Chas. D. Walcott, 



XT. S. Geological Survey. 



VOL. XXXVIII. SEPTEMBEE, 1889. 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OF SCIENCE. 



EDITOES 



JAMES D. and EDWARD S. DANA. 



ASSOCIATE EDITOES 



Professoes JOSIAI-I P. COOKE, GEORGE L. GOOD ALE 

 and JOHN TROWBRIDGE, of Cambridge. 



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

 New Ha yen, 



Peofessoe GEORGE F. BARKER, of Philadelphia. 



THIRD SEEIES. 

 VOL. XXXVIII.— [WHOLE NUMBER, CXXXVIIL] 



No. 225.— SEPTEMBER, 1889. 



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

 1889. 



TUTTLE, MOREHOUSE & TAYLOR, PRINTERS, 371 STATE STREET 



Published monthly. Six dollars per year (postage prepaid). $6.40 to foreign sub- 

 scribers of countries in the Postal Union. Remittances should be made either by 

 money orders, registered letters, or bank checks. 



