508 
plateaux of brickearths are probably the deposit of the 
floods caused by the sudden melting of the winter snow, 
similar to that which takes place in Northern Siberia and 
in the area north of the Canadian lakes. The winter cold 
would be sufficiently intense to allow of the Northern groups 
of mammalia living in the winter; and the musk sheep 
might have been obliged to leave the Pleistocene " tundras/' 
and take shelter in the zone of the elk, and even the bison, 
in an unusually severe season. On the other hand, in the 
summer, the animals that are now found in the temperate 
zones of Europe might advance even into the country of the 
elk and the reindeer ; and even carnivora, now confined to hot 
climates, find their way into the temperate zone of the day. 
Thus the Hyaena vulgaris, or common living hyaena, is found 
fossil in the South of France, without penetrating as far 
north as Britain, France, or Germany. In fact, the evidence 
afforded, both by the fauna and deposits of the Pleistocene, 
seems to us to prove that the climate in Pleistocene Britain 
was more severe than it is now; that at a time when Britain 
formed a portion of the Europaeo- Asiatic continent it more 
closely resembled that now obtaining in the fur countries 
of Northern Asia than elsewhere; and, lastly, that it was 
subject to oscillation, by which the migrations of the her- 
bivores were directed northward or southward, as the case 
may have been. Strong evidence is afforded by the thick 
woolly covering of the carcases of certain larger pachyderms 
— as the Mammoth and Tichorhine rhinoceros of Siberia — 
that the temperature of the countries in which they resided 
was very severe. The Hippopotamus major, also, which was 
cotemporary, may have been, in like manner, supplied with 
warm covering ; but of this fact we have no proof, and the 
aquatic habits of this last mammal militate somewhat against 
this supposition, and are apparently incompatible with a 
climate suited to the reindeer and other terrestrial mammals 
confined to cold climates. 
