234 Reports and Proceedings — Geological Society of London. 



of two New Species." By Miss Jane Donald. (Communicated by 

 Professor Tlieodore Groom, M.A., D.Sc, F.G.S.) 



Shells having more convex whorls, or less sigmoidal lines of 

 growth than L. sinuosum, cannot be left within the genus Loxonema. 

 The two new species described resemble the type in form and in the 

 sinuosity of the lines of growth ; but the whorls are ornamented with 

 spiral strige, two of which frequently stand out and give the shell 

 a banded appearance. Both species are of Silurian age : one was 

 obtained from the Aymestry Limestone near Ledbury, and from 

 beds of about the same age at Llangadock ; and the other from the 

 Wenlock Limestone, Dudley. 



2. "On some Gasteropoda from the Silurian Rocks of Llangadock 

 (Caermarthenshire)." By Miss Jane Donald. (Communicated by 

 Professor Theodore Groom, M.A., D.Sc, F.G.S.) 



These fossils occur almost entirely in the state of casts and moulds. 

 Eleven distinct forms have been made out, referable to some genera ; 

 but only seven are sufficiently well preserved for specific determina- 

 tion. Five of these are new, including one described in the previous 

 communication ; a new genus is described, for the reception of 

 Euompliahis funatus. The first species described comes nearest to 

 examples placed in the genus Plethospira, as represented by Fl. Semele, 

 with which it might be placed in a new subgenus. Three other 

 species, including two new ones, resemble shells refei'red to Bemboscia. 

 The three species are turriculated, and the baud is situated on the 

 angle of the whorls, a little distance above the suture. The specimens 

 described come from the horizons of the Upper Llandovery, the 

 Wenlock, the Lower Ludlow (including the Aymestry Limestone), 

 and the Upper Ludlow. 



IL— March 22nd, 1905.— J. E. Marr, Sc.D., F.E.S., President, in 

 the Chair. The following communications were read : — 



1. "An Experiment in Mountain-building: Part IL" By the 

 Eight Hon. the Lord Avebury, P.O., F.R.S., P.S.A., F.G.S. 



In this paper some experiments are described which were con- 

 ducted by an apparatus by means of which pressures could be 

 applied in two directions at right angles to one another, a space 

 of 2 feet square being reduced to one 22 inches square. In the 

 first series, plastic materials such as cloth and thin oilcloth were 

 used, with layers of sand between them. Two main folds crossing 

 at right angles were formed, the upper one shifted over the lower. 

 The use of two layers of linoleum produced a different type of 

 folding, and the lower layers of the linoleum were broken along the 

 principal ridges. In the second series a layer of plaster was intro- 

 duced ; this was found to be fractured, tilted up into a ' writing-desk' 

 form, and foi'ced irregularly into the sandy layers. Overthrusts were 

 thus produced, so that in some cases a boring would have passed 

 through two or even four layers of the rigid substance. In other' 

 cases the edges of the primary fracture broke off more or less 

 regularly, and the detached pieces were pushed up, assuming 



