Reports and Proceedings — Geological Society of London. 43 



The area dealt with is the irregularly-shaped periclinal mass forming 

 the southern end of the Pennine anticline, with a few small outliers. 

 The base of the limestone is not shown, and the whole series exposed 

 constitutes a greatly expanded development of the uppermost zone of 

 the typical Avonian succession of the South- Western Province, namely, 

 the Bibunojihyllum-zonQ. The most extensive section — that along the 

 Midland Railway, between Longstone and Buxton — shows a thickness 

 of about 1,500 feet. Three subzonal divisions are distinguished, as 

 follows : — 



D3. Subzone of Cyathaxonia rnshiana : represented in the South-Westem 

 Province by horizon € and the lower part of the Millstone Grit. 



D2. Subzone of Lonsdaliajloriformis: correlated with the Upper Dibunophyllmn 

 zone (D2) of the South-West. 



Di. Subzone of Bihunophyllum 9 : correlated with the Lower Dibunophyllum 

 zone (Dj) of the South-West. 

 An abnormal development of the Lonsdalia-swbzone, consisting 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 Avestern half of the area. The passage-beds 

 between the Carboniferous Limestone and the Pendleside Series are 

 included in the Cyathaxonia'Suhzone. Locally, these passage- 

 beds attain a thick development. A local unconformity between the 

 Carboniferous Limestone and the Pendleside Series, indicating con- 

 temporaneous elevation and erosion, occurs in the eastern part of the 

 area. A close general similarity exists between the Dibu?iophyUum- 

 zone of the Midland area and that of North Wales. These two areas 

 should be regarded as constituting a Midland Province. A comparison 

 of the Dibunophyllum- zone of the Midland with that of the 

 South- Western Province brings out the following more important 

 differences : — (a) The Brachiopod fauna of the Lonsdalia-suhzone of 

 the Midland Province is considerably richer than that of the equivalent 

 part of the South- Western sequence, {b) The Cyathaxonia-subzone 

 of the Midland Province, which attains a maximum development in 

 Derbyshire and JSTorth Staffordshire, is practically undeveloped in the 

 South- Western Province. 



The paper concludes with a description of certain corals and 

 Brachiopods from the Midland area, some species and varieties 

 being new. 



2. "Brachiopod Homosomorphy : ' Spirifer ylaher.' '^ By S. S. 

 Buckman, F.G.S. 



The smooth, catagenetic, stage of shells may have been attained by 

 the loss of different distinctive features, pointing to polygenetic 

 origins. The series of shells figured by Davidson as Spirifera glabra 

 do not all agree in being smooth ; some are radially costate, some have 

 a pronounced mesial fold, others hai'dly any, some are very transverse, 

 others are narrow. There is good evidence that several of the forms 

 ranged under this species nxe ReticidaricB(Jsi''QtOj), more or less smooth. 

 Thus Sp. obtusus, regarded by Davidson as a synonym of Sp. glabra, 

 shows faint reticulation, has the dental plates, and must be classed as 

 a Reticularia ; while quite smooth forms with similar plates also occur 

 {Sp. lata, Brown, and Sp. glaberrimus, de Koninck). But other forms 



