﻿/ 
  

  

  THE 
  

  

  AMERICAN 
  

  

  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 
  H. 
  A. 
  ROWLAND, 
  of 
  Baltimore, 
  

  

  Mr. 
  J. 
  S. 
  DILLER, 
  of 
  Washington. 
  

  

  FOURT 
  H 
  SERIES. 
  

   VOL 
  JX— 
  [WHOLE 
  NUMBER, 
  CLIX.] 
  

  

  V 
  

  

  WITH 
  FIVE 
  PLATES 
  

  

  NEW 
  HAVEN, 
  CONNECTICUT 
  

   1 
  9 
  00. 
  

  

  arc; 
  1&3 
  

  

  