The non-Marine Lamellibranchs of the North Wales Coalfield

Abstract

In the recent correlation of the Upper Carboniferous of England and Wales published by Professor A. E. Trueman (1933) the most obvious omission was a consideration of the North Wales coalfield. At that time, indeed, only three lamellibranch species had been reported from the area. In the present paper knowledge of the fauna is extended and the modern zonal scheme is applied to the coalfield. The floral zones recently introduced by Dr. E. Dix (1934) can be partially distinguished in the area, but these form the subject of a separate paper (Wood 1936b). The results are in accord with those based on the lamellibranchs. The area dealt with is shown on the map (Fig. 1), while the relationship of the lamellibranch zones and the coal-seams can be seen from Fig. 8. The Geological Survey memoirs dealing with the coalfield (Wedd & King 1924; Wedd & others 1923, 1927) contain little account of the fauna of the Coal Measures. The shell Carbonicola robusta (J. de C. Sowerby) (sic) was recorded from above the Main Coal at Mancot, near Hawarden, and was considered to indicate the Lower Coal Measure age of this seam. Anthracomya calcifera Hind was collected from the Upper Coal Measures to the south of Ruabon, while this shell and A. phillipsi (Williamson) were found in the Upper Coal Measures south of the Dee, outside the limits of the area dealt with in this paper. No other records were published, and shells were stated to be rare in the Coal Measures