Shell large for genus, equivalve, inequilateral, ovate-triangular, compressed anteriorly, sculptured with radial ribs and faint concentrics. Antero-dorsal margin almost straight, anterior and ventral margins broadly rounded, posterior margin somewhat flattened, curving broadly over the postero-dorsal margin. There is a small flat-topped prodissoconch, obliquely inclined. A line running rather sinuously from the beaks to the junction of the posterior and ventral margins divides the outer surface of the valves into a main disc and a posterior area, the posterior area being set at a slight angle from the central disc. Sculpture consisting of widely spaced, rather sinuous, narrow, raised radials which become obsolete towards the beaks, 10 on the main disc, 5 on the posterior area. These are crossed by a few major, irregular, concentric growth lines and very fine, regular closely spaced concentrics. Lunular area moderate, deeply excavated. Hinge plate narrow. Posterior and antero-ventral areas of valve margin crenulated. Interior of valve marked by radials and growth lines. Length ( Anterior-posterior) 4,36 mm.; height (Dorsal-ventral) 6,0mm.; inflation ( single valve ) 1,18 mm.
This species is closest to H. meleagrina Bernard, from which it differs at sight in the much stronger, more numerous radials, and in the considerably higher shell.