CLASS REPTILIA 



547 



Order 3. Crocodilini. CROCODILES, ALLIGATORS, GA VIALS, 

 and CAIMANS (Fig. 451). These reptiles are lizard-like in form, 

 but have the jaws extended into a long snout. The nostrils 

 are at the end of the snout and the eyes protrude from the head 

 so that the crocodilians can float at the surface with only these 

 parts above the water. The skin is thick and leathery, covered 

 with horny epidermal scales, and with dorsal, and sometimes 



FIG. 451. CROCODILINI. A long-snouted gavial (Gavialis gangcticus) on top 

 of an American crocodile (Crocodilus americanus) . A Nile crocodile (Crocodilus 

 niloticus} in the foreground. A " mugger " (Crocodilus palusiris) in the right 

 upper corner. Notice peculiar floating attitude of young. (From Gadow.) 



ventral bony plates somewhat like those in the shell of the 

 turtles. The nostrils and ears are provided with valves and are 

 closed when the animal is under water. 



The limbs are well developed. There are five digits on the 

 fore limbs and four more or less webbed digits on the hind limbs. 

 The tail is a laterally compressed swimming organ. The anus 

 is a longitudinal slit. Two pairs of musk glands are present, 

 one on the throat, and one in the cloaca. 



Some of the peculiarities of the internal, structures are as 



