5—^5775 



THE 



AMERICAN 



JOURNAL OF SCIENCE. 



Editor: EDWARD S. DANA. 



ASSOCIATE EDITORS 



Professors GEORGE L. GOODALE, JOHN TROWBRIDGE, 

 W. G. EARLOW 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 Ithaca, 



Professor JOSEPH S. AMES, of Baltimore, 



Mr. J. S. DILLER, of Washington. 



FOURTH SERIES 



VOL. XXXIII-[WHOLE NUMBER, CLXXXIII] 



WITH THREE PLATES. 



NEW HAVEN, CONNECTICUT. 



1912. 



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