274 



THE DENTAL SYSTEM OF THE PRIMATES [SECT. A 



Professor Rose (quoted by Bolk, op. cit. p. 8 of reprint) has 

 established the fact that the first permanent molar (in Man) 

 develops precociously, at an early period, i.e. in relation to the 

 deciduous rather than to the permanent teeth. Moreover, 

 Professor Bolk points out that in the Platyrrhine monkeys 

 known as the Hapalidae (Marmozets), the process described by 

 him has affected the last molar teeth [assumption (a) supra] 

 while it has not yet extended to the premolar region. Dr Adloff 

 himself has pointed out the close relation of premolars and molars, 

 suggesting that the differentiation of the premolars has proceeded 

 from a more ancient (molar) type, and constitutes a modification 

 of the primitive dentition 1 . To this subject attention must now 

 be turned. 



Fig. 199. Diagrams illustrating Professor Bolk's theory of the relations of the 

 premolar and molar teeth in the Platyrrhine (A) and Katarrhine (B) Primates. In 

 (B) the dental germs Pm 3 and M 3 (enclosed by oval contour lines) are regarded as 

 failing to mature. 



V. The evolution of the incisor and other types of teeth 

 in the Primate dentition. 



Before this subject is discussed the characteristic phenomenon 

 of the replacement of one set of teeth by another demands further 

 consideration here. 



(a) We have seen that the teeth are, in the Primates, naturally 

 divisible into four classes (incisor, canine, premolar, and molar 

 teeth) for the most part easily distinguishable, though at the same 

 time there may be seen, even in a single jaw, such as that of an 



1 For further information on this subject, reference should be made to the great 

 work of Mr C. S. Tomes, A Manual of Dental Anatomy, 7th edition, 1914, especially 

 pp. 337 ct seq. 



