PROBLEMS OF HUMAN DENTITION 129 



that the fourth molar of man, or his distomolar as I term it, is 

 homologous with the third molar of the platyrrhine monkeys. 

 This tooth, being a real molar, belongs therefore to the inner 

 row. And now the question arises whether there can still be 

 developed a tooth corresponding with the interstitium dentale 

 between the third molar of man and his distomolar. Such a tooth 

 would represent a third paramolar. In the scheme of figure 21 

 this element is drawn at its theoretically deduced place, but, 

 being of dubious occurrence, is indicated by a mark of interro- 

 gation. Considered from a merely theoretical point of view, 

 the occurrence of such a rudimentary tooth is not at all an 

 unthinkable possibility. But in man it is very difficult to 

 recognize such an element practically. For, suppose, in some 

 one, it should really be developed, it would then be situated as 

 a rudimentary tooth behind the third molar. But the disto- 

 molar possesses an identical position. Therefore it would be 

 very difficult to distinguish an eventually occurring third para- 

 molar from a distomolar, both teeth being developed rudimentary 

 elements, situated behind the third molar. There is only one 

 instance to prove the occurrence of a third paramolar in man 

 indisputably, viz.: the occurrence of two rudimentary teeth 

 behind the third molar. Such a case is recorded by Turner.^ 

 In an Australian aboriginal skull, this author found two sockets 

 behind the left upper wisdom-tooth in each of which a super- 

 numerary molar was contained. It seems ver}^ probable to me, 

 that one of these was the distomolar and the other the Para- 

 molar III. 



In examining the individual variations in lower monkeys, the 

 third paramolar appears not merely as a theoretical conception; 

 for in platyrrhine monkeys with the original number of three 

 molars, all belonging to the inner row, a supernumerary molar 

 sometimes appears, corresponding with the interstitium dentale 

 between the second and third molar. A very fine specimen of 

 this interesting variation is described and represented by Bateson 

 in his ''Materials for the Study of \'ariation," p. 208. The 



^ Turner, W. An Australian skull with three supernumerary upper molar 

 teeth. Journ. Anat. and Phys., vol. 3-4. 



