.Smithsonian Institution (*U . & "^Ufc^f VVUasVJ,') 



vol: XXX^- ™ 



MAY, 1914. 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OF SCIENCE. 



Editor: EDWAED S. DANA. 



ASSOCIATE EDITORS 



Professors GEOEGE L. GOODALE, JOHN TROWBEEDGE, 

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



Professors ADDISON E. VEEEILL, HOEACE L. WELLS, 



LOUIS V. PIESSON, HEEBEET E. GEEGOEY 



and HOEACE S. UHLEE, of New Haven, 



Professor HENEY S. WILLIAMS, of Ithaca, 



Professor JOSEPH S. AMES, of Baltimore, 



Mr. J. S. DILLEE, of Washington. 



WITH PLATE IX. 



FOURTH SERIES 



VOL. XXXVII— [WHOLE NUMBER, CLXX 



rfgSnian Ihst/fi: 

 No. 221— MAY, 1914./%^ 



HAY 1 1914 



NEW HAVEN, CONNECTICUT. 



1914. 



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



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

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