THE 



AMERICAN" 



JOURNAL OF SCIENCE 



Editor: EDWARD S. DANA. 



ASSOCIATE EDITORS 



Professors GEORGE L. GOODALE, JOHN TROWBRIDGE, 

 and WM. M. DAYIS, of Cambridge, 



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



SCHUCHERT, 'H. E. GREGORY, and HORACE S. 



TJHLER, of New Haven, 



Professor JOSEPH S. AMES, of Baltimore, 

 Mr. J. S. DILLER, of Washington. 



FOURTH ^/'onai Mitt?* 



VOL. L— [WHOLE NUMBER, COJ. 



-2. 6 -2- C> 4- ?- 



NEW HAVEN, CONNECTICUT. 



19 20. 



