Pleurosigma

1 definition found

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

  Pleurosigma \Pleu`ro*sig"ma\, n. [NL. See {Pleuro-}, and
     {Sigma}.] (Bot.)
     A genus of diatoms of elongated elliptical shape, but having
     the sides slightly curved in the form of a letter S.
     {Pleurosigma angulatum} has very fine striations, and is a
     favorite object for testing the high powers of microscopes.


     [1913 Webster]