RECENTLY DISCOVERED TERTIARY VERTEBRATA OF EGYPT. 307 



The mammalian fauna of Madagascar is a comparatively poor one, 

 and is completely wanting in many of the typically African groups of 

 mammals. Tullberg has accounted for this by supposing that the 

 eastern part of Africa, with Madagascar, was separated from the 

 main southern and western African continent by a belt of sea, and that 

 it was only after the isolation of Madagascar that these two parts of 

 the Ethiopian continent united, and the richer fauna of the southern 

 and western portions spread over the whole. This probably occurred 

 in the Oligocene, at which time the union with southwestern Asia 

 and EluroiDC took place, followed by the dispersal into the northern 

 continent of the Proboscidea and other groups. 



The importance of Africa in the history of the Mammalia is fur- 

 ther increased by the fact that, as Stromer has pointed out, some part 

 of the region has probably been above the sea since Permo-Triassic 

 times, during which a great variety of land reptiles existed, some of 

 which, the Theriodonts, approximate very closely to the mammalian 

 type, and, in fact, are probabl}' the stock from which the Mannnalia 

 sprung. This being so, it is by no means improbable that somewhere 

 in this continent beds of Jurassic and Cretaceous age will be found, 

 containing remains of animals which will completely bridge the gap 

 between the two great and now widely distinct groups — the Mam- 

 malia and ReiDtilia. 



