the world > animals > invertebrates > subkingdom Metazoa > grade Triploblastica or Coelomata > class Gastropoda > [noun] > superorder Branchifera > order Opisthobranchiata > member of (3)
Any marine gasteropod of the order Opisthobranchiata (see quot. 1879).
A gastropod mollusc of the subclass Opisthobranchia, comprising marine forms (mostly sea slugs) having the gills behind the heart. Cf. prosobranch, n.
= opisthobranch, n. rare.