3 88 SCIENCE PROGRESS 



observed in existing primitive races, such, for instance, as the 

 Australians. 



The front teeth are not "projecting," but set squarely in the 

 jaw ; they are curved, however, especially the roots, in accor- 

 dance with the generally rounded contour of the front end of 

 the jaw — precisely recalling, in this respect, the curvature of the 

 teeth in the upper jaw of the Neandertal race as represented 

 by the Gibraltar skull. They show considerable signs of wear, 

 much more so than the back teeth (molars and premolars) ; and 

 since the dentition is complete, the wisdom teeth having been 

 ''cut," this shows that the front teeth probably played a more 

 important part than in existing and even primitive races. 



The jaw which bears this thoroughly human dentition is 

 itself surprisingly simian ; it stands, indeed, almost midway 

 between that of Homo sapiens and that of an anthropoid ape 

 such as the chimpanzee. The differences between a human 

 and a simian jaw are most salient at the anterior extremity. 

 In existing men the profile of this part of the lower jaw is 

 usually, though not always, a more or less sigmoidal curve, 

 concave above, just below the teeth, and convex below where 

 it follows the chin. The chin is a characteristic human feature. 

 A line drawn from the upper to the lower extremity of the 

 curve is more or less vertical, varying a few degrees on one 

 side or other of a perpendicular let fall from the upper 

 extremity when the general alveolar surface of the jaw is 

 placed horizontally. 



In the case of the apes there is no inflexion below the 

 incisors and there is no chin ; the profile is a simple rapidly 

 retreating curve. 



It has long been known, from observations on the jaws of 

 Spy and Krapina, that the chin was very much reduced or 

 even altogether absent in the Neandertal race ; in the 

 Heidelberg jaw, however, not only is this the case, but the 

 profile has returned to the simple rounded outline which is 

 met with in the apes, differing chiefly by its more gradually 

 retreating slope. 



The inner face of the anterior extremity of the jaw also 

 presents several interesting peculiarities. In modern races 

 this surface slopes steeply downwards from the back of the 

 incisors and exhibits no marked subdivision into different 

 regions. In the anthropoids its slope is far less steep, and 



