Dr. Cyrus Adler, 



Librarian U. S. Nat. Museum. 



VOL. XXI. 



FEBRUARY, 1906. 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OF SCIENCE. 



Editor: EDWAKD S. DANA. 



ASSOCIATE EDITORS 



Professors GEOEGE L. GOODALE, JOHN TROWBKIDGE, 

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



Professors ADDISON E. VEEEILL, HOE ACE L. WELLS, 

 L. V. PIESSON and H. E. GEEGOEY, of New Haven, 



Professor GEOEGE F. BAEKEE, of Philadelphia, 

 Professor HENEY S. WILLIAMS, of Ithaca, 

 Professor JOSEPH S. AMES, of Baltimore, 

 Mr. J. S. DILLEE, of Washington. 



FOURTH SERIES 

 YOL. XXI— [WHOLE NUMBER, CLXXL] 



No. 122— FEBRUARY, 1906. 



NEW HAVEN, CONNECTICUT. 



1906 



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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