8 



ARKIV FÖR ZOOLOGI. BAND 3. N:0 3. 



races (with equal sut. sagittalis and sut. frontalis) is at least 

 Vs of Slit. nasalis and so it is also in O. afer and cethiopicus 



according to my own measure- 

 ments. 



The suture between the na- 

 sal and frontal on either side 

 forms in O. afer with t hat of 

 the other side almost a right 

 angle in the mesial line but in 



0. erikssoni these sutures form 

 together an even, strongly and 

 broadly rounded arch (fig. 2). 



In O. afer the greatest breadth 

 of both nasals is not contained 

 twice in their greatest length 

 in the mesial line, but in O. 

 erikssom this is the case. 



In O. cethiopicus the frön t o- 

 nasal suture forms an angle 

 with larger aperture than 90°, 

 but rounded at the posterior 

 end, and the greatest width of 

 both nasals is not contained 

 twice in the length of the na- 

 sals. 



In O. haussanus the frön to- 

 nasal suture forms »einen viel 

 ti ef er (than in O. afer) gerad- 

 linig abgestumpften rechten 

 Winkel dessen Schenkel nach 

 aussengebogensind» (Matschie 



1. c. 1899 p. 105). The author 

 of this form has kindly fur- 

 nished me with a sketch of this 

 feature in O. haussanus, from 



^ ^, „ , ^ ., . which I have been able to see 



Fig. 2. Skull of O. ertkssom upper . • .1 • 



view, ^2 nat. size. its great difterence in this re- 



spect from other species. 

 Matschie has pointed out that O. haussanus has a very 

 long lacrimale, which extends along ^/i of the lower lateral 

 suture of the frontal from the orbit to the nasal. The lacri- 



