Chas. D. Walcott, 



U. S. Geological Survey. 



YOL. XXXYIII. 



AUGUST, 1889. 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OF SCIENCE. 



EDITOES 



JAMES D. and EDWARD. S. DANA. 



ASSOCIATE EDITOES 



Professoes JOSIAH P. COOKE, GEORGE L. GOODALE 

 and JOHN TROWBPJDGE, of Cambridge. 



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

 New Haven, 



Professor GEORGE F. BARKER, of Philadelphia. 



THIRD SERIES. 



YOL. XXXYIII.— [WHOLE NUMBER, CXXXYIIL] 



No. 224.— AUGUST, 1889. 



WITH PLATES Vl-VIII. 



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

 1889. 



I'UTTLK, MOREHOUSE & TAYLOR, PRINTERS, 371 STATE STREET 



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

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