Chas. D. Walcott, 



U. S. Geol. Survey. 



VOL. XLIV. SEPTEMBER, 1892. • 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OF- SCIENCE. 



EDITORS 



JAMES D. and EDWARD S. DANA. 



ASSOCIATE EDITORS 



Professors JOSI AH P. COOKE, GEORGE L; GOODALE 

 and JOHN TROWBRIDGE, of Cambridge. 



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



New Haven, 



Professor GEORGE F. BARKER, of Philadelphia. 



THIRD SERIES. 



YOL. XLIV.— [WHOLE NUMBER, CXLIV:] 



No. 261.— SEPTEMBER, 1892. 



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



1892. 



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