﻿Vol. 6 1.] COAL-MEASURES OF NORTH STAFFORDSHIRE. 547 



Arley Mine of Lancashire was made at least as long ago as the 

 publication of Green's memoir, and probably much earlier. The 

 identity of the Gannister Coal with the Bullion Mine of Lancashire 

 was established by the clearest evidence. The Gannister or Halifax 

 Hard Coal was characterized throughout Yorkshire by its hard sand- 

 stone-floor, by the roof of shale with marine organisms, and by the 

 occurrence (within the seam itself) of hard nodules containing perfectly- 

 preserved plant- structures. In Lancashire, it was characterized in 

 the same manner ; and it was very gratifying to learn that the Authors 

 had established the fact of its extension into North Staffordshire. 



Dr. F. A. Bather, responding to Dr. Wheelton Hind's request 

 that he should say something about the fragments of Archceocidaris, 

 pointed out that these consisted of radioles, tuberculate interambu- 

 lacral plates, and teeth. The teeth and plates appeared to be 

 different from those belonging to A. Urei and A. scotica. Among 

 other species from Britain or Belgium, comparison was only possible 

 with A. vetusta, Phillips, and A. benburbensis, Portlock, two forms 

 which M'Coy regarded as a single species. Although these radioles 

 differed in several features from A. benburbensis, the speaker had 

 declined to give them a new name, until he had been able to study 

 specimens which could safely be determined as A. vetusta, for the 

 interpretation of which Phillips's description was quite insufficient. 

 The occurrence of this genus was interesting, since, although 

 common enough in the Coal- Measures of North America, it was not 

 so in this country ; further, echinoids were certain proof of the 

 existence of thoroughly salt-water conditions. 



Mr. Stobbs, in reply to Mr. Walcot Gibson's remarks concerning 

 the use of the term ' true Coal-Measures,' said that he knew of no 

 other convenient name for the important sequence of Coal-Measures 

 from the Millstone Grit to the base of the thick — and so far as 

 workable coal-seams were concerned — barren, overlying Coal- 

 Measures, as developed in the Midlands. Whether shales containing 

 Lingulce only were to be regarded as strictly marine or not, did not 

 affect the utility of the horizon for purposes of stratigraphy, pro- 

 vided that the fauna was distinct and unmixed with other forms 

 of freshwater character, and that the band was persistent ; and 

 experience in North Staffordshire showed that they might expect 

 these conditions to hold. 



With reference to Dr. TealFs query as to the evidence upon which 

 the Authors relied for the correlation of a marine band in one 

 coalfield with a similar horizon in another coalfield, sometimes 

 the striking character of the fauna in each instance was sufficient 

 in itself. In other cases, in addition to the marine fossils, the 

 Authors observed the relative position of the bed in the series, 

 and its proximity to one of those zones of freshwater mollusca 

 which had been established by Dr. Wheelton Hind ; but the speaker 

 fully admitted that caution was necessary in this matter. He 

 thanked the Fellows for the reception accorded to the paper. 



Dr. Wheelton Hind said that the fossil-horizons were recognized 

 by their aggregate contents, and by the relations of the marine bands 

 to others containing definite species of Carbonicola and Anthracomya. 



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