Analthea hexagona, n. sp.

Hipponyx cornucopiæ, Hutton, Cat. Mar. Moll. N.Z., 1873, p. 32 (not of Lamarck). Hipponyx australis, Hutton, Journ. de Conch., vol. xxvi, 1878, p. 30; Man. N.Z. Moll., 1880, p. 88; Proc. Linn. Soc. N.S.W., vol. ix, 1884, p. 939 (not of Lamarck).

This species differs from H. australis, Lamk., in the more or less distinct hexagonal, rarely pentagonal, outline of the aperture. The interior has a light-green central area, which is cinereous or brown in australis, and the margin is light-purple. The radiate riblets, similar to those of australis, are mostly visible only on young specimens; adult shells are strongly corroded, but incremental lines are sometimes visible. The greatest diameter of the aperture of my largest specimen is 22 mm.; the altitude is extremely variable.

Hab.—A rock in Tauranga Harbour, and Chatham Islands. Type in my collection.