Protoconch small to large, of 1,5-4 smooth, convex whorls. Teleo-conch large, spire about equal in height to the aperture plus canal, sculpture of primary to quarternary spiral cords or riblets, axials often form prominent knobs on shoulder of whorls. Aperture ovate, with moderately long anterior canal which can be strongly twisted to almost straight. Outer lip not much thickened, with internal lirations; inner lip smooth, with sharply delineated callous deposit. Columella long, somewhat sinuous, tapering towards the end; siphonal fasciole weak to prominent.Operculum: Leaf shaped, with a terminal nucleus. A shallow median furrow visible externally. Muscle scar large, occupying most of the central area. A raised rim present on the inside of the outer edge (i e that edge opposite the outer lip when the animal is retracted). Radula: Each transverse row with a large central tricuspid tooth, the cusps short and almost equal in size and the base narrow. Two lateral teeth usually with 3 subequal cusps (4 in P. benthicolus Dell (Dell, 1956: 97, text fig. B 1)). Powell (1929) has figured the radulae of some New Zealand species and Dell (1956) has discussed radular variation in some New Zealand species.