anterior and posterior angle. Anterior end short, not quite one-fifth of the total length, convex, the dorsal margin descending, concave; posterior end very distinctly truncated, the dorsal margin convex; basal margin broadly convex, with an angle behind the middle and on meeting the posterior truncation. Lunule narrow and long. Escutcheon depressed, long and narrow. Sculpture consisting of distant (about 10 on adult shells), thin, erect, inequidistant concentric laminae, sharply raised posteriorly and at the intersection of the submedian and posterior ridge; interspaces with fine growth-lines and traces of fine radiate striae. Margins finely crenulate. Left valve with a subvertical, long and narrow cardinal; the median tooth stout, triangular, bifid; the posterior cardinal nearly horizontal, long and thin.