Opisthobranchia
Pronunciation : O*pis`tho*bran"chi*a, O*pis`tho*bran`chi*a"ta
Part of Speech : n.
Etymology : [NL., from Gr. (Zo?l.)
Definition : Defn: A division of gastropod Mollusca, in which the breathing organs are usually situated behind the heart. It includes the tectibranchs and nudibranchs.
pl.
Source : Webster's Unabridged Dictionary, 1913