﻿

  PAL^ONTOLOGI 
  OF 
  ILLINOIS. 
  

  

  Column 
  of 
  medium 
  size, 
  round, 
  composed 
  at 
  the 
  upper 
  end 
  of 
  

   high 
  joints-. 
  

  

  The 
  ornamentation 
  of 
  the 
  radials 
  consists 
  of 
  indistinct 
  ntric 
  

  

  curves 
  suh-])arallel 
  with 
  the 
  arched 
  upper 
  surface 
  of 
  the 
  1 
  

   The 
  ornamentation 
  of 
  the 
  oral 
  plates, 
  as 
  in 
  most 
  Bpeoies 
  of 
  J 
  

   crinvj, 
  is 
  sharply 
  divided 
  by 
  two 
  longitudinal 
  lines, 
  the 
  median 
  part 
  

   (which 
  in 
  position 
  and 
  somewhat 
  in 
  form, 
  at 
  the 
  four 
  lateral 
  

   of 
  the 
  body, 
  corresponds 
  to 
  the 
  large 
  anal 
  plate 
  of 
  the 
  ; 
  

   siilc) 
  is 
  more 
  or 
  less 
  destitute 
  of 
  ornament. 
  The 
  two 
  sides, 
  how- 
  

   ever, 
  are 
  crowded 
  with 
  rows 
  of 
  small 
  grannies, 
  arranged 
  so 
  i 
  

   divide 
  the 
  field 
  into 
  narrow 
  parallel 
  spaces, 
  which 
  are 
  trai 
  

   arranged, 
  and 
  of 
  the 
  width 
  of 
  the 
  pore-pieces. 
  

  

  Observations. 
  — 
  EUxacrinuB 
  obovattu 
  differs 
  from 
  I 
  

   crinus) 
  angrdarit, 
  Lyon, 
  in 
  the 
  greater 
  length 
  of 
  the 
  body, 
  and 
  in 
  

   haying 
  straight 
  and 
  not 
  concave 
  sides. 
  It 
  resembles, 
  p< 
  ri 
  

   closest 
  Elaacrinus 
  [Nucleocrinut) 
  Uieina 
  Hall, 
  and 
  may 
  he 
  identical 
  

   with 
  the 
  larger 
  form 
  noticed 
  in 
  the 
  same 
  paper, 
  and 
  which 
  Hall 
  consid- 
  

   ered 
  a 
  variety 
  or 
  more 
  adult 
  phase 
  of 
  the 
  above 
  si 
  Hall 
  de- 
  

   scribes 
  the 
  latter 
  a,s 
  more 
  expanded 
  in 
  the 
  upper 
  part 
  of 
  the 
  I 
  

   with 
  the 
  base 
  proportionally 
  narrower, 
  and 
  this 
  agrees 
  with 
  our 
  

   species; 
  hut 
  the 
  hody 
  is 
  comparatively 
  longer 
  than 
  in 
  Hall's 
  smaller 
  

   type; 
  while 
  it 
  should, 
  if 
  represent 
  i 
  ng 
  the 
  adult 
  form 
  of 
  the 
  other. 
  

   (according 
  to 
  Wachsmuth; 
  see 
  the 
  preceding 
  paper), 
  on 
  the 
  

   trary 
  be 
  wider 
  and 
  not 
  higher. 
  In 
  Elaacrinut 
  /».•;»,/ 
  the 
  1 
  

   almost 
  on 
  a 
  plane 
  with 
  the 
  radials. 
  and 
  the 
  smbulaors 
  touch 
  the 
  

   bottom, 
  which 
  is 
  not 
  the 
  case 
  in 
  /•-'. 
  obovattU', 
  in 
  the 
  former 
  the 
  

   lower 
  truncate 
  portions 
  are 
  much 
  wider, 
  and 
  the 
  1 
  

   being 
  deeply 
  concave, 
  are 
  provided 
  with 
  an 
  elongate 
  node 
  in 
  the 
  

   center. 
  

  

  The 
  above 
  description 
  was 
  made 
  from 
  ten 
  Bpecimens 
  of 
  all 
  s 
  

   the 
  largesi 
  one 
  measaril 
  inch 
  and 
  thn- 
  quarters 
  in 
  lei 
  

  

  the 
  smallest 
  S< 
  \eii 
  eight 
  lis 
  of 
  an 
  inch. 
  

  

  logical 
  }»>sitt">i. 
  Pound 
  in 
  the 
  shale- 
  of 
  the 
  Hamilton 
  

  

  group 
  at 
  Buffalo, 
  ill 
  linn 
  stone 
  of 
  the 
  same 
  age 
  at 
  Iowa 
  City, 
  and 
  

   ,-it 
  the 
  top 
  of 
  the 
  Hamilton 
  group 
  in 
  the 
  Thunder 
  Bay 
  region 
  of 
  

   Northern 
  Michigan. 
  

  

  The 
  original 
  specimens 
  an 
  in 
  the 
  collection 
  of 
  Mr. 
  Charles 
  W 
  

  

  ninth 
  and 
  in 
  mv 
  own. 
  

  

  