Mesopeplum costatostriatum (Marshall, 1918)
MARSHALL, P. 1918. The Tertiary molluscan fauna of Pakaurangi Point. Kaipara Harbour. Transactions of the Royal Society of New Zealand, 50: 263-277 [p. 273, pl. 22, figs. 1-3]
1918 Pecten costatostriatus Marshall, 1918
P. Marshall, 1918, plate 22.
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«Shell small, slightly inequilateral, fan-shaped: height, 17 mm.; breadth, 18 mm. Ears very unequal. Anterior ear large, nearly triangular, but with the outer margin rounded. It bears 7 radiating ribs crossed by a number of transverse bars which are almost spiny. The radiating ribs which are near the hinge-line are much stronger than the others. Posterior ear much stronger, smaller, with 5 ribs less strongly crossed by transverse bars. Right valve with about 40 rounded radiating ribs, many of which subdivide into 3 each near the ventral margin. Each rib is crossed by a large number of transverse striations: these are so deep as to almost make the ribs appear to be composed of a large number of overlapping plates. Towards the ventral margin these may develop into small spiny processes. Interstices about as wide as the ribs, and crossed by a large number of fine transverse lines.
I am much indebted to Mr. Buter for examining this species, which he rightly remarks is closely related to P. burnetti Zittel. This species is perhaps the most abundant of the pectens at Pakaurangi Point. Type in the Wanganui Museum.» PATRICK MARSHALL, 1918
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