Orbiculoidea sp.

Sun, Yuanlin & Baliński, Andrzej, 2008, Silicified Mississippian brachiopods from Muhua, southern China: Lingulids, craniids, strophomenids, productids, orthotetids, and orthids, Acta Palaeontologica Polonica 53 (3), pp. 485-524 : 491

Orbiculoidea sp.

Type species: Orbicula forbesii Davidson, 1848 ; Wenlock , Silurian; West Midlands, England .

Fig. 5O.

Material.—Five very fragmentary dorsal valves, non−silicified.

Remarks.—The specimens described here are small fragments of dorsal valves with preserved posterior regions of the valve including subcentral larval shell. The larval shell is subcircular in outline with somewhat flattened posterior margin, with hemiperipheral growth and delicate concentric growth lines, otherwise the valves are smooth. At higher magnification, however, very delicate pitted micro−ornamentation is discernible; the pits attain about 2 µm in diameter on average. Postlarval shell shows holoperipheral growth and distinct, elevated, loosely spaced concentric fila. It seems that the specimens represent the cosmopolitan and stratigraphically long ranging genus Orbiculoidea d’Orbigny, 1847 .

Stratigraphic and geographic range.—The specimens were found in samples D4 and MH 2.