354 SECTIONAL TRANSACTIONS.— C. 



the palasontological change is of greater magnitude than that which takes 

 place between the Westphalian and the Stephanian. It is also suggested 

 that it is comparable with the Palaeobotanical Break noted by Prof. Gothan 

 between Lower and Upper Namurian. 



In South Wales the flora of a part of the Upper Coal Series resembles 

 that of the Lower Stephanian, while the occurrence of certain species in the 

 Keele Series of Warwickshire may possibly indicate that these strata should 

 be correlated with the Upper Stephanian. 



Dr. A. Raistrick. — Use of microspores in the correlation of coal seams. 



Two seams of coal have been studied in great detail over a wide area by 

 means of microspore separations : the Trencher bone seam of Lancashire, 

 and the Busty seam of Durham. In the first case, a marked change in the 

 microspore content of the seam in one district is correlated with changes in 

 the structure of the seam and the proportions of its constituent subsections. 

 In Durham, the samples examined are of the Top and Bottom Busty seams, 

 taken at more than fifty localities, the older correlation and naming being 

 accepted for sampling. The microspore analysis shows three distinct areas 

 in the coalfield, the pair of ' Busty ' seams giving uniform diagrams over 

 each single area, but the diagrams being different in different areas. The 

 areas of different microspore content coincide approximately with areas of 

 different physical and chemical properties of the coals, and a suggested 

 revision of the Busty correlation is given. Some indication of correlation 

 between different coalfields is discussed. 



Dr. J. Weir. 



Lamellibranch zones are easily defined in the Scottish Productive Coal 

 Measures, and some of Wright's subzones can be recognised. 



The succession of affinis, pulchr a-maximum, librata, and atra subzones 

 occurs in Lancashire and in Scottish coalfields and in both areas is termin- 

 ated by marine deposits — Dukinfield and Skipsey's respectively — that are 

 recognised as equivalent on the basis of their marine faunas. Such corre- 

 sponding sequences of faunal episodes are valuable in inter-coalfield corre- 

 lation. 



Wright's pseudorobusta subzone, at the base of the Middle Coal Measures 

 in Lancashire, is a useful datum in districts where the Lancashire tripartite 

 division is inoperative. In Scotland the base occurs at or near the base of the 

 Coal Measures and, as in Lancashire, it is followed by the os-lancis sub- 

 zone, the modiolaris zone generally and finally by the affinis-atra subzonal 

 succession. That is, in Lancashire terminology, the Scottish Productive 

 Coal Measures are essentially Lower Middle Coal Measures, and the 

 evidence of the shells is substantiated by the plants. As there is no un- 

 conformity at the base of the Coal Measures in Scotland it appears legitimate 

 to regard part of the Scottish Millstone Grit, possibly the upper two thirds, 

 as equivalent to Lower Coal Measures and not to Millstone Grit of Lanca- 

 shire. The meagre lamellibranch fauna of the Scottish Millstone Grit tends 

 to confirm this view. 



It is doubtful if the definition of major palaeontological subdivisions (of 

 higher rank than zones) would serve any useful purpose. In Scotland, sub- 

 division of the Coal Measures is possible only at Skipsey's Marine Band, 

 a recognised formational boundary, which marks approximately a change 

 in the physical character of the sediments as well as modification of the 



