NOVEMBER, 1909. 



Established by BENJAMIN SILLIMAN in 1818. 

 THE 



AMERICAN 



JOURNAL OF SCIENCE. 



Editor: EDWAED S. DANA. 



ASSOCIATE EDITORS 



Professors GEOKGE L. GOODALE, JOHN TROWBRIDGE, 

 W. G. FARLOW and WI. 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. XXYIII-[WHOLE NUMBER, CLXXVIIL] 

 • No. 167— NOVEMBER, 1909. 



WITH PLATES I AND II. 



NEW HAVEN, CONNECTICUT. 



1909. 



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