﻿PALEONTOLOGY 
  OP 
  ILLINOIS 
  

  

  The 
  genius 
  Acrocrinu* 
  departs 
  from 
  most 
  Paheoerinoidea 
  in 
  two 
  

   important 
  points. 
  The 
  plates 
  of 
  the 
  calyx, 
  which 
  in 
  all 
  

   with 
  a 
  large 
  number 
  of 
  plates 
  d< 
  from 
  tl 
  • 
  - 
  to 
  

  

  the 
  top 
  of 
  the 
  calyx, 
  in 
  Acrocrimu 
  decidedly 
  increase 
  in 
  the 
  same 
  

   direction. 
  Another 
  striking 
  departure 
  is 
  that 
  the 
  radials 
  are 
  not 
  

   -connected 
  with 
  the 
  basals, 
  and 
  partly 
  not 
  even 
  among 
  each 
  otl 
  

   but 
  are 
  separated 
  by 
  several 
  rings 
  of 
  plates, 
  which 
  in 
  their 
  i 
  

   are 
  partly 
  radial, 
  partly 
  interradial, 
  and 
  which 
  have 
  apparently 
  

   representation 
  in 
  other 
  genera 
  of 
  the 
  PaUBoerinoidi 
  

  

  The 
  specimen 
  under 
  consideration 
  is 
  composed 
  of 
  96 
  plates, 
  some 
  

   of 
  them 
  extremely 
  minute. 
  There 
  air 
  two 
  comparatively 
  li 
  

   equal 
  in 
  size, 
  the 
  suture 
  passing 
  from 
  the 
  anterior 
  to 
  the 
  p 
  

   side, 
  which 
  together 
  form 
  a 
  concavity 
  within 
  the 
  truncate 
  pari 
  <<f 
  

   the 
  calyx. 
  The 
  basal 
  disk 
  is 
  surrounded 
  by 
  a 
  ring 
  of 
  tweh 
  

   small 
  triangular 
  pieces, 
  and 
  these 
  in 
  turn 
  are 
  nd 
  

  

  series 
  of 
  seven 
  plates 
  each, 
  arranged 
  like 
  the 
  former, 
  occupying 
  I 
  

   azygous 
  Bide, 
  and 
  are 
  separated, 
  in 
  place 
  by 
  radial-, 
  by 
  ■ 
  row 
  <.f 
  

   four 
  hexagonal 
  Bpecial 
  anal 
  plates, 
  which, 
  with 
  the 
  o 
  that 
  

  

  the 
  upper 
  side 
  of 
  the 
  upper 
  plate 
  is 
  not 
  excavated, 
  ! 
  itly 
  the 
  

  

  form 
  and 
  size 
  of 
  the 
  four 
  radial 
  plates 
  at 
  the 
  anterior 
  ray. 
  I 
  

   ray 
  has 
  exceptionally 
  four 
  radials. 
  hexagonal 
  like 
  the 
  anals, 
  which, 
  

  

  with 
  their 
  truncate 
  Bide, 
  are 
  connected 
  among 
  each 
  other, 
  and 
  with 
  

   the 
  beptagonal 
  piece 
  of 
  the 
  second 
  ring 
  heretofore 
  described. 
  I 
  

   four 
  lateral 
  rays 
  doI 
  only 
  consist 
  of 
  hut 
  three 
  plates, 
  hut 
  these 
  

   radials 
  have 
  also 
  a 
  very 
  different 
  form, 
  and 
  are 
  partly 
  die 
  

   The 
  first 
  is 
  hexagonal, 
  with 
  upper 
  and 
  low< 
  angular, 
  I 
  

  

  second 
  pentangular, 
  angular 
  below. 
  Only 
  in 
  a 
  BJDgli 
  ray 
  of 
  ' 
  

  

  oimen 
  do 
  the 
  angles 
  of 
  the 
  two 
  plates 
  toi 
  

  

  four 
  others 
  they 
  are 
  separated 
  by 
  plates 
  from 
  different 
  interradial 
  

   areas, 
  which 
  join 
  lure, 
  then 
  suture 
  forming 
  ■ 
  line 
  1" 
  

  

  angles 
  Of 
  the 
  two 
  radial-. 
  The 
  first 
  and 
  second 
  1 
  ire 
  all 
  

  

  connected 
  by 
  u 
  truncate 
  Bide. 
  The 
  third 
  radial- 
  are 
  on< 
  -half 
  wid 
  

   than 
  high, 
  hexagonal, 
  contrary 
  to 
  the 
  first 
  an 
  l. 
  which 
  an 
  

  

  little 
  highi 
  r. 
  

  

  . 
  - 
  • 
  

  

  trill 
  111 
  

  

  ' 
  

  

  