526 



GENERAL CHARACTERS OF REPTILES. 



the extremities of the ribs, and which form a kind of border to 

 the carapace, evidently represent the sternal portions of these 



FIG. 305. SKELETON OF LAND TORTOISE, WITH THE PLASTRON REMOVED. 



vc, cervical vertebrae ; vd, dorsal vertebras ; c, ribs ; cs, sternal ribs, or marginal pieces 

 of the carapace ; o, scapula ; cl, clavicle ; co, coracoid bone ; b, pelvis ; /, femur ; 

 t , tibia ; p, fibula. 



bones ; which, in Mammalia, remain in a cartilaginous state, but 

 which amongst Birds are completely ossified. In some Tortoises, 

 even, they remain cartilaginous ; and in almost all these animals 

 several of them are supported at their edges upon the borders 

 of the Plastron. 



465. The plastron is formed by the sternum, which presents 

 an extraordinary development, and is extended from the base of 

 the neck to the commencement of the tail, (Fig. 327). The 



