SECTIONAL TRANSACTIONS.— C. 327 



If this line is accepted it appears that it may fit with the boundary required 

 in Scotland. The cephalopod evidence as far as it is known supports this 

 view ; particularly is this true of the distribution and range of Tylonautilus 

 nodiferus and Anthracoceras glabrum, which are widely known in zone E 

 of England and which occur in Scotland in the Upper Limestone Group. 



Mr. Bisat has taken the base of zone E as the base of his Lancastrian, 

 but Dr. M. Macgregor has pointed out that it might well be taken at the 

 base of zone H. This would accord in general with our views on the evi- 

 dence in South Wales, although so far very little is known concerning the 

 palaeontology of zone H in South Wales. 



As Dr. Macgregor has pointed out, this line would be more in accord 

 with that drawn by the late Dr. Kidston on palaeobotanical evidence. 

 Kidston, it will be recalled, emphasised the importance of a plant break 

 which he considered to occur a third of the way up the Roslin Sandstone 

 Group of Scotland, this line forming the boundary between his Lower and 

 Upper Carboniferous floras. He believed that he was also able to recognise 

 this plant break in north Staffordshire. In our opinion this line does not 

 coincide with any great floral change of the nature indicated by Kidston. 

 The change in flora is merely of similar character to those occurring at higher 

 horizons in the Upper Carboniferous, and the importance ascribed to it by 

 Kidston probably arose from the examination of an inadequate sequence. 



There is no evidence for a great plant break in north Staffordshire or 

 South Wales. Certainly there is a change in flora, but no break of the type 

 suggested by Kidston. 



Dr. W. B. Wright. 



The speaker regretted the absence from this symposium of any con- 

 tribution from Mr. W. S. Bisat, whose palaeontological work was the basis 

 of all modern stratigraphical correlation of marine facies in the Upper 

 Carboniferous. Having established in these beds a zonal system of remark- 

 able precision and constancy, he was enabled thereby to prove the occurrence 

 of extensive transgression and overlap at their base. The very difficult 

 problem of establishing the horizon of the uppermost beds of the Lower 

 Carboniferous present in any district has been attacked by many of the 

 disciples of Vaughan, but by none more successfully than Dr. Hudson, 

 who had established the local absence of great thicknesses of the Yoredale 

 series. There is thus no doubt as to the existence of a great mid-Carboni- 

 ferous unconformity, and interest centres at present rather round its character 

 and the reasons for its local absence. In this connection much still remains 

 to be done. In the Buxton area, the peculiar conditions of which have been 

 so fully described by Prof. Fearnsides, there is definite evidence of emer- 

 gence in the karst-like weathering of the limestone surface beneath the 

 overlying shales. Further evidence of a similar character has been adduced 

 by Dr. Hudson in the Craven district. 



Afternoon. 

 Excursion to Doncaster, Park Nook, Stotfield, etc. 



Saturday, September 3. 



Excursion to the Yorkshire coast. 



