polybranchiata

from The Century Dictionary.

• A suborder or superfamily of nudibranchiate gastropods, characterized by the development, of dorsal gill-like appendages variously distributed, but never disposed in a rosette round the anus.
• In De Blainville's classification (1825), one of five orders of his second section of Paracephalophora monoica symmetrica, composed of the two families Tetracerata and Dicerata.