446 CHORD ATA, 



The crocodiles resemble the Mammalia in the following 

 characters : — 



1. The teeth are thecodont (in sockets) and confined 

 to maxilla, premaxilla and dentary. 



2. The maxilla and palatine form a bony palate. 



3. The heart is four-chambered, a septum dividing the 

 ventricle into two. 



4. There is an incomplete diaphragm. 



Fig. 316. — Ventral View of Crocodile's Skull x J. {Ad nat.] 



Premaxilla. 



Maxilla. 



Palatine. 



Transverse. ^.^^ T^B^ Malar. 



Note the thecodont teeth in single row on premaxilla and maxilla, the back- 

 ward position of the internal nas, the transverse bone, single 

 occipital condyle and quadrate-suspensorium. 



True crocodiles are found in the rivers of tropical Africa 

 and in central America. The alligators are found in the 

 Southern States, West Indies and South America. The 

 gavials are small Crocodilia found in the Ganges and its 

 tributaries. 



