MAN NATURALLY OMNIVOROUS. 187 



dividing and preparing the food, must exhibit, in figure and 

 construction, a relation to the nature of the aliment. They 

 rise, in the true carnivora, into sliarp pointed promi- 

 nences, and those of" the lower shut within tliose of 

 the upper jaw : when the series is viewed together, the 

 general outline may be compared to the teeth of a saw. 

 These animals are also furnished with long, pointed, and 

 strong cuspidati or canine teeth, which are employed 

 as weapons of ofFenq.e and defence, and are very serviceable 

 in seizing and lacerating their prey : they constitute in 

 some animals, as the lion, tiger, &c. very formidable wea- 

 pons. The herbivorous animals are not armed v/ith these 

 terrible canine teeth : their molares have broad fiat surfaces, 

 opposed in a vertical line to each other in the two jaws. 

 Plates of enamel are intermixed with the bone of the tooth 

 in the latter; and, as its superior hardness makes it wear 

 less rapidly than the other textures of the teeth, it appears 

 on the grinding surface in rising ridges, which must greatly 

 increase the triturating effect. In carnivorous animals the 

 enamel is confined altogether to the surface of the teeth. 



The articulation of the lower jaw differs in the two 

 cases as much as the structure of the teeth. In the carni- 

 vora it can only move backwards and forwards ; all la- 

 teral motion being precluded by rising edges of the glenoid 

 cavity : in the herbivora it has, moreover, motion from side 

 to side. Thus we observe, in the flesh eaters, teeth calcu- 

 lated only for tearing, subservient, in part at least, to the 

 procuring of food, as well as to purposes of defence, and 

 an articulation of the lower jaw, that precludes all lateral 

 motion. In those which live on vegetables, the form of the 

 teeth and the nature of tlie joint are calculated for the la- 

 teral or grinding motion. The former, having rudely torn 

 and divided the food, swallow it in masses, while in the 

 latter it undergoes considerable comminution before it is 

 swallowed. The teeth of man have not the slightest re- 

 semblance to those of the carnivorous animals, except that 

 their enamel is confined to the external surface. He pos- 

 sesses, indeed, teeth called canine, but they do not exceed 



