

THE 



AMERICAN 



JOURNAL OF SCIENCE 



Editor: EDWARD S. DANA. 



ASSOCIATE EDITORS 



Professors GEORGE L. GOODALE, JOHN TROWBRIDGE, 

 and Wl. M. DAVIS, of Cambridge, 



Professors A. E. YERRILL, HORACE L. WELLS, CHARLES 



SCHUCHERT, L. V. PIRSSON, H. E. GREGORY, 



and HORACE S. UHLER, of New Haven, 



Professor JOSEPH S. AMES, of Baltimore, 

 Mr. J. S. DILLER, of Washington. 



FOURTH SERIES 



VOL. XLVIII— [WHOLE NUMBER, CXCVIII]. 



NEW HAVEN, CONNECTICUT. 



19 19. 





