88 AFRICAN DESERTS. 
united by the fibres and roots of various plants, 
which draw a certain portion of nourishment at all 
times even from the parched soil of the karroos, and 
which in the rainy season cover the whole country 
with rich and spontaneous verdure. The karroos of 
Southern and Central Africa are thus similar in 
their principal characters to the steppes of Northern 
Asia, excepting that their intertropical position, and 
the consequent changes of dry and rainy seasons, 
vive the Central African deserts a variety which the 
Asiatic do not possess. It also adapts them much 
better to the support of animal life, particularly for 
the support of such graminivorous animals as _pos- 
sess speed of foot to enable them to traverse great 
distances in a short space of time, in search of the 
often widely-dispersed situations in which their con- 
genial food is to be found. Accordingly, no country 
abounds with such innumerable flocks of antelopes, 
gazelles, &e., or with such numberless varieties and 
species of these animals as the karroos of Southern 
and Central Africa. Out of nearly seventy species 
which naturalists have enumerated as belonging to 
the antelope genus, no fewer than fifty are proper to 
Africa, and of these upwards of twenty-five have 
been found within the Colony of the Cape of Good 
Hope, er in the countries immediately bordering 
upon it towards the east and north. This is cer- 
tainly one of the most singular circumstances in 
African Zoology, or indeed in the geographical distri- 
