luiary, kj. j. i\at. iviuseum. 



VOL. XLII. 



NOVEMBER, 1916. 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



<1j5onian 



[* NOV 2 



AMEEICAN^ 



JOURNAL OF SCIENCE. 



Editor: EDWARD S. DANA. 



ASSOCIATE EDITORS 



Professors GEORGE L. GOODALE, JOHN TROWBRIDGE, 

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



Professors ADDISON E. VERRILL, HORACE L. WELLS, 



LOUIS V. PIRSSON, HERBERT E. GREGORY 



and HORACE S. UHLER, of New Haven, 



Professor HENRY S. WILLIAMS, of Ithaoa, 



Professor JOSEPH S. AMES, of Baltimore, 



Mr. J. S. DILLER, of Washington. 



FOURTH SERIES 



VOL. XLII— [WHOLE NUMBEK, OXOII]. 

 No. 251— NOVEMBER, 1916. 



WITH PLATE I. 



NEW HAVEN, CONNECTICUT. 



1916. 



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