﻿562 THE CARBONIFEROUS LIMESTONE OE [Aug. I905, 



this definite and certain, thanks to Dr. Vaughan's masterly stud} 7 of 

 the Avon and other sections round Bristol. 



The Author had had the treble advantage of working in an 

 area where the stratigraphical sequence was obvious, where there 

 had been very little movement, and where the fossils occurred in 

 certain definite zones ; and the speaker thought it might be said 

 that, so far as the Mendip, Bristol, and South-Wales area of Lower 

 Carboniferous rocks was concerned, they were now zoned by the 

 corals and brachiopods. Unfortunately, other families of fossils 

 were very rare there. The speaker had stated, on more than one 

 occasion, that he had been unable to adopt any method for zoning 

 the Lower Carboniferous rocks of the Midlands, and he was of 

 opinion that the same hard-and-fast lines did not obtain there as 

 near Bristol. For example, Zaphre,ntis did occur above a Yisean 

 fauna, and many other apparent inconsistencies existed with the 

 Bristol life-zones. But, a solution having been obtained for one 

 district, he was hopeful that something would be discovered which 

 would enable them to unravel the riddle of the Midlands. 



With regard to the fauna of the Mendip and Bristol Carboniferous 

 area, the speaker was astonished at the limited number of species. 

 Many brachiopods, common in the Midlands, had not been found. 

 Lamellibranchs and gasteropods were extremely rare, and cephalo- " 

 poda were almost entirely unrepresented. On the other hand, the 

 speaker had never met, in the Midlands, with Camarophoria 

 isorliyncha and ' Atliyris ' cf. glabristria, so common at the Milton- 

 Road quarries. He had also failed to meet in the Midlands with 

 Seminula ficoidea, which was so characteristic of certain zones in 

 the Avon section. 



Assuming that the Carboniferous Limestone of Belgium extended 

 by way of the Mendips and South Wales to the South of Ireland, the 

 contrast between the richness of the fauna, of Belgium on the east 

 and Ireland on the west, and that of the Bristol area was marked, 

 and pointed to distinct bathymetrical conditions. 



Mr. C. B. Wedd stated that, in mapping the Matlock district of 

 Derbyshire for the Geological Survey, he was attempting a sub- 

 division of the Carboniferous Limestone on the lines employed by 

 Dr. Vaughan and the Author, but was relying chiefly on the corals. 

 Owing to the anticlinal form of the limestone-mass, it had not 

 been possible to examine a sufficiently-great thickness to test 

 Dr. Yaughan's subdivisions completely ; but, so far as comparison 

 could be made between the Matlock and Bristol districts, be found 

 points of agreement underlying a certain anfount of discrepancy. 

 The Dibunophyllum-tyge of coral was characteristic of a high 

 horizon in the Matlock as in the Bristol district, and various forms 

 of Liihostrotion also agreed fairly well in their distribution. So far, 

 he had reason to believe that in the Matlock area certain corals 

 characterized certain horizons, and had a limited vertical range. 



The limestone described in the present paper appeared to belong 

 to a lower horizon than any that he had yet examined in Derbyshire, 

 and consequently the contemporaneous igneous rocks associated with 



