of the upper-wings[1069].
c Hamuli (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[1070].
d Pterygium (the Pterygium). In under-wings this is a small wing-like appendage, fixed at the base of the wing in some Lepidoptera[1071].
e Alula (the Winglet). A small concavo-convex scarious appendage, fixed behind the wings at their base, in many Diptera[1072].
f Halteres (the Poisers). Small capitate processes or organs, observable under the wings of Diptera, attended by a spiracle[1073].
B Metapnystega (the Metapnystega). A corneous scale or lamina that covers the pneumatic organs in the Metathorax, situated sometimes in the Pleuræ, as in the Coleoptera; at others in the Postfrænum, as in Tenthredo L.; and sometimes, as in the Libellulina, between that part and the abdomen[1074].
C Metaphragma (the Metaphragm). A nearly vertical septum or partition, attached behind to the Postfrænum, and usually deeply cleft at its apex in Coleoptera, of a rather horny consistence, which forms the upper separation of the second cavity of the Alitrunk from that of the Abdomen[1075]. It affords a point of attachment for many muscles of both alitrunk and abdomen. It includes the Septula.
a Septula (the Septula). The lesser ridges and partitions raised on the surfaces of the metaphragm, and on those of other parts of the cavities of the trunk, serving as points of attachment to various muscles[1076].
4. Postpectus (the Postpectus). The underside of the second segment of the alitrunk[1077]. It includes the Mesostethium, Parapleuræ, Metasternum, Postfurca, Opercula, and Pedes Postici.
A Mesostethium (the Mesostethium). A central piece between the intermediate and posterior legs, and bounded laterally in Coleoptera by the Parapleuræ—along the middle of which, where it exists, the Metasternum runs[1078].
B Parapleuræ (the Parapleuræ). Two pieces, one on each side of the Postpectus, included between the Scapularia, Mesostethium, and Pleuræ[1079]. They include the Spiracula Parapleuritica.
a Spiracula Parapleuritica (the Parapleuritic Spiracles). Two spiracles, one in each of the Parapleuræ of Tetyra[1080].
C Metasternum (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 vitticollis, 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, Diptera, &c.[1081] It includes the Pectines.
a Pectines (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, resembling the teeth of a comb[1082].
D Postfurca (the Postfurca). A process of the Endosternum, 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[1083].
E Opercula (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 Tympana in male Tettigonia F.[1084] Perhaps these may be regarded as a kind of Metapnystega in a new situation.
F Pedes Postici (the Hind-legs). The pair of legs affixed to the postpectus[1085]. They include, the Acetabulum, Coxa, Trochanter, Femur, Tibia, and Tarsus.
a Acetabulum (the Socket). The socket in the Postpectus in which the leg is planted[1086]. It includes the Pessella.
A Pessella (the Pessella). Two little acute processes, fixed one in each, in the socket of the hind-legs in male Tettigoniæ, which appear designed to keep down the Opercula[1087].
b Coxa (the Hip). The first joint of the leg which plays in the socket[1088].
c Trochanter (the Trochanter). The second joint of the leg, by which the thigh inosculates in the Coxa. It appears to have no motion separate from that of the thigh. It is sometimes biarticulate[1089].
d Femur (the Thigh). The third joint of the leg, long and usually compressed[1090]. It includes the Gonytheca.
A Gonytheca (the Knee-pan). A concavity at the apex of the thigh, underneath, to receive the base of the Tibia[1091].
e Tibia (the Shank). The fourth joint of the leg, very long, and usually triquetrous[1092]. It includes the Epicnemis, Molula, Talus, Calcaria, and Coronula.
A Epicnemis (the Epicnemis). An accessory joint at the base of the Tibia in many Arachnida, which does not appear to have separate motion[1093].
B Molula (the Knee-ball). The convex and sometimes bent head of the Tibia, armed with a horny process on each side, by which it is attached to the thigh[1094].
C Talus (the Ankle). The apex of the Tibia, where it is united to the Tarsus[1095].
D Calcaria (the Spurs). One, two, or more moveable spines, inserted usually at the apex of the Tibia; and in many Carabi L., Lepidoptera L., and Trichoptera K., in the middle also. They may be regarded as a kind of fingers auxiliary to the Tarsus, and furnish often an important character in the discrimination of genera[1096].
E Coronula (the Coronula). A coronet or semicoronet of fixed spines observable at the apex of the posterior Tibia in Fulgora candelaria, &c.
f Tarsus (the Tarsus). The fifth principal portion of the legs; consisting in the majority of insects of 1-5 joints, but in the Phalangidæ of sometimes as many as 50[1097]. It includes the Planta, Digitus, and Solea.
A Planta (the Instep). The first joint of the Tarsus is so called when it is remarkably long and broad[1098]. It includes the Calx.
a Calx (the Heel). The curving part of the Planta, by which it inosculates with the Tibia.
B Digitus (the Toe). The remaining joints of the Tarsus taken together[1099]. It includes the Allux and Ungula.
a Allux (the Toe-ball). The last joint but one of the Tarsus, when remarkable, as in Rhyncophorous beetles (Curculio L.)[1100].
b Ungula (the Claw-joint). The last joint of the Tarsus, which bears the claws[1101]. It includes the Arthrium, Unguiculi, and Plantula.
α Arthrium (the Arthrium). A very minute joint at the base of the claw-joint, in most Tetramerous and Trimerous beetles[1102].
β Unguiculi (the Claws). One or two pair of moveable incurved claws, which usually arm the apex of the Ungula[1103].
γ Plantula (the Plantula). A minute accessory joint, sometimes attached within the claws to the apex of the Ungula[1104]. Ex. The Lucanidæ. It includes the Pseudonychia.
* Pseudonychia (the Spurious Claws). Two stiff clawlike bristles, that terminate the Plantula[1105].
C Solea (the Sole). The underside of the Tarsus[1106]. It includes the Pulvilli.
a Pulvilli (the Pulvilli). Cushions of short hairs very closely set; or of membrane, capable of being inflated, 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 suspend itself, or walk against gravity[1107]. Ex. Timarcha, Buprestis, Priocera K., the Gryllina, Muscidæ, &c.
III. ABDOMEN (the Abdomen).
The Abdomen is the third or posterior section of the body which follows the Truncus[1108]. It includes the Tergum, Venter, Petiolus, Cauda, and Anus.