TRANSACTIONS OF THE SECTIONS. 65 



the Silurian formation, the Ludlow group, is only found on the western side of 

 the main part of the coal-field. If we draw a nearly north and south line, start- 

 ing from Ettingshall Park Farm, running between Hurst Hill and Sedgley Beacon, 

 and contiuue it down through Cradley to the south, we find that to the west of 

 that line, wherever the Silurian rocks rise to the surface, namely, at Sedgley, at 

 Turner's Hill, and at the Lye Waste, they consist of the Ludlow or upper divi- 

 sion, while all to the east of that line, wherever the Silurian rocks rise to the sur- 

 face, or have been reached by shafts through the coal-measures, they consist of the 

 Dudley and Wenlock division." 



All the localities of this shale are east of this line, and accordingly it belongs 

 to the Wenlock series. 



Annelida from Guernsey. 

 By E. Ray Lankester, Scholar of Downing College, Cambridge. 

 This paper contained an account of the Annelids and Turbellarians obtained by 

 the Dredging Committee in Guernsey. The author had been able to distinguish 

 seventy-seven species from this coast, of which four at least, belonging to the 

 Polynoina, were new to science ; others not previously obtained from British loca- 

 lities were also in the list of the new species ; one, a Halosydna, the author named 

 after Mr. Jeffreys, the other forms were also named and characterized ; Harmotho'e 

 Sarniensis was remarkable for its unusual development of elytra, which were twenty 

 pairs in number. 



On the British S2iecies of Cephalaspis and the Scotch Pteraspis. 

 By E. Pay Lankester. 

 The author stated that he had acquired a very large mass of evidence by the 

 assistance of various friends, particularly Mr. Powrie, of Poswallie, Forfar. From 

 these specimens he concluded that there were at least five British species of Cephal- 

 aspis; and they were — C. Lyellii of Agassiz, confined to the Scotch beds (which are 

 very low), and perhaps occurring also in the passage-beds of Herefordshire, as 

 C. ornatm, a form only known by fragments ; C. Murchisuni of Egerton, from the 

 passage-beds of England ; C. asterohpis of Dr. Harley, a well-marked form found 

 in the cornstones ; C. Salweyi of Egerton, .also well characterized ; and lastly, the 

 species common in the English cornstones, which appears to differ considerably 

 from C. Lyellii, as the author showed. This species will be named, and other de- 

 tails given, in the monograph on these fishes in which Mr. Lankester is engaged in 

 conjunction witli Mr. Powrie. 



The Relative Extent of Atmospheric and Oceanic Denudation, with a parti- 

 cular reference to certain Bod's and Valleys in Yorkshire and Derby- 

 shire. By D. Mackintosh, F.G.S. 



The object of the author was to show that most of the cliffs, projections, and 

 pillars of rock hitherto attributed to weathering , are really due to the former action 

 of the sea during the last great submergence of the land. Many of the escarp- 

 ments or cliffs of Yorkshire and Derbyshire present evidences that they coidd only 

 have been formed by the battering, undermining, and displacing agency of the 

 sea. " The multitudes of scattered blocks and fragments frequently found lying 

 under escarpments, do not in general present the appearance of their having fallen 

 since the last emergence of the land. They exist in too great numbers, at too great 

 a distance from the parent cliff, or arranged in such positions as to point to the pe- 

 culiar action of the sea." The Brimham rocks, nine miles from Harrogate, " fringe 

 an eminence which a geologist can scarcely err in regarding as an upheaved 

 island, partly spared, and partly wrecked by the sea. . . . The shapes of most of 

 the rocky pillars at Brimham must have originated in the jointed structure of the 

 millstone-grit strata of which they are the remains. The passages between them 

 have evidently been chiefly excavated by the displacement of blocks, and not so 

 much by disintegration. Some of the rocks have been more or less smoothed and 

 rounded ; but a little practice will enable a geologist to distinguish between the 

 effects of frost and rain, and the shapes communicated to rocks bv waves, tides, 

 ' 1865. 5 



