262 THE DENTAL SYSTEM OF THE PRIMATES [SECT. A 



It is perhaps worthy of* notice that among the large anthropoid 

 apes, the accessory molar teeth are found more frequently in the 

 lower jaw than is the case with the Cebidae and lower Primates. 

 This is especially true of the Orang-utan. But taking the three 

 large anthropoid apes together, the upper jaw still provides a 

 greater number of instances of the anomaly in question. 



Completely formed accessory molar teeth are not common in 

 the Hominidae, although the palate and alveolar arcade in many 

 crania of aboriginals of Australia seem to be spacious enough to 

 accommodate them. It is however in the cranium of such an 

 aboriginal native that Sir William Turner records the occurrence 

 of no less than three accessory molar teeth, and such anomalies 

 are more frequent in the Melanesian and Australian aborigines 

 than in other Hominidae. 



INCISOR TEETH. 



It remains to consider additions to the incisor series. Super- 

 numerary incisor teeth constitute a large proportion of the 

 anomalies of the human dental system, but as in the preceding 

 categories, care must be taken to 

 distinguish between veritable cases 

 of accessory teeth and instances 

 where the apparently supernumerary 

 tooth is merely a retained tooth of 

 the milk dentition. The distinction 

 is not always easy to draw, and an 

 instance of this is shewn in Fig. 197, 

 where however the length of root 

 exhibited by the supernumerary Figi 197- Mandible of an ab- 

 tooth is evidence against the case or 8 inal Australian, with a super- 

 . ■ /<• i -ii numerary incisor tooth. (Mus. 



being one of retention (for the milk Anat. Cant.) 



teeth are not so deeply rooted as 



those of the permanent series, and the root is subject to a process 

 of phagocytic absorption which in fact leads to the ultimate sepa- 

 ration of the deciduous tooth from its articulation). 



In regard to other anomalous conditions of the incisor teeth, 

 records of gemination (cf. gemination in the molar teeth, p. 260, 



