There is still another kind of real ivory—the fossil ivory—which is now extensively used in many countries, although it may be difficult to decide whether it was known to the ancients or to mediæval carvers. In prehistoric ages a true elephant, says professor Owen, “roamed in countless herds over the temperate and northern parts of Europe, Asia, and America.” This was the mammoth, the extinct _Elephas primigenius_. The tusks of these animals are found in great quantities in the frozen soil of Siberia, along the banks of the larger rivers. Almost the whole of the ivory turner’s work in Russia is from Siberian fossil ivory, and the story of the entire mammoth discovered about half a century ago embedded in ice is well known to every one. Although commonly called _fossil_, this ivory has not undergone the change usually understood in connection with the term fossil, for their substance is as well adapted for use as the ivory procured from living species. With regard to the tusks of elephants, African and Asiatic ivory must be distinguished. The first, “when recently cut, is of a mellow, warm, transparent tint, with scarcely any appearance of grain, in which state it is called _transparent_ or _green_ ivory; but, as the oil dries up by exposure to the air, it becomes lighter in colour. Asiatic ivory, when newly cut, appears more like the African, which has been long exposed to the air, and tends to become yellow by exposure. The African variety has usually a closer texture, works harder, and takes a better polish than the Asiatic.” It would be mere guessing to attempt to decide the original nature of ancient or mediæval ivories. Time has equally hardened and changed the colour of both kinds, whether African or Asiatic.