Solid, narrowly oblong; umbos directed forwards, at about the anterior third, approximate, inflated; anterior end short, round; posterior end sloping convex; post-dorsal angle a very obtuse curve, post-ventral angle a much smaller curve; ventral border slightly concave; margin simple, smooth; a groove, formed by a stout, projecting internal lamina, runs from the umbo backwards within the post-dorsal border; obsolete accremental striae, and, especially towards the front, distant, rounded, low, concentric ridges; periostracum dark. Holotype: length 10.9 mm, height 4.1 mm.— off Beachport, 200 fathoms; one right valve. (Reg. No. D.13042, S.A. Mus.)
Loc.: S.A.
Remarks: The narrowly produced shape distinguish the species.