in natural history, &c. A hard, solid and firm substance, of a white colour, and capable of a very good polish. It is the tusk of the elephant, (See Elephas,) and is hollow from the base to a certain height, the cavity being filled up with a compact medullary substance, seeming to have a great number of glands in it. It is observed, that the Ceylon ivory, and that of the island of Achem, do not become yellow in the wearing, as all other ivory does; for this reason the teeth of these places bear a larger price than those of the coast of Guinea.