Vol. VI No. 19 



November 19, 1910 



JOUKNAL 



OF THE 



WASHINGTON ACADEMY 



OF SCIENCES 



BOARD OF EDITORS 

 William R. Maxon N. Ernest Dorset Adolph Knopf 



NATIONAL MUSEUM BUREAU OP STANDARDS GEOLOGICAL. 8UBVT5T 



PUBLISHED SEMI-MONTHLY 

 EXCEPT IN JULY, AUGUST, AND SEPTEMBER. WHEN MONTHLY 



BY THE 



WASHINGTON ACADEMY OF SCIENCES 



OFFICE OF PUBLICATION 



WILLIAMS <fe WILKINS COMPANY 



BALTIMORE, Ml). 



Entered as eeoond-clas& matter July 14, at the post office at Baltimore, Maryland, under the Act of 



July 16,1894 



