366 MR. T. F. SIBLY ON THE CARBONIFEROUS [May I906, 



The course of the fault can be traced with some accuracy, and 

 the limestone-exposures bordering the fault are of interest. At 

 several points, the limestone has been converted into a fine-grained 

 white or pinkish marble. This is especially well seen in a working 

 on the south-western slope of the valley, about 300 yards south, a 

 few degrees west, of the quarry. At other points near the fault, 

 the grey limestones are very compact in texture, and strongly 

 veined with calcite. 



To sum up, the geological features of this locality, as I read them, 

 are as follows : — 



(1) Millstone Grit, with associated shales and sandstones, extends un- 



interruptedly down the valley, the outcrop forming a narrow strip, 

 about two-thirds of a mile long and 150 to 200 yards wide : on the 

 north-west and on the south-east, its outcrop is terminated by the 

 Dolomitic Conglomerate. 



(2) Upper Dibunopkyllmn-beds lie conformably under the grit on the north- 



eastern side. 



(3) The Semimela-beds, exposed farther north-eastward, in Ebbor Rocks and 



elsewhere, are considerably disturbed. Their relation to the Dibuno- 

 phylkim-beds is uncertain, but is probably complicated by faulting. 



(4) A great thrust-fault has brought up the Carboniferous Limestone on the 



south-west, throwing Zaphrentis-beds and Syrinyothyris-beds against the 

 shales of the Mill stone- Grit Series. 



VIII. Notes on certain Corals and Brachiopods included 



IN THE EaTJNAL LlSTS. 



(i) CORALS. 

 Amplexiis. 



Amplextjs cf. coralloides, Sow. 



The specimens included here, whieh are all obtained from the Upper 

 Zaphrentis-Zone, have the following characters : — Form : large and 

 cylindrical. Septa short, stout, and practically equal in thickness 

 throughout their length, being square-cut at the end. Fossula not 

 very strongly developed. 



AmrLExus sp. 



Specimens which occur commonly in the Syringothyris-Zone, 

 near Whatley, have short, thickened, tapering septa. The fossula. 

 is well-developed. The form is large and cylindrical. 



Zaphrentis (restricted), Vaughan, Quart. Journ. Geol. Soe. 

 vol. lxi (1905) p. 269. 



Zaphrentis aff. cornucopia, mut. C. 



Compare Zaphrentis aff. eornueopies (Mich.), Edwards & Haime, Vaughan, 

 op. cit. p. 271 & pi. xxii, figs. 3-3 d. 



This mutation, which characterizes the Syringothyris-Zone in the 

 Mendip area, differs from the typical Z 2 form, described and figured 



