84 



THE COMMON FROG. 



[chap. 



upon the first appearance of vertebrate limbs, differen- 

 tiated in a fashion which thenceforward becomes 

 universal. 



The bones of the wrist in the frog, again, present a 

 nearer resemblance to those in man than do those of 

 most reptiles, and this is still more the case in some 

 other members of the frog's class, e.g. Salamandra 



Fig. 48. Fig. 49. 



Fig. 48. — Skeleton of anterior extremity of an eft. 

 Fig. 49. — Skeleton of posterior extremity of the same. 



and other Efts. Nevertheless, there are certain 

 reptiles, and, strange to say, they are once more 

 Chelonians, which agree in this resemblance — as m.ay 

 be seen in the hand of the tortoise — Chelydra 

 serpentina. 



The bones of the fingers show, moreover, a greater 

 likeness, in certain respects, to those of beasts than to 

 those of reptiles. No finger has a greater number of 



