128 THE VITAL FUNCTIONS. 



in a mill. The tuberculated teeth, of which the 

 surfaces present a number of rounded eminences, 

 correspondin^i^ to depressions in the teeth opposed 

 to them in the other jaw, act more by their direct 

 pressure in breaking down hard substances, and 

 pounding them, as in a mortar. 



Tlie position of the teeth in the jaws is another 

 ground of distinction. In those Mammalia M^hich 

 exhibit the most complete set of teeth, the fore- 

 most in the row have the sharp-edged or chisel 

 shape, constituting the blades of a cutting instru- 

 ment ; and they are accordingly denominated in- 

 cisors. The incisors of the upper jaw are always 

 implanted in a bone, intermediate between the two 

 upper jaw bones, and called the intermaxillary 

 bones.* The conical teeth immediately following 

 the incisors, are called cuspidate, or canine teeth, 

 from their being particularly conspicuous in dogs ; 

 as they are, indeed, in all the purely carnivorous 

 tribes. In the larger beasts of prey, as the Lion 

 and the Tiger, they become most powerful w'ea- 

 pons of destruction : in the Boar they are likewise 

 of great size, and constitute the tusks of the ani- 

 mal. All the teeth that are placed farther back in 

 the jaw are designated by the general name of 

 molar teeth, or grinders, but it is a class which in- 

 cludes several different forms of teeth. Those teeth 

 which are situated next to the canine teeth, partake 

 of the conical form, having pointed eminences : 



* Those teeth of the lower jaw which correspond with the incisors 

 of the upper jaw, are also considered as incisors. In Man, and in 

 the species of Qiiadrunitma that most nearly resemble him, the su- 

 tures which divide tlic intermaxillary from the maxillary bones are 

 obliterated before birth, and leave in the adult no trace of their 

 former existence. 



