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tootli, at least with the now living tonus; on the contrary, the first 

 premolar is often stronger than the second (Cebus, CHuysothrix, 

 Mycetes, Hapale). Then not a single indication can be observed in 

 the Ontogenese of the set of teeth of man, which indicates that a 

 tooth should have become lost beliind the canine tooth, the papillae 

 succeed each other very regularly in their origin and place. Moreover 

 if it were right that a molar and a premolar became lost behind 

 the canine tooth the remarkable fact remains still unexplained, that a 

 rudimentary tooth appears so often between the first molar and the 

 last premolar. 



So I cannot agree with eilher of the two opinions which prevail 

 now about the differentiation ot the set of teeth of the Primates, 

 but I am of the opinion that it came about in ([uite another way. 

 To be short, my opinion about it is as follows : the set of teeth of 

 the catarrhine Primates has originated from that of the platyrrhines 

 by the disappearance of the last or third molar and of the last 

 or third premolar while the third milkraolar has lost its character 

 of temporary tooth and has become a ]iermanent tooth. 



This opinion is explained by the two following formulas. If we 

 overlook the original number of four milkmolars and premolars, 

 and number the elements of the platyrrhine set of teeth according 

 to their now present amount this set of teeth may be wi'ilten 

 according to the following formula : 



y,. ƒ,. ('. I\. /',. F,. 



/, . /„. c. in,, m... )ii,. M,. J/.,. M,. 



/j. (.J. e. m^. m^. m^. il/,. J\I^. 3f,. 

 J,. /,. C. F,. F,. F,. 



The catarrhine set of teeth has originated from this, as /-*, and jy, 

 iiavc fallen away in the upper and lower jaw, whereas ni^ becomes 

 J7j in both jaws, by which as a matter of course Mi of the 

 platyrrhines becomes ;!/., of the catarrhines, the AI^ of tlie former 

 becomes 3f, of the latter. If it had remained the i/, of the platyrrhines 

 would have become M^ of the catarrhines. Those things are stated 

 in the following formula in \viiich the reduced teeth are put between 

 parenthesis. 



/,. I„_. C. F,. iV [/^,|. 



ij. i^. c. m^. in^. i/j. J/j. M^ L^'AJ- 



i^. i^. c. m,. m,. M,. M^. M,. [ifj. 

 J, J,. C. F,. P.,. [F,]. 



So the di(ferentiati(in of the set of teeth of the Primates is accord- 



