As Calyptraea maculata:
Shell rounded, convex, rather thin, with a lateral summit. Sculpture consisting of well-marked, flattish, and rugose growth-lines. Colour greenish-yellow to light brown ; interior white, a large spot of purple or purplish-brown near the centre. Epidermis thick, horny, lamellate in the direction of the growth-periods, and produced into rays and ragged processes. Spire small, conic, salient, lateral, and posterior. Protoconch small, of 1,5 convex whorls, the first smooth, the following half with a few microscopic growth-hues and spiral striae. Whorls 3 to 4, convex, the last very large. Suture superficial. Aperture roundly oval, entire, polished. Basal plate white, with very fine growth-lines, the free margin thin, sharp, lightly concave. Columella lateral, dilated at its insertion, and furnished with a triangular lamina, which partly hides the rather wide false umbilicus.
Diameter—Maj., 33 mm.; min., 28 mm.: height, 10 mm. (large specimen).
Dentition.—Hutton, T.N.Z.I., xiv, 163, pl. 7, f. A. Type in the Mus. Hist. Nat., Paris.
Hab.—Throughout New Zealand and at the Chatham Islands. Brought to England by Captain Cook.
Remarks.—The species was first figured by Quoy and Gaimard, and their name therefore stands in preference to the earlier name of Lesson. Young shells have mostly the basal plate white, and the whole roof purplish-brown. The height of the shell is very variable.
Fossil.—Miocene and Pliocene.