Page:Memoirs of the Geological Survey of Great Britain, Volume 1.djvu/410

Rh Among the animal population of the barren grounds we find north of the 70th degree the reindeer, the musk ox, a wolf, the Arctic fox, the white bear, the Arctic hare and the ermine and the shrew. Between 60° and 70° most of these animals live associated with the brown bear. The Canadian otter, the American hare, the zibet, Felis canadensis, the elk and the Bos americanus, most of which are abundant in the wooded region and accompanied there with other species of Cervus, Lepus, Meles, Vulpes, Ursus, Felis and Lutra.

It seems to me that we have in these two divisions of the great Boreal American province a parallel to the successive epochs of the fauna of Britain after the upheaval of the bed of the glacial seas—a first when our country was in the condition of the barren grounds, bare and treeless, when the reindeer, the Irish elk, the Bos primigenius, lived along with species of bear, fox, wolf, hare, cat and beaver—the assemblage of animals found in the freshwater marl basins below peat; a second when forests of pine, oak and beach overspread the land, and forest-living animals, tree-browsing herbivora, prowling and lurking carnivora, and most, if not all, of our existing indigenous mammals became the population of Britain. The change from the first condition into the second was in all probability gradual and marked by the gradual extinction or retirement of species adapted for the colder, and the introduction of such as were fitted for the more temperate epochs.

In one point our parallel fails us. The great pachyderms which appear to have inhabited Britain after the Drift period, and the assemblage of horses and hyenas have no analogues in the zoological provinces of Boreal America. Every where in the northern hemisphere these remarkable animals appear to have lived during the epoch preceding the historical, and to have become extinct before the advent of man. Their parent region appears to have been Siberia. There they abounded during the last tertiary epoch. Thence they migrated westwards when the regions of the glacial ocean were converted into land. The climatal and geographical conditions which induced their diffusion were but the harbingers of others which led to their destruction. They retired probably to their original specific centres and perished in the land of their origin. From their associates we can judge of their habits, and there can scarcely be a doubt that the ancient elephants and rhinoceroses of Britain and the associated extinct quadrupeds were creatures adapted to severer climatal conditions than those now prevailing in our area, and not like the existing forms of the genera to which they belonged, members of faunas more southern than our own. Probably the existing zoological features of Northern and Central Asia present the truest