_This animal, which is from two to three feet in length, is a native of the American and Asiatic seas; and is also sometimes found in the Mediterranean._ The plates or scales of the hawk's-bill turtle constitute that beautifully variegated and semi-transparent substance called _tortoise-shell_. This, after having been softened by means of boiling water, is capable of being moulded into almost any form; and is in request by opticians and other artists for many purposes both useful and ornamental. The ancient Greeks and Romans were so partial to the use of tortoise-shell that they decorated with it their doors, the pillars of their houses, and even their beds; and the great consumption of it at Rome may be imagined by the relation of Velleius Paterculus, who informs us that, when the city of Alexandria was taken by Julius Cæsar, the magazines or warehouses were so full of this article that he proposed to have it made the principal ornament of his triumph. The best tortoise-shell which is brought into this country pays an import duty of 1s. 4½d. per pound; and the quantity vended at the East India Company's sales in 1808 was no less than 13,728 pounds. The _flesh_ of the hawk's-bill turtle is not only of bad flavour, but is said to be even in some degree poisonous; persons who have partaken of it having been seized with vomiting and other unpleasant symptoms. The _eggs_, however, are esteemed peculiarly delicious. 194. _The COMMON, or GREEN TURTLE_ (Testudo mydas, Fig. 52), _is a marine species of tortoise, distinguished by its oval shape; by the fore-feet only having two claws, the scales neither folding upon each other, nor having any ridge, and the middle scales being thirteen in number._ _These, which are the largest kind of tortoise that is known, are sometimes six feet and upwards in length, and five or six hundred pounds in weight._ _They are found, and generally in great numbers, on the unfrequented sea-shores of most countries within the torrid zone._ This species of turtle is one of the most valuable gifts of Providence, to the inhabitants of tropical climates, and to mariners frequenting those climates. It affords them an abundant supply of agreeable and nutritive food. So numerous are they, in some places, that instances have occurred of forty or fifty having been obtained in the course of three hours. They are generally caught whilst asleep on the shore. The seamen go gently to the places where they are found, and successively turn them on their backs. From this position they are unable to recover their feet, and thus are perfectly secured until a sufficient number can be collected for conveyance on ship-board. Turtles are sometimes killed with spears whilst lying at the bottom of the sea in shallow water, or whilst swimming on the surface.