254 BRANCH CHORDATA 



exposing only a small part of its body, it can see and hear well 

 the approach of an enemy. " Crocodiles are the only reptiles 

 whose nostrils open in the throat behind the palate instead of 

 directly into the mouth cavity. This enables the crocodile to 

 drown its victim without drowning itself, for by keeping its 

 snout above water it can breathe with its mouth wide open."^ 

 When under water the nostrils are closed by a valve. 



Limbs and Tail. — Their four limbs are stout, short, and 

 powerful. The tail is strong and compressed. It aids the 

 animal in locomotion, in self-defense, and in knocking its prey 

 off the bank into the water, where it is seized and held under 

 water until strangled to death. 



Habits. — They are aquatic and nocturnal in activity, feed- 

 ing at night upon fishes, birds, mammals, and whatever they can 

 capture. Hornaday describes how an alligator dismembered 

 its victim. It seized the prey by one leg, whirled itself round and 

 round till the leg was twisted off. He saw another shake a com- 

 panion until the skin of its back was torn in two. 



They hibernate in temperate regions, and estivate or migrate 

 in tropical regions when drought overtakes them. 



The Florida crocodile digs burrows in the sandy banks. The 

 entrances are wholly or partly under water. At the farther end 

 the l)urrow is wide enough for the crocodile to turn round in. 



They lay their large white eggs in the sand away from the 

 water, or build rude nests or mounds in which they deposit their 

 eggs in layers and watch and defend them until the young are 

 hatched. Ditmars says, "The alligator has entire head broad, 

 bluntly rounded at snout. The crocodile has head triangular; 

 becoming very narrow toward snout." 



The ga'vial of India (Fig. 207) is long, and slender snouted. The animal 

 may reach a length of 20 feet, but is harmless to man, being a fish-eater. 



Alligators.— The male alUgator may reach a length of 12 feet and the 

 female that of 8. The male has a heavier and more powerful head and is 

 the more brilliantly colored during the breeding season. The large nest is 

 built by the female on the bank of a stream or pool. The young are active 

 and shift for themselves. The aUigator finds its northern limit in North 

 Carolina, about 3.5° North Latitude. From here south they abound near 

 the mouths of creeks and rivers as far south as the Rio Grande _ They 

 ascend the Mississippi to 33° 50" North Latitude, or to the mouth of the 

 Red River. . . r x i r 



There is a small species of alligator in China. It is about b leet long, ot 

 a greenish black color dotted with yellow. 



1 Dodge, p. 476. 



