President's Address. 85 



Many years ago the late Mr J. W. Salter recorded from the 

 Upper Limestone Clroups of Valleyfield, near Penicuik, a 

 shell under the name of Strophalosia sir lake * Mr A. Soiner- 

 vail declines to accept this on the ground tliat Strophalosia is 

 not a Carboniferous genus. Had he, however, referred to Mr 

 Davidson's Carboniferous Monograph he would have found 

 this to be simply a synonym for Productus striatits, used by 

 Professor Morris.f The latter shell, although not recognised 

 as a Scotch species by Mr Davidson, I believe to occur at 

 the locality mentioned. 



Unusual interest is attached to the Mollusca of the two 

 great coal-bearing sub-divisions of the Scotch Carboniferous 

 area, the Middle Coal and Iron, or Edge Coal Group, and 

 the Coal Measures proper. The first has been almost wholly 

 studied in two areas, around Possil and Govan, near Glasgow, 

 in the West, and the neighbourhood of Bo'ness, Linlithgow- 

 shire, in the East. As noted by Mr J. Young | there are 

 very few persistent bands of limestone or other calcareous 

 strata, but the series consists of numerous thin seams of free 

 coal, cannel coal, blackband ironstone, beds of bituminous 

 shale, and bands of clay ironstone, etc. This disposition 

 holds good for both areas, and is probably very similar to 

 that of the higher Coal Measures. As a rule the absence of 

 marine fossils and the prevalence of fresh water types is al- 

 most as marked a feature as in the Coal Measures, and 

 much more so than in the Calciferous Sandstone Series. 

 This is especially the case in the Possil series, but at rare in- 

 tervals a return to temporary marine conditions is evidenced 

 by the presence of Lingida.^ The Possil Upper Series 

 (Possil Up. Coals and Ironstone) contains no Mollusca, but in 

 the Middle Series (Possil Lr. Coals, etc.) one Brachiopod, 

 Lingula squamiformis, occurs very abundantly.il On the 

 other hand, the Lower Series of beds (Govan Ironstones) con- 

 tains a fairly marine fauna, if we reckon from the various 

 localities conjointly, giving us Brachiopoda -i sp., Bivalves 6 



* Mem. Geol. Survey, Scotl., No. 32, p. 142. t Catalogue, 1S54, p. 155. 



X "Notes on the Section of Strata in the Gilmorehill Quarry" (Trans, 

 Geol. Soc, Glasgow, 1869, iii., pt. 2, p. 298). 



§ Young, loc. ciL, p. 300. II Ibid., pp. 307, 308. 



