456 Dr. Whcelion Hind 8f John T. Stohhs— 



The above general succession was made out from field-work and 

 from analysis of the fossils collected during that work, but our 

 conclusions received confirmation from an unexpected source which 

 it is desirable to mention here. A few years au^o a water-level was 

 driven from Baggilt to the East Halkyu Mine, which passed 

 through the whole series from the Coal-measures to the Carboniferous 

 Limestone. We are much indebted to Mr. J. Powell Jones, of 

 Holj'well, for calling our attention to this, and for showing us the 

 section of the tunnel. Mr. Jones also took the trouble of pointing 

 out to us the debris from the excavation of the tunnel in the order 

 in which it was di-awn (so far as he could certify this), it having 

 been tipped seriatim over a great area of ground. We saw several 

 typical large Pendleside bullions, and from the shales we collected — 



J'osidoniella Uevis (Brown). Nautiloid form. 



rterinopecten papyraceus (Sow.). Acrolepis Hopkinsi (?). 



Goniatites. Listracatithus sp. 



We also observed a grit which Mr. Jones informed us was met 

 with near the top of the cherts, and which was crowded with 

 detached fish-remains (teeth, spines, etc.), representing undoubtedly 

 the great bed at the top of the section at Gwernymynydd (p. 398). 

 The full thickness of the Holywell shales was about 1,000 »feet, as 

 proved by this adit-level. 



With respect to the correlation of the numerous exposures of 

 Carboniferous Limestone there is more difficulty ; we may, however, 

 as a ])relimiuary, make some observations on the range and dis- 

 tribution of the most important and most abundant fossils (chiefly 

 Corals and Brachiopods) which occur throughout this district. 



Seminnla Jicoio'es, Vaughan. This form cliaracterises the lowest 

 beds of the series, which may be seen at Llandulas and south of 

 Dyserth. Its vertical range is rather limited, and for that reason 

 it is of great value for stratigraphical purposes. At Llandulas and 

 Minera it is associated with Daviesiella Llnngollensis (Da v.), which 

 also appears to have a limited range and yet possess a wide 

 distribution. Both forms were very numerous ; the latter occurs at 

 Llandulas, Minera, and Eglwyseg ridge. 



CijathophjUuin Mnrchisoui, E. & H. The range of this coral is 

 very considerable, and its zone is mainly above that of Semimda 

 Jicoides, although they possil)ly overlap to a slight extent. In the 

 lower portion of the zone, it is very abundant at Bwloh-y-gwynt, 

 near Dyserth, near Llanferres, Llanarmon, Eglwyseg ridge, and near 

 Sweeney Mountain, and at nearly all these localities it is associated 

 with Chonetes papilionncea, Phill., which is also abundant. The 

 highest beds in which it occurs are seen near Axton Mine, at Hendre, 

 and at Treflach Wood Quarries, where it occurs near the base of 

 Productus giijanleus zone, and is associated with Campophyllum 

 Murchisoni. E. & B. 



Oynthophyllnm cf. reginm, Phill. This coral was found in beds 

 just below the highest of the series at Hendre, Minera, Corwen, 

 Eglwyseg ridge, and Treflach Wood Quarries, and was always 

 associated with Lithostrotion irregulare (Phill.), L. Jniiceum (Flem.), 



