[Read before Wellington Branch, 8th July, 1943; received by the Editor, 8th July, 1943; issued separately, December, 1943]

Most of the mollusca described or noted below were collected during the geological survey of Moeraki Subdivision, North Otago, by D. A. Brown, now of the Fleet Air Arm. Some have been in the Geological Survey collection for many years. Two necessary changes in nomenclature are included. The types of all specimens described below are in the Geological Survey collection.

The writer is indebted to Mr. N. de B. Hornibrook (now of N.Z. Expeditionary Force) for the very fine photographs of Plate 27.

Limopsis hampdenensis (Marshall).

1919. Sarepta tenuis Marshall, Trans. N.Z. Inst., vol. 51, p. 233, pl. 15, fig. 9.

1919. Limopsis hampdenensis Marshall, Trans. N.Z. Inst., vol. 51, p. 232, pl. 15, figs. 12, 13.

H. J. Finlay (1926, pp. 446, 448) stated that tenuis and hampdenensis, far from differing generically, were probably not even specifically distinct, and belonged to Limopsis. He also implied that as tenuis preceded hampdenensis on the page, it would take precedence in nomenclature.

Through the kindness of Mr. J. Grant, Director of Wanganui Museum, the writer has been able to examine both types, and can confirm the specific identity.

The single type of L. tenuis has been broken and is imperfect, but the larger of Dr. Marshall's figured types (fig. 13) of hampdenensis is well preserved. Consequently, since Dr. Finlay's statement was tentative, it seems best to select hampdenensis rather than tenuis as the specific name for these shells. Page-precedence depends on “other things being equal” (Article 28, recom. C.), and in this case “other things” are not equal.

Chlamys venosa (Hutton). Plate 25, figs 1, 2.

1873. Pecten venosum, Hutt., Cat. Tert. Moll., p. 30.

1928. Chlamys venosa (Hutt.), Marw., Trans. N.Z. Inst., vol. 58, p. 454.

This shell has not previously been figured. It was recorded by Park (1918, pp. 72 and 74) from G.S. 966, Tuffs in Oamaru Stone, Teschmakers, and G.S. 963, Tuffs in or below Oamaru Stone, Trig M., Alma. It has now been collected from Geol. Surv. Locality 2141, green tuffs, Bridge Point, 3 miles south of Kakanui. All of these localities belong to the Kaiatan Stage (Oligocene).

Janupecten subteres n. sp. Plate 25, figs 3, 7.

Shell large, subcircular, thin, flat. Sculpture between that of Janupecten and Lentipecten. Right valve with very faint, flat radial ribs on ears and on posterior and anterior flanks, dorsal and distal margins of ears strongly serrate. Left valve smooth. Surface of both valves, when well preserved with minute, regular, concentric ridges, about 7 per mm.

Height, 93 mm.; length, 92 mm.; inflation (1 valve), 10 mm.

Localities: G.S. 2118, Greensand, Green Valley, Waihemo Surv. Dist. (type); G.S. 1314, G.S. 1821, Greensand, Wharekuri; G.S. 2108. Greensand, Te Raumaku School, Otorohanga district.

Age: Duntroonian (Upper Oligocene).

This shell is so like a Lentipecten that it is questionable whether it is really a Janupecten. The Lentipecten stock, however, extends without sculpture from the Bortonian up to the Urenuian. If subteres is an offshoot of this line, the resemblance of its sculpture to that of Janupecten (and Serripecten) becomes rather a remarkable coincidence. It seems better regarded as a further development of the Janupecten uttleyi-polemicus line that has lost almost all its radials. Convergence of two lineages through obsolescence of sculpture is more likely than through the development of a peculiar sculpture.

The smooth left valve is very like that of L. hochstetteri (Zitt.), but the anterior and posterior margins of the ears are straighter.