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 vertebre, but towardsthe 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 vertebre consisting 
only of the centra. 
II. The Skull. 
The skull of the alligator is very massive and 
has several peculiarities. 1. 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 
