﻿Varies D. Walcott, 



fice Geological Survey. 



No. 192. Vol. XXXII. DECEMBER, 1886 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OF SCIENCE 



EDITORS 



JAMES D. and EDWARD S. DANA. 



ASSOCIATE EDITORS 



Professors ASA GRAY, JOSIAH P. COOKE, and 

 JOHN TROWBRIDGE, op Cambridge, 



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

 New • Haven, 



Professor GEORGE F. BARKER, of Philadelphia. 



THIRD SERIES. 



VOL. XXXII. -[WHOLE NUMBER, CXXX1LJ 



No. 192— DECEMBER, 1886. 



WITH PLATES X TO XIII. 



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

 1886. 



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