XCU PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



certain beds apparently intermingled with the carboniferous rocks of 

 the district. He notices " dark slates and limestones, with traces of 

 plants, goniatites and other remains analogous to mountain limestone 

 fossils," as forming the beds on the south, on which certain hard 

 sandstones and shales repose. Beyond the latter, northward, instead 

 of the common carboniferous rocks of the district, beds of flagstone, 

 a thin-bedded slate and a calcareous rock come in. These are suc- 

 ceeded on the north by coarse gritty rocks, interstratified with shells 

 of the coal-measure series. The flagstones are worked at Yeolm- 

 bridge, Werrington Park. Fossils in the quarry are rare, and consist 

 of Turbinoloj)sis celtica, Sanguinolaria elliptica and Bellerophon 

 hiulcus ; but in an old quarry in the range of the same beds, near 

 Underwood farm, about a mile distant, organic remains are more 

 numerous. Mr. Pattison there found Turbinolopsis celtica, Amplexus 

 tortiiosus, Crinoidea, Sanguinolaina elliptica, Avicula, Orthis, Acro- 

 culia 1, Orthoceras, Goniatites ?, Clymenia ?, Bellerophon hiulcus and 

 Phacops Latreillii. 



The Rev. D. Williams communicated a paper '' On the several 

 Volcanic interferences which alternate and are concurrent with, and 

 eventually supersede, the Old Red Sandstone of the British Isles." In 

 it he considers that there have been three protracted periods of vol- 

 canic interferences during the accumulation of the old red sandstone 

 of this country. 



Mr. Richard Edmonds noticed his further success in finding the 

 abundant remains of Helix pulchella beneath the sand-hillocks on the 

 coast of Cornwall, a fact of interest, he observes, inasmuch as the 

 author of the Cornish Fauna has remarked that if the remains of 

 these land shells be of frequent occurrence in such situations, '*we 

 must come to the conclusion that they were once abundant in Corn- 

 wall, but are now gradually becoming extinct in this locality." As 

 bearing upon this point, Mr. Edmonds gives the following list of land 

 shells found beneath the surface of the Phillack Towans (Sand-hills), 

 with the exception of Zonites pygmceus, taken from Whitesand Bay 

 Towans. Those marked with an asterisk are not now found living 

 within ten miles of Penzance : — Bulimus acutus, B. obscurus, Cary- 

 chium ?ninimum, Clausilia biplicata, Conovulus bidentatus, C. denti- 

 culatus. Helix aspersa, H. caperatay H. ericetorum, H. fulva^, H. 

 fiisca, H. hortensis, H. nemoralis, H. pulchella, H. virgata. Pupa 

 Anglica, P. marginata^, P. umbilicata. Vertigo edentula, V. pa- 

 lustris^, V. pygtncea'^, Vitrina pellucida, Zonites alliarius, Z. cel- 

 larius, Z. nitidulus, Z. pyginceiis*, and Z, rotundatus. It may be 

 needful to observe that Phillack Towans are seven miles from Pen- 

 zance, and that though now receiving additions, the mass of them 

 belongs to a relative level of sea and land on the Cornish coasts dif- 

 ferent from the present, the north-western part having been formed 

 at the period anterior to the raising of so many beaches on this coast. 

 Indeed these Towans constituted the contemporaneous continuation 

 of those beaches, being composed of the sand drifted by the winds 

 from the shores then existing. 



Mr. John Garby presented to the Society a very valuable catalogue 



