Opisthostoma coronatum van Benthem Jutting, 1952  

van Benthem Jutting (1952)'s description

"Shell short-cylindrical, higher than O. trapezium. White, somewhat shining and transparent. Last whorl equally broad as the penultimate one or a little narrower. First whorl smooth, subsequent ones ornamented with fine, white, distantly placed, vertical ribs, standing out wing-like away from shell. In fresh specimens, the ribs are msot developed on the periphery of the two large last whorls, giving these a crown-like apperance, Between the ribs there is a fine spiral striation. whorls 4-4 1/2, the two first small and little projecting, the comparatively large and convex, separated by a deep suture. in the type specimen there are 15 ribs on the last whorl, counting from the aperture to the spot where the deviating distal part of the last whorl touches the penultimate one. On the penultimate whorl the holotype has 22 ribs. Distal part of the last whorl directed upward and obliquely back ward, adnate. umbilicus open, rather wide. Aperture rounded, obliquely facing the sky. Peristome continuous, circular or round-triangular. With double or multiple margin. Operculum unknown."