Shell of medium size, conical, white, and translucent. Protoconch of medium size, of 2J short, smooth, glassy whorls, the nucleus small, the next 2 whorls nearly equal. Mature whorls 6, nearly flat, the sutures channelled, body whorl with a gentle curve to the base. Sculpture of relatively few and distant axial ribs and spirals, the axials the strongest, rising at their intersections into medium-sized gemmules. The axials number 14 to the whorl; there are 5 spirals on the body whorl and 3 on each of the earlier whorls. The basal fold is strong, and indented by the axial ribs which cross the intervening channel. Aperture arcuate, oblique and thrust well forward anteriorly, outer margin slightly thickened internally and with a very wide, external varix, which is even wider at its anterior end, and crossed by the continuation of the spiral ribs. Columella with a deep sinus which is laterally reflected. Length of holotype 4-2 mm; other specimens vary from shghtly under 4 to about 4,5 mm.
Locality.—Darwin (J. Laseron), holotype and 8 paratypes.
Remarks.—This resembles P. allanae in general form and appearance, but differs by having a protoconch about twice the size, by the additional whorl, and by the fewer axials and spirals.