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Tuatara: Volume 29, Issues 1 and 2, August 1987

Note: Two Gastropod “Curios” from Stewart Island

Note: Two Gastropod “Curios” from Stewart Island

However long one's beachcombing life, there is always the chance of picking up on some familiar stamping ground, something one has never seen before.

In 1982, within a day or two of Christmas, I was hurrying along from Leasks Bay to Oban (Half Moon Bay to locals), and dropped down to the beach below the slipway. The tidemark is always interesting there, as shells from cleaned cod can wash ashore. But what caught my eye was a frail, translucent, partly transparent shell shaped rather like the bush snail Rhytida australis which I used to collect for A.C. O'Connor. This one was colourless with a faint whitish sheen. Part of the outer margin was broken off and hanging by a particle. It is almost impossible to convey the fragility of this clear, delicate film (so to speak) of shelly substance in lines not too fine to be reproduced in print. Some fine gold-coloured specks of mica sand still cling to the shining, very faintly iridescent interior. I think the shell has taken on a pearly lustre since I picked it up — it was like the frailest glass, as I recall it lying on the beach, ready to blow away. Lamellaria cerebroides Hutton, 1883 (Plate 31 in A.W.B. Powell's New Zealand Mollusca) is recorded from Stewart Island (Glory Harbour), and matches my specimen in size (23-27 mm). The animal is much larger: 50-60 mm. long, a wrinked, reddish-brown colour marbled with yellowish-grey. Powell says (p. 150) that L. cerebroides is rare in the north, but distributed throughout New Zealand waters down to the Auckland Islands. “Off Oamaru, 30-40 fathoms” is one locality, Dunedin being the type one. Not a particularly uncommon sea slug; but it was interesting to come upon its far from durable shell. (Fig. 1)

The other specimen (Fig. 2) looks like a fragment of an outsize operculum from a giant Turbo smaragdus (cat's-eye) shell. My father, R.H. Traill, cannot recall where he picked it up, but thinks it was one of those sandy places with signs of long occupancy by the Maori: Native Island, the Old Neck or West Ruggedy Beach, for instance, or perhaps Bravo Island. It is solid, not crumbly, and the structure of successive whorls shows up in the fractured area. The central portion is about the size of a normal full-grown T. smaragdus operculum. Whether brought by Archaic Polynesians from some distant Pacific beach, or dropped from a sealer's or whaler's pocket, one can only speculate. Does anyone know of a foreign page 2 cat's-eye shell with an aperture big enough to accommodate this door-stop of an operculum? It is c. 5 cm. across at its widest, compared with the 2 cm. or so of your average full-grown cat's-eye operculum.


Powell, A.W.B. 1979., New Zealand Mollusca, marine and freshwater shells. Collins, Auckland. 500pp.

page 3

The following three papers were originally presented at a symposium of the Systematics Association of New Zealand (Systanz) Annual Conterence in Auckland, 27-29 August, 1986, titled: The Plant Variety Rights Bill. Editor.