74 
The most striking difference between the two species consists in the 
development of the hairs on the tips of the ears in O. callotis so as to form 
a long black tuft ; in O. deisa the hairs at the extremity of the ear are scarcely 
longer than those covering the adjacent edges of that organ. Lastly, in 
QO. callotis, the hairs along the median dorsal line are reversed in direction 
ot growth frem a point only a little behind the middle of the back ; whereas 
in O. beisa the parting is situated on the rump. 
Hab. British East Africa, south of the River Tana, and interior of German 
East Africa. 
Southwards of the River Tana in British East Africa, or thereabouts, the 
Beisa appears to be replaced by a nearly allied form, distinguishable by 
the conspicuous tufts which adorn the tips of its ears and by other less 
noticeable characters. It will be easily understood that this animal was not 
at once distinguished from the typical form by those who first met with it, 
and was consequently referred to ‘“ Oryx beisa” by Mr. Hunter in his 
Appendix to Willoughby’s ‘ Big Game in East Africa,’ and by other earlier 
authorities. 
It was not, in fact, until 1892 that the conspicuous difference of this 
species from O. beisa, as regards its ears, attracted notice, when Mr. Rowland 
Ward, F.Z.S., first called Thomas’s attention to it. Thomas, after examining 
into the subject, brought it before the notice of the Zoological Society of 
London on March 15th of that year, and proposed to call the new form 
Oryx callotis. _'Thomas’s communication was subsequently printed in the 
Society’s ‘Proceedings’ accompanied by a good coloured figure of the 
mounted head of the typical specimen, which was subsequently presented 
by Messrs. Rowland Ward and Co. to the British Museum. 
As will be seen by reference to Mr. Rowland Ward’s ‘ Records of Big 
Game,’ the horns of this typical specimen are among the shortest of the series 
of 18 specimens of this species of which measurements are there given, the 
longest pairs being over 30 inches in length. These latter are, no doubt, 
those of females, which in all the species of Oryx seem to be rather longer 
and thinner than those of males. 
In the first volume of ‘ Big Game Shooting’ in the ‘ Badminton Library,’ 
Mr. F. J. Jackson gives us the following account of Oryx callotis in British 
East Africa :— 
