Vol. VI No. 15 



September 19, 1916 



JOUENAL 



OF THE 



WASHINGTON ACADEMY 



OF SCIENCES 



BOARD OF EDITORS 

 William R. Maxon Edson S. Bastin N. Ernest Dorset 



WATlnie \L MU8F.OM GEOLOGICAL 8CBVEY BUREAU OF 6TAMDARD8 



PUBLISHED SEMIMONTHLY 

 EXCEPT IN JULY. AUGUST, AND SEPTEMBER, WHEN MONTHLY 



BI THB 



WASHINGTON ACADEMY OF SCIENCES 



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WILLIAMS A WILKINS COMPANY 



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Entered aa second-elase matter July 14, 1011, at tbe post office at Baltimore. Maryland, under the Act of 



July 16. 1894 



