Planorbis

1 definition found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Planorbis \Pla*nor"bis\, n. [NL., fr. L. planus flat + orbis a
     circle.] (Zool.)
     Any fresh-water air-breathing mollusk belonging to
     {Planorbis} and other allied genera, having shells of a
     discoidal form.
     [1913 Webster]