72 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



in proximal end of tibia, the third (/jpc) on ventral wall of basal half 

 of tibia; all inserted on fine, tendon-like apodeme (/^P ^P) arising 

 from unguitractor plate at base of claws. 



IV. THE LEGS AND THEIR MUSCLES 



The legs of the grasshopper are all of typical form and segmenta- 

 tion, but the hind legs, being specially developed as organs of leaping, 

 are not only of greater size than the others but difl:'er from them in 

 certain details of structure and in the relative proportions of some 

 of the muscles. When the grasshopper sits in an ordinary resting posi- 

 tion it supports itself principally on the first and second pairs of legs, 

 the tibiae of the hind legs being flexed against the under surfaces of 



in 



Fig. 40. — Middle leg of Dissosteira, anterior surface. 



Ar, aroHum; Cx, coxa; Fm, femur; Tar, tarsus; Tb, tibia; Tn, trochantin; 

 Tr, trochanter ; Un, claw. 



the femora, with the knees usually held low and the tarsi barely touch- 

 ing the ground. (The grasshopper of illustrations commonly rests on 

 all three pairs of legs, with the hind knees elevated and the tibiae ex- 

 tended.) In its natural resting attitude, the insect is always ready for 

 a leap, the spring being caused by a forcible extension of the hind 

 tibiae, probably accompanied by a strong depression of the trochantero- 

 femoral parts of the legs. The chief function of the first and second 

 legs is the support of the body and the directing of the few movements 

 of walking or of changing the resting position ; the first legs are ac- 

 tively used also during feeding for grasping and manipulating the 

 edge of the leaf. When the grasshopper walks the hind legs are used 

 with the others in the usual fashion. 



In describing the legs it is customary to use terms of orientation 

 as they would apply if the appendage were extended laterally at right 

 angles to the body. Preaxial and postaxial surfaces are called anterior 

 and posterior, and upper and lower surfaces are dorsal and ventral. 



