Trachelobranchiate :: Trachelobranchiate (a.) Having the gills situated upon the neck; -- said of certain mollusks.
Tracheobranchia :: Tracheobranchia (n.) One of the gill-like breathing organs of certain aquatic insect larvae. They contain tracheal tubes somewhat similar to those of other insects.
Zygobranchia :: Zygobranchia (n. pl.) 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.
Zygobranchiate :: Zygobranchiate (a.) Of or pertaining to the Zygobranchia.