458 Geological Society : — 



3. "On Platysiagum sclerocephalum and Palceospinax prisons , 

 Egerton." By Sir Philip de Malpas Grey-Egerton, Bart., M.P., 

 F.R.S., F.G.S. 



The two species of fossil Pishes noticed in this paper were de- 

 scribed by the author in the 13th Decade of the Memoirs of the 

 Geological Survey, published in 1872. They are both from the 

 Lias of Lyme Regis. He now described some new specimens which 

 add to our knowledge of their characters. An example of Platysi- 

 agum shows the position of the dorsal fin, which is placed very far 

 back, occupying a place opposite to the interval between the ventral 

 and anal fins, and the form of the trunk, which is of nearly uniform 

 depth from the occiput to the base of the dorsal fin. The structure 

 of the dorsal fin w 7 as described in detail. The new specimen of 

 Palceospinax prisons shows especially the position of the second 

 dorsal spine, which is placed over the 50th vertebra, the first being 

 on the 16th, the fish thus most nearly approaching the existing 

 Cestracion, which it also resembles in its dentition. In other re- 

 spects it seemed to be most nearly allied to Acaniliias. 



4. " On a new genus of Silurian Asteriadse." Bv Thos. "Wright, 

 M.D., P.R.S.E., F.G.S. 



The specimen described showed the outline of a small Starfish, 

 with a large disk and short rays, in a slab of Wenlock Limestone 

 from Dudley. The outline of the ten rays was described as marked 

 out by the border of small triangular spines, the other plates of the 

 disk and rays being absent. Each ray was terminated by a stem- 

 like multiarticulate process as long as the ray, from towards the 

 extremity of which spring slender lateral processes, giving it a tufted 

 appearance. This Starfish, which is in the collection of Dr. Grind- 

 rod, is named by the author Trichotaster plumiformis. 



May 28, 1873.— Prof. Ramsay, F.R.S., Vice-President, 

 in the Chair. 



The following communications were read : — 



1. " The Glaciation of the Northern part of the Lake-district." 

 By J. Clifton Ward, Esq., F.G.S. 



The author stated the leading questions to be settled by his in- 

 vestigation of the northern part of the Lake-district as follows : — 

 The fact of the glaciation of the district being granted, and of this 

 he adduced abundant evidence, the questions that arose were whether 

 the glaciating agent worked from north to south, whether it came 

 from within or from without the district, and finally, whether the 

 agent was floating ice, a system of local glaciers, or an unbroken 

 ice-cap. As the result of his investigation, he maintained that there 

 is no evidence that a great ice-cap from the north ever swept over 

 this district. The ice-scratches trending along the principal valleys, 

 but sometimes crossing watersheds, indicate a great confluent 

 glacier -sheet, at one time almost covering a great part of the dis- 

 trict, the movement of which was determined by the principal water- 

 shed of the Lake -district. In the part of the Lake-district under 



