tristoma

CIDE DICTIONARY

tristoma, n. [NL., from Gr. tri- (see Tri-) + sto`ma mouth.].

 Any one of numerous species of trematode worms belonging to Tristoma and allied genera having a large posterior sucker and two small anterior ones. They usually have broad, thin, and disklike bodies, and are parasite on the gills and skin of fishes.  [1913 Webster]