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Show 264 JNSJo:CTA. called the CMque or Chigre in America, most probably forms particular genus. It insinuates itself unde1· the nails of th: toes and the skin of the heel, where, by the speedy development of the ova contained in a membranous sac under the venter, it soon acquires a size equal to that of a pea. The numerous family, to which it gives birth, produces a ma. lignant ulcer, that is cured with difficulty, and which sometimes proves mortal. These difficulties are genc1·ally avoided by rub. bing the feet with bt•uised toba-cco leaves and other bitter and acrid plants. The Negroes extract the animal f1·om its domicil with much address. Various Quadrupeds and Birds are infested with Fleas which ap. pear to differ specifically from these two. ORDER V. COLEOPTERA( I). Coleopterous Insects have four wings, the two superior or which resemble horizontal scales, joining in a straight line along the inner margin ; the inferior wings are merely folded transversely and covered with others, which form cases or covers for them, usualJy denominated the elytra(2). Of all Insects, these are the most numerous and the best known. The singular form and brilliant colouring of many species, the volume of their bodies, the greater solidity of their teguments, which facilitates their preservation, the numerous advantages which the study derives from the various forms of their external organs, &c., have secured to them the particu· Jar attention of naturalists. Their head presents antenn~ of various forms, and almost always composed of eleven joints; two compound eyes, but (1) The Eleutherata, Fab. '(2) Fol' the anatomical characters of the Coleoptel'a, sC'e Ann. des Sc. Nat. VUT, p. 36, where a resume is given by M. Dnmeril . 265 none simple( I); and a month consisting of a' labrum, two mandibles, usually of a scaly substance, two jaws, each furnished with on<; or tw9 pal pi, and of a ·labium form.ed of two pieces, the mentum and the ligula, and accompanied by two palpi, co!llmonly inserted. i,nto til~ l~tter. . Those of the jaws, or when they have two, the exterwr ones, neve1· consist of mot•e than four joints; those of the lip usually have 'three. 'The anterior 'segment of the trunk, or that which is before the wings, usually called the corselet, bears the fit·st pair of legs, and is much larger than the two other seginents(2). The latter are int'imately united with the base of the abdomen, and their inferior portion or pectus gi vcs insertion to the· second and third pair·s of legs(3). The second, on which the 'scutellum is placed, is narrowed before, and forms a short pedicle which fits into the interior of the first, and serves as a pivot, on which it moves. The elytra and wings arise from the lateral and superior edges of the metathorax. The ely~ra are crust.aceous, and wheJl at rest, join along their internal margin, an.d always horizontally. .They almost always conceal the wings, which are wide and transversely folded. Several species are apterous, but the elytra still exist. The abdomen is sessile or united to the trunk in its greatest width. It is composed externally of six or seven annuli, membranous above, OJ' less solid than underneath. The iiuinber of joints in the tarsi varies fr'Om three( 4) to five. The Coleoptera undergo a complete m~tamor~hosis. · The (1) In some of the Drachclytt•a two small yellowish poi'nts have been obs~rved, that have been taken fot• ocelli: but without, as I imagine, any careful examination, particularly as the Forficulre, a genus of the Orthoptcra that is nearest to the Coleoptera, exhibit none. (2) The internal membrane, oh each side, behind, presents a stigma, a charac. ter which I believe had not yet been observed, although it was presumed to exist. (3) The mesothorax is always short and narrow, and the metathot•itx frequently spacious, and longitudinally sulcated in the middle. . (4) lf we may judge from analogy, the Coleoptera, termed Monomera, have proba~ly three joints in the tarsi, the two first of which escape obset·vation; thia . section and that of the Dimera have been suppressed. VoL. III.-2 I |