294 Messrs Duckworth & Fraser, A Description of 



commonest situation (between the 2nd premolar and 1st molar 

 teeth) does not by any means preclude the possibility of their being 

 persistent remains of the " temporary " teeth, and while we cannot 

 consider the question as finally answered, the following considera- 

 tions seem to us to discountenance the view which regards these 

 as fragments of " temporary " teeth : viz. 



(a) the comparative constancy of their position on the 

 alveolar margin ; 



(6) and the rarity of their occurrence in the mandible ; 



(c) the differences which are exhibited by various races of 

 Man in presenting these appearances; this will be more fitly dealt 

 with later ; 



(d) the comparatively great frequence of their occurrence 

 symmetrically on both sides of the palate; 



(e) the fact that the recognisable persistent milk teeth are 

 usually of considerably greater size than these rudiments ; the 

 rudiments are admittedly in one case (2154, Australian) of fair 

 size; 



(f) the variation in the frequency of occurrence which will 

 be seen to characterize the different species of anthropoid apes. 



On the other hand there is a slight indication of greater 

 frequency in young adults than in senile individuals, but on the 

 whole there is sufficient evidence to justify the view that at least 

 some of these rudiments are not vestigial temporary teeth. 



In considering the other possibilities regarding their nature, 

 we have had the advantage of a discussion with Dr Marett Tims, 

 to whom the specimens were submitted, and who suggests that 

 these are examples of dental rudiments considered to belong to a 

 third or post-permanent dentition, such as are very constantly 

 demonstrable embedded in the alveolar arcade of certain mammals 

 (carnivora), though they do not as a rule make their way to the 

 surface. These are developed, however, on the lingual side of the 

 alveolar ridge, whereas the masses are observed by us to occupy 

 positions on the lingual or the buccal alveolar margin, or even 

 both simultaneously, so that while a certain number of these 

 rudiments probably fall into the category proposed by Dr Tims, on 

 the whole we think that it is most reasonable to adopt the view 

 that they are aborted third premolars which constitute a human 

 type of dentition similar to that of the New World Apes. Should 

 further investigation prove this to be a correct view, it would 

 constitute a link connecting man more closely with these platyr- 

 rhine primates. 



We do not deal at present with the occurrence of enamel on 



