/ Library, U. S. Nat. Museum. 



VOL. Ill 



MARCH. 1922 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OF SCIENCE. 



Editob: EDWARD S. DANA. 



ASSOCIATE EDITORS 



! Professors WILLIAM M. DAVIS and REGINALD A. DALY, 



of Cambridge, 



Professors HORACE L. WELLS, CHARLES SCHTJCHERT, 



HERBERT E. GREGORY, WESLEY R. COE and 



FREDERICK E. BEACH, of New Haven, 



Professor EDWARD W. BERRY, of Baltimore, 

 Drs. FREDERICK L. RANSOME and WILLIAM BOWIE, 



of Washington. 



FIFTH SERIES 



VOL. Ill— [WHOLE NUMBER, CCIII], 

 No. 15— MARCH, 1922. 



WITH PLATE III. 



NEW HAVEN, CONNECTICUT. 



19 2 2. 



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



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

 Postal Union ; $6.25 to Canada. Single numbers 50 cents; No. 271, one dollar. 



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

 of March 3, 1879. 



