tristoma

Tris"to*ma, n. Etym: [NL., from Gr. Tri-) + (Zoöl.) Defn: 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.

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