282 Geological Society : — 



maintained that they must originally have been formed on a com- 

 paratively level sea-floor, and that the inequalities in distribution 

 had been produced by subsequent differential movement to the ex- 

 tent of 500 feet or more to the north and west above that experienced 

 to the east and south, where the chronological succession remained 

 unbroken, also that the inequalities below the level of the Westleton 

 beds had been produced since the period of their deposition, as, for 

 instance, the gorge of the Thames at Pangbourne and Goring, and 

 most of the Preglacial valleys in the district ; furthermore, evidence 

 was adduced in favour of the formation of the escarpments of the 

 Chalk and Oolites since Westleton times, whilst certain observations 

 supplied data for estimation of the relative amounts of pre- and 

 post-glacial denudation of the valleys. 



It was stated, in conclusion, that the time for the vast amount 

 of denudation was so limited that it was not easy to realize that 

 such limits could suffice, but the author did not see how the con- 

 clusions which he had arrived at could well be avoided. 



January 8, 1890.— W. T. Blanford, LL.D., F.R.S., President, 

 in the Chair. 



The following communications were read : — 



1. "On some British Jurassic Fish-remains referable to the 

 genera Eurycormus and Hypsocormus." By A. Smith Woodward, 

 Esq., F.G.S. 



2. " On the Pebidian Volcanic Series of St. Davids." By Prof. 

 C. Lloyd Morgan, F.G.S. 



After a brief sketch of the principal theories that have been pro- 

 pounded, the author concluded that our knowledge of this series 

 has not yet reached " a satisfactory position of stable equilibrium." 

 His own communication was divided into three sections. 



The Relation of Pebidian to Cambrian.- — There are four localities 

 where the junction is described — Caerbwdy Valley, St. Non's Bay, 

 Ogof Golchfa, and Ramsey Sound. The stratigraphy of the second 

 of these was given with much detail, and illustrated. The author 

 concluded that here, together with clear signs of local or contem- 

 poraneous erosion, the general parallelism of the strike of Pebidian 

 and Cambrian is most marked. There is no evidence of any bending 

 round of the conglomerate against the strike of the Pebidians. The 

 stratigraphical evidence in each of the localities having been con- 

 sidered, together with the evidence offered by the materials of the 

 Cambrian conglomerate and local interstratification with the volcanic 

 beds (the interdigitation at Carnarwig being well marked), he con- 

 cluded that there was no great break between the conglomerate and 

 the underlying Pebidians. The uppermost Pebidian already fore- 

 shadowed the sedimentary conditions of the Harlech strata, and the 



