344 CxEOGKAPHICAL DISTEIBUTION OF SPECIES. [Ch. XXXVIII. 



should be characterised hj a peculiar indigenous fauna is a 

 fact in perfect accordance with Buffon's theory of natural 

 barriers. 



We have already stated that the sea even in post-tertiary 

 times covered the space now occupied by the Sahara, so that 

 Africa was for vast periods surrounded by water on every side 

 but the north-east, where it was connected by an isthmus 

 with Asia. Such a connection might explain why there are 

 some few species, such as the lion, 

 common to Africa and Asia, and also why many Asiatic 

 genera are represented by allied African species. The ele- 

 phant, for example, of Africa, though so nearly resembling that 

 of India, is distinct, being smaller, having a rounder head and 

 larger ears than the Indian one, and having only three instead 

 of four toes on each hind foot. There are three African 



dromed 



from 



hippopotamus 



Mio 



cene Period, and in Europe in the Pliocene and Post-Pliocene. 

 Also the giraffe, the gorilla, the chimpanzee, the blue-faced 

 baboon, the four-fingered monkey [Colohus), and many carni- 

 vora, such as Proteles, allied to the hyaena. In proportion 

 as we advance towards the southern part of the Ethiopian 

 region we find in the temperate zone other forms, many of 

 them agreeing generically with those inhabiting the zone of 

 corresponding climate north of the equator in Asia. Among 

 these are the quagga and the zebra ; answering to the horse, 

 the ass, and the jiggetai of temperate Asia. Amongst 

 pachydermatous animals the hyrax is peculiar, amongst the 

 ruminantia the Cape buffalo and many antelopes, such as the 

 springbok, the oryx, the gnu, the leucophoe, the pygarga, 

 and several others. 



om Africa by the Mozamb 

 ide, Madagascar forms, wii 

 immediate vicinitv. a zooL 



^ 



vhicli 



of which all the species except one, and nearly all the genera, 

 are peculiar. The one exception alluded to consists of a small 

 insectivorous quadruped (Centefes), found also in the Mauri- 

 tius, to which place, how^ever, it is supposed to have been 



