2IO CHARACTERS OF VERTEBRATE ANIMALS 



Three species are known of the Alligator proper, one being 

 found in China, and the others in the south-east part of North 

 America, of which two by far the best known is the Pike- 

 headed or Mississippi Alligator {^Alligator Mississippiensis), 

 which may attain the length of about 15 feet. The first name 

 given to this creature expresses a resemblance to the fresh-water 

 fish well known as the Pike. 



The remaining members of the Alligator group, the Caimans 

 or Jacares, are limited to Central America and the tropical parts 

 of South America. The different species vary greatly in size; 

 all but one, however, being much smaller than the Mississippi 

 Alligator. Unlike the Alligators proper the Caimans possess 

 ventral scutes, and those which make up the dorsal armour are 

 firmly united with one another. 



Crocodiles proper have a very wide distribution throughout 

 the tropics, being found in America, Africa, South Asia, and 

 North Australia. The head is somewhat narrower and longer 

 than in alligators, and the teeth are not so markedly unequal. 

 Although, as before, the large first lower tooth bites into a 

 pit, this is not the case with the large fourth lower tooth, which 

 merely bites into a groove and is partly visible when the mouth 

 is shut. The united part of the lower jaw is rather longer than 

 in alligators, as might be expected from the shape of the head, 

 and there is no ventral bony armour as in caimans. The hind- 

 limbs have a jagged posterior fringe, and the feet are more 

 completely webbed than in alligators. 



Probably the most familiar species is the Nile Crocodile 

 (Crocodilus Niloticus), which was regarded as sacred by the 

 ancient Egyptians, and like other animals which figured in 

 their religion was considered worthy of embalmment. It has now 

 been exterminated in the lower Nile, where it was formerly 

 very abundant, and its range includes South Africa, Senegal, 

 Madagascar, and Syria. Large specimens may considerably ex- 

 ceed the Mississippi Alligator in size. 



The Indian Crocodile (Crocodilus palustris) ranges from 

 Baluchistan to the Malay region, and avoids the tidal parts of 

 rivers. Another Indian species, the Estuarine Crocodile (C 

 porosus), has exactly the contrary habit, as the name indicates, 

 and is not only common in estuaries, but swims out to sea for 

 a considerable distance. This fact is interesting, for the vast 



