&Z73 



THE 



AMEKICAN 



JOURNAL OF SCIENCE. 



Editor: EDWARD S. DANA. 



ASSOCIATE EDITORS 



Professors GEO. L. GOODALE, JOHN TROWBRIDGE, 

 W. G. FARLOW and WM. M. DAVIS, of Cambridge, 



Professors A. E. VERRILL, HENRY S. WILLIAMS and 

 L. V. PIRSSON, of New Haven. 



Professor GEORGE F. BARKER, of Philadelphia, 



Professor JOSEPH S. AMES, of Baltimore, 



Mr. J. S. DILLER, of Washington. 



FOURTH SERIES. 

 VOL. XII— [WHOLE NUMBER, CLXIL] 



WITH NINE PLATES. 



NEW HAVEN, CONNECTICUT. 

 1901. 



