548 EXTERNAL ANATOMY OF INSECTS. 



cially the last, almost covers and conceals it ; but in the 

 remaining ones it is merely suspended to it. In the 

 former also, especially in the Coleoptera, it seems more 

 separate and distinct from the manitrunk than from 

 the abdomen, and more independent of its motions 

 than of those of the latter part : but in the Hymeno- 

 ptera and Diptera its greatest separation is from the 

 abdomen in both respects. In many insects, as in the 

 Lamellicorn beetles, the mole-cricket, &c, the mani- 

 trunk terminates posteriorly, drawing a line from the 

 base of the prothorax to the antepectus, in an oblique 

 section ; in other tribes, as in the Cerambyx L., the 

 Predaceous beetles, &c, the section here is often vertical, 

 but in the alitrunk the anterior one is always verti- 

 cal, while the posterior, by which it articulates with the 

 abdomen, in the Orders with an ample thoracic shield, is 

 oblique, so that the pectoral portion is more ample than 

 the dorsal. 



ii. As to its composition, the alitrunk is usually much 

 more complex than the manitrunk ; for, besides the in- 

 struments of motion, it consists of numerous pieces. It 

 may be regarded as formed of two greater segments, the 

 first bearing 'he elytra, or the primary wings, and the 

 intermediate legs ; and the second, the secondary wings 

 and the hind legs. 



1. Collare a . The first segment of the alitrunk is the 

 middle piece of the whole trunk, and therefore, when 

 spoken of per se, may be called the meditruncus. It 

 consists primarily of an upper and lower part, which 

 in the table are denominated the mesothorax and the 



' Plate IX. g . 



