Chas. D. Walcott, 



U. S. Geol. Survey. 

 VOL. XLIV. AUGUST, 1892. 



Established by BENJAMIN SILLIMAN in 1818. 



T H E 



AMERICAN 



JOURNAL OF SCIENCE. 



EDITORS 



JAMES D. and EDWARD S. DANA. 



ASSOCIATE -EDITORS 



Professors JOSI AH P. COOKE, GEORGE L. GOOD ALE 

 and JOHN TROWBRIDGE, or Cambridge. 



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



New Haven, . 



Professor GEORGE F. BARKER, of Philadelphia. 



THIRD SERIES. 



YOL. XLIV.— [WHOLE NUMBER, CXLIV.] 



No. 260.— AUGUST, 1892. 



WITH PLATES I-V. 



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

 1892. ■ 



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