\Zyg`o*bran"chi*a\, n. pl. [NL., from Gr. ? a yoke
+ ? a gill.] (Zo["o]l.)
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.