12 
NEW YORK ZOOLOGICAL SOCIETY. 
species after another into this Altai deer, which is in turn almost 
indistinguishable from our great American wapiti, how can we 
escape the conclusion that the centre of radiation of the genus 
Cervus was in Eurasia, and our wapiti so recent an immigrant 
from the Old World that it has not had the time to evolve, under 
the varied influences of its new habitat, well marked species, 
there being at most only two or three races of subspecific value. 
Turning to the fossil record we find that no member of this 
genus has been found in America of an earlier age than the Mid- 
dle Pleistocene. 
A similar line of reasoning applied in turn to each of the large 
American animals, enables us to draw what appear to be accurate 
conclusions, not only as to their original home, but as to the rela- 
tive duration of the type in America. 
Not all our animals, however, came from the Old World, al- 
though the predominating types undoubtedly did. South Amer- 
ica contributed a few types, and others, like the raccoon, peccary, 
prong-horn and American deer, are either autocthonous, or else 
have been here so long that their specialization has taken place 
entirely on this continent. 
. To take up the possible places of origin of our living mammals 
in the inverse order of their importance, we find them to be: a 
migration by a possible land bridge over the Atlantic; migration 
from South America; development in North America, and last, 
and by far the most important, migration from Eurasia by way 
of Behring Sea. 
ATLANTIC BRIDGE. 
A mid-Atlantic land connection has been suggested, but has 
little evidence in its favor, and can be practically disregarded, 
and, while there is no doubt that continuous land connected 
Greenland, Spitzbergen and Scandinavia in Pleistocene times, no 
known element of our fauna was derived from this source. 
SOUTH AMERICA. 
South America was entirely separated from North America 
until the Pliocene, but apparently since that period, has been more 
or less continuously united to North America. The southern 
continent, during this long period of isolation, before the Plio- 
cene, developed several groups of large and clumsy animals which 
almost defy classification, but which stand close to the Ungulates, 
