As Cerithidea tricarinata:
Shell small, turreted, longitudinally plicate and spirally grooved. Sculpture consisting of strong, rounded, subnodulose, longitudinal ribs, 10 to 15 on the penultimate whorl, stopped on the body-whorl by a spiral sulcus on the periphery of the base ; spire-whorls and posterior half of the body-whorl with 3 or 4 spiral grooves, sometimes reduced to 2 ; base with 3 subequidistant well-marked spiral ridges, with occasionally others on the neck. Colour brown. Spire elevated, about three times the height of the aperture ; outlines faintly convex. Protoconch eroded. Whorls 9 to 10, flattened, regularly increasing ; base nearly flat, excavated round the neck. Suture impressed, sometimes margined. Aperture oblique, broadly ovate, channelled above, produced at the base into a short, oblique, and truncated canal. Interior brown, with a few lighter spiral bands. Outer lip convex, slightly thickened and expanded, sharp. Columella vertical, nearly straight, truncated at the base. Inner lip spreading over a short distance of the columella, sharply limited on the outside, extending over the parietal wall to the spiral ridge, which enters the aperture Operculum normal.
Diameter, 5 mm. ; height, 14,5 mm.
Animal unknown.
Type in the Canterbury Museum, Christchurch.
Hab.—Katikati (type) ; Ngunguru Harbour ; Whangarei; Tiri Tiri Island ; Hauraki Gulf and Auckland Harbour ; Kawhia ; Governor's Bay, Lyttelton ; Chatham Islands (Dr. Dendy).