External features: body gelatinous and bellshaped. Fins medium to large, with distinct lobe near the anterior fin insertion. Thick primary web. Intermediate web absent. Each arm bears a single longitudinal row of suckers alternating with paired, medium-sized cirri. Internal features: optic lobe spherical, optic nerves pass though white body as a single boundle of fibres. Shell U-shaped with other edges of lateral walls parallel, not tapered to single fine points. The genus comprises 14 species.
COLLINS M.A (2003) Zool. J. Linn. Soc. 139: 93-127.