MASTICATION. 



29 



with their uses. The incisive, intended only to cut or divide 

 the food, have hut a single short root ; the canine penetrate 

 much more deeply into the jaws than the incisives ; and the 

 molar, called on to undergo still stronger pressure, are firmly 

 fixed hy two or three roots into the alveolar cavities. 



Large Molar. Small Molar. Canine. Incisive. 



Not preceded by any deciduous teeth. Preceded by deciduous teeth. 



Fig. 20. Human Teeth. 



53. The harmony of organization "between the teeth and 

 their uses is 'such, that in general it is easy, hy a sight of 

 the teeth of an animal, to say to what class it belongs, and to 



Fig. 21. Teeth of a Carnivorous 

 Animal . 



Fig. 22. Teeth of an Insectivorous 

 Animal. 



predict much, a priori, as to its nature. Thus, in carni- 

 vorous animals the molars are not grinding teeth, properly so 

 called, hut present a sharp edge, dividing the prey like a pair 

 of scissors (Fig. 21) ; in insectivorous animals the teeth have 



