274 



COMPARATIVE ANATOMY OF THE TEETH. 



FIG. 75. A 



molars than those of the chimpanzee or orang. The upper 

 and lower bicuspids are also smaller in proportion to the 

 molars, than those of these animals. 



In the human teeth 

 the crowns of the true 

 molars are observed to 

 be larger in proportion 

 to the bicuspids, still 

 larger in proportion to 

 the canines and incisors, 

 and larger in proportion 

 to the jaws, and have 

 the borders of their 

 grinding surface more 

 round than is found in 

 the chimpanzee and 

 orang. When the per- 

 manent teeth appear, it 

 is remarked that the 

 first true molar in both 

 upper and lower jaw is 

 " much more worn," in 

 comparison with the other molars, than in the chimpan- 

 zee and orang, in consequence of the longer time which 

 elapses between the appearance of the first and last true 

 molars of the human teeth and those of these animals, 

 and consequently the greater amount of friction the first 

 molars are subject to. 



The number of teeth in these quadrumana is the same 

 as in man. The deciduous set are the same in number. 

 The following contrast between the human deciduous teeth 

 and those of the chimpanzee and orang, is from the pen of 

 Mr. Owen. 



"The upper milk incisors of the chimpanzee," he says, 

 "are relatively larger than in man, especially the middle 

 pair, but the disproportionate size of these is still more man- 



FIG. 75, A represents the superior dental arch of man. 



FIG. 75, B represents the superior dental arch of a chimpanzee. 



