172 DIFFERENT KINDS OF TEETH. 
namely, the African and the Indian; as also between each 
of these and the great extinct species known as the Mam- 
moth (fig. 99). In the great gnawing teeth of the Rabbit, 
L. 2, “3. 
Fig. 99.—Motar TEETH oF ELEPH 
1, African Elephant; 2, Indian Elephat 
Fig. 98.—Mo1ar Tootn or Masropon. 3, Mammoth. 
&c., the front surface only is covered with enamel; and as — 
this is worn away more slowly than the ivory, it stands up as ~ 
a sharp edge (fig. 91), which is always retained, however 
much the tooth may be worn away. 
183. Of all the teeth, the molars may be regarded as the 
most useful. They are seldom absent in the Mammalia ; and 
their office is usually essential to the proper digestion of the 
food. Animal flesh (the most easily digested of all substances) 
needs but to be cut in small pieces ; but the hard envelopes 
of beetles and other insects 
must be broken up; and the ~ 
tough woody structure of the ~ 
grasses, and the dense coverings 
Oe of the seeds and fruits on which ~ 
- cael the herbivorous animals are — 
supported, must be ground 
down. The incisors and canines 
Fig. 100.—Skuxt or Boar. are chiefly employed among 
Carnivorous animals for the purpose of seizing their living” 
prey, and are never deficient in them ; but they are less re- 
quired in Herbivorous animals; and either or both kinds are 
not unfrequently deficient. Sometimes, however, they are not ¥ 
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