328 SECTIONAL TRANSACTIONS.— C. 



changes coincide with the thickest and most widespread coal seams. It is probably 

 due to these conditions, and to their apparent uniformity over relatively wide areas 

 at certain periods, that such organisms as sedentary LameUibranchs can be employed 

 for correlation. 



It is undesirable to attempt to provide more than a tentative classification of the 

 Upper Carboniferous until more information is available, especially concerning the 

 position of its base (which appears to have been fixed at different horizons in Scotland, 

 and in England and Wales, and which has been taken at difierent horizons by workers 

 on fauna and flora'), and concerning the relation in Britain of the Westphalian (as 

 used by de Lapparent) and the Stephanian, which probably embraces some part of 

 the measures now referred to the Radstockian. 



Dr. D. A. Weay and Dr. A. E. Trueman. — The Sequence of non-marine 

 LameUibranchs in the Upper Carboniferous of Yorkshire. 



Non-marine lameUibranchs have been systematically collected from upwards of 

 sixty horizons in the Upper Carboniferous of Yorkshire, and their study has shown 

 that the sequence is very similar to that already described by Dr. W. B. Wright from 

 Lancashire,^ and also by Messrs. CUft and Trueman from the adjoining coalfield of 

 Nottinghamshire and Derbyshire.' 



The earliest forms so far recorded come from shales below the Huddersfield White 

 Rock, the uppermost member of the Middle Grit Series in the Millstone Grits ; or 

 about 250 feet below the base of the Rough Rock. Forms of Anthracomya from the 

 shales at the base of the Coal Measures, which appear to be related to Anthracomya 

 bellula Bolton are very distinctive, and constitute a readily recognisable horizon. 

 Several new species of Anthracomya and Carbonicola occur in the lower part of the 

 Coal Measures ; these have recently been recognised at comparable horizons in other 

 coalfields. Bands characterised by non-marine lameUibranchs are very numerous in 

 the measures between the Silkstone and Barnsley coals, and include forms distinctive 

 of the corresponding horizons in the adjoining North Midland coalfields. A factor 

 which is likely to prove of considerable economic importance is the distinctive fauna 

 in the measures overlying the Barnsley coal, and the Mansfield Marine Band respec- 

 tively. 



The following divisions can be recognised : — 



Phillipsii Zone. — Measures above the Shafton or ' Top ' Marine Band. 



Similis-Pulchra Zone. — Measures between the Shafton Marine Band and the 

 Barnsley coal. 



Modiolaris Zone. — ^Measures between the Barnsley coal and the Green Lane, 

 ThomcUffe Thin or Middleton Little seam. 



Ovalis Zone. — Measures below the Green Lane coal. Fauna well developed above 

 the Wheatley Lime or Silkstone Four-foot coal. 



Several interesting conclusions can be drawn from a comparison of the succession 

 of the faunas in the North Midland coalfields. Thus the Better Bed coal of Yorkshire, 

 the KUburn seam of Derbyshire and the Arley Mine of Lancashire which have already 

 been correlated with one another by one of us,'' on stratigraphical considerations occur 

 in closely corresponding positions within the Ovalis Zone. In a similar manner the 

 Deep Hard or Parkgate coal of the York, Derby and Nottingham coalfield corresponds 

 in the succession with the well-known Trencherbone seam of Lancashire ; while the 

 famous Barnsley or Top Hard seam would appear to be almost certainly represented 

 in Lancashire by the Furnace or Rams Mine. 



Dr. D. A. Wray. — The Succession of Marine Bands in the Goal Measures 

 of Yorkshire. 

 It was not until the development of the concealed coalfield of South Yorkshire and 

 Nottinghamshire within the past thirty years that any close attention was devoted to 

 the numerous marine fossils which occur at several horizons in the Coal Measures of 

 Yorkshire. In 1845, Phillips recognised the wide persistence of the marine band 



1 See, for example, J. Pringle and J. W. Jackson, The. Naturalist, 1928, p. 377. 

 ^ Summary of Progress of Geol. Survey, 1928, Part ii., p. 36. 

 •'' Qiiart. Journ. Oeol. Soc, Vol. Ixxxv., p. 77. 

 * Proc. Yorks. Geol. Soc, Vol. xxi., 1929, p. 272. 



