312 Geological Society : — 



Suffolk. An examination of the Kentish layer showed it to con- 

 sist of 45 per cent, of quartz, 15 per cenb. of glauconite, and 40 

 per cent, of flint. Amongst the rarer minerals are felspar, magne- 

 tite, spinel, zircon, garnet, rutile, tourmaline, actinolite, epidote, and 

 chalcedony ; and there are a few microscopic organisms, either Radio- 

 larians or Diatoms, and some Foraniiniferal casts. 



The Sudbury greensand has 75 per cent, of its grains consisting 

 of glauconite, and of the quartz- and flint-graius only 10 per cent, 

 are flint ; several of the rarer minerals found in Kent occur here 

 also. 



The large flint- percentage in the Kentish grains was alluded to 

 in support of the existence of an unconformity at the base of the 

 Tertiary deposits of that area ; and the relatively small percentage 

 of flint in the sands now being formed along a very similarly situated 

 shore, was suggested to be due to the drifting of debris derived from 

 the coasts composed of Tertiary and Wealden rocks, whicli became 

 mixed with the material brought down by the Thames. 



5. " On the Occurrence of Elephas meridionalis at Dewlish, 

 Dorset." By the Eev. 0. Fisher, M.A., F.G.S. 



6. " On Perlitic Felsites, probably of Archaean age, from the 

 flanks of the Herefordshire Beacon, and on the possible Origin of 

 some Epidosites." By Frank Eutley, Esq., F.G.S. 



The author has previously described a rock from this locality in 

 which faint indications of a perlitic structure were discernible. In 

 the present paper additional instances were enumerated and a descrip- 

 tion was given. The perlitic structure is difficult to recognize, owing 

 to subsequent alteration of the rock. 



Decomposition-products, apparently chiefly epidote, with possibly 

 a little kaolin, have been found in great part within the minute 

 fissures and perlitic cracks. 



The author suggested, from his observations, that felsites, resulting 

 from the devitrification of obsidian, quartz-felsites, aplites, &c, may, 

 "by the decomposition of the felspathic constituents, pass, in the first 

 instance, into rocks composed essentially of quartz and kaolin ; and 

 that by subsequent alteration of the kaolin by the action of water 

 charged with bicarbonate of lime and more or less carbonate of iron 

 in solution, these may eventually be converted into epidosites. 



He regarded it as probable that the rocks are of later Archaean or 

 Cambrian age. 



7. " The Ejected Blocks of Monte Somma," Part I. Stratified 

 Limestones." By H. J. Johnston-Lavis, M.D., F.G.S. 



Introductory. — The author referred to the Hamilton collection, now 

 in the British Museum, and to the work of Prof. Scacchi, who enume- 

 rates 52 mineral species as having been found in the ejected blocks, 

 and indicated the importance of these from a geological and volcano- 

 logical point of view. His own collection contains over 600 specimens, 

 showing the graduation from unaltered limestones, through various 

 stages of change into numerous varieties of "true metamorphic 



