206 ROMANCE OF THE BEAVER 
are believed to be the ancestors of the present-day 
species, as their fossilised remains have been found 
in the pliocene deposits in which were preserved the. 
skeletons of the Mastodon and Mammoth, so that 
these animals lived during the tertiary period and 
from the evidence which nature thus preserved 
there is no reason to believe that the beaver, as we 
know them to-day, differs in any marked way from 
those of prehistoric ages. The earliest European 
Beaver was probably the chalicomys which has been 
found in the Miocene beds of the Continent. It 
was considerably smaller than the existing form 
and “ differed from all living rodents in having a 
perforation of the lower end of the upper arm-bone 
or humerus ” (Lydekker). The largest of the 
family was the Castoroides, whose skull was only 
about four inches less in length than that of a lion 
and was probably the largest of any of the rodents. 
The beaver, both American and European, had the 
largest range of any animal, those in Europe having 
existed all over Europe, including Great Britain 
(not Ireland) and Asia as far as the Euphrates. 
During the Pleistocene period they lived in Italy as 
far as Rome, while the American species ranged 
all over North America from the Arctic Sea to 
Mexico. Atthe present time the American beaver, 
Castor Canadensis, is chiefly restricted to the more 
northern portion of the Continent of North 
America ; none are found in the region of the great 
plains, nor in the more southerly and easterly 
