TORTOISE, in zoology, a name for merly taken to include all the Chelonians, but now, unless qualified by an adjective, confined to the individuals of the family Testudinielte. Tortoises, in the wider sense, are sluggish reptiles, long-lived, and extremely tenacious of life under ad verse surroundings, and have survived from remote antiquity, while higher ani mal types, formerly contemporaneous with them, have become extinct, and have been succeeded by very different forms. They have an osseous exoskeleton, which is combined with the endoskeleton to form a kind of bony case or box in which the body of the animal is inclosed, and which is covered by a coriaceous skin, or, more usually, by horny epidermic plates. The exoskeleton consists essen tially of two pieces: a dorsal piece, gen erally convex (the carapace), and a ven tral piece, usually flat or concave (the plastron), by some regarded as an ab normally developed sternum, while others consider the bones of which it is com posed as integumentary ossifications. All the bones of the skull, except the lower jaw and the hyoid bone, are anchylosed. There are no teeth, and the jaws are cased in horn, so as to form a kind of beak. Tongue, thick and fleshy; heart three-chambered, ventricular septum im perfect. The lungs are voluminous, and respiration is effected by swallowing air. All will pass prolonged periods without food, and will live and move for months after the removal of the entire brain.
The most familiar example of true or land tortoises is the dry land terrapin of the Southern States (see TERRAPIN). It is found in the countries bordering on the Mediterranean, and is said to range as far N. as Switzerland and the S. of France. It is about 12 inches long; the scales are granulated in the center, streaked on the margins, and spotted or marbled with black and yellow. A sue eulent vegetable diet is common to the whole family, and all but the tropical species hibernate. The Greek tortoise is an article of food in the S. of Europe. and the flesh of all the species appears to be good, while their eggs are regarded as delicacies. But the most interesting forms are gigantic tortoises formerly found in great numbers in the Mascarene and Galapagos Islands. Five species of this group are known, and two of them, Testudo elephantine, the gigantic land tortoise of Aldabra, and T. abingdonii, the Abingdon Island tortoise, grow to enormous size.
In military terms, a method of defense, used by the ancients, formed by the troops arranging themselves in close or der and placing their bucklers over their heads, making a cover resembling a tor toise shell; a TESTUDO (q. v.).