134 Reports and Proceedings. 



rV. — On the Connexion of Certain Phenomena with the Origin of 

 Mineral Veins. By J. Arthur Phillips, F.C.S., M.Inst.C.E., 

 etc. Phil. Mag., Dec, 1871. 



THE Certain Phenomena referred to by the author are the 

 Solfataras, fissures giving ofi" steam, which occur in most vol- 

 canic districts. The most remarkable are those known as the Steam- 

 boat Springs in the State of Nevada, where some of the crevices are 

 over 1000 yards in length, and are often entirely filled with boiling 

 water, containing various mineral salts in solution. In the course of 

 time incrustations (sometimes to the thickness of several feet) are 

 formed on each side of the fissures, composed chiefly of hydrated 

 silver, but containing also oxides of iron and manganese, traces of 

 copper, minute crystals of iron-pyrites, etc. 



The author thinks that these phenomena tend to show that the 

 Theory of Ascension, which teaches that veins are the result of deposits 

 of mineral substances which have been introduced into fissures from 

 below, is the most rational method in which to view this formation. 

 For further corroboration he gives analyses of water issuing from 

 lodes in some of the deeper Cornish mines which were found to hold 

 mineral substances in solution. 



e.:bi=ok,ts jld^d iPiaooiEizEnDiisrca-s. 



'Geological Society of London. — I, — January 10, 1872. — Joseph 

 Prestwich, Esq., F.E.S., President, in the Chair. — The following 

 communications were read : — 1. " On Cy do stigma, Lepidodendron, 

 and Knorria from Kiltorkan." By Prof. Oswald Heer, F.C.Gr.S. 



In this paper the author indicated the characters of certain fossils 

 from the Yellow Sandstone of the South of Ireland, referred by him 

 to the above genera, and mentioned in his paper " On the Carbon- 

 iferous Flora of Bear Island," read before the Society on November 

 9th, 1870 (see Q. J. G-. S., vol. xxvii., p. 1). He distinguished as 

 species Gyclostigma Kiltorhense, Haughton, G. minutvm, Haught., 

 Knorria acicularis, Gopp, var. Bailyana, and Lepidodendron Vel- 

 tJieimianum, Sternb. 



Discussion. — Mr. Carruthers was glad that he had made the observations which 

 he did on Professor Heer's former paper, as it had caused the Professor to give the 

 reasons on which his opinions were based. He was doubtful whether the success 

 which had attended Professor Heer's determination of species from leaves justified the 

 application of the same principles to mere stems. He could not accept the difference 

 in size or distance of leaf -scars as a criterion of species, inasmuch as they were merely 

 the result of the difference in the age and size of the parts of the plants on which 

 they were observed. Even Professor Heer himself had united together specimens 

 presenting greater differences in this respect than those which he distinguished. He 

 considered Cyclostigma Kiltorhense, C. minutum, and Lepidodendron Veltheimianum 

 to be founded on different parts of one species. In the Kiltorkan fossils the outer 

 surface of the original stems was often broken up into small fragments, the phyllotaxy 

 on which proved them to be portions of large stems, and not entire branches. As to 

 Knorria, it was certainly the interior cast of the stem of Li-pidodend7-on, with casts of 

 the channels through which the vascular bundles passed with some cellular tissue 

 to the leaves ; and the specimen figured showed that it belonged to a branch similar to 



