Art. LIV.—Description of a New Species of Pecten from the Oamaru Series.

By Professor James Park, F.G.S., Director Otago University School of Mines.

[Read before the Otago Institute, 9th August, 1904.]

Pseudamussium (Pecten) huttoni. (Plate xi., fig 5A, “Reise der ‘Novara,’” Paläontologie, bd. i.)

1873: Pecten hochstetteri, Hutton, Cat. Tert. Moll. N.Z., p. 30. 1897: Pseudamussium hochstetteri (?) Zittel; Harris, Cat. Tert. Moll. Brit. Mus., part i., p. 323.

Suborbicular, equivalve, equilateral, thin, compressed; both valves smooth; ears subequal, obtuse, smooth.

Dimensions.—Height, 80 mm.; length, 76 mm.

Formation.—A characteristic form of the Oamaru series of Miocene or Oligocene age. It ranges from the marine greensands overlying the Tertiary coal to the summit of the Oamaru stone. It has never been found above or below the Oamaru series.

Localities.—Winton, Milburn, Clarendon, Caversham, Waitati, Waikouaiti, Hampden, Maheno, Kakanui River, Awamoa Creek, Oamaru Creek, Totara, Ngapara, Enfield, Black Point, Duntroon, Marawhenua, Wharekuri, Waihao Forks, Pareora Gorge (lower end), White Rock River, Tengawai, Kakahu, Castle Rock, Waipara, Mount Brown, Mount Donald, Point Elizabeth, Cape Farewell, West Whanganui, Mokau, Raglan, Aotea, Whangarei, Paparoa, Pahi.

Remarks.—For the past thirty years this beautiful shell has been known to geologists as Pecten hochstetteri. It is easily distinguished from P. hochstetteri, which is radiately ribbed on the right valve, smooth on the left valve, and in mature specimens does not exceed a height of 56 mm. and a length of 54 mm.

In plate xi., fig. 5A, a right valve of P. huttoni is figured in error as the smooth valve of P. hochstetteri. It was doubtless this error which originally led to the confusion with respect to the two species.