24 ARKIV FÖR ZOOLOGI. BAND 3. N:0 3. 



specimen proved to be very interesting from a certain point of 

 view. It had namely on one side of the upper jaw (fig. 8) no 

 less than 10 teeth and on the other 14 (!) while the lower jaw 

 was not at all remarkable with resp. 5 and 6 teeth. The 

 three hindmost teeth on either side of the upper jaw ha ve 

 the same appearance as the »molars» in similar position of 

 normal skulls and may be regarded as such. A similar opi- 

 nion may be expressed about the next tooth the hindmost 

 prsemolar. The following three teeth are, as usual, smaller 

 but may be the homologues of the anterior praemolars of 

 normal skulls. But in addition to these normal teeth, so to 

 say, there are on the right side 3, on the left 7 teeth, and 

 how shall those be homologised? Are they small rudimen- 

 tary members of the permanent dentition or remains of the 

 milk-dentition which have been belated? One of the 7 super- 



Fig. 8. Part of upper jaw of O. afer shewmg soven supernumerary teeth. 



About ■•/» nat. size. 



numerary teeth on the left side has a peculiar position being 

 situated on the mesial side of the hindmost praemolar and 

 is still not so far developed that its tip has reached the 

 level of the palatal surface. This tooth is larger than the 

 other supernumerary teeth and is only surpassed in size by 

 the molars and hindmost prsemolar. This tooth may perhaps 

 help to explain to which dentition these teeth belong, be- 

 cause it has two deep holes, products of resorption, on its 

 side. This may perhaps hint that the tooth belongs to the 

 milk-dentition (but it might also mean that the tooth is a 

 supernumerary teratological product which is on the way to 

 be reabsorbed). If it belongs to the milk-dentition it ought 

 to be, to judge from its position just in front of the molars, 

 the hindmost milkmolar. Such an interpretation cannot, how- 

 ever, be made, because Oldfield Thomas^ has proved that 



1 Proc. R. Soc. London. VoL XL, VII. 



