CLASS INSECTS. 373 



organs of prehension, the leg being flexible and disposed like 

 a claw, the edge being armed with spines. The mantis reli- 

 giosa (Fig. 346), a large insect of the south of France, is 

 armed in this way. 



Finally, there are insects (several diurnal butterflies. Fig. 

 347) in which the anterior limbs are so small or rudimentary 

 as to escape notice, as if they had only four pair of limbs. 



Fig. 345. Courtiliere. 



516. The wings of insects are laminated appendages, 

 composed of a double membrane, supported internally by 

 more solid " nervures." When scarcely developed, they are 

 soft and flexible ; but they soon dry, and become stiff and 

 elastic. There are never more than two pairs, sometimes 

 only one, and they vary in form ; they always spring from 



Fig. 346. Mantis Eeligiosa. 



the last two rings of the thorax. When they really serve for 

 flight they are thin, translucent, and covered with microscopic 

 scales like dust, as is seen in butterflies ; but the anterior 

 wings often become hard and opaque, and becoming useless 

 as wings form elytra, i. e., protecting sheaths for the others 

 (a, Fig. 348). At other times these same wings, still mem- 



