INTRODUCTION 73 



animals belonging to types hitherto unknown and undreamed of. The an- 

 cestors of the two great groups wliich Osborn had hypothetieally placed on the 

 map of Africa, namely, the Proboscidea and the Hyracoidea, were successively 

 found here as well as the remarkable unknown group of Eml)rithopoda, in- 

 cluding ArsinoUheriiim. The Sirenia or seacows, which had been discovered 

 many years earlier near Cairo, were traced back to primitive forms, and then 

 the ancestors of the archaic whales, or Zeuglodontia, a group also previously 

 discovered here, were traced back to their early stages of evolution. These 

 discoveries proved to be epoch-making, marking a turning point in our knowl- 

 edge of the origin and distribution of the Mammalia, and arousing such 

 witlesjjread interest that for the time being North Africa becomes the storm 

 center of mammalian palaeontology. (See p. 199.) 



From our present knowledge it appears that Africa may have been, 

 therefore, the source or original home of the following orders of mammals: 



Proboscidea, Mastodons and elephants. 



Sirenia, Seacows or manatees and dugongs. 



Zeuglodontia, Primitive or ancestral whales, showing evidence of descent from 



land-living, carnivorous forms.' 

 Hyracoidea, Large ancestral forms of the modern diminutive 'dassies' and 



conies. 

 Embrithopoda, Represented by the giant Arsinodherium, a large herbivorous 



quadruped with a pair of great horns on the front part of the 



skull. 



Autochthonous and migrant orders of Africa. — It is well to place in im- 

 mediate contrast with the list of Holarctic Orders on p. 68 all those orders of 

 mammals which have thus far been found in the Eocene and Oligocene of 

 northern Africa in the Fayiim region, keeping in mind most emphatically 

 that this proba]:)ly represents only a part of the whole mammalian fauna of 

 Africa in these early geological times, and that great discoveries are still to be 

 made, especially among the order Insectivora. These mingled orders present 

 or discovered in Africa are as follows: 



Carnivora-Creodouta ' Sirenia 



Rodcntia-Theridomyidae Embrithopoda 



Artiodactyla Hyracoidea 



Proboscidea Zeuglodontia 



Primates 



Certain orders of mammals are conspicuous by their absence from this 

 ancient Ethiopian list, although one or more of them may well be found when 

 we know more of the palaeontology of the "dark continent." Among these 

 absent or undiscovered forms are: 



' Zeuglodonts are also observed in the Upper Eocene of the eastern United States. 



