546 EXTERNAL ANATOMY OF INSECTS. 
remaining ones it is merely suspended to it. In the 
former also, especially in the Coleoptera, it seems more 
separate and distinct from the manitrank than from 
the abdomen, and more independent of its motions than 
of those of the latter part: but in the Hymenoptera 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 manitrunk terminates 
posteriorly, drawing a line from the base of the prothorax 
to the antepectus, in an oblique section ; in other tribes, 
as in the Capricorn and Predaceous beetles, &c., the 
section here is often vertical, but in the alitrunk the an- 
terior one is always vertical, 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 ‘wo greater segments, the 
first bearing the elytra, or the primary wings, and the 
intermediate legs ; and the second, the secondary wings 
and the hind legs. 
1. Collare*. 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 
medipectus. 'The first piece in the former that requires 
notice is the collar. I formerly regarded this piece, 
* Prate IX. g’. 
