INTERNAL ANATOMY OF INSECTS. 185 
With regard to the organs of the trunk, we have more 
certain and satisfactory information ; — the muscles of the 
legs having been described by Lyonet and Cuvier, and 
those of the wings most particularly by Chabrier. In 
caterpillars, the muscles are situated in the interior of 
the articulations that form the legs : they consist of seve- 
ral bundles appropriated to each, which have their at- 
tachment in the parities of the preceding joint, near the 
margin, and are inserted in the margin of that they 
move a . Lyonet counted twenty-one muscles in the leg 
of the caterpillar of the Cossus ; but eight of these were 
appropriated to the claw, or rather formed a pair of se- 
mipenniform muscles, having their insertion at the inner 
angle of its base b . In perfect insects, according to Cu- 
vier, each joint of the legs is furnished with a pair of 
antagonist muscles — a flexor and extensor, the former 
being the lower, and the latter the upper muscle ; and this 
pair has its insertion in the joint it moves, and its attach- 
ment usually in the preceding one : but those of the 
coxoe — which are rotators, causing it to turn backwards 
or forwards — and the extensor of the thigh, have their 
attachment in the parictes of the trunk, and to the endo- 
sternum ; one of the rotators of the anterior coxa, and 
the extensor of the anterior thigh to the antcfurca ; of 
the intermediate pairs to the medifurca, and of the poste- 
rior to the postfurca c . Every joint of the tarsus has also 
its flexor and extensor. In the ground- and water-bee- 
tles (Eutrech'ma and Eunech'ma), &c, whose posterior 
coxae are immoveable, the thigh includes two pair of an- 
■ Cuv. Anal. Comp. i. 436. Plate XXI. Fig. 0. 
b Ibid, a, b. Lyonet Anal. 37. 
c Cuv. ubi snpr. 458--. Vol. III. p. 3G8, 378, 382. 
