Trapezoidal, solid, inflated, subequilateral; rounded anteriorly and posteriorly, the anterior byssal gape scarcely discernible; umbos prominent; sculpture, on right valve, of fine radial riblets crossed by almost as strong concentric ribs giving a fenestrated appearance, but on left valve, which is larger, the concentrics are slightly more valid than the radials; ligamental area narrow; hinge line straight, narrow, and vertically striated for the median quarter, broadened at either end; four almost horizontal teeth posteriorly, and four oblique teeth anteriorly, the teeth striate; margin crenulate within. Length 4 mm., height 3.8 mm., section 3 mm. Type locality: 100 fathoms, 40 miles north of Cape Wiles, South Australia.
Distribution: Cape Jaffa to 80 miles west of Eucla, 90-300 fathoms. S.W.A.,
S.A.