DIFFERENCES BETWEEN CROCODILES, ETC 587 



the eggs. The mothers take some care of the young, which require to 

 be defended even from the appetite of the males. 



Crocodiles are relatively sluggish, and fond of basking passively, 

 sometimes hiding in the mud during the hot season. They are remark- 

 able for the long continuance of growth, which does not seem to have 

 so definite a limit as in most other animals. 



Classification of Crocodilia. 



(a) The true Crocodiles, of the genus Crocodilus, occur in Africa, 

 Southern Asia, tropical Australia, Central America, and the West Indies. 



The Indian Crocodile (C. porosus) may measure about 18 ft. in 

 length, and even larger forms have been recorded. The sacred 

 African crocodile ( C. vulgaris) is still formidably common in some of 

 the fresh waters of tropical Africa. 



The eggs and the young are often eaten by a mammal called the 

 Ichneumon, and by a species of lizard. The adults have few enemies 

 except man. They seem to live in friendly partnership with little birds 

 (Phivianus tegypticus), which remove parasites from the body, and in 

 their familiarity almost justify the account which Herodotus gives of 

 their cleaning the reptile's teeth. 



(b) The Alligators, of the genus Alligator, are, with the exception of 

 one Chinese species, confined to N. and S. America. In N. America, 

 A. mississippiensis, in S. America A. sclerops, are common. 



(c) The Gavials or Gharials, of the genus Gavialis, are distinguished by 

 their long narrow snout. In the Ganges and its tributaries, G. gangeti- 

 cus, said to attain a length of 20 ft. , is common. They feed chiefly on 

 fishes. ' ' Old males have a large cartilaginous hump on the extremity 

 of the snout, containing a small cavity for the retention of air, by which 

 means these individuals are enabled to remain under water for a longer 

 time than females or young. " 



DIFFERENCES BETWEEN CROCODILES, ALLIGATORS, 

 AND GAVIALS. 



