DWARF DEER OF SOUTH AMERICA 355 



(pp. 107 112), when I argued that the South American 

 deer had not originated in North America, as is generally 

 assumed, but in South America from European ancestors. 



I venture to think that most palaeontologists will agree with 

 my contention, which is by no means a new one, that there is 

 quite a remarkable affinity between the living western South 

 American groups of mammals and those of the early European 

 Tertiaries. It is my interpretation of the causes which pro- 

 duced this striking feature that will not so readily commend 

 itself. The faunas of the West Indies and Central America 

 form the chief difficulty to the acceptance of my theory. I 

 acknowledge that comparatively few traces remain in these 

 countries of the vast migration that swept across them. In 

 the West Indies, I presume, the subsequent submergence must 

 have destroyed the principal part of the original fauna, while 

 Central America in its present form did not exist at the time 

 when the mid-Atlantic land bridge spanned the ocean. Com- 

 petition with newer arrivals, moreover, must have been very 

 keen, so that Central America became unfitted for the survival 

 of European relict forms. This explanation does not appear 

 altogether satisfactory. But the crux of the problem is North 

 America. By what possible system of land bridges can 

 western South America have received part of its fauna from 

 Europe and have exchanged certain groups in return without 

 North America having become affected ? This seems all the 

 more puzzling considering that I drew special attention in 

 Chapter IX. to the conspicuous faunistic relationship between 

 southern Europe and California. The faunas of western 

 North America and western South America as a whole are 

 strikingly different, and yet I have indicated certain points 

 of resemblance, especially between some of the more ancient 

 members of the two faunas. If we supposed the mid- 

 Atlantic land bridge of early Tertiary times to have been 

 connected at first with both western North America and 

 western South America, while disconnected at all other points 

 with these continents, certain very ancient points of resem- 

 blance between the two continents and with Europe might 

 thus receive a satisfactory explanation. If the same land 

 bridge had then become entirely separated from North 

 America, remaining united with South America, the faunistic 



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