682 SCIENCE PROGRESS 



Creodonts (Hycenodon, Ptcrodon, etc.) and of an Anthracotheroid 

 approximating to Brachyodus, is evidence of this earlier junction. 



The relations of Africa with Madagascar are also interesting. 

 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 lyy sup- 

 posing 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 Mada- 

 gascar 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 South-western Asia and Europe 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 further 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 probably 

 the stock from which the Mammalia 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 Mammalia 

 and Reptilia. 



