Ovately heart-shaped, subequilateral; sculpture of very fine, numerous, radial striae; umbos rather oblique, tipped with white; shell whitish-brown,' with short, radial, broken red streaks, faint or obsolete; periostracum brown. South Australian specimens, length 45 mm., height 41 mm., section 30 mm. Type locality: King George Sound, Western Australia. Some show few valid radials with a well crenulated margin; others have very numerous and very fine radials, which are radially finely incised; some of those with valid radials are longer than high, others are nearly equal while some are oblique; some have the hinge plate deep with solid teeth, others have the hinge plate thin with stout teeth. The ribs have from one to eight radial incisions in each, and these secondary riblets may be equal, subequal, or very unequal.

Shell length to 45 mm. Sculpture: fine radial riblets, in bundles of 6-10, which widen at the ventral margins and arc crossed by fine concentric lirae. Colour: white, ornamented with brown umbonally and on ribs, umbones often purple tinged. Periostracum: brown, consisting of erect spathulale setae set in the interstices of the riblets. Habitat: littoral sand. Distribution: south Western Australia,South Australia, Victoria, New South Wales to south Queensland. Note: Western Australian shells lend to be elongate and compressed posteriorly, as does the type of penelevis Cotton from South Australia. Victorian and New South Wales shells are almost equilateral and inflated.

South(WesT) Australia. Common on ocean beaches, Beachport to Rottnest, W.A., and dredged to 28 fathoms. S.W.A., S.A., Tas., Vict.