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Genus Ostrea. Linné, 1758.
Type: Ostrea edulis Linné.
Subgenus Gigantostrea, Sacco, 1897.
Type: Ostrea gigantica Solander.
Ostrea (Gigantostrea) wollastoni Finlay. (Figs. 16, 17.)
1873. Ostrea incurva Hutton, Cat. Tert. Moll., p. 35 (not of Nilsson).
1915. Ostrea incurva Hutton: Suter N.Z. Geol. Surv. Pal. Bull. No. 3, p. 53, pl. 3, fig. 1, pl. 7, figs. 2a, b.
1927, Ostrea wollastoni Finlay, Trans. N.Z. Inst., vol. 57, p. 528.
A giant specimen was collected by Mr. Christie. It measures 165 mm. long and 183 mm. high. The depth of the left valve is
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110 mm., of this the body cavity occupies about 45 mm., so the shell substance is 65 mm. thick. The right valve is almost flat and has a maximum thickness of 49 mm. The total weight is 9 lbs. 7 ozs. The external surface is not well preserved, but radial ribs are absent. The outline is more circular than that of the type, and the ligamental area relatively larger.
Perhaps O. suteri v. Ihering (1907, p. 94) would be a better classification. This species was introduced only incidentally; but the locality, Westport, was given, and also characters to distinguish it from O. hatcheri Ortmann and O. patagonica d'Orb.