342 W. Qunn — Carboniferous Rocks of England ^ Scotland. 



EXPLANATION OF PLATE XIII. 



Fig. 1. MillestToma Nicholsoni, nov. Turoniaii: Abu Roasch, Egypt. Fig. la, 

 half of the cceuosteum, showing the knobbed surface [a) and the sinuous 

 grooves {b) ; nat. size. Fig. lb, transverse section across the same specimen, 

 showing the gastropod whicli forms the nucleus of the cceuosteum ; nat. size. 

 Fig. Ic, part of the surface of the same specimen ; x 8 diam. {a, cyclo- 

 S3'stem ; b, weathered part of the surface, showing reticular structure of the 

 coenosteum). Fig. Id, part of a horizontal section across the same specimen ; 

 X 8 diam. {e, horizontal canals). Fig. le, part of a vertical section across 

 the same specimen ; x 8 diam. {p, pillars ; t, tabulae ; c, calcite crystals). 



Fig. 2. Sporadipora dichotoma (Mos.). Part of a transverse section through the 

 margin of a cceuosteum, cutting the marginal zooids vertically ; x 8 diam. 



Fig. 3. Ditto, part of another section from the same, showing the central zooids 

 cut transversely, and the extensive vesicular tissue ; x 8 diam. 



Fig. 4. Beliopora carulcea (Ell. & Sol.). Part of a transverse section across the 

 central part of a corallum, showing a large gastropore ; x 8 diam. 



Fig. 5. Sermatostroma episcopale, Mch. Devonian : Devonshire. Part of 

 a vertical section showing the pillars and tabulae ; x 8 diam. (After 

 Nicholson.) 



11. — Notes on the Correlation of the Lower Carboniferous 

 EocKS of England and Scotland. 

 By "William Gunn, F.G.S., of H.M. Geological Sm-vey of Scotland. 

 rjpHE substance of the following paper was given at a meeting of 

 X the Geological Society of Edinburgh on January 20th this year. 

 Its object is to show that the group of Lower Scottish Limestones 

 about Dunbar and round the Midlothian Coalfield does not 

 represent any part of the Mountain Limestone of Yorkshire, 

 but is the equivalent of the upper part of the Yoredale Series of 

 Phillips, while the Edge Coals and Upper Limestones of Midlothian 

 represent a series of beds which in Yorkshire and Northumberland 

 lie above the true Yoredale Series of Phillips, and which were 

 included by him in the Millstone Grit. It necessarily follows from 

 this correlation that the lower part of Phillips' Yoredale Series, 

 together with the Scar or Mountain Limestone of Yorkshire, are 

 represented in Scotland by the Calciferous Sandstone Series, which is 

 mainly a fresh-water deposit. 



This correlation of the Lower Carboniferous rocks of the North, 

 of England with those of Scotland was determined in the year 1881, 

 after an examination of parts of the coast of Haddingtonshire and 

 Berwickshire in company with two of my colleagues, Mr. H. H. 

 Howell, now Director of the Geological Survey, and the late Mr. W. 

 Topley, who both accepted at the time the general views here stated. 

 Mr. Topley thought them of so much importance that he wished to 

 join with me in writing an elaborate paper on this correlation, and 

 I drew up some notes on the subject, but for various reasons the 

 paper was never completed or published. However, the principal 

 results have been from time to time orally communicated to several 

 of my colleagues. 



To illustrate the paper four vertical sections are given repre- 

 senting the rocks below the Millstone Grit, each section being drawn 

 to the scale of 600 feet to an inch. The most soutljerly of these gives 

 tlie succession of beds from the top of Ingleborough down to the 



