VOLUME XXIV 



THE 



NUMBER 7 



Journal of Geology 



A Semi-Quarterly 



Edited By 



THOMAS C. CHAMBERLIN AND ROLLIN D. SALISBURY 

 With the Active Collaboration of 



SAMUEL W. WILLISTON, Vertebrate Paleontology ALBERT JOHANNSEN, Petrology 



STUART WELLER, Invertebrate Paleontology ROLLIN T. CHAMBERLIN, Dynamic Geology 



ALBERT D. BROKAW, Economic Geology 



ASSOCIATE EDITORS 



SIR ARCHIBALD GEIKIE,' Great Britain 



CHARLES BARROIS, France 



ALBRECHT PENCK, Germany 



HANS REUSCH, Norway 



GERARD DeGEER, Sweden 



T. W. EDGEWORTH DAVID, Australia 



BAILEY WILLIS, Leland Stanford Junior University 



GROVE K. GILBERT, Washington, D.C. 



CHARLES D. WALCOTT, Smithsonian Institution 



HENRY S. WILLIAMS, Cornell University 



JOSEPH P.IDDINGS, Washington, D.C. 

 JOHN C. BRANNER, Leland Stanford Junior University 

 RICHARD A. F. PENROSE, Jr., Philadelphia, Pa. 

 WILLIAM B. CLARK, Johns Hopkins University 

 WILLIAM H. HOBBS, University of Michigan 

 FRANK D. ADAMS, McGill University 

 CHARLES K. LEITH, University of Wisconsin 

 WALLACE W. ATWOOD, Harvard University 

 WILLIAM H. EMMONS, University of Minnesota 

 ARTHUR L. DAY, Carnegie Institution 



OCTOBER-NOVEMBER 1916 



THE GENESIS OF LAKE AGASSIZ: A CONFIRMATION - W. A. Johnston 625 



THE LOWER EMBAR OF WYOMING AND ITS FAUNA - E. B. Branson 639 



EVOLUTION OF THE BASAL PLATES IN MONOCYCLIC CRINOIDEA CAMERATA. Ill 



Herrick E. Wilson 665 

 DISCOVERY OF THE GREAT LAKE TROUT, CRISTIVOMER NAMAYCUSH, IN THE 



PLEISTOCENE OF WISCONSIN -------- L. Htjssakof 685 



ASSUMPTIONS INVOLVED IN THE DOCTRINE OF ISOSTATIC COMPENSATION, 

 WITH A NOTE ON HECKER'S DETERMINATION OF GRAVITY AT SEA 



William Herbert Hobbs 690 

 A STAGE ATTACHMENT FOR THE METALLOGRAPHIC MICROSCOPE 



Albert D. Brokaw 718 

 REVIEWS -------- 720 



THE 



UNIVERSITY OF CHICAGO 



CHICAGO, ILLINOIS, U.S.A. 



PRESS 



Agents 



THE CAMBRIDGE UNIVERSITY PRESS, London and Edinburgh 



KARL W. HIERSEMANN, Leipzig 



THE MARUZEN-KABUSHIKI-KAISHA, Tokyo, Osaka, Kyoto, Fukuoka, Sendai 



THE MISSION BOOK COMPANY, Shanghai 



