1815. Lehrb. Nat., pt. 3, No. 1, p. 255.
Type (by tautonymy) Turbo clatthrus L. (= communis Lamk. = spurius Oken).
Recent, Europe.

This is the first record of Clathrus from New Zealand. It is easily distinguished from Epitonium by the absence of a basal disc.

Clathrus mackayi n. sp. Plate 27, fig. 33.

Shell very large, solid, imperforate, no basal disc. Holotype of 4 ½ whorls, the body with 20 and earlier whorls with 19, 17, and 16 ribs. These ribs differ considerably in thickness, and each whorl bears two, some three, considerably thicker, variciform ribs, irregularly placed. (Four fragmentary paratypes show much greater extremes in rib-thickness, but the arrangement and number of thick ones is quite irregular.) Ribs recurved, with finely laminate edges, nearly all curving back from suture against corresponding rib on previous whorl, and drawn up to a pointed crest to form broad subsutural channel. Interspaces with very fine, somewhat irregular, vertical striae, crossed by extremely fine spiral grooves super-imposed on faint indications of spiral threads which are irregularly, developed but of the order of 20 per whorl. Aperture strongly effuse below, producing a broad, strongly marked, raised fasciole.

Height (incomplete), 58 mm.; diameter (incomplete), 32 mm.

Localities: G.S. 626 (type), G.S. 1211, Isis bed, Campbell's Beach, Allday Bay, North Otago (Waitakian Stage, Upper Oligocene).

This species is named in honour of its collector, New Zealand's greatest field geologist, Alexander McKay.