ORTHOPTERA OF INDIANA. 



137 



■Jun 



convex, while its front margin is rendered still more rigid by being 

 overlapped by the internal margin of the upper wing or tegmina. 

 The numerons veins radiating from the base are so arranged that 

 their elasticity causes the wing to fold upon itself like a fan as soon 

 as its margin is released. The principal veins correspond in position 

 to those of the tegmina, and have the same names. Both tegmina 

 and wings are wanting in a numljer of species of Orthoptera, while 

 in others the tegmina are present and the wings absent. 



The Legs of a locust are six in number, arranged in pairs, one 

 pair being joined to each of the divisions of the thorax. The first 

 and second pairs are much smaller than the third, but the number 

 and. name of the joints is the same. They unite with the body at 

 a different angle from the hind or third pair, and are therefore 

 adapted to crawling and clinging to grass stems or other support, 

 rather than to leaping. 



The hind pair or leaping legs of the locust are composed of five 

 parts: 



The "coxa'' (c), or basal division, 

 which is joined to the thorax; a 

 small segment, the "trochanter," 

 (tr), immovably joined to the upper 

 apical portion of the coxa; the "fe- 

 mur" (f), a long, swollen, club- 

 shaped segment, which makes up 

 nearly half the length of the limb. 

 When the animal is at rest, it ex- 

 tends upward and backward, with 

 its apical end above the dorsal sur- 

 face of the body. This joint con- 

 tains powerful leaping muscles. The 

 "tibia" (ti), is about as long as the 

 femur, but is very slender and of uniform diameter. When 

 at rest it extends downward and backward, at an acute angle 

 from the apex or knee of the femur, but in the act of jumping it is 

 thrown backward and the limb becomes straight. It bears on each 

 of its lower outer margins a row of spines, and at the end, one or 

 more pairs of longer spines or spurs known as "calcaria." The tibiae 

 of the fore legs of many Orthoptera are much modified for use in 

 burrowing or prehending food. The "tarsus" (ta) or foot of the 

 locust is made up of three movable joints. The first and longest 

 has upon its lower surface a soft pad (p) which, by its adliesion to 

 foreign bodies, serves as a point of resistance in leaping. The second 



39-Geol. 



Fig. 12. Hind leg of a locust. 

 (After Lugger.) 



