ETHIOPIAN- MAMMALIA. 83 



thus on the continent three strictly-defined faunal sub-regions : 1, 

 the pasture-lands already described, constituting the East- Central 

 African sub-region, through whose vast expanse there is manifest a 

 strong identity in the character of the animal products, the same 

 or very closely related animal forms being in many instances found 

 at the extreme points of the region ; 3, the forest tract, constitut- 

 ing the West African sub-region, whose animal products naturally 

 differ very essentially from those of the last; and, 3, the desert 

 or Sahuran sub-region, containing a comparatively limited fauna, 

 which, with almost insensible gradations, merges into the fauna of 

 the Mediterranean transition tract. To the same division belong 

 in great measure the desert tracts of Arabia, or that portion of the 

 peninsula lying to the south of the Tropic of Cancer. The Island 

 of Madagascar, with Mauritius, the Seychelles, &c., forms an in- 

 dependent sub-region of its own. 



Zoological Characters of the Ethiopian Realm.— The mam- 

 malian-fauna of the Ethiopian region is characterised no less by 

 the remarkable development of its carnivore and hoofed animals 

 (Ungulata) than by the peculiarities presented in its quadrumanous 

 types. Of the hoofed animals there are two families which are 

 absolutely restricted to the region: the Hippopotamidae, or hip- 

 popotami, and the Camelopardidae, the giraffes. The former com- 

 prise two species, the common hij^popotamus (H. amphibius), which 

 is found in nearly all the larger African rivers from the Cape to 

 the Sahara, and from the Zambesi to the Senegal, and the smaller 

 Liberian hippopotamus (Choeropsis Liberiensis), from the river St. 

 Paul on the west coast, characterised by the possession of only one 

 pair of incisors instead of the normal tw^o pairs.* The latter in- 

 cludes but a single species, the well-known giraffe (Camelopardalis 

 giraffa), which ranges throughout the greater portion of the African 

 open country, and to a certain extent also invades the forest region. 

 As to the pigs (Suidae), a family very closely related to the Hippo- 

 potami, the Ethiopian region is deficient in the genus Sus, which 



* In antiquity the hippopotamus appears to have been very abundant in 

 the waters of the Nile as far down as Lower Egypt. Even as late as 1600 

 hippopotami were trapped at Damietta, situated at tlie mouth of one of the 

 arms of the Nile, and in the early part of this century they were still ob- 

 served by Euppell in Nubia. At present they are found in the Nile only in 

 its upper course. 



