No. 678. 



Vol. LVII of Whole Series. 



Price 2s. 



r"TCCTn 



The 



m^ 



.**i, 



oaal Mus« 



eologica 



ciZlllC 



fiDontbl^ 3ounial of (BeolOGV 



WITH WHICH IS INCORPORATED 



THE GEOLOGIST. 



HDITM) ]5Y 



HENEY WOODAVAED, LL.D., F.E.S. 



E. H. EASTALL, M.A. 



ASSISTED BV 



Pkof. J. W. GREGORY, D.Sc. F.R.S. Sm JETHRO J. H. TI'.IALT^, Sc.D.. F.li.S. 



F. H. HATCH, Ph.D., M.Inst. M.M. Prob'. W. W. WATTS, Sc.U., F.R.S. 



Prop. J. E. MARR, Sc.D., F.R.S. HENRY WOODS, M.A., F.R.S. 



A. SIMITH WOODWARD. DL.D., F.R.S. 



DECEMBER, 1920. 



CONTENTS :— 



Editoeial Notes. 



Page 

 .. 529 



OKlGlNAIi ARTIOLKS. 



Noteson theGenus Sph(srocoryphc. 

 ByW.B. E.King. (Plate XIII.) 532 



North American Species of Ethe- 

 ridgina. By D. K. Greger. 

 (Plate XIV.) 535 



A new Ammonite Genus from 

 Charmouth. By L. F. Spath. 

 " (Plate XV.) 538 



Mineral Composition of Fenland 

 Silt. By F. Hardy 543 



Original Articles (continued). Page 



A Theory of the Marginal Drift. 

 By W.'b. Weight 551 



Beviews. 



An Introduction to Palseontology... 556 



Excavations in Turkestan 557 



Eeports and Proceedings. 



Mineralogical Society 558 



Edinburgh Geological Society 560 



Index 561 



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