Shell low, conical, reticulated, white or translucent, variegated with gray or olive green lines or dots mostly radiately disposed; form variable with station, but usually in the young and in more normal adults both slopes of the cone are a little concave near the apex. The anterior slope slightly convex; the posterior slope straight or a little concave, and usually a little longer than the other, though these characters vary with station. Base is rounded oval, symmetrical and equal at both ends, with a thin simple margin. Sculpture of slightly irregular sudden enlargements of the shell, giving the effect of very narrow steps, over which some twenty moderately strong and as many more faint flattened radii seem to flow. In other specimens these steplike edges are produced into low laminae, and the ribs are also stronger and at the intersections nodulous, or even a little scaly. Apex erect, truncate by the pore, which is circular, simple, and within margined by a narrow horseshoe shaped callus. Exterior dull or unpolished, interior shining, with the color rays and ribs visible through the thin shell. Two specimens measure, alt. 4.0 and 6.0, Length 10.6 and 9.5, lat. 6.6 and 6.5 mm., respectively.

Shell very thin and small, about 9 mm. in length, conical and elevated. Slopes concave near the apex, becoming later straight or slightly convex. Summit anterior to shell center, a little curved forward and pierced by the orifice. The latter is about I mm. long and circular in shape. Sculpture consists of 17 or 18 principal ribs between which are intercalated 3 riblets, the central one being stronger than the other two. The shell is crossed by close-set concentric threads which form small nodules or scales where they intercept both ribs and riblets. Shell dull, may be unicolored either white or olive-green: or may be white with the green color forming an interrupted band at the margin. Some of the principal anterior ribs arc colored orange. The shell is translucent, the color of the exterior being visible on the inside : the stronger sculpt lire of the outside showing through in the form of shallow grooves, while the riblets are seen as line lines. Interior surface glossy. Internal callus of the orifice truncated-oval, the same color as the rest of the inside.

This is a well marked species, not particularly close in its relationships to other Western Atlantic Diodora. It is rare and only a few specimens have been obtained in fairly deep water (100 to 805 fathoms).

Range. Southern Florida and south through the Greater and Lesser Antilles, probably to Trinidad.

Records: FLORIDA : off Palm Beach (100 fathoms): off Lower Keys. CUBA: off Bahia Honda. Blake, station 21 (287 fathoms): off Habana, Blake, station 24-7 (170 fathoms) (both MCZ). LESSER ANTILLES: of Grenada, Blake, station 247 (170 fathoms)