Chas. D. Walcott, 



U. S. Geol. Survey 



sff 



YOL. XLIY. JULY, 1892. 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OF SCIENCE. 



EDITORS 



JAMES D. and EDWARD S. DANA. 



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Professors JOSIAH P. COOKE, GEORGE L. GOODALE 

 and JOHN TROWBRIDGE, of Cambridge. 



Professors H. A. NEWTON and A. E. YERRILL, of 

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Professor GEORGE F. BARKER, of Philadelphia. 



THIRD SERIES. 



YOL. XLIY.— [WHOLE NUMBER, CXLIY.] 



No. 259.— JULY, 1892. 



NEW HAYEN, CONN.: J. D. & E. S DANA. 



1892. , 



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