Source : Webster's Revised Unabridged Dictionary (1913)

Tomopteris \To*mop"te*ris\, n. [NL., fr. Gr. ? a cut + ? wing
   (but taken to mean, fin).] (Zo["o]l.)
   A genus of transparent marine annelids which swim actively at
   the surface of the sea. They have deeply divided or forked
   finlike organs (parapodia). This genus is the type of the
   order, or suborder, Gymnocopa.