﻿90 Reports and Proceedmgs — 



other and to the sides of the fibre. These spicules are still suffi- 

 ciently well preserved to be figured and measured individually, 

 though they have undergone a pseudomorphic change,' by which 

 their original composition has been exchanged for a calcareous one. 

 A similar replacement has occurred in the case of various species of 

 Manon and Porospongia ; and this fact is of great interest, as showing 

 that the extinct and anomalous order of Calcispongias, which these 

 fossils were supposed to indicate, has no necessary existence, since 

 their calcareous nature is a superimposed one, and their original 

 structure agrees completely with that of existing siliceous forms. 

 I'haretrospongia Strahani itself exhibits close affinities to an un- 

 described sponge now living in the Australian seas. 



2. " On the remains of a large Crustacean, probably indicative of 

 a new species of Eurypterus, or allied genus {Eurypterus ? Stevensoni) 

 from the Lower Carboniferous series (Cement-stone group) of Ber- 

 wickshire." By Eobert Etheridge, jun., Esq., F.G.S., Palaeontologist 

 to the Geological Survey of Scotland. 



The fragmentary Crustacean remains described in this paper are 

 referred by the author to a large species of Eurypterus. They ai'e 

 from a rather lower horizon in the Lower Carboniferous than that 

 from which Eurypterus Scouleri, Hibbert, was obtained. The animal 

 was probably twice the size of E. Scouleri. The remains consist of 

 large scale-like markings and marginal spines which once covered 

 the surface and bordered the head and the hinder edges of the body- 

 segments of a gigantic Crustacean, agreeing in general characters 

 with the same parts in E. Scouleri, but differing in points of detail. 

 For the species, supposing it to be distinct, the author proposes the 

 name of E. Stevensoni. 



Mr. H. "Woodward remarked that the remains of Eurypteri from the Carboni- 

 ferous rocks are so distinct from the Upper Silurian Eurypteri of America, Shrop- 

 shire, Lanarkshire, and Russia, as probably to entitle them to be placed in a distinct 

 genus ; and, indeed, at some future day, when more remains are obtained, they may 

 perhaps have to be arranged among the Arachnida, along with many curious 

 fragments which have been called Arthropleura, discovered by Mr. M'Murtrie in 

 the Radstock Coal-field, by Mr. Jordan in the Saarbriick Coal-basin, and by Mr. 

 Gibbs in the IVI anchester Coal-field. Eurypterus Scouleri occurs at Kirton with 

 Sphenopteris Hibberti in a remarkable siliceous deposit, probably thrown down by an 

 old thermal spring in the Carboniferous period. 



Prof. Ramsay remarked that the rock from which the fossils were derived seemed 

 to him to be pretty nearly the equivalent of the Burdie-House Limestone, which he 

 had long ago thought might be to a considerable extent formed by calcareous deposits 

 from thermal waters, probably during a period of great volcanic activity. This 

 would be in favour of Mr. Woodward's opinion. 



3. " On the Silurian Grits near Corwen, North Wales." By 

 Prof. T. McKenny Hughes, M.A., F.G.S. 



The author commenced with a description of sections near 

 Corwen, in North Wales, from which he made out that the grits 

 close to Corwen were not the Denbigh grits, but a lower variable 

 series, passing in places into conglomerate and sandstone with 

 subordinate limestone and shale. This series, under the name of 

 ' The Corwen Beds,' he described in detail, having traced them round 

 the hills S. of Corwen, also near Bryngorlan, S. of the Vale of 

 Clwyd, on Cyrnybrain, and S. of Llangollen. He had noticed in 



