270 THE DENTAL SYSTEM OF THE PRIMATES [SECT. A 



process not yet arrested. That it is correct to hold the jaws 

 accountable can scarcely be doubted in so far as the white races 

 are concerned. But the occurrence of reduced dentitions in natives 

 of Melanesia, where the jaws and even the remaining teeth are of 

 great size, shews that some other factor is probably involved. 

 Thus the dentition may be subject to an evolution in which the 

 reduction of the jaws plays a subsidiary part only. Professor Rose 

 is quoted by Dr Adloff as appealing to cerebral growth, which may 

 indeed prove an important factor, though Dr Adloff does not 

 agree that it is so 1 . 



We have seen that the dental formula of the Katarrhinae 

 (including the Hominidae) shews a reduction in the number of 

 the teeth as contrasted with that of the Platyrrhinae. At this 

 stage it is convenient to enumerate and review the various for- 

 mulae of interest in relation to the evolution of the human type. 



Thus it will be found that the " primitive " mammalian dental 

 formula allows for many more teeth than even that of the lower 

 Primates. 



Osborn regards that primitive formula as 



(a) If C T Pmf M|. 



Oldfield Thomas and other writers give the formula as 



(b) If Cj Pmf Mf. 



Brunsmann (quoted by Kiikenthal, Jahr. der Anatomie, 1902) 

 seems to have postulated a stage in human ancestry in which the 

 formula was 



(c) I f C | Pm f M f . 



The Lemurine and Platyrrhine Primates 2 provide as their 

 formula 



(d) If C{ Pm f M f . 



The Katarrhinae (including normal Hominidae) have as their 

 formula 



(e) If C{ Pmf Mf. 



1 Cf. Adloff, Z.f. M. u. A. 1907, pp. 110 et seq. 



- The Hapalidae (or Marmozets) form an exception to this rule, their dental 

 formula being If C{ Pm § M § . 



