AND 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 light 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 limitation chiefly to elevated regions in the 
tropics (Grévy’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 
caffer), very common at the Cape, but extending north- 
wards into Angola and Mozambique. While related to 
the jerboas the animal resembles the common hare in size 
and colour, but it has along 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. 
