AISTD DESERTS 133 



zebra and the quagga formerly occurred in vast herds, 

 the wild ass, an inhabitant of a region where food is 

 always scanty, occurs in smaller parties. Its sober tint 

 harmonizes with the uniform colour of the desert, and 

 the fact that the domesticated form will eat dry and 

 prickly food points back to the days when its ancestors 

 contented themselves with the thorny herbs of the 

 desert. The stripes of the zebra and quagga apparently 

 harmonize with the hght and shade playing through 

 the open bush country of their native haunts. It will 

 be noted that the presence of the various forms of wild 

 horses on the plains to the north and south of Africa, 

 and their Hmitation chiefly to elevated regions in the 

 tropics (Grevy's zebra), speaks to a relative intolerance of 

 heat, a not uncommon feature in the larger ungulates. 



As to the rodents, we note that in Africa those of 

 the savanas are relatively unimportant, while in South 

 America, with the paucity of ungulates, there are many 

 large and important rodents. 



We have already spoken of the jerboas, which extend 

 from the steppes of Asia into the deserts of North 

 Africa, and have noted their special adaptations. In 

 the southern half of the continent the place of the 

 jerboas is taken by the so-called jumping hare {Pedetes 

 cajfer), very common at the Cape, but extending north- 

 waids into Angola and Mozambique. While related to 

 the jerboas the animal resembles the common hare in size 

 and colour, but it has a long hairy tail, and elongated 

 hind-legs. It feeds upon all-fours, but escapes from its 

 enemies by taking long bounds, stated sometimes to 

 cover as much as thirty feet. The animals are bur- 

 rowers and nocturnal, and frequent arid districts. 

 True hares also occur in Africa, but offer no special 

 features. 



