Page:Jardine Naturalist's library Entomology.djvu/115

Rh as of two divisions, which may be distinguished as the anterior and posterior wings of the scapulæ. The spiracle of the mesothoracic segment, which had been long overlooked, owing to its latent position, is found beneath and a little beyond the posterior wings. The patagia and tegulæ of the Lepidoptera and Hymenoptera, (which we shall afterwards allude to, when considering these orders) are attached, the latter to the mesonotum, the former to the posterior wing of the scapula. The mesosternum forms the under side of the mesothoracic case, being directly opposite to the mesonotum. It is in all cases distinct, and sometimes comprehends a considerable area, in which the sockets of the middle legs are included. The only primary segment of the thorax remaining to be considered, is the Metathorax which, like that last described, supports a pair of legs and a pair of wings. It does not attain a high degree of development in any of the orders, except among the Coleoptera and Orthoptera; its structure, consequently, can be most satisfactorily investigated in these. It may likewise be regarded, according to the authority we have chiefly followed in describing the constituent parts of the thorax, as consisting of seven pieces, which bear considerable resemblance to those of the mesothorax. The dorsal portion is the metanotum, commonly quadrangular, with the front emarginate, and the anterior angles consequently advanced. The