Trionyx
Pronunciation : Tri*on"yx
Part of Speech : n.
Etymology : [NL., fr. Gr. Tri-) + (Zo?l.)
Definition : Defn: A genus of fresh-water or river turtles which have the shell imperfectly developed and covered with a soft leathery skin. They are noted for their agility and rapacity. Called also soft tortoise, soft-shell tortoise, and mud turtle.
Note: The common American species (Trionyx, or Aspidonectus, ferox) becomes over a foot in length and is very voracious. Similar species are found in Asia and Africa.
Source : Webster's Unabridged Dictionary, 1913