68 COMPARATIVE ZOOLOGY. 
be classed into incisors, canines, premolars, and molars. 
For such a dental series exhibits a double purpose, pre- 
hension and mastication. The chisel-shaped front teeth 
are fitted for cutting the food, and hence called éncisors. 
These vary in number: the Lion has six in each jaw; the 
Squirrel has two in each jaw, but remarkably developed ; 
the Ox has none in the upper jaw, and the Elephant none 
in the lower; while the Sloth has none at all. The ca- 
Fie. 32.—Skull of the Babirusa, or Malayan Hog, showing growth and curvature of 
S) 
the canines. 
nines, so called because so prominent in the Dog, are 
conical, and, except in Man, longer than the other teeth. 
They are designed for seizing and tearing; and they are 
the most formidable weapons of the wild carnivores. 
There are never more than four. They are wanting in 
all Rodents, and in nearly all herbivorous quadrupeds. 
The molars, or grinders, vary greatly in shape, but close- 
