Shell large, elevated, oval, rather thin, apex much incurved and overhanging at five-sixths of the length. The sides are arched so that the shell only touches a plane surface by its extremities. Colour, exterior gray, interior white. Fissure deeply slit. Sculpture : about sixty sharp elevated radiate riblets which frill the interior margin and are parted by narrow deep interstices in which arise fine secondary riblets. A concentric series of numerous dense imbricating scales traverse both ribs and furrows. Slit fasciole elevated, two thin erect walls include fine close curved transverse scales. The interior of the fasciole is marked by a heavy streak of callus. Length 24 mm. ; breadth 18 mm. ; height 9 mm.
A single specimen from two hundred and fifty fathoms.
This is the largest Australian species, and only two or three species in the world exceed it in size.

Australia. New South Wales. Eastern Victoria and Tasmania.