Subovate, almost equilateral, very convex, solid; sculptured with about 20 radiating nodulose ribs, the interspaces somewhat narrower than the ribs and crossed by distant thickish lirae; umbos prominent, incurved; hinge margin, on each of the sunken broadly triangular ligament pit, transversely minutely denticulated; outer margins bluntly dentate; interior regularly grooved, the furrows corresponding with the external costae. Holotype: length 6 mm, height 7 mm, section 4.5 mm.—Backstairs Passage, 33 fathoms. (Eeg. No. D.13054, S.A. Mus.) Loc: Beachport to Bunbuxy, beach and dredged to 300 fathoms. S.W.A, S.A.
Remarks: Specimens may reach to twice this size. The holotype figured by Tate is a very poor worn specimen.