﻿PALAEONTOLOGY 
  OP 
  ILLINOIS. 
  

  

  PoTEBIOGBnfUS 
  PoPBHSIS, 
  Worthen. 
  

  

  pl 
  nix. 
  ric.u 
  

  

  Bui: 
  of 
  the 
  Illinois- 
  E 
  

  

  Boby 
  small, 
  obconic, 
  gradually 
  enrolling 
  from 
  the 
  base 
  to 
  the 
  sum- 
  

   init 
  of 
  the 
  radial 
  plates, 
  where 
  it 
  La 
  abort 
  once 
  and 
  a 
  half 
  

   long, 
  composed 
  of 
  smootb, 
  slightly 
  protuberant 
  plat. 
  

   project 
  about 
  one-half 
  their 
  length 
  beyond 
  the 
  oolumn, 
  and 
  form 
  a 
  

   low 
  pentagonal 
  cap. 
  

  

  Bubradials 
  on 
  the 
  anterior 
  side 
  hexagonal, 
  about 
  as 
  wide 
  as 
  I 
  

   Radials 
  pentagonal, 
  once 
  and 
  a 
  half 
  as 
  wide 
  as 
  long, 
  and 
  truncated 
  

   Bquarely 
  across 
  their 
  upper 
  margins 
  for 
  tb. 
  kion 
  of 
  the 
  brachial 
  

  

  plates. 
  

  

  Brachials 
  pentagonal, 
  length 
  and 
  breadth 
  about 
  equal, 
  rounded 
  

  

  ternary, 
  and 
  sharply 
  angular 
  above, 
  supporting 
  on 
  their 
  sloping 
  

   Bides 
  the 
  first 
  divisions 
  of 
  the 
  rays. 
  All 
  the 
  arms 
  on 
  the 
  anterior 
  

   Bide 
  divid. 
  again 
  on 
  the 
  seventh, 
  eighth 
  or 
  ninth 
  plate 
  the 
  

  

  brachials, 
  and 
  one 
  of 
  them 
  gives 
  off 
  a 
  I 
  branch 
  on 
  the 
  eighth 
  

  

  plate, 
  while 
  the 
  others 
  are 
  not 
  preserved 
  beyond 
  the 
  Beoond 
  division 
  

   above 
  the 
  brachials. 
  The 
  arms 
  are 
  composed 
  of 
  Bhorl 
  wide 
  plat 
  

   the 
  two 
  first 
  above 
  the 
  brachial-, 
  being 
  about 
  t* 
  

   Buoceeding 
  ones, 
  and 
  all 
  a 
  little 
  wedge-shaped. 
  Th< 
  arms 
  are 
  only 
  

  

  about 
  half 
  as 
  wide 
  above 
  the 
  second 
  bifurcation 
  :is 
  below. 
  Anal 
  

  

  plates 
  unknown. 
  

  

  Column 
  round, 
  composed 
  near 
  the 
  base 
  of 
  thick 
  and 
  tbinni 
  r 
  pl 
  

   alt. 
  mat. 
  ly 
  arranged. 
  

  

  This 
  Bpeoies 
  lb 
  related 
  to 
  Pot. 
  [Scapk.) 
  Randolph* 
  1. 
  Burv. 
  

  

  () 
  f 
  HI., 
  V..1. 
  .". 
  '1. 
  but 
  differs 
  in 
  its 
  wider 
  and 
  D 
  arly 
  

  

  ,11,1 
  ftnl] 
  ,,i. 
  in 
  thi 
  bifurcation 
  of 
  ti 
  

  

  -„,„ 
  <,iul 
  locality: 
  Chest 
  t 
  bin. 
  -ton. 
  . 
  I 
  . 
  111. 
  

  

  No. 
  -'. 
  L64, 
  Illinois 
  Stat, 
  collection. 
  

  

  p., 
  Worthen. 
  

  

  IVullrlll, 
  ' 
  

  

  In 
  ,,f 
  in.diue 
  than 
  h 
  

  

  mooth, 
  slightly 
  

  

  