THE DECIDUOUS DENTITION 



249 



As was stated at the beginning of this chapter two views are 

 held regarding the milk dentition, first that it represents fea- 

 tures possessed also in ancestral forms by the permanent set 

 and secondly that it displays specializations for the require- 

 ments of the young animal. We now see that these views are 

 not mutually contradictory but each is true so far as it goes. 



The term "milk molar" as appears from the foregoing de- 

 scription is no more adequate than the name "milk premolar" 



- Fig. 91. — Deciduous dentition of Gibbon (Hylobates concolor, Harlan; 9.88-4). The 

 first molars, central incisors and right lower lateral incisor of the permanent set have 

 erupted and may readily be distinguished by their white color. 



to express in a word the characters of the deciduous cheek 

 teeth. We have noted in earlier chapters that in the perma- 

 nent dentition the premolars cannot always be distinguished 

 clearly from the molars by their appearance. Nor can we de- 

 fine the premolars as possessing forerunners while the molars 

 do not, for in most instances there is no tooth preceding the 

 first premolar of the permanent set (see Fig. 93). According to 



