This section is from the book "A Manual Of British Vertebrate Animals", by Leonard Jenyns. Also available from Amazon: A Manual Of British Vertebrate Animals.
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.
Feet, especially the anterior pair, elongated; compressed, Jin-shaped.
Shell covered with a continuous coriaceous skin: claws obsolete.
Shell covered with horny plates: feet with claws.
 
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