Vol. V No. 17 



October 19, 1915 



JOUENAL 



OF THE 



WASHINGTON ACADEMY 



OF SCIENCES 



BOARD OF EDITORS 



Fred. E. Wright William R. Maxon Edson S. Bastin 



obopht8ical laboratort national museum qeoloaicai, 8urvet 



PUBLISHED SEMI-MONTHLY 

 EXCEPT IN JULY, AUGUST, AND SEPTEMBER, WHEN MONTHLY. 



BT THX 



WASHINGTON ACADEMY OF SCIENCES 



OFFICE OP PUBLICATION 



THE WAVERLV PRESS 



BALTIMORE, MD. 



