98 CRABS AND INSECTS. 



known as labial palpi. Near the compound eyes rise the 

 sense-organs, or antenna. The thorax is separated into 

 three segments : the first, prothorax, bearing the first pair 

 of legs ; the second segment, or mesothorax, bears the elytra 

 or first pair of wings in the beetles, hard, chitinous store- 

 house for the wings proper (here is also attached the sec 



Third leg. 



FIG. 1 10. Skeleton of common beetle. (After Morse.) 



ond pair of legs) ; the third segment, or metathorax, bears 

 the third pair of legs and the second pair of wings, that 

 are elastic membranes stretched over a framework of 

 tubes. The abdomen bears the sting, ovipositor, or spin- 

 nerets, as the case may be. The legs are generally com- 

 posed of from six to nine joints, and usually terminate in 

 two hooks, with perhaps pads or suckers (Fig. in). 



Digestion. The mouth-parts (Fig. 112, a) are modified 

 in different insects for sucking, biting, stinging, etc. The 



