THE GEOGRAPHICAL DISTRIBUTION OF MAMMALS 



171 



tinent, detached at a comparatively recent date; the southern 

 extremity of Florida also belongs to this subregion. 



The two subregions into which continental South America 

 is divided are not altogether satisfactory and will doubtless 

 require change when the distribution of South American 

 mammals has been more accurately determined. 



Fig. 89. — Fox-like Wolf {Cerdocyon gracilis). 

 W. S. Berridge, London. 



Bj- perniiiiion of 



''Richness combined with isolation is the predominant 

 feature of Neotropical Zoolog}^ and no other region can 

 approach it in the number of its peculiar family and generic 

 types " (Wallace). Just as North America has received many 

 immigrants from the Old World, so it has sent many mi- 

 grants into South America, materially changing the character 

 of the Neotropical mammalian fauna, but these intruders may 

 be readily identified and almost seem to be out of place in their 

 new surroundings. Not all of these northern migrants were 



