VII.] LEADING CHARACTERISTICS. 259 



that genus which originally entered the country having been 

 developed into the more specialised Phacochxrus. Attention has 

 already been called to the fact that the molars of some of the 

 Indian Tertiary species of Sus show a distinct approximation to 

 those of Phacochairus, and further evolution might easily lead to 

 the development of the latter. Since this genus is unknown in a 

 fossil state from other regions, is it improbable that it has originated 

 from Sus within the limits of its present habitat ? 



Summarising the results of the foregoing survey of the mam- 

 malian fauna of Ethiopia, it would appear that the Sahara has for 

 a very long period formed a barrier between Ethiopian Africa and 

 the northern part of the continent. When first populated by 

 Tertiary mammals, Ethiopia and Madagascar were in union, and 

 formed but a single zoological province, which would seem to 

 have been to a great extent isolated from the rest of the Old 

 World during the Miocene epoch. Had such conditions persisted 

 |his province would have been entitled to form a primary 

 zoological realm by itself. During the Pliocene epoch, however, 

 Madagascar became separated, while a more complete union of 

 the continent with Asia by way of Syria or Arabia permitted the 

 influx of larger and higher mammals from the eastward. Hence 

 there is a most intimate relationship between the Pliocene fauna 

 of India and the one now inhabiting Ethiopia ; but the distinc- 

 tion between the two areas at the present day is fully sufficient 

 to justify the separation of the Ethiopian from the Oriental region. 

 Of all the zoological regions of the world, the Ethiopian may be 

 regarded as the one which has been most recently evolved ; and 

 it may be shortly characterised by the sole possession of the 

 gorilla and chimpanzees ; the absence of bears and deer ; and the 

 presence of the African elephant, hyraces, rhinoceroses devoid of 

 front teeth, zebras, hippopotami, wart-hogs, giraffes, numerous 

 genera of antelopes, and aard-varks, as well as by the great de- 

 velopment of its large ungulates in general. It shares with the 

 Oriental region the distinction of being the sole habitat at the 

 present day of man-like apes, true civets ( Viverra), linsangs, palm- 

 civets 1 , ratels (Mellivora), elephants, rhinoceroses, and pangolins 



1 Also in the Austro-Malayan region. 



172 



