Body enclosed in a double shield; the head, neck, limbs, and tail, alone free; the upper shield formed by the union of the ribs and dorsal vertebrae, the lower one by the pieces of the sternum: jaws horny, without teeth: four feet.

I. Cheloniadje

Feet, especially the anterior pair, elongated; compressed, Jin-shaped.

1. Sphargis

Shell covered with a continuous coriaceous skin: claws obsolete.

2. Chelonia

Shell covered with horny plates: feet with claws.