INTERNAL ANATOMY OF INSECTS. 185 



With regard to the orga?is 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 parictes 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 

 coxae which are rotators, causing it to turn backwards 

 or forwards and the extensor of the thigh, have their 

 attachment in the parietes 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 antefurca ; 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 (Eutrechma and Euncchma), &c., whose posterior 

 coxse are immoveable, the thigh includes two pair of an- 



a Cuv. Anat. Comp. i. 436. PLATE XXI. FIG. 6. 



b Ibid, a, b. Lyonet Anat. 37. 



c Cuv. ubi supr. 458-. VOL. III. p. 368, 3?8, 382. 



