TORTOISE-SHELL, the large scales of the carapace, or shield, of a species of sea turtle, the chelonia imbricata and testudo mbricata of several authors—caretta imbricate& of Dr. Gray. It is found in the Indian ocean, Amboyna, New Guinea, Seychelles, Havana, and the Red sea. Tortoise-shell is so called because formerly the order of animals to which it belongs was little known, and all were confounded under the general name of tortoises. A remarkable peculiarity in this species is the arrangement of the thirteen plates forming the carapace, which, instead of being joined together by their edges, so as to make apparently one piece, are thinned off at their edges, and overlap each other like the tiles of a roof. They vary in size according to the part of the shield they occupy. The larger are sometimes from a foot to 18 in. long, by 0 in. broad; the thick ness rarely exceeds the eighth of an inch. The beautiful mottled color and semi-trans
parent characters of this material are well known. A remarkable quality is possessed by tortoise-shell, which very greatly increases its usefulness for the ornamental purposes to which it is generally applied—that is, its property of being easily softened by a heat equal to boiling water, and of retaining any form when cold which has been given to it when heated. Pieces cab also be welded together by the pressure of hot irons properly applied. In Britain, the chief use of tortoise-shell is making combs for the hair; but it is also used for inlaying small pieces of ornamental furniture and various other fancy objects. In India, China, and Japan its use is well understood, and some very beauti ful articles are made of it, exhibiting _rrreat skill and taste. Great Britain alone consumes about 1•11,- tons, of the value of