Shell small, solid, white, very inequilateral, wedge-shaped. Beaks low and rounded, tips small, directed backwards, situated at about the posterior tenth of the length. Anterior end greatly produced, gently descending and straight dorsally, narrowly rounded medially, and broadly convex, almost straight, along the ventral margin. Posterior end abruptly truncated, subangled at about half the height and again below at the junction with the ventral margin. Hinge of right valve with a short very oblique triangular cardinal, and a long groove running parallel to, and almost for the entire length of, the anterior dorsal slope. Left valve not seen. Anterior muscle scar elongate-ovate, posterior one circular. Pallial line interrupted by a broad fairly deep sinus. Length 5,2 mm.; height 3,7 mm.; thickness 1,2 mm. (Holotype).

Although the extreme truncation of the posterior end in this species results in a shell of very different outline from that of the genotype, the essential features of hinge and pallial sinus are closely similar.

New Zealand. Off Three Kings Islands, St. 934, 92 m.