CHAPTEE II 



limbs, toes, claws, webs, fins, and tongues in 



amphibians 



Limbs and Toes 



The typical form of each order is illustrated in 

 the last chapter. In place of a tail the frogs have 

 their hind limbs capable of stretching out directly in 

 line with the body. This gives them a great thrust 

 in leaping and swimming, and the long legs thus trail- 

 ing act like a feather on an arrow in one case, and 

 like a rudder in the other. The fore legs of the tail- 

 less forms are weak, and are used mostly in alio^htinoj 

 and in propping up the forepart of the body. These 

 nearly all leap. 



In the tailed forms, the legs are all usually rather 



weak, and there is no great difference in the size of 



the fore and hind pairs, as there is in the frogs. To 



this order the forward pair seems the more important 



since they serve to drag the creature slowly along, and 



they are never lost, though the rear ones are gone in 



the sirens. So, also, the fore limbs first develop in 



their tadpoles, while in those of the frogs the rear 



limbs show first. In one tailed form, known as the 



Congo snake (though it is not a snake), all four of the 

 3 7 



