108 INTRODUCTION. 
shores ; they being nearly as abundant in some parts 
of Canada as in the United States. 
Leaving out of consideration the ocean, which of 
course confines whole tribes and orders of animals 
within one area, it would seem necessarily to result, from 
the preceding facts and observations, that merely geo- 
graphical features do not much affect the distribution of 
species ; and that their territorial range, under simi- 
lar and favorable conditions, is, irrespective of geo- 
graphical limits, very wide. The vast area between the 
Rocky Mountains and the Atlantic Ocean may, for 
these animals, be considered as one zoological district ; 
and it may be assumed that they are diffused through- 
out the whole of it, except where they are restrained by 
climate, or by other general or local causes. 
The following tabular view exhibits the distribution 
of the species mentioned in this work, according to 
the geographical divisions before defined, so far as un- 
derstood at this time. The species believed to have 
been introduced from other countries are printed in 
italic letters. 
