The Collaborative International Dictionary of English v.0.48:

Isopleura \I`so*pleu"ra\, n. pl. [NL. See Iso-, and Pleura.]
   (Zool.)
   A subclass of Gastropoda, in which the body is symmetrical,
   the right and left sides being equal.
   [1913 Webster]

   Note: The intestine terminates at the posterior end of the
         body, and the gills and circulatory and reproductive
         organs are paired. It includes the chitons
         (Polyplacophora), together with Neomenia and
         Ch[ae]toderma, which are wormlike forms without a
         shell.
         [1913 Webster]