/Library, U. S. Nat. Museum. 



jSS^^^!^^ 



yOL. XLIV. 



AUGUST, 1917. 



Established by BENJAMIN SIIIIMAN in 1818. 



THE 



.A.MERIOAN 



JOURNAL OF SCIENCE. 



Editor: EDWARD S. DANA. 



ASSOCIATE EDITORS 



Professors GEORGE L. GOODALE, JOHN TROWBRIDGE, 

 W. G. FARLOW 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. XLIY— [WHOLE NUMBER, %fg^^].. 



No. 260— AUGUST, 19K7.4' 



^V.; 



NEW HAVEN, CONNECTICUT. 



1917 



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



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

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Entered as second-class matter at the Post Office at New Haven, Conn., under the Act 

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