Zool. [mod. L. triōnyx, f. Gr. τρι-, TRI- + ὄνυξ nail; cf. Gr. τριώνυχ-ος having three nails.] Name of a genus of chelonian reptiles, so called because only three of the five toes have nails. There are several species, including T. triunguis, sinensis, ferox, the Nilotic, Chinese, and American Trionyx.
1835. Kirby, Hab. & Inst. Anim., II. xxii. 433. The Trionyx, also, a kind of tortoise, devours them [the young crocodiles] as soon as hatched.
1878. Bell, Gegenbaur’s Comp. Anat., 427. These are wanting in Trionyx.
1896. List Anim. Zool. Soc., 570. Trionyx muticus, Unarmed Trionyx; Hab. North America.
