Common river terrapin - Carapace moderately depressed, with a vertebral keel in the young, which keel disappears in the adult; nuchal broader than long; first vertebral as broad in front as behind, or a little broader; vertebrals 2 to 4 subequal, much broader than long in the young, nearly as long as broad and as broad as the costals in the adult, the postero-lateral border of the third vertebral strongly concave.