﻿PAL.EONTOLOGY 
  OF 
  ILLINOIS. 
  

  

  I'..ti:i;1(ki;ims 
  ForNTAiNKN>i-. 
  Wbrthen. 
  

  

  PL 
  XXX. 
  Fit;. 
  II. 
  

   :i;n. 
  February 
  

  

  Bull'Illi 
  N". 
  1. 
  of 
  II 
  \- 
  

  

  Body 
  andei 
  medium 
  size, 
  rapidly 
  spreading 
  from 
  the 
  base 
  to 
  the 
  

   top 
  of 
  the 
  radial 
  series, 
  where 
  it 
  is 
  about 
  twice 
  as 
  wide 
  as 
  high. 
  

   Basalfl 
  small 
  and 
  concealed 
  by 
  the 
  first 
  columnar 
  joints. 
  Subra 
  

  

  '.uial 
  and 
  heptagonal, 
  length 
  and 
  breadth 
  about 
  equal. 
  Badials 
  

   once 
  an. 
  I 
  a 
  half 
  as 
  wide 
  as 
  long, 
  pentagonal, 
  with 
  a 
  well 
  d« 
  

   suture 
  between 
  them 
  and 
  the 
  brachial 
  plates. 
  Brachials 
  about 
  twice 
  

   as 
  long 
  as 
  wide, 
  pentagonal, 
  and 
  narrower 
  in 
  the 
  middle 
  than 
  at 
  the 
  

   ends 
  and 
  supporting 
  two 
  arms 
  on 
  their 
  apper 
  slop, 
  . 
  the 
  

  

  brachial 
  on 
  the 
  anterior 
  ray 
  being 
  longer 
  and 
  more 
  sons 
  than 
  

  

  the 
  <>thei>. 
  arms 
  apparently 
  hut 
  two 
  to 
  the 
  ray. 
  and 
  

   long 
  zigzag 
  joints, 
  constricted 
  in 
  the 
  middle 
  and 
  giving 
  »'tf 
  "»> 
  "Itcr- 
  

   ides 
  from 
  their 
  apper 
  angles 
  strong 
  pinnules, 
  thai 
  are 
  about 
  

  

  half 
  a- 
  large 
  in 
  diameti 
  r 
  as 
  the 
  arm-. 
  

  

  Tin- 
  first 
  anal 
  plate 
  i- 
  nearly 
  quadrangular 
  in 
  form, 
  and 
  l 
  

   tween 
  two 
  of 
  the 
  Bubradiala 
  and 
  under 
  the 
  left 
  aide 
  of 
  the 
  right 
  

  

  terior 
  radial. 
  The 
  Beoond 
  and 
  third 
  are 
  a 
  little 
  -mailer 
  than 
  

  

  and 
  above 
  these 
  there 
  i> 
  a 
  doable 
  series 
  of 
  small 
  plate- 
  thai 
  

  

  op 
  to 
  the 
  base 
  of 
  the 
  ventral 
  tube. 
  

  

  Tli 
  is 
  species 
  is 
  rather 
  closely 
  related 
  to 
  /' 
  S 
  Hut. 
  

  

  of 
  Hall, 
  low 
  . 
  part 
  -J. 
  hut 
  differs 
  from 
  that 
  in 
  tin 
  form 
  and 
  

  

  proportions 
  of 
  the 
  plat.- 
  of 
  the 
  body, 
  and 
  in 
  the 
  

  

  of 
  th< 
  

  

  ■ti>>„ 
  tmd 
  locality: 
  St. 
  Louis 
  lin 
  fountain 
  creek, 
  Monroe 
  

  

  county, 
  Dlinois. 
  

  

  No. 
  2, 
  I 
  ".">. 
  Illinois 
  State 
  collection. 
  

  

  I 
  

   iiik! 
  v\.n> 
  nil 
  frOI 
  

  

  