INSECTA. 805 



the liveliest colors. The scales are imbricated, each has a peauncle, 

 and they form in conjunction, a kind of mosaic work, exhibiting the charac- 

 teristic figures and colorings of this part. In the large class of Coleoptera, 

 in place of upper or anterior wings, two large scales or plates, opaque, more 

 or less thick and solid, and which open and shut longitudinally, forms for 

 the membranous wings, coverings which are called wing-cases, or elytra, 

 (involucre/). In the greater part of the Orthoptera, thes« wing-cases, or upper 

 wings, become thick and solid, and are furnished with ribs ; in the Hemip- 

 tera, they are in a great part membranous ; and the gradual transition from 

 crustaceous coverings, to membranous and transparent organs, indicate that 

 the wing-cases in the Coleoptera, though scarcely contributing to the action 

 of flight, are modified wings. The form and disposition of the wings is 

 much varied. In some they are straight and extended, or folded longitu- 

 dinally like a fan, in repose ; in others, they are folded transversely, as in 

 the Coleoptera ; and in others again, as the earwig, while one portion of the 

 wings is folded transversely, the other takes the fan-like fold. The wings 

 vary also in their place of position. In some insects, they are found inclined 

 or sloped like a roof; in others they are placed horizontally, lying or crossed 

 over one another, or sometimes separated ; some, as the butterflies, raise 

 their wings vertically in repose ; and small hooked setae placed along the 

 side of the upper wings, serve to retain the lower ones in their position. 

 In the nocturnal Lepidoptera, this is effected by a stiff, scaly, and pointed 

 bristle. Among the insects with four wings, the form and relative size of 

 these wings vary much. By their rapid motion, they often produce a hum- 

 ming sound ; and among the males of some Orthoptera, a stridulous noise, 

 which has been called their song. This sound is produced by the friction 

 of the margins of their elytra upon one another, or by the rubbing of the 

 posterior feet against the wings, and is conceived to be produced for the pur- 

 pose of calling their females. 



The feet in insects are composed of the hip or coxa, of two joints ; the 

 thigh, (femur,) the leg, (tibia,) and the toe, (tarsus,) divided into many 

 phalanges. The number of joints in the tarsi is constantly five in some 

 orders ; but in others it varies from one to five, and sometimes even the pos 

 terior tarsi have a joint less than the anterior ones. Upon the difference in 

 these members the principal divisions of the Coleoptera are established. The 

 last joint of the tarsi is simple, or divided into two lobes, almost always 

 terminated by two claws or hooks, between which, in many, are remarked 

 from one to three membranous cushions or suckers. In the form of the 

 feet, and particularly the tarsi, there are certain modifications, correspond- 

 ing to the habits of the insects. The two anterior ones have sometimes the 

 under part of the thighs grooved, and armed with slight dentations ; and 

 their legs or tarsi, in this case, terminated by a strong spine, fold with 

 facility on the side of the thighs, and form an organ of prehension. The 

 insects which have the anterior feet disposed in this manner, use them for 



68 



