potamian

from The Collaborative International Dictionary of English v.0.48

Potamian \Po*ta"mi*an\, n. [Gr. ? river.] (Zool.)
   A river tortoise; one of a group of tortoises ({Potamites},
   or {Trionychoidea}) having a soft shell, webbed feet, and a
   sharp beak. See {Trionyx}.
   [1913 Webster]