BARREN-GROUND CARIBOU. 111 
nally separated with no physical barrier between them. Accord- 
ing to a universal law of selection the larger males of the wood- 
land caribou would have driven off the males of the smaller 
species, whenever they did meet on the common ground, and 
would have left their impress upon their progeny, which being 
larger and stronger than the pure bloods would soon have 
usurped the entire paternity of the race and all distinction would 
long since have been obliterated. It is no answer to this to refer 
me to different varieties of the same species occupying different 
and distant localities, and which vary in size, for instance, as 
much as these do, as the Virginia deer or the mule deer. Those 
species are not migratory, so that they remain substantially in the 
same locality for many generations, if not driven away by vio- 
lence, so that climate, aliment, and other accidental conditions 
may in time produce a hereditary impress upon those occupying 
the particular locality where the particular causes exist. This is 
not possible with migratory animals, where as in this case noth- 
ing but an imaginary line separates the territory occupied by 
each, and where even that line is frequently if not annually over- 
stepped by individuals. Even without the habit, mentioned by 
Richardson, of the southern species migrating north and the north- 
ern species south in the fall, the habit of migration would in time 
have brought them together, when the larger males of the south 
would have become the progenitors of the entire race, and the 
broad distinctions, now so conspicuous and so constant, would 
have been lost. If not migratory, then we might accept the 
explanation suggested by their different localities as a sufficient 
reason for the differences observed. 
Why, then, do these two members of this great family live 
upon contiguous and even overlapping territories and continue so 
completely separated, with no visible cause to keep them apart ? 
It must be because of inherent constitutional, specific differences. 
It is evident that their well-beings require different conditions of 
life arising from organic differences which are permanent and in- 
flexible : one cannot live and prosper where the other must live 
in order to prosper. 
We learn of the differences which have been pointed out, as it 
were, by accident, for their habitat is so remote and inaccessible 
that the Barren-ground Caribous have been rarely visited by com- 
petent naturalists, and I have no doubt that when they shall be 
carefully studied and thoroughly understood by competent ob- 
servers, still broader distinctions between the two species will be 
