MAN AND APES. 159 



To find a similarity to man in this respect 

 we have again to descend through the whole 

 series of apes, till we come to the lower and 

 more aberrant forms of the Half-apes, and 

 there alone, in the little Tarsier of Celebes, 

 we once more meet with teeth placed in serial 

 continuity, as in man. 



3. A third character which may here be 

 mentioned, is one exhibited by the masticating 

 surfaces of the larger grinding teeth of the 

 upper jaw. We find in man on the mastica- 

 ting surface of each of these teeth an oblique 

 ridge, running from the front inner angle of 

 such surface outwards, and backwards to its 

 hind outer angle. 



This character is found also in the teeth of 

 the Orang, Chimpanzee, and Gorilla, but it 

 does not exist in those of the Gibbons, nor in 

 those of any of the lower Simiadce. Here, then, 

 we seem to come upon a striking character 

 as to affinity with man — a character the more 

 deep and significant, in that it is hard to 

 see how the presence of this slight ridge 



