128 PROF. DR. L. BOLK 



and four that of the premolars. However it is not my inten- 

 tion to enter into the questions surrounding these lost compo- 

 nents of primate-dentition, but to confine myself to the molar 

 region. 



It is very remarkable that in the scheme of our dentition, 

 drawn up in figure 21 (both rows), both the first and the second 

 dentitions are complete. Each tooth of the inner row (or second 

 dentition) is situated opposite an interstitium dentale of the 

 outer row, i.e., the milk dentition. The lost third premolar 

 corresponds with the dental interstice between the first perma- 

 nent molar (i.e., the third milk molar of our ancestors) and the 

 Paramolar I, and the second molar alternates with the Para- 

 molar I and Paramolar II. 



The scheme shown in figure 21 demonstrates, in a very con- 

 vincing manner, that only in considering our first permanent 

 molar as an element of the outer row do both dental arches appear 

 complete and without interruption. This fact is considered by 

 me as a strong proof in favor of the correctness of my views 

 regarding the manner in which human dentition evolved from 

 that of a platyrrhine forefather. 



In the second paragraph stress has been laid upon the abso- 

 lute absence of a paramolar tubercle or a paramolar root on the 

 first permanent molar of man. This absence is so typical, that 

 it may be regarded as a characteristic morphological feature of 

 our first molar. The cause of this peculiarity, briefly indicated 

 previously, becomes intelligible at first sight in looking at the 

 scheme of figure 21. The paramolar cusp of the second and 

 third molar represents the rudimentarily developed Paramolars 

 I and II of the outer row, coalesced with the second or third 

 molar. The first molar, however, is itself a component of the 

 outer row, and a tooth never develops at the buccal side of the 

 same. It is impossible, therefore, to find an additional buccal 

 cusp on this tooth. I may be permitted to repeat that this 

 fact also emphatically proves the correctness of my opinion as 

 to the odontological significance of our first molar. 



Furthermore, by the scheme in figure 21, the following ques- 

 tion suggests itself. In the first section it is demonstrated 



