having two pairs of gills: said of nautiloid cephalopods
See tetrabranchiate in American Heritage Dictionary 4
(tĕtˌrə-brăngˈkē-ĭt, -ātˌ)
adjective
Of, relating to, or being a cephalopod of the order Tetrabranchiata, characterized by two pairs of gills and including the chambered nautilus and many fossil species.