3( 



377? 



THE 



/ 



AMERICAN 



JOURNAL OF SCIENCE. 



EDITORS 



JAMES D. and EDWARD S. DANA. 



ASSOCIATE EDITORS 



Professors ASA GRAY, JOSIAH P. COOKE, and 

 JOHN TROWBRIDGE, of Cambridge, 



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



New Haven, 



Professor GEORGE F. BARKER, of Philadelphia. 



THIRD SERIES. 



VOL. XXXI. -[WHOLE NUMBER, CXXXI.J 

 Nos. 181—186. 



JANUARY TO JUNE, 1886. Jfe$ 



*2- o GIGS 



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

 1886. 



