of such animals as Elephants,
Lions, the Rhinoceros, and the Hippopotamus afforded an irrefragable
proof that the climate of Europe must have been a warm one, at any
rate during Post-Glacial times. The existence, also, of numbers
of Mammoths in Siberia, was further supposed to indicate that
this high temperature extended itself very far north. Upon the
whole, however, the evidence is against this view. Not only is
there great difficulty in supposing that the Arctic conditions of
the Glacial period were immediately followed by anything warmer
than a cold-temperate climate; but there is nothing in the nature
of the Mammals themselves which would absolutely forbid their
living in a temperate climate. The _Hippopotamus major_, though
probably clad in hair, offers some difficulty--since, as pointed
out by Professor Busk, it must have required a climate sufficiently
warm to insure that the rivers were not frozen over in the winter;
but it was probably a migratory animal, and its occurrence may
be accounted for by this. The Woolly Rhinoceros and the Mammoth
are known with certainty to have been protected with a thick
covering of wool and hair; and their extension northwards need
not necessarily have been limited by anything except the absence of
a sufficiently luxuriant vegetation to afford them food. The great
American Mastodon, though not certainly known to have possessed a
hairy covering, has been shown to have lived upon the shoots of
Spruce and Firs, trees characteristic of temperate regions--as
shown by the undigested food which has been found with its skeleton,
occupying the place of the stomach. The Lions and Hyaenas, again,
as shown by Professor Boyd Dawkins, do not indicate necessarily
a warm climate. Wherever a sufficiency of herbivorous animals
to supply them with food can live, there they can live also;
and they have therefore no special bearing upon the question of
climate. After a review of the whole evidence, Professor Dawkins
concludes that the nearest approach at the present day to the
Post-Pliocene climate of Western Europe is to be found in the
climate of the great Siberian plains which stretch from the Altai
Mountains to the Frozen Sea. "Covered by impenetrable forests,
for the most part of Birch, Poplar, Larch, and Pines, and low
creeping dwarf Cedars, they present every gradation in climate
from the temperate to that in which the cold is too severe to admit
of the growth of trees, which decrease in siz