Chas. i). Walcott, 



U. S. Geological Survey. 

 * VUL. XL. NOVEMBER, 1890. 



Established by BENJAMIN SILLIMAN in 1818. 



a&WAicoTz 



THE 



AMERICAN 



JOURNAL OF SCIENCE. 



EDITOES 



JAMES D. and EDWARD S. DANA. 



ASSOCIATE EDITORS 



Professors JOSIAH P. COOKE, GEORGE L. GOODALE 

 and JOHN TROWBRIDGE, of Cambridge. 



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

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Professor GEORGE F. BARKER, of Philadelphia. 



THIRD SERIES. 



VOL. XL.— [WHOLE NUMBER, CXL.] 

 No. 239.— NOVEMBER, 1890. 



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

 1890. 



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