﻿68 MR. T. F. SIBLT ON THE FAUNAL SUCCESSION IN THE [Feb. I908, 



(C) Comparison of the Cyatha.vo?iia~suhzoue of the Midland 

 area witli the Cyatha.vo7iia-^eds of the Rush sequence, 

 Co. Dublin. 



The close similarity between the faunas of the Cyathaxonia-Beds 

 of the Midland succession and the Rush sequence, respectively, will 

 be apparent, on comparing my fauual lists (pp. 50 & 51) with those 

 tabulated^ by Dr. A. Taughan in his account of the Rush beds. A 

 few specially-noticeable differences may be mentioned. Cyaihaxonia 

 contorta, which occurs at Rush, is replaced in the Midlands by 

 C. cosiata. Beaumontia, which is locally abundant in the Midland 

 area, is not recorded from Rush. The brachiopod-fauna of the 

 Midland series, while agreeing with that of the Rush beds in its 

 main essentials, is considerably more varied. 



YIII. Stjmmabt of Conclusions. 



(1) The base of the Carboniferous Limestone is not exposed in the 



Midland area. The most extensive section in the area, 

 namely, that along the course of the Midland Railway between 

 Longstone and Buxton, shows a thickness of about 1500 feet 

 of Carboniferous Limestone. All the beds seen in this section 

 are included in the Dibunopliylhi.m-Zo'ne, which may be 

 correlated, broadly, with the Dibuiwphylluni-Zone of the 

 South- Western Province. 



(2) Three subzonal divisions are distinguished in the Midland 



sequence. These, in descending order, are as follows : — 



Dg^zSubzone of Cyathaxonia rushiana. Eepresented iu the typical 



succession of the South- Western Province by Horizon e and the 



lower part of the Millstone Grit. 

 Do^^Subzone of LonsdoJia floriformis. Correlated with the Upper 



Dihunophy Hum-Zone (D.^) of the South- Western Province. 

 D^=:Subzone of Dibunophyilum 0. Correlated with the Lower 



Dibu/wpJii/llum-Zone (D^) of the South-Western Province. 



(3) An abnormal development of the Lonsdalia-auhzoney con- 



sisting of richly-fossiliferous brachiopod-beds, in which the 

 typical coral-fauna has very little representation, forms a 

 conspicuous local feature in various parts of the western half 

 of the area. 



(4) The passage-beds between the Carboniferous Limestone and the 



Pendleside Shales are included in the Cyathaxonia-suhzone. 

 Locally, these passage-beds attain a thick development. 



(5) A local unconformity between the Carboniferous Limestone 



and the Pendleside Series, indicating contemporaneous ele- 

 vation and erosion, occurs in the eastern part of the area. 



(6) A close general similarity exists between the Dibunophyilum^ 



Zone of the Midland area and that of North Wales. These 



1 Quart. Journ. Geol. Soc. vol. lxii(1906) pp. 297-99 & 301. 



