Librarian U. S. Nat. Museum. 



. „ — ^. FEBRUARY, 1910. 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OF SCIENCE. 



Editor: EDWAKD S. DANA. 



ASSOCIATE EDITORS 



Professors GEORGE L. GOOD ALE, JOHN TROWBRIDGE, 

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



Professors ADDISON E. VERRILL, HORACE L. WELLS, 

 L. V. PIRSSON and H. E. GREGORY, of New Haven, 



Professor GEORGE F. BARKER, of Philadelphia, 

 Professor HENRY S. WILLIAMS, of Ithaca, 

 Professor JOSEPH S. AMES, of Baltimore, 

 Mr. J. S. DILLER, of Washington. 



FOURTH SERIES 

 VOL. XXIX-[WHOLE NUMBER, CLXXIX] 



No. 170— FEBRUARY, 1910. 



WITH PLATE I 



NEW HAVEN, CONNECTIC 



1910. 



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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