198 



ZOOLOGY. 



Order 5. Crocodilia. — The crocodile, caiman, gavial, and 

 alligaLor are the examples of this well-known group. 'J'hey 

 present a decideil step in advance of other rei)tilcs, the 

 heart approaching that of birds, in having the ventricle 

 completely divided by a partition into two chambers; the 

 venous and arterial blood mingle outside of the heart, not 

 in it, as in the foregoing orders. The brain is also more 

 like that of birds. The nostrils are capable of closing, so 

 that crocodiles and alligators dj'aw their prey under the 

 water and hold them there until they are drowned; but they 

 are obliged to drag them ashore m order to eat tiiem. The 



Fia. 240.— Head of the Florida Crocodile. 



skin is covered with large bony, epidermal scales. The 

 conical teeth are lodged in sockets in the jaws. The feet 

 ai'e partly webbed. Tlie crocodiles and gavials lay from 

 twenty to thirty cylindi'ical eggs in the sand on river banks. 

 Tlie crocodiles arc distributed throughout the ti'f)pics, even 

 Australia; the gavials are mostly confined to India and 

 Malaysia, and also Australia. The group is represented in 

 the Southern States l)y the alligator [A. Mississippieusis). 

 It is nearly two metres (10-13 feet) long; while the Florida 

 crocodile (0. ncutux. Fig. 240) in which the jaws are much 

 )iariower, is over two and a half metres (14 feet) long. It 

 inhabits the rivers of Florida, where it is very i-are, and also 

 the West Indies and South America. 'J'ho cayman of 

 Guiana belongs to a distinct genus, Caiman, and is char- 

 acteristic of the rivci's of tropical South America. 



