Smithsonian Institution. 



VOL. XLI. 



JUNE, 1916. 



Established by BENJAMIN SILLIMAN in 1818. 



JUL 21 1916 



THE 



AMERICAN 



JOURNAL OF SCIENCE. 



Editor: EDWAED S. DANA. 



ASSOCIATE EDITOES 



Professors GEOKGE L. GOODALE, JOHN TROWBEIDGE, 

 W. G. FAELOW and WM. M. DAVIS, of Cambridge, 



Professors ADDISON E. VEEEILL, HOEACE L. WELLS, 



LOUIS V. PIESSON, HEEBEET E. GEEGOEY 



and HOBAGE S. UHLEE, of New Haven, 



Professor HENEY S. WILLIAMS, of Ithaoa, 



Professor JOSEPH S. AMES, of Baltimore, 



Mr. J. S. DILLEE, of Washington. 



FOURTH SERIES 



VOL. XLI— [WHOLE NUMBEK, CXCIJ. 

 No. 246— JUNE, 1916. 



NEW HAVEN, CONNECTICUT. 



1916. 



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