AFFINITIES OF NORTH AND SOUTH 245 



New World was the same then as it is now, and that Central 

 and South America had already been evolved in anything like 

 the present outlines. As I shall endeavour to demonstrate 

 later on, South America did not then exist as a distinct great 

 continent. A large land-mass evidently lay in the neigh- 

 bourhood of the existing State of Brazil and another further 

 south. And as far as we know, the southern land-mass was 

 the original home of the edentates. Between it and Central 

 America on the site of the present South American continent 

 there were one or more broad marine channels, or oceans, as 

 we might call them. And yet the edentates succeeded in 

 attaining North America. I do not now wish to discuss my 

 reasons for the supposition that western Mexico was then 

 united by a direct land bridge with Chile. I only mention it 

 in order to indicate that the appearance of edentates in the 

 Eocene of North America does not afford a proof of the ex- 

 istence of Central America at that time, nor during the 

 Miocene Period. 



Professor Osborn, as I mentioned before, indicates the 

 nature of the land connection between North and South 

 America in the da,wn of the Tertiary Era on a map which he 

 kindly allowed me to copy (Fig. 21). However, he expresses 

 the belief that already in early Eocene times, that is to say 

 almost before the appearance of the above-mentioned arma- 

 dillo in North America, the land bridge had ceased to exist. 

 We are too apt, I think, to look upon South America as exclu- 

 sively the home of edentates, forgetting that many other mam- 

 mals may have originated there too. We may not all agree 

 with Dr. Ameghino * in attaching the importance he does 

 to that continent as a source of the Tertiary mammalia, 

 but I believe we possess other evidences of a faunistic inter- 

 change between Chile and Patagonia on the one hand, and 

 western North America on the other, during the ages that 

 passed between the Lower Eocene and the Miocene. 



In southern Africa we meet with a group of small blind 

 subterranean creatures, the golden moles (Chrysochloridae) 

 which are among the most primitive mammals in existence. 

 They are quite confined at present to South Africa. But 



* Ameghino, Fl. " South America, the Source of Mammalia." 



