90 
Reports and Proceedings — 
other and to the sides of the fibre. These spicules are still suffi- 
ciently well preserved to be figured and measured individually, 
tliougb they have undergone a pseudomorphic cbange, by which 
tbeir original composition bas been exchanged for a calcareous one. 
A similar replacement lias occurred in the case of various species of 
Manon and Porospongia ; and this fact is of great interest, as sbowing 
that the extinct and anomalous Order of Calcispongiae, which these 
fossils were supposed to indicate, has no necessary existence, since 
tbeir calcareous nature is a superimposed one, and their original 
structure agrees completely with that of existing siliceous forms. 
Pharetrospongia 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 Robert 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 are 
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 cbaracters 
with the same parts in E. Scouleri , but dififering 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, Sbrop- 
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 
tragments which have been called Arthropleura, discovered by Mr. M'Murtrie in 
the Radstock Coal-field, by Mr. Jordan in the Saarbrück Coal-basin, and by Mr. 
Gibbs in the M 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 bepretty nearly the equivalent of the Burdie-House Limestone, which he 
had long ago thought might be to a considerable cxtent 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 
‘ Tlie Corwen Peds,’ he described in detail, having traced them round 
the hills S. of Corwen, also near Bryngorlan, S. of the Yale of 
Clwyd, on Cyrnybrain, and S. of Llangollen. He had noticed in 
