138 CROCODILES AND ALLIGATORS. 



that alligators were confined to the New World, but 

 recently it has been found that one species exists in 

 China. This is, indeed, a very curious instance of what 

 is known as discontinuous distribution, and one which 

 only finds a complete parallel in the case of the tapirs, of 

 which there is one species inhabiting the Malay peninsula 

 and adjacent islands, while all the others are restricted to 

 South America. There aie several species of alligators, 

 which are divided into two groups, according as to whether 

 an armour of bony plates, or scutes, is or is not developed 

 on the under surface of the body. In the true alligators, 

 which agree with all living crocodilians in having a dorsal 

 armour of these bony scutes, the upper teeth vary from 

 seventeen to twenty in number, and those of the lower 

 from eighteen to twenty, while there is no bony armour 

 on the under surface of the body. The two well-known 

 species are the Mississippi and the Chinese alligator, in 

 addition to which there is a third American form of 

 which the exact habitat is unknown. The second group 

 of alligators, or caimans, as they are called in Brazil, is 

 confined to South America, where it is represented by five 

 species. These are characterized by having from eighteen 

 to twenty upper, and from seventeen to twenty -two lower 

 teeth on each side, and also by the lower surface of the 

 body being protected by a shield of bony scutes, which 

 overlap one another like the tiles on a roof, and each of 

 which is composed of two separate pieces united together 

 by what is known as a sutural union. 



The above, then, are the chief differences which distin- 

 guish alligators and caimans on the one hand from 

 crocodiles on the other, and they are such as surely do not 

 justify the statement that naturalists merely pretend to 

 distinguish between the two. Alligators and crocodiles do 

 not, however, exhaust the list of living crocodilians, since 

 we have two peculiar species differing from all the others 

 by the great length of their snouts, and respectively 

 inhabiting the Ganges and the rivers of Borneo the 

 former being known as the garial, and the latter as 

 5Schlegel's garial. In both of these reptiles the numerous 

 teeth are long and slender, and differ from one another 



