No. 432. New Series.— Decade IV.— Vol. VII.— No. VI. Price Is. 6d. nett- 



THE 



GEOLOGICAL MAGAZINE 



louthlu Jaui|iuil o( cSfoIogij. 



WITH WHICH IS INCORPORATED 



"THE aEOLOGJ^IST." 



EDITED BY 



HENRY WOODWARD, LL.D., F.R.S., F.G.S., &,c. 



ASSISTED BY 



ROBERT ETHERIDGE, F.R.S. L. So E., F.G.S., &c., 



WILFRID H. HUDLESTON, M.A., F.R.S., F.L.S., F.G.S., &c., 



GEORGE J. HINDE, Ph.D., F.R.S. , F.G.S., &,c., AND 



HORACE BOLINGBROKE WOODWARD, F.R<S-^{E'G:t, 



JUNE, 1900. 



OOnSTTEItTTS, 



I, Okiginal Articles. page 



1. Bala Lake and the River 

 System of North Wales. By 

 Philip Lake, M.A., F.G.S. 

 (Plate XL) Contiiiued from 



p. 215 241 



2 . The Pareutrock of the Diamond. 

 By Prof. T. G. Bonney, D.Sc, 

 LI,.D., F.R.S 246 



3. Derived Limestones. By Prof. 



W. J. Sollas, D.Sc., F.R.S. . 248 



4. On the Genus Conocorijphe. By 

 F. R. CowPEE Reed, M.A., 



F G.S 250 



5. Occurrence of a Blue Amphibole 

 in Hornblende. By Henry J. 

 Seymour, B.A., F.G.S. (With 

 two Illustrations.) 257 



6. On lihadhiichfhi/s moncnsis. By 

 E. D. Wellbvrn, L.RC.P., 

 F.G.S., etc. (With an Illustra- 

 tion.), 260 



7. Tortoise from the Wealden of 

 the Isle of Wight. By R. W. 

 Uooley, Esq. (With a full- 

 page Illustratiou.) 263 



8. Stability of the Land around 

 Hudson Bay. By J. B. Tyrrell, 

 M.A., B.Sc, F.G.S 266 



Original Articles — confiii'ifd. page 

 9. A Geological Examination of 

 Snowdon. By J. R. Daky.x.s, 

 Esq. (With an Illustration.)... 267 

 10. Diagram of Composition of 

 Igneous Rocks. By H. Warth, 

 Esq. (With two Illustrations ) 273 



II. Reviews. 



Bollettino della Societa Sismo- 

 logica Italiana, Vol. V. By 



III. 



Dr. Charles Davison, F.G.S. 



Reports and Proceedings. 

 Geological Society of Loudon - 

 March 21, 1900 



275 



276 



2. April 4, 19(10 278 



April 

 May 9, 



1900 

 1900. 



IV. CORUESPONDENCE. 



1. The Rev. R. Ashington Bullcn, 

 F.G.S 



2. Mr. Hugh J. L. Beadnell, 

 F.G.S 



V. Obituary. 



Mr. G. H. Morton, F G.S 



280 

 282 



287 



288 



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(t:r The Volume for 1899 of the GEOLOGICAL MAGAZINE is ready, 

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