Smiths 



sonian Institution. ^U.« $„ ~Y\jfc, "YV^^^O 



YOL. XXXYIL MARCH, 1914. 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OF SCIENCE. 



Editor: EDWARD S. DANA. 



ASSOCIATE EDITORS 



Professors GEORGE L. GOODALE, JOHN TROWBRIDGE, 

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



Professors ADDISON E. VERRILL, HORACE L. WELLS, 



LOUIS V. PIRSSON, HERBERT E. GREGORY 



and HORACE S. UHLER, of New Haven, 



Professor HENRY S. WILLIAMS, of Ithaca, 



Professor JOSEPH S. AMES, of Baltimore, 



Mr. J. S. DILLER, of Washington. 



FOURTH SERIES 



VOL. XXXVII— [WHOLE NUMBER, CLXXXYIIJ. 



No. 219— MARCH, 1914. 



WITH PLATE VIII. 



NEW HAVEN, CONNECTICUT. 



1911. 



THE TUTTLE, MOREHOUSE & TAYLOR CO., PRIMERS, 123 TEMPLE STREET. 



Published monthly. Six dollars per year, in advance. $6.40 to countries in the 

 Postal Union ; $6.25 to Canada. Remittances should be made either by money orders 

 registered letters, or bank checks (preferably on New York banks). 



