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 Souih 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 
moro 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 
A A 2 
