﻿INVEETEBEATES. 
  301 
  

  

  Column 
  round, 
  composed 
  of 
  short, 
  even 
  joints, 
  with 
  numerous 
  

   cirrhi 
  attached 
  at 
  short 
  intervals 
  on 
  opposite 
  sides, 
  which 
  are 
  com- 
  

   posed 
  of 
  rounded 
  joints 
  about 
  half 
  the 
  diameter 
  of 
  those 
  composing 
  

   the 
  column. 
  

  

  This 
  species 
  may 
  be 
  readily 
  distinguished 
  from 
  P. 
  venustus 
  and 
  

   P. 
  clytis, 
  by 
  the 
  bell-shaped 
  form 
  of 
  its 
  body 
  and 
  zigzag 
  arrange- 
  

   ment 
  of 
  the 
  arms. 
  

  

  Position 
  and 
  locality 
  : 
  Chester 
  limestone, 
  bluffs 
  of 
  the 
  Kaskaskia 
  

   river, 
  four 
  miles 
  above 
  Chester, 
  111. 
  

  

  No. 
  2,452, 
  Illinois 
  State 
  collection. 
  

  

  POTERIOCRINUS 
  CULTIDACTYLUS, 
  Hall. 
  

  

  PI. 
  XXX, 
  Fig. 
  1. 
  

  

  Poteriocrlnus 
  cultidaclylus. 
  Hall, 
  1859. 
  

  

  Supplementary 
  report 
  on 
  the 
  Palaeontology 
  of 
  Iowa, 
  p. 
  62. 
  

  

  "Body 
  elongato-turbinate 
  and 
  slightly 
  expanding 
  at 
  the 
  base 
  of 
  

   the 
  arms, 
  which 
  are 
  regularly 
  bifurcating 
  and 
  but 
  slightly 
  spread- 
  

   ing. 
  Basal 
  and 
  subradial 
  plates 
  unknown. 
  Eadial 
  series 
  consisting 
  

   of 
  three 
  plates 
  in 
  each 
  ray, 
  the 
  upper 
  one 
  of 
  which 
  is 
  a 
  bifurcating 
  

   plate. 
  First 
  radial 
  plates 
  pentagonal, 
  besides 
  the 
  truncated 
  angles. 
  

   Second 
  radials 
  about 
  as 
  long 
  as 
  wide, 
  quadrangular 
  with 
  truncated 
  

   angles. 
  Third 
  radials 
  pentagonal, 
  obtusely 
  wedge-formed 
  above, 
  and 
  

   supporting 
  on 
  each 
  side 
  a 
  series 
  of 
  eight 
  arm-plates, 
  the 
  upper 
  one 
  

   of 
  which 
  is 
  a 
  bifurcating 
  plate 
  ; 
  above 
  this, 
  on 
  tbe 
  outer 
  side, 
  there 
  

   is 
  a 
  bifurcation 
  on 
  the 
  twelfth 
  to 
  the 
  sixteenth 
  plate, 
  while 
  the 
  divis- 
  

   ion 
  on 
  the 
  other 
  side 
  remains 
  simple 
  so 
  far 
  as 
  can 
  be 
  traced 
  in 
  the 
  

   specimen. 
  This 
  character 
  applies 
  to 
  all 
  except 
  the 
  anterior 
  ray, 
  

   where 
  the 
  bifurcation 
  takes 
  place 
  on 
  the 
  twentieth 
  plate 
  above 
  tbe 
  

   first 
  division. 
  

  

  The 
  anal 
  series 
  consists 
  of 
  a 
  number 
  of 
  small 
  usually 
  hexagonal 
  

   plates. 
  

  

  The 
  plates 
  of 
  the 
  arms 
  are 
  round 
  upon 
  the 
  exterior 
  face, 
  a 
  little 
  

   wider 
  on 
  one 
  side 
  than 
  the 
  other 
  in 
  alternating 
  order. 
  The 
  surface 
  

   is 
  finely 
  granulose, 
  without 
  peculiar 
  markings." 
  

  

  The 
  above 
  description 
  was 
  not 
  drawn 
  from 
  the 
  specimen 
  figured, 
  

   but 
  from 
  one 
  found 
  many 
  years 
  ago, 
  and 
  now 
  in 
  the 
  writer's 
  collec- 
  

   tion, 
  but 
  was 
  not 
  accessible 
  when 
  the 
  figures 
  for 
  this 
  volume 
  were 
  

   drawn. 
  

  

  