Cyrus Adler, 



Librarian U. S. Nat. Museum. 



YOL. XIII. MARCH, 1902. 



Established by BENJAMIN SILLIMAN in 1818. 

 THE 



AMERICAN 



JOURNAL OF SCIENCE. 



Editor: EDWARD S. DANA. 



ASSOCIATE EDITORS 



Professors GEO. L. GOODALE, JOHN TROWBRIDGE, 

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



Professors A. E. VERRILL, HENRY S. WILLIAMS and 

 L. V. PIRSSON, of New Haven. 



Professor GEORGE F. BARKER, of Philadelphia, 



Professor JOSEPH S. AMES, of Baltimore, 



Mr. J. S. DILLER, of Washington. 



FOURTH SERIES. 



YOL. XIII— [WHOLE NUMBER, OLXIIL] 



No. 75.— MARCH, 1902. 



WITH PLATES II-VI. 





NEW HAVEN, CONNECTICUT. 

 1902. 



THE TUTTLE, MOREHOUSE & TAYLOR CO., PRINTERS, 125 TEMPLE STREET. 



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

 Postal Union. Remittances should be made either by money orders, registered 

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