CHAPTER II 
THE SKELETON 
A. THE EXOSKELETON 
HE exoskeleton is well developed in the 
Crocodilia, and forms a very considerable 
protection to its bearer. It is both dermal 
and epidermal in origin. 
The epidermal skeleton of the alligator consists of 
oblong horny scales, arranged in transverse rows; 
the long axes of the scales are parallel to that of the 
body. On the tail, except along the mid-dorsal 
line, and on the ventral side of the trunk and head 
these scales are very regular in outline and arrange- 
ment; on the sides of the head and trunk and on 
the legs they are much smaller and less regularly 
arranged, while along the mid-dorsal line of the 
tail, especially in its posterior half, they are ele- 
vated into tall keels that give the tail a large 
surface for swimming. The first three digits of 
both manus and pes are armed with horny claws, 
which also belong to the epidermal part of the 
exoskeleton. 
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