417. The presence of petrified marine objects in places where some of the fossil bones are found, is no proof that the latter have come from the sea, though it is produced as such both by Pallas himself, and afterwards by Kirwan. These marine bodies are the shells and corals that have been parts of calcareous rocks, from which being detached by the ordinary progress of disintegration, they are now contained in the beds of sand or gravel where the animal remains are buried. They have nothing in common with these remains; they are real stones, and belong to another, and a far more remote epochs. Such objects being found in the same place where the bones lie, argues only that the strata in the higher grounds, from which the gravel has come, are calcareous; and nothing can show in a stronger light the necessity of distinguishing the different condition of fossil bodies, united by the mere circumstance of contiguity, before we draw any inference as to their having a common origin. If the marine remains were in the same condition with the bones; if they were in no respect mineralized; then the conclusion, that both had been imported by the sea, would have great probability; but without that, their present union must be held as casual, and can give no insight into the origin of either. 418. On the whole, therefore, no conclusion remains, but that these bones have belonged to species of elephants, rhinoceros, &c. which inhabited the very countries where their remains are now buried, and which could endure the severity of the Siberian climate. The rhinoceros of the Wilui certainly lived on the confines of the Polar Circle, and was exposed to the same cold while alive, by which, when dead, its body has been so long, and so curiously preserved. These animals may also have lived occasionally farther to the south, among the valleys between the great ranges of mountains that bound Siberia on that side. Fossil bones are but rarely found in these valleys, probably because they have been washed down from thence into the plains. We must observe, too, that those animals may have migrated with the seasons, and by that means avoided the rigorous winter of the high latitudes. The dominion of man, by rendering such migration to the larger animals difficult or impossible, must have greatly changed the economy of all those tribes, and narrowed the circle of their enjoyments and existence. The heaps in which the fossil bones appear to be accumulated in particular places, especially in North America, have a great appearance of being connected with the migrations of animals, and the accidents that might bring multitudes of them into the same spot.