An order of Reptilia, having toothless jaws fashioned like the beak of a bird, two pairs of limbs fitted for walking or swimming, and the body incased in a bony box or leathery shell, consisting of a carapace and a plastron, to the formation of which the ribs and dorsal vertebræ are specially modified; the turtles and tortoises.In a restricted sense, one of three suborders of Chelonia, contrasted with Athecæ and Trionychoidea, and containing the whole of the order excepting the Sphargididæ and the Trionychidæ.