340 INSECTA. 



tages, which the study derives from the forms of their external organs, &c., 

 have secured to them the particular attention of naturalists. 



Their head presents antenna: of various forms, and almost always composed 

 of eleven joints; two compound eyes, but none simple; and a mouth consist- 

 ing of a labrum, two mandibles, usually of a scaly substance, two jaws, each 

 furnished with one or two palpi, and of a labium formed of two pieces, the 

 mentum and the ligula, and accompanied by two palpi, commonly inserted 

 into the latter. Those of the jaws, or when they have two, the exterior 

 ones, never consist of more 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 thorax, bears the first pair of legs, and is much larger than 

 the two other segments. The latter are intimately united with the l>ase of 

 the abdomen, and their inferior portion or pectus gives insertion to the second 

 and third pairs of legs. 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 meta- 

 thorax. The elytra are crustaceous, and when at rest, join along their internal 

 margin, and 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, 

 or less solid than underneath. The number of joints in the tarsi varies from 

 three to five. 



The Coleoptera undergo a complete metamorphosis. The larva resembles a 

 worm, having a scaly head, a mouth analagous to that of the perfect insect in 

 the number of its parts, and usually six feet. Some few species are destitute 

 of them, or have merely simple mammillae. 



The pupa is inactive and takes no nourishment. The habitations, mode of 

 life, and other habits of these insects, in both states, vary greatly. 



I divide this order into four sections, according to the number of joints in 

 the tarsi. 



The first comprises the PENTAMERA, or those in which all the t:irsi consul of 

 five joints, and is composed of six families. 



FAMILY I. 



CARNIVORA. 



Two palpi to each maxilla, or six in all ; antenna; almost always filiform or 

 setaceous, and simple. 



The maxilla? are terminated by a scaly hook or claw, and the interior side is 

 furnished with cilia or little spines. The ligula is fixed in an emargination of 



