MOOSE DEER 
33 
necessity. This problem of the Bering Strait land bridge, 
however, will be more fully discussed later on (pp. 83—86). 
The moose, or elk as it is called in Europe, has been stated 
to occur in the Caucasus, but its range only extends to the 
forests north of this mountain range. Like the reindeer, it 
occurred much further south formerly, even as far as 
northern Italy, and yet no theories as to a former arctic 
climate are founded on this fact. In Caesar’s time the elk was 
still abundant in the Black Forest in southern Germany, 
while it is now confined to certain parts of Russia and 
Scandinavia. 
Many other American species resemble the moose in their 
range, except that they manifest more clearly their Asiatic 
origin. The further west we travel the more often do we 
meet with such types of animals. 
We have now become acquainted with species that seem 
to be of arctic American or Greenland origin. A few 
apparently travelled across from Europe. Others were partly 
of southern extraction having advanced northward from the 
United States, and partly derived from a western invasion of 
the continent. What we want to find out next is the geological 
age of some of these invasions into boreal America. The 
writings on this subject of the prominent biological authors 
are largely biassed by the prevalent geological opinions with 
regard to the nature of the Ice Age. 
It is currently believed that a climatic change towards the 
end of the Pliocene Period caused ice-masses to form in 
various Canadian centres, so as to produce continental 
glaciers of the type of the ice-sheet now covering Greenland. 
These glaciers are supposed to have spread from at least three 
centres in Canada, termed the Labradorean, Keewatin, and 
Cordilleran. During this time, viz., in our most recent 
geological age, the “ Pleistocene Period,” fully one half of 
North America is thus assumed to have been gradually buried 
beneath these vast sheets of ice. Ice is believed to have ex¬ 
tended practically all over the continent from Newfoundland 
in the east to Vancouver in the west, and from the Arctic 
Ocean to the present site of the City of St. Louis.* Relying 
* Russell, I. C., “ North America,” p. 315. 
L.A. D 
