10 



ARKIV FÖR ZOOLOGI. BAND 3. N:0 3. 



molar to the anterior side of 

 the second prsemolar (fifth tooth 

 from behind) only 52,3 ^o^ of 

 the distance from the last men- 

 tioned praemolar to the tip of 

 the prsemaxillary (fig. 3), but 

 in O. af er the same percentage 

 is from 69,2 to 76,7 and in O. 

 cpthiopicus 69,0. Tf the distance 

 between the foremos t prsemolar 

 and the tip of the prsemaxil- 

 lary is compared with the length 

 of the whole dental series the 

 difference becomes still more 

 striking for in t hat case the 

 length of the dental series is 

 in O. erikssoni only from 64, o 

 to 70,0 per cent of the other 

 measurement, but in O. afer it 

 is from 96,8 to 140, o and in 

 iO. ceihiopicus 96,6 percent. 



In O. cethiopicus and senega- 

 lensis the height of the processus 

 angularis of the mandible above 

 the alveolar plan is not very 

 great, so that the distance be- 

 tween the latter and the upper 

 end of the former is decidedly 

 less than the distance between 

 proc. angularis and proc. condy- 

 loideus. In the adult O. afer 

 and O. haussanus proc. angu- 

 laris has a higher situation so 

 that its distance from proc. con- 

 dyloideus is about equal to (or 

 even shorter than) its distance 

 from the alveolar plane. In this respect O. erikssoni resembles 

 the two first mentioned species as its proc. angidaris sits at a 



Fig. 3. Skull of E. erikssoni seen 

 from below, '/-.> nat. size. 



^ On the other side where the second prsemolar has an abnormal 

 position and is separated from the hindmost prsemolar by considerable 

 interspaoe the percentage is 60. 



