No. 163, Vor. XXVIIL  SULY, 1884. 
Established by BENJAMIN SILLIMAN in 1818 
AM HREOC AN 
JOURNAL OF SCIENCE. 
EDITORS | : 
JAMES. D. ann E. S. DANA, anp B. ‘SILLIMAN. 
ASSOCIATE : EDITORS 
Proressors H. A. Ew eeR AND ar 
New Haven, : 
Proreason GEORGE F-. BARKER, oF r Pi 
| WITH PLATES I AND It 
