﻿Jlias. 
  D. 
  Walcott, 
  

  

  U. 
  S. 
  Geol. 
  Survey. 
  

  

  YOL. 
  IX. 
  MARCH, 
  1900. 
  

  

  Established 
  by 
  BENJAMIN 
  SILLIMAN 
  in 
  1818. 
  

  

  THE 
  

  

  AMERICAN 
  

  

  JOURNAL 
  OP 
  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. 
  

  

  FOURTH 
  SERIES. 
  

   YOL. 
  IX— 
  [WHOLE 
  NUMBER, 
  CLIX.] 
  

  

  No. 
  51.— 
  MARCH, 
  1900. 
  

  

  XEW 
  HAVEN, 
  CONNECTICUT. 
  

   1900. 
  

  

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

  

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