32 THE CLASS OF INSECTS. 



to the binder edge ; there are also sets of dorsal and ventral 

 muscles going in an oblique or vertical course. The muscles 

 are either colorless and transparent, or yellowish white ; and 

 of a soft, almost gelatinous consistence. In form they are 

 simply flat and thin, straight, band-like, or pyramidal, barrel 

 or feather-shaped. They act variously as rotators, elevators, 

 depressors, retractors, protrusors, flexors, and extensors. 



'Tha muscular power of insecta is enormous. The Flea will 

 leap two hundred times its own height. Certain beetles can 

 support enormous weights. Newport cites the case of Geo- 

 trupes stercorarius v{\\\q\\ is "able to sustain and escape from 

 beneath a pressure of from twenty to thirt}^ ounces, a prodi- 

 gious weight when it is remembered that the insect itself does 

 not weigh even so many grains." Some beetles have been 

 known to gnaw through lead-pipes, and the Stag-beetle of 

 Europe, Lucarms cervus, has, as stated by Mr. Stephens, 

 gnawed "a hole an inch in diameter through the side of an 

 iron canister in which it was confined." 



"The motions of the insect in walking as in flying are 

 dependent, in the perfect individual, entirely upon the thoracic 

 segments, but in the larva chiefly upon the abdominal. Al- 

 though the number of legs in the former is alwaj^s six, and in 

 the latter sometimes so many as twenty-two, progression is 

 simple and easy. Miiller states (Elements of Physiology, p. 

 i>70, Translation) that on watching insects that move slowly 

 he has distinctly perceived that three legs are always moved at 

 one time, being advanced and put to the ground while the 

 other three propel the body forwards. In perfect insects, those 

 moved simultaneously are the fore and hind feet on one side, 

 and the intermediate foot on the opposite ; and afterwards the 

 fore and hind feet on that side, and the middle one on tht; 

 other, so that, he remarks, in two steps the whole of the legs 

 are in motion. A similar uniformity of motion takes place 

 in the larva, although the whole anterior part of the bodj'^ is 

 elevated and carried forwards at regular distances, the steps of 

 the insect being almost entirely i)erformed by tlie 'false,' or 

 abdominal legs." 



^'■Inflight the motions depend upon the mcso- and meta- 

 thoracic segments conjointly, or entirely upon the former. The 



