Chas. D. Walcott, 



U. S. Geol. Survey. 



YOL. XLIY. . OCTOBER, 1892. 



Established by BENJAMIN SILLIMAN in 1818. 



m I 



THE 



AMERICAN 



JOURNAL OF SCIENCE. 



EDITOES 



JAMES D. and EDWARD S. DANA. 



A&Sv?51 T ^ TE EDITORS 



Professors JOSIAH P. COOKE, GEORGE L. GGOdALE 

 and JOHN TROWBRIDGE, of Cambridge. 



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

 New Hav: is, 



Professor GEORGE F. BARKER, of Philadelphia. 



THIRD SERIES. 



YOL. XLIY.— [WHOLE NUMBER, CXLIY.] 

 No. 262.— OCTOBER, 1892. 



WITH PLATES VI-VI1I. 



NEW HA YEN, CONN.: J. D. & E. S. DANA. 

 18 92. 



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