The leatherback-turtle is a rare marine turtle of the tropical seas (Sphargis coriacea), which has a leathery case instead of a shell. It is the largest of existing Chelonia, known specimens having a case four feet in length, and a live-weight of not less than 1,000 pounds. When young its case is thin, soft and flexible, but as age advances the jacket becomes stiffened by the formation within it of great numbers of little adjoining bony plates and the exterior shows strong longitudinal ridges.
   The leatherback-turtles are powerful swimmers and wander throughout oceans, feeding upon jellyfishes, crustaceans, cuttlefishes and olher animal food. Late in the summer it seeks some sandy shorf of islet, where the female buries her eggs after the manner of other sea-lurtles. These eggs are good to eat, but the flesh of the animal is not of good taste, and is said to be unwholesome.