50 



THE THOEAX OR TEUNK. 



CHALCTS-CLAVTPES. 



The legs of insects are constriictecl on the opposite 

 plan from that of vertebrates. Instead of consisting, as 

 the arms or legs of the quadrupeds or the human system, 

 of a central bone or hai'd substance for a lever, with the 

 muscles as cords, and their attendant organs wrapped 

 around it, each joint is a tube, and serves as the bone or 

 skeleton of the limb, and includes within it the moving 

 muscles, nerves and other special organs. 



HIND LEG OF BEES. 



a, coxa ; &, trochanter ; c, femur ; d, tibia ; g, tarsus. 



The legs of insects generally consist of five pieces; the 



coxa or hip — the trochanter — the femur, or thigh — the 



tibia, or shank — the tarsus, or foot. These parts are 



not, however, the same in structure with those that bear 



