Shell. A slender, semitransparent conical shell usually with a straight spire lacking the curvature of sinuosa but occasionally a little crooked because of the angle between protoconch and adult shell which makes the spire cyrtoconoid on one side; apical angle about 20°. The whorls arc nearly always extremely flat-sided, less so in the protoconch. The periphery of the body whorl is well rounded. The sutures are linear, very slight, in fresh shells clearly adapical of the false ones, which lie sometimes more oblique to the shell axis. The space between the two is usually whiter or more opaque than the rest of the shell. In old shells which have become opaque only the true sutures arc visible. Ornament is absent except for occasional irregular and indistinct growth lines. Varices occur as nearly straight, opisthocline lines, though sometimes a little flexuous.
The protoconch has 2—3 smooth whorls, usually coiling on an axis different from that of the adult shell, the change being abrupt and often accompanied by an equally sudden increase in breadth. Its breadth and height are about equal at 300—350 µm.
Aperture. Much as in P. sinuosa, but distinctly broader, the outer lip commonly extending beyond the profile of the spire. The basal canal is broad, the out-turned columellar lip rather narrow; the columellar lip tends to curve smoothly into the rest of the inner lip. The outer lip often shows an almost straight and gently opisthocline course; a shallow anal sinus may occur, but it is usually less marked than in sinuosa.
Colour. Colourless or slightly opalescent white when fresh, becoming opaque white when empty and old.
Size, Up to 6X2 mm. Last whorl = 43—49% of total shell height; aperture - 37—33% of total shell height, its breadth half or a little more of its height. Animal, colour. As in P. sinuosa.

Geographical distribution. This species seems to occur from the Mediterranean northwards to Scandinavia, though locally recorded only from the northern parts of the North Sea. Habitat. On sandy, muddy or gravelly bottoms, 20—120 m deep. It is rather scarce. Food. Presumably these animals attack echinoderms like their relatives, but which is not known.