xlvi INTRODUCTION. 



retreating northwards or southwards, according to the temperature that regulates the 

 supply of food necessary for its existence. Thus, in North America, Sir John Frankhn 

 writes that the migrations of the animals afford a means of foretelling the severity of the 

 season. If the reindeer retreat far south then a severe winter is to be apprehended ; if, 

 on the contrary, they remain very nearly in their usual winter haunts, the season invariably 

 is a mild one. The reindeer of Northern 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, hving upon the chase, 

 endure the severity of famine. M. Von Matiuskin, the Lieutenant of Admiral Von 

 Vy'rangel, had the good fortune to see one of these migratoiy bodies of reindeer crossing a 

 river, consisting of many thousands, divided into herds of two or three hundred each. 

 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 ?Iearne's time (a.d. 1770 — 72) near Fort Churchill, has left that district 

 to be occupied now by the elk and the waipiti. 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. 

 Of the district in America, where the animals inhabiting the high northern latitudes 

 meet with those that live under a comparative temperate climate, Sir John Richardson 

 writes : — " The subsoil north of latitude 50° is perpetually frozen, the thaw on the coast 

 not penetrating above three feet, and at Great Bear Lake, in latitude 64°, not more than 

 twenty inches. The frozen substratum does not of itself destroy vegetation, 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."^ 



But in the vast plains of Siberia, extending from the Altai Mountains to the Arctic 

 Sea, we find probably a nearer approach to the Pleistocene climate of Western Europe. 

 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 

 size as the traveller advances northwards, and are replaced by the grey mosses and lichens 

 that cover the low marshy " tundras." The maximum winter cold, registered by Admiral 

 Von Wrangel,^ at Nishne Kolymsk, 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 subsistance to the Jakutian 



1 Back's 'Journey to the Arctic Sea,' 4to, 1836, appendi.\, p. 4/9. 



2 Op. cit. 



