﻿"Uhas 
  U. 
  Walcott, 
  

  

  U. 
  S. 
  Geol. 
  Survey. 
  

  

  VOL. 
  III. 
  

  

  APRIL, 
  1897. 
  

  

  Established 
  by 
  BENJAMIN 
  SILLIMAN 
  in 
  1818. 
  

  

  THE 
  

  

  AMERICAN 
  

  

  JOURNAL 
  OF 
  SCIENCE. 
  

  

  Editor: 
  EDWARD 
  S. 
  DANA. 
  

  

  ASSOCIATE 
  EDITORS 
  

  

  Professors 
  GEO. 
  L. 
  GOODALE, 
  JOHN 
  TROWBRIDGE, 
  

   H. 
  P. 
  BOWDITCH 
  and 
  VV. 
  G. 
  FARLOW, 
  of 
  Cambridge, 
  

  

  Professors 
  O. 
  C. 
  MARSH, 
  A. 
  E. 
  YERRILL 
  and 
  H. 
  S. 
  

   WILLIAMS, 
  of 
  New 
  Haven, 
  

  

  Professor 
  GEORGE 
  F. 
  BARKER, 
  of 
  Philadelphia, 
  

   Professor 
  H. 
  A. 
  ROWLAND, 
  of 
  Baltimore, 
  

   Mr:- 
  J. 
  S. 
  DILLER, 
  of 
  Washington. 
  

  

  FOURTH 
  SERIES. 
  

  

  YOL. 
  Ill— 
  [WHOLE 
  NUMBER, 
  CLIIL] 
  

  

  No. 
  16.— 
  APRIL, 
  1897. 
  

  

  WITH 
  PLATE 
  VI. 
  

  

  NEW 
  HAYEN, 
  CONNECTICUT. 
  

  

  18 
  9 
  7. 
  

  

  TUTTLE, 
  MOREHOUSE 
  & 
  TAYLOR, 
  PRINTERS. 
  125 
  TEMPLE 
  STREET. 
  

  

  Published 
  monthly. 
  Six 
  dollars 
  per 
  year 
  (postage 
  prepaid). 
  $6.40 
  to 
  foreign 
  sub- 
  

   scribers 
  of 
  countries 
  in 
  the 
  Postal 
  Union. 
  Remittances 
  should 
  be 
  made 
  either 
  by 
  

   money 
  orders, 
  registered 
  letters, 
  or 
  bank 
  checks. 
  . 
  

  

  