EXTERNAL ANATOMY OF INSECTS. 543 



very wide in proportion to its length — Dytiscus, Helceus j 

 at others very long in proportion to its width — Colliuris, 

 Brentus, Mantis, &c. In Plata, and many other Ho- 

 mopterous Hemiptera, it is extremely short ; extremely 

 long in Glioma; in Sagra and Donacia its width about 

 equals its length ; in Plater, Dytiscus, and many Hete- 

 ropterous Hemiptera, it is narrowest before ; in Langu- 

 ria it is every where of equal width ; in Anthia, Carabus, 

 &c., it is widest before ; and, lastly, in the Scarabceidce 

 MacLeay it is usually widest in the middle. 



ii. Antepectus a . — The antepectus, as was before ob- 

 served 5 , in some tribes forms one piece, without any 

 kind of separation, with the prothorax ,• but very often 

 this is not the case. In Carabus L. it occupies almost 

 the whole under-side of the manitrunk ; but in Plater, 

 in which the or a is very wide, the antepectus is merely 

 the middle portion of that part. In Carabus F. &c. be- 

 tween the ora and the base of the arms is a convex tri- 

 angular piece, distinguished from the rest of the ante- 

 pectus by a spurious suture ; and in Pentatoma and other 

 Heteropterous Hemiptera a similar piece is observable, 

 which terminates in a convex bilobed subtriangular 

 sheath, receiving the base of the clavicle c . This piece 

 seems a prop to that part, and analogous to the scapula 

 of the medipectus and parapleura of the postpectus. I 

 shall say no more upon the antepectus, as it is seldom 

 remarkable. In the mole-cricket, however, one peculia- 

 rity distinguishes it: it is in this of an elastic leathery 



« Plate VIII. b. " See above, p. 536. 



c Something of the kind is observable at the base of the other 

 legs in this tribe. 



