Word Study
Zygobranchia
CIDE DICTIONARY
Zygobranchia, n. pl. [NL., from Gr. zygo`n a yoke + a gill.].
A division of marine gastropods in which the gills are developed on both sides of the body and the renal organs are also paired. The abalone (Haliotis ) and the keyhole limpet (Fissurella ) are examples. [1913 Webster]
For further exploring for "Zygobranchia" in Webster Dictionary Online