Russia are equally dependent upon the season for their locality; and if an unusual season occurs, to put the animals off their accustomed route, the inhabitants of the district at the mouth of the Kolyma, living upon the chase, endure the severity of famine. M. von Matiuskin, the lieutenant of Admiral von Wrangel, had the good fortune to see one of the migratory bodies of Reindeer, consisting of many thousands divided into herds of two or three hundred each, in the act of crossing a river. By some such oscillation of temperature which regulates the supply of food for the herbivores, the remains of the animals of two contiguous zoological provinces may be found together in one spot, as in the case of the northward retreat of the Musk-sheep, which, living in Hearne's time (A.D. 1770) near Fort Churchill, has left that district to be occupied now by the Elk and Wapiti. In this manner the admixture of the remains of animals living at the present day respectively in a severe and in a temperate continental climate may be accounted for in the Pleistocene caverns and brick-earths. Sir John Richardson writes:—"The subsoil north of lat. 50° is perpetually frozen, the thaw on the coast not penetrating above 3 feet, and at Great Bear Lake, in lat. 64°, not more than 20 inches. The frozen substratum does not of itself destroy vegetable life; for forests flourish on the surface at a distance from the coast, and the brief, though warm, summer gives birth to a handsome flora, matures several pleasant fruits, and produces many carices and grasses." The climatal extremes of temperature are very great, the minimum winter temperature at Fort Reliance, on the northern shore of the Great Slave Lake (N. lat. 62°50″, long. 109° W.) being registered by Capt. Back, 17th Jan. 1834, as being −70°, and the maximum at the end of May +106°. These observations are confirmed by those of Sir John Franklin, at Fort Franklin (lat. 65°, long. 123°), where, on Dec. 25, 1826, the temperature was −43°, and on the 31st May +93°. Such a great variation as this could not have happened in the latitude of Britain, France, or Germany; nor is it required by the circumstances of the case.
In the vast plains of Siberia also, extending from the Altai Mountains to the Arctic Sea, we find a near approach to the Pleistocene climate of North-western and Central Europe. Covered by impenetrable forests, for the most part of birch, poplar, larch, and pine, and, in the north, of 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 size as the traveller advances northwards, and are finally replaced by the grey mosses and lichens that cover the low marshy tundras. The minimum temperature registered by Admiral von Wrangel at Nishne Kolynisk on the banks of the Kolyma is −65° in January. "Then breathing becomes difficult, the wild Reindeer, that citizen of the polar region, withdraws to the deepest thicket of the forest, and stands there motionless, as if deprived of life, and trees burst asunder from the intensity of the cold. Throughout this area roam Elks, Black Bears, Foxes, Sables, and Wolves, that afford subsistence to the Jakutian and Tungusian hunters. In the northern part countless herds of
