But there is no need to go back to the past for examples. The Mexicans of the present day use obsidian hatchets, as their fathers did before them; the Esquimaux use nephritis and jade weapons with Remington rifles. Nordenskiöld tells us that the Tchoutchis know of no weapons but those made of stone; that they show their artistic feeling in engravings on bone, very similar to those found in the caves of the south of France. In 1854, the Mqhavi, an Indian tribe of the Rio Colorado (California), possessed no metal objects; and it is the same with the dwellers on the banks of the Shingle River (Brazil), the Oyacoulets of French Guiana, and many other wandering and savage races. Père Pelitot tells us that the natives living on the banks of the Mackenzie River are still in the stone age; and Schumacker has given an interesting example of the manufacture of stone weapons by the Klamath Indians dwelling on the shores of the Pacific. It has been justly said: “The Stone age is not a fixed period in time, but one phase of the development of the human race, the duration of which varies according to the environment and the race.”30 In thus limiting our idea of the stone age, we may conclude that alike in Europe and in America,31 there has been a period when metal was entirely unknown, when stones were the sole weapons, the sole tools of man, when the cave, for which he had to dispute possession with bears and other beasts of prey, was his sole and precarious refuge, and when clumsy heaps of stones served alike as temples for the worship of his gods and sepulchral monuments in honor of his chiefs. Excavations in every department of France have yielded thousands of worked flints, and there are few more interesting studies than an examination of the mural map in the Saint Germain Museum on which are marked with scrupulous exactitude the dwelling-places of our most remote ancestors, and the megalithic monuments which are the indestructible memorials of our forefathers. In the Crimea were picked up a number of small flints cut into the shape of a crescent exactly like those found in the Indies and in Tunis, and the Anthropological Society of Moscow has introduced us to a Stone age the memory of which is preserved in the tumuli of Russia. On the shores of Lake Lagoda have been found some implements of argillaceous schist, in Carelia and in Finland tools made of slate and schist, often adorned with clumsy figures of men or of animals. The rigor of the climate did not check the development of the human race; in the most remote times Lapland, Nordland, the most northerly districts of Scandinavia, and even the bitterly cold Iceland, were peopled. The Exhibition of Paris, 1878, contained some stone weapons found on the shores of the White Sea.