Jhas D. Walcott, 



U. S. Geol. Survey 



VOL. IV. 



JULY, 1897. 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OP SCIENCE. 



Editor: EDWARD S. DANA. 



ASSOCIATE EDITORS 



Professors GEO. L. GOODALE, JOHN TROWBRIDGE, 

 H. P. BOWDITCH and W. G. FARLOW, of Cambridge, ' 



Professors O. C. MARSH, A. E. VERRILL and H. S. 

 WILLIAMS, of New 11/ yen, 



Professor GEORGE F. BARKER, of Philadelphia, 

 Professor H. A. ROWLAND, of Baltimore, 

 Mr. J. S. DILLER, of Washington. 



FOURTH SERIES. 



VOL. 1Y— [WHOLE NUMBER, CLIY.] 



No. 19.— JULY, 1897. 



NEW HA YEN, CONNECTICUT. 



1897. 



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