Shell minute, globose, equivalve, almost equilateral, semitransparent, thin and fragile. Surface smooth and glossy with rather close and slightly irregularly spaced almost obsolete concentric growth lines. Prodissoconch large with a projecting rounded rim, produced anteriorly and posteriorly into swollen upturned processes. Anterior and posterior dorsal slopes steep, gently arcuate, subangled below on meeting the broadly convex ventral margin. The anterior end is slightly more produced than the posterior, resulting in the subangle being slightly higher in front. In the right valve there is first a thickening of the valve edge towards the hinge-plate forming an elongated pseudolateral, confluent at the proximal end and elsewhere parallel with an elongated strong anterior cardinal; then the central spoon-shaped resilium pit, followed by two posterior cardinals. The upper posterior cardinal originates high up on the valve, margin, spreads in a curve along hinge line and then bends sharply downwards. The lower posterior cardinal borders the lower edge of hinge-plate and is everywhere separated from the upper cardinal. In the left valve there is a rather short anterior lateral situated high up towards hinge line, near and parallel to the anterior edge of valve, with a slight groove between it and valve edge for the accommodation of the thickened edge of the opposite valve. Parallel to this is a large elongated anterior cardinal separated by a moderately wide and deep cavity for the reception of a similar cardinal in the right valve; then the resilium pit, followed by an elongated posterior cardinal prominently hooked at the proximal end and not reaching to the top of hinge line. There are two subequal adductorscars, one on each side near edge of valve, at about half height of shell. Colour white.
Length, 0.8 mm.; height, 0.8 mm.; thickness, 0.4 mm. (two valves).
Holotype and figured paratypes presented to Auckland Museum.
Habitat, off Wanganui in 10-12 fathoms, N.Z. (dredged by Mr. W. La Roche, 1927) ; Rangaunu Bay in 12 fathoms (dredged by Mr. W. La Roche).