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THE 



. AMERICAN" 



JOURNAL OF SCIENCE. 



Editor: EDWAED S. DANA. 



ASSOCIATE EDITORS 



Professors GEOEGE L. GOODALE, JOHN TEOWBEIDGE, 

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



Professors ADDISON E. VEEEILL, HOEACE L. WELLS, 



LOUIS V. PIESSON, HEEBEET E. GEEGOET 



and HOEACE S. TTHLEE, of New Haven, 



Professor HENEY S. WILLIAMS, of Ithaca, 



Professor JOSEPH S. AMES, of Baltimore, 



Mr. J. S. DILLEE, of Washington. 





FOURTH SERIES 



VOL. XXXIV— [WHOLE NUMBER, CLXXXIV]. 



WITH ONE PLATE. 



NEW HAVEN, CONNECTICUT. 



1912. 



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