﻿INTRODUCTORY 
  REMARKS. 
  

  

  For 
  the 
  use 
  of 
  several 
  of 
  the 
  crinoids 
  described 
  and 
  figured 
  in 
  

   this 
  volume, 
  I 
  am 
  indebted 
  to 
  the 
  liberality 
  of 
  Mr. 
  L. 
  A. 
  Cox, 
  of 
  

   Keokuk, 
  Iowa, 
  who, 
  by 
  his 
  zeal 
  and 
  indefatigable 
  industry 
  as 
  a 
  col- 
  

   lector, 
  has 
  brought 
  together 
  one 
  of 
  the 
  finest 
  collections 
  of 
  these 
  

   beautiful 
  fossils 
  ever 
  obtained 
  from 
  the 
  Keokuk 
  limestone, 
  and 
  a 
  

   part 
  of 
  them 
  were 
  found 
  in 
  a 
  higher 
  position 
  in 
  the 
  Keokuk 
  group 
  

   than 
  that 
  from 
  which 
  this 
  class 
  of 
  fossils 
  has 
  usually 
  been 
  obtained. 
  

   These 
  came 
  from 
  a 
  sandy 
  stratum 
  only 
  a 
  few 
  inches 
  in 
  thickness, 
  

   situated 
  near 
  the 
  dividing 
  line 
  between 
  the 
  geodiferous 
  shales 
  of 
  

   the 
  Keokuk 
  group 
  and 
  the 
  overlying 
  Warsaw 
  beds, 
  which 
  form 
  the 
  

   upper 
  part 
  of 
  the 
  river 
  bluff 
  about 
  a 
  mile 
  below 
  the 
  steamboat 
  land- 
  

   ing, 
  where 
  the 
  fossils 
  were 
  obtained. 
  

  

  Another 
  very 
  interesting 
  and 
  productive 
  locality 
  was 
  found 
  by 
  Mr. 
  

   N. 
  K. 
  Burket, 
  of 
  Keokuk, 
  in 
  the 
  Keokuk 
  limestone 
  at 
  Hamilton, 
  

   Illinois, 
  and 
  from 
  this 
  a 
  part 
  of 
  the 
  following 
  species 
  were 
  obtained. 
  

   These 
  came 
  from 
  a 
  cherty 
  layer 
  some 
  three 
  or 
  four 
  inches 
  in 
  thick- 
  

   ness, 
  intercalated 
  near 
  the 
  top 
  of 
  the 
  quarry 
  rock 
  at 
  Hamilton, 
  some 
  

   five 
  or 
  six 
  feet 
  below 
  the 
  base 
  of 
  the 
  geodiferous 
  shales. 
  These 
  two 
  

   very 
  limited 
  horizons 
  have 
  furnished 
  all 
  the 
  Keokuk 
  species, 
  with 
  

   one 
  or 
  two 
  exceptions, 
  that 
  are 
  described 
  and 
  illustrated 
  in 
  the 
  fol- 
  

   lowing 
  pages. 
  

  

  The 
  species 
  from 
  the 
  St. 
  Louis 
  and 
  Chester 
  groups 
  were 
  all 
  col- 
  

   lected 
  by 
  the 
  author, 
  and 
  form 
  a 
  part 
  of 
  the 
  Illinois 
  State 
  

   Collection. 
  A. 
  H. 
  W. 
  

  

  