376 Geological Society. 



rine. The lower layers of the ironstone nodules contain, in general, 

 the greatest number of shells, and the upper the greatest number of 

 plants ; but the bed called the " Chance-penny ironstone," the 

 highest wrought, contains the greatest abundance of a species of 

 Productus. The most remarkable fossils obtained by the author, 

 are the remains of Trilobites hitherto undescribed. He procured 

 them from a bed of ironstone in the centre of the coal-measures. 

 He notices also a Coleopterous insect, and another apparently be- 

 longing to the genus Aranea, in the possession of Mr. Antice of 

 Madeley, and which were obtained from ironstone nodules. 



A paper was then read, entitled, " Notes on the Forest of Wyre 

 Coal-field," by the Rev. Thomas England, F.G.S. 



The district, described in this memoir, is bounded on the east by 

 the Severn, on the north by the coal-field of Coalbrookdale, on the 

 west by the Rea and the Hopton to their junction with the Teme, 

 and on the south by the latter river and the Abberley Hills. 



A paper was lastly read " On a Freshwater Formation contain- 

 ing Lignite in Cerdagne in the Pyrenees," by Charles Lyell, Esq., 

 Foreign Sec. G.S. 



The upper part of the basin of the river Segre in Cerdagne pre- 

 sents an example, rare in the Pyrenees, of a great longitudinal valley 

 running east and west, or nearly parallel to the axis of the chain. 

 This basin is formed by a depression in the central region of granitic 

 rocks, which, in the eastern division of the Pyrenees, is of consider- 

 able breadth. The lacustrine strata occupy the lower parts of the 

 depression, reposing horizontally on the granite, hornblende schist 

 and argillaceous schist. The breadth of the freshwater formation 

 is about five miles, and its elevation above the sea probably between 

 three and four thousand feet. Its eastern limits are seen to the east- 

 ward of Livia, where the boundary is formed by the ridge of granite 

 from which the head waters of the Segre descend. At this outcrop 

 the freshwater clays are seen to be covered with beds of such gravel 

 as might now be supplied from the waste of the surrounding moun- 

 tains of granite and schist. On crossing the ridge of granite from 

 the basin of Segre to that of the Tet, the author found no recur- 

 rence of the freshwater strata in the valley of the last-mentioned 

 river. The northern outcrop of the lacustrine deposit is well seen 

 at Ur, between Porte' and Puycerda, where the strata consist chiefly 

 of coarse gravel resting on highly inclined hornblende schist. The 

 deposit is for the most part composed of variously coloured clays, 

 often laminated, in which shells of the genera Limneus and Planor- 

 bis abound, as at Estavan, near Livia, in French Cerdagne, where 

 lignite has been worked, and where there are bituminous clays con- 

 taining impressions of plants. Lignite is still procured from pits at 

 Prats, near Senabastre, in Spanish Cerdagne. 



The author offers no opinion as to the tertiary epoch to which 

 the formation may belong, for the shells obtained at Estavan, al- 

 though entire, were too much flattened to allow M. Deshayes to 

 determine the species. As some portions of the freshwater beds, 

 especially those to the eastward, are highly elevated above others, 



