Il] THE EXISTING EQUIDAE 57 



Great Oasis. Though Nubia extends on both sides of the Nile 

 in modern times, Strabo 1 and other ancient geographers ex- 

 pressly make it part of Libya, the name given to the region 

 west of the Nile, just as Ethiopia was applied to the region on 

 the eastern side. 



This passage strongly corroborates the evidence of Herodotus 

 that in the fifth century B.C. there were wild asses in the region 

 lying west of the Nile. 



As we have just seen, the African wild ass when found in 

 Somaliland shows zebra-like markings on its legs, and as this 

 ass is found on the east side of the Nile in modern Nubia it 

 may be that it had managed to get across the barrier of the 

 Nile. On the other hand, the Arabs must have been familiar 

 with the various kinds of Abyssinian ass, and therefore the 

 mere occurrence of stripes on the legs of the wild animals of 

 the oasis would not have called for special remark. It is more 

 likely therefore that the wild asses of the oasis were a distinct 

 species striped black on white like the Somaliland zebra, but of 

 a smaller size, or else some variety of the Chapman-Burchell 

 group of zebras, to which we shall presently come as we keep 

 advancing southwards. 



It is therefore quite possible that the Hippotigris exhibited 

 at Rome in the time of Caracalla may have been brought from 

 the Great Oasis or some other part of what was called Libya by 

 the ancients the vast region lying between the Nile and the 

 Atlantic. 



Up to recently three types of zebras were generally re- 

 cognized. From the minute study of the ever-growing material 

 made by Mr R. I. Pocock 2 and Prof. Ewart 3 we are led to con- 

 clude " that though there are three distinct types of zebras, it 

 cannot be maintained any longer that all three types can be 

 readily distinguished from each other by their marking." These 

 three classes are (1) the GreVy, (2) the Burchell, and (3) the 

 Mountain or ' Common ' Zebra. 



(11) The Grevy Zebra or Somali Zebra (Equus grevyi), 

 found in the mountains of Somaliland and in Shoa, first became 



1 776. 2 Ann. Mag. Nat. Hist., ser. 6, Vol. xx. (1897), pp. 3352. 



3 Penycuik Experiments (1899), p. x. 



