Chas. D. Walcott, 



U. S. Geological Survey. 



No. 205. Vol. XXXV. • J AN [JAB Y, 1888. 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OF SCIENCE. 



EDITORS 



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ASSOCIATE EDITORS 



Professors ASA GRAY, JOSIAII P. COOKE, 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. XXXV. -[WHOLE NUMBER, CXXXV.J 

 No. 205— JANUARY, 1888. 



WITH PLATE I. 



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

 1888. 



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