514 ZOOLOGY. 



vertebrae of E. platyurus Cope, of the New Jersey marl- 

 beds, had vertebrae nearly as large as those of an elephant, 

 while the creature was whale-like in bulk, the neck long and 

 flexible, the paddles short. The skull was light, with a 

 long, narrow, very flat muzzle, It must have been the ter- 

 ror of those times ; it was about fifteen metres (45 feet) 

 in length. (Cope.) 



Order 9. Crocodilia. The crocodile, caiman, gavial, and 

 alligator are the types of this well-known group. They pre- 

 sent a decided step in advance of other reptiles, the heart 

 approaching that of birds, in having the ventricle completely 

 divided by a septum into two chambers ; the venous and arte- 

 rial blood mingle outside of the heart, not in it, as in the 

 foregoing living orders. The brain is also more like that of 

 birds, the cerebellum being broader than in the other rep- 

 tiles. The nostrils are 

 capable of closing, so 

 that crocodiles and 

 alligators draw their 

 prey under the water 

 and hold them there 

 until they are drown- 

 ed ; but they are 



Fig. 451.-Head of the Florida Crocodile.-After obliged to drag them 



Hornaday. ashore in order to eat 



them. The skin is covered with bony, epidermal scales. The 

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

 are concave in front and convex behind, or the reverse ; the 

 quadrate bone is immovable. The feet are partly webbed. 

 The crocodiles and gavials appeared during the Jurassic pe- 

 riod, but the early forms were marine and like gavials, the 

 head being long and narrow in front, with biconcave verte- 

 brae. They lay from twenty to thirty cylindrical eggs in the 

 sand on river banks. The crocodiles are distributed through- 

 out the tropics, even Australia ; the gavials are mostly con- 

 fined to India and Malaysia, and also Australia. The group 

 is represented in the Southern States by the alligator (A. 

 Mississippiensis Daudin). It is nearly four metres (10-12 

 feet) long; while the Florida crocodile (0. acutus Cuvier, 



