( 791 ) 



still. And it is my opinion lIuU iIr' rudiments of a tooth which so 

 often occur in tiie indicated place are indeed traces of the 1\ which 

 has got lost. 



There conld still he mentioned some more anomalies in the set 

 of teeth of man (the growing together of M^ with a snperfluons 

 tooth, the pushing out of 3/, and replacing by a new tooth (so 

 called third dentition) which would be explained l)v m_v hypothesis, 

 but 1 will not look more closely into this matter in this |ilace. 



By my opinion about the differenlation of the set of teeth of tiie 

 Primates I come into conflict with a rather universally prevailing 

 opinion about the morphological significance of the first molar oi 

 the Placentalia. This molar is universally considered with all Pla- 

 centalia as a perfectly homologieal element of- the set of teeth. 

 Thus says Schi.osser ') e. g. speakiiig of the first molar of man : 

 "Niemand wird siclier die Honiologie dieses Zahnes mit dem ersteii 

 Molaren der übrigen Placentalier bestreiten dürfen". Where I now 

 homologise M■^ of man with m^ of the Platyrrhines I come into 

 conflict with this opinion. If we however try to find motives for the 

 above mentioned opinion in literature, we seek in vain. And so it 

 seems to me, that here we have to do with a dogma, which is not 

 without danger for the comparative anatomy of the set (tf (cclh. 

 For it lies at hand that as soon as in the whole I'ow of ihe Pla- 

 centalia one element of the set of teeth is ti.xed in its morphological 

 significance, that then Ihe homologating of the other elements nuist 

 join itself to this aprioristical principle. And where such a thing is 

 possible to a certain degree with a canine tooth, which is sharply 

 distinguished from the other teeth l)y its peculiar form, it is absolutely 

 impossible with a definite molar which possesses no specific mor- 

 phological qualities. 



I cannot finish this communication before having pointed to a 

 phenomenon, which is immediately related to the here communicated 

 point of view. If we compare the set of teeth of man with that 

 (tf the olher catarrhine Primates, it appears that the process, by 

 which the catarrhine set of the teeth orginated froni the platyrrhine 

 type, is still progressive with man, and that the human set of teeth 

 is on its way to differentiate from that of the other Catarrhines in 

 the same way, as these differentiated from the Platyrrhines one time. 

 I shall try to show this in short. The still active differentiation of 

 the human set of teeth appears from different facts. First as to the 

 [jremolars. In comparison to all other Primates the premolars of men 



^) M. ScHLOssER. Das Milchgebiss der Siiugetiere. Biol. Centralblatt, Bnd. 10, biz. 89, 



