CONCLUSIONS 231 



ones came direct from Europe. Professor Suess,* on the 

 other hand, favours a north Atlantic land connection in high 

 latitudes between Greenland, Iceland and Scotland, and he 

 thinks its origin dates back to the beginning of the Miocene 

 period. Considering that there is such unanimity in favour 

 of some kind of land bridge between the Old World and the 

 New at this time, it is strange that Professor Schuohertf 

 should entirely isolate North America in his palaeogeographi- 

 cal maps from the Old World, not only in Miocene, but even 

 in Pliocene times. 



Although the Pliocene fauna, according to Professor 

 Osborn (p. 81)', is as yet only imperfectly and sparsely 

 known, being characterised by hosts of southern invaders 

 which now flood the continent, a direct land bridge between 

 North America and the Eurasiatic continent must likewise 

 have existed, unless we assume that the mighty elephant 

 Tetrabelodon (Dibelodon) which is represented by several 

 species in the New World, reached North America by way 

 of South America. Whether the still existing more hardy 

 stock of Asiatic immigrants came to North America towards 

 the end of Pliocene, as I argued in a previous chapter 

 (p. 97), or during Pleistocene times, is a question which had 

 not hitherto, I think, been seriously debated. That their pre- 

 sence in North America is due to a wide land bridge across 

 Bering Strait (see Fig. 7) seems to me evident. 



In this very brief survey of the past faunas of NortH 

 America I have endeavoured to show that an important centre 

 of evolution and dispersal existed in western North America 

 in the past, just as it exists to a lesser degree at the present 

 day. The strong faunistic affinity between western North 

 America and western Europe, which we can still trace at this 

 moment among many of the invertebrates and lower verte- 

 brates of the two areas, seems to be the outcome of an ancient | 

 direct geographical communion between these land-masses. | 

 Certain features in mammalian palaeontology appear to 

 strengthen my views, which are primarily based on a study 

 of the modern fauna. In the succeeiding chapters I shall 

 bring forward further evidence showing that North America 



* Suess, E., •' Antlitz der Erde," Vol. in.2, p. 765. 

 t Schuchert, C, " Paleogeography," PL 98—100. 



