192 COMPARATIVE DENTAL ANATOMY 



man than among savage races, of course, although 

 dental diseases are not unknown among the lat- 

 ter. There is not so much of a gap between the 

 higher species of the Apes and the lower races 

 of Man as might be supposed, scarcely more than 

 between the lower and higher races of Man. As 

 the teeth of Man are strong and well made, they 

 approach the Simian form and integrity; as they 

 are defective and ill-formed they depart from it. 

 The best dentures are those which have animal 

 perfection of organization. The reversions to 

 lower forms often presented by the teeth of Man 

 are of peculiar interest, and exhibit their descent 

 and animal relationship in a remarkable degree. 

 The teeth of Man being rudimentary as compared 

 with the lower Primates, these reversions are not 

 unexpected. Some of the instances of reversion 

 may be noted as follows : Man has but thirty-two 

 teeth, while the typical mammalian formula is 

 forty-four. He has thus lost twelve teeth, some 

 of which sometimes reappear as so-called " super- 

 numerary teeth," but are in reality due to ata- 

 vism, and are reversions. Thus a third incisor, 

 or third premolar, or fourth molar are sometimes 

 seen. The upper incisors may be scoop-shaped 

 (like the Shrews or some Lemurs), or may have 

 a cingulum on the base, like the Quadrumana ; or 

 may be deeply ridged or notched (as it always 

 is at birth), recalling the cleft incisors of the 



