Shell large, exceeding 33 mm. in length and 20 mm. in height, conical, its height being two-thirds of the shell length, colour ashy grey, probably due to the long stay in the mud; aperture broadly ovate; anterior slope straight or feebly convex, posterior slope somewhat concave below the apex, extending downward in a straight line to the margin; apical whorls small, smooth, coiled down a little below the summit and situated at about the posterior third of the shell length ; anal fasciole narrow, formed by very closely set transverse lamellae ; fissure also narrow, one-fourth of the length of the anterior slope; sculpture compact, consists of numerous closely set radial ribs; at the apical area there are about 40 primary ribs, but below numerous finer ribs are intercalated between them, thus the total number of ribs attaining more than 100; also numerous concentric lamellae intersect the radiating ribs, giving scaly aspects on the point of intersection of ribs; margin crenulated by the terminations of the ribs. Height 19.3 mm., length of aperture 32.9 mm., breadth of aperture 27.0 mm.

Emarginula hawaiiensis DALL is the nearest ally of this new species in the general appearances, but may be easily distinguished from this in having the apex situated more posteriorly.

Japan. Type locality: Tosa Bay, Shikoku (about 100 fathoms in depth).