Mastodon and mammoth bones have been discovered in Europe from the earliest times, and a history of the remarkable theories to which they had given rise before the time of Cuvier is very interesting. By the learned of by-gone times the fossils have been mistaken for the bones of Ajax, the "body of Orestes," unicorns, the teeth of St. Christopher, and the remains of Hannibal's elephants. The middle ages have given us a whole library on the subject of a race of giants, whose remains were clearly recognized in the huge bones. In America, in colonial times, Governor Dudley, of Massachusetts, was "perfectly of opinion" that the mastodon tooth discovered near Albany in 1705 "will agree only to a human body, for whom the flood only could prepare a funeral; and without doubt he waded as long as he could keep his head above the clouds, but must at length be confounded with all other creatures." At what period the monster became extinct in Europe is a question to which geology gives no answer from the point of view of human history. The evidence rests upon the variously computed age of the beds in which the fossil bones occur. In France, for instance, it is known that the mammoth, whose bones are found in the strata underlying, and therefore older than, the Somme Valley peat, became extinct before the peat stratum, thirty feet thick, which contains no bones, had formed. It had grown, says M. Boucher de Perthes, at the rate of three inches in a hundred years; and if, as geologists say, the mammoth bones of Niagara Falls were deposited in their bed before six miles of the present river gorge were worn by the cataract out of the solid rock, they may be, according to Lyell, 31,000, or Desors, 380,000 years old. In Siberia, whence most of our information comes, many carcasses of these huge animals have been found preserved entire in the frozen mud. When and how did they perish? Possibly, says the geologist, all at once, overwhelmed by some sudden cataclysm, which, burying the carcasses in the mud, was immediately followed by an intense cold that has lasted ever since; possibly, again, great freshets in the northern rivers, overtaking the migrating herds, swept their carcasses from warmer regions to the shores of the Polar Sea. In Europe, the fact that the mammoth survived into the human period was proved some years ago by the discovery of human stone implements associated with mammoth bones in the river gravels of the Somme Valley, France, and in the Virgin Cave at Brixham, South Devon, England; but more interesting still, was the discovery of prehistoric carvings of the great elephant, sketches from nature made by the "cave-men," and found in their subterranean dwellings along the river Dordogne in France, illustrations of which will be given in the following pages.