58 The Alligator and Its Allies 



or six of the caudals are long and narrow. They 

 gradually diminish in length until the eighteenth 

 caudal, back of which they are no longer to be seen. 

 The zygapophyses are mostly about the same as in 

 the more anterior vertebras, but towards the posterior 

 end of the tail the postzygapophyses come to lie 

 between rather than above the prezygapophyses. 

 The neural canal diminishes, of course, in size 

 towards the tip of the tail until it is no longer 

 present, the last five or six vertebras consisting 

 only of the centra. 



//. The Skull. 



The skull of the alligator is very massive and 

 has several peculiarities. I. The bones of the 

 dorsal surface are rough and pitted, especially in 

 old animals. 2. The jaws are enormously large in 

 proportion to the brain cavity, and are armed with 

 many large teeth. 3. The mandibular articula- 

 tion is some distance caudad to the occipital 

 condyle. 4. The interorbital septum is mainly 

 cartilaginous. 5. There is a complicated system 

 of Eustachian passages connecting with the back of 

 the mouth by a single opening. 6. The posterior 

 nares are placed very far back and the palate is 

 correspondingly long. 



The skull as a whole may be divided into three 

 regions: the cranium, the lower jaw, and the hyoid; 

 these will be described in the order given. 



The Cranium, As a matter of convenience the 



