Valves dissimilar in shape, size, and sculpture. Left valve larger and more convex, thin, opaque white in the centre, transparent at the periphery smooth except for a few delicate concentric growth lines; hinge line straight, about two-thirds of the length of the valve; auricles nearly equal, latticed by radiating and concentric threads; umbo projecting, w7ith a callous crest; ventral margin rounded, produced posteriorly; hinge plate narrow, finely wrinkled; chondrophore small, projecting into the cavity of the valve. Right valve smaller, overlapped ventrally by the left, less oblique, pale yellow, opaque; umbo not projecting, auricles unequal, the anterior narrow and produced; beneath it a byssal notch, but no pectinated teeth; sculptured by concentric growth lines and superficially by numerous fine, irregular, radiating threads, connected by close-set transverse bars which include narrow hexagonal spaces; this structure is seen to peel off in places, and is, therefore, probably epidermial, and perhaps corresponds to the pustules of the Atlantic species. Left valve, length 3.2 mm, height 2.7 mm.; right valve, length 2.6 mm, height 2.5 mm. Type locality: off Port Kembla, New South Wales, 63-75 fathoms. Loc.: Beachport to King George Sound, W.A, 40-150 fathoms. S.W.A, S.A, Tas, Vict, N.S.W.
Remarks: Chlamydella obliqua Hedley, appears to be the same species; a large series from South Australia and Western Australia shows intergradation. Left valves show gradual transition from no concentric lamellae to numerous. The stippling in the right valve (attributed to obliqua) is probably the typical condition, its absence accidental. Adult specimens have the ventral margin of the right valve turned abruptly backwards at an obtuse angle following the curve of the left valve; this is absent from juveniles, and hence does not appear in Hedley's figure, but is apparent in other New South Wales specimens.