OUR BEST FEATURES 



In the first type the inner and outer borders of the 

 crown as seen from in front tend to be straight 

 and vertical; in the second type the opposite 

 borders diverge sharply toward the lower end of 

 the crown; and in the third the outer border has a 



Fig. 73. The Three Types of Central Upper Incisors (after 

 J. Leon Williams). 



Lower row, first type; middle row, second type; upper row, third type. 



marked double curve. Exactly these same three 



variants he found also in all the existing species of 



anthropoid apes and he rightly considers that this 



fact, taken in conjunction with hundreds of other 



items of similar purport, affords decisive evidence 



of close kinship between man and anthropoids. 



The upper lateral incisors in anthropoids (Fig. 



74) as a rule are more primitive in retaining the 



139 



