Vol. VII No. 12 



June 19, 1917 



JOUKNAL 



OF THE 



WASHINGTON ACADEMY 



V 



OF SCIENCES 



BOARD OF EDITORS 

 N. Ernest Dorsey Adolph Knopf A. S. Hitchcock 



BUREAU OF STANDARP8 GEOLOGICAL SURVET BUREAU Or PLANT rUDUBTBT 



PUBLISHED SEMI-MONTHLY 

 EXCEPT IN JULY, AUGUST, AND SEPTEMBER, WHEN MONTHLY 



WASHINGTON ACADEMY OF SCIENCES 



OFFICE OF PUBLICATION 

 WILLIAMS & WILKINS COMPANY 



Kntered as second-class matter July 14, 1911, at the post office at Baltimore, Maryland, under the Act of 



July 10, 1894 



