﻿35 
  1 
  

  

  PALEONTOLOGY 
  OF 
  ILLIN( 
  

  

  lli.TKi.usniisMA 
  i.uac 
  ilk, 
  Wachsmnth, 
  Nov. 
  Sp. 
  

  

  //, 
  !, 
  roaohUtna 
  graoi 
  • 
  . 
  Wa< 
  iismith. 
  

  

  Fin. 
  1. 
  *ulo 
  viewof 
  aspocimon. 
  Fiff.SLhorl 
  itton 
  Of 
  the 
  li> 
  The 
  

  

  iirst 
  Qgare 
  enlarged 
  three 
  diameters, 
  the 
  other 
  M\ 
  <•. 
  

  

  Body 
  subolavate 
  or 
  irregularly 
  pyriform, 
  pointed 
  at 
  the 
  i 
  

  

  deeply 
  excavated 
  in 
  the 
  direction 
  of 
  the 
  rays. 
  From 
  the 
  foot 
  of 
  the 
  

   basals 
  to 
  the 
  radial 
  sinus 
  the 
  form 
  Is 
  eloDgate-obeonical, 
  the 
  - 
  

   at 
  the 
  outer 
  surface 
  being 
  straight 
  or 
  nearly 
  so. 
  The 
  radials 
  are 
  

   arched, 
  with 
  an 
  angularity 
  along 
  the 
  median 
  line, 
  which 
  culminates 
  

   in 
  the 
  lips, 
  hut 
  almost 
  disappears 
  on 
  approaching 
  the 
  hasi-radial 
  

   suture. 
  Intermediate 
  between 
  the 
  ambulacra 
  there 
  are 
  five 
  pyra- 
  

   mids, 
  formed 
  by 
  the 
  junction 
  of 
  the 
  adjacent 
  limbs 
  of 
  two 
  contigu- 
  

   ous 
  radials, 
  without 
  the 
  assistance 
  of 
  oral 
  plates. 
  Four 
  of 
  I 
  

   are 
  sharply 
  pointed, 
  projecting 
  conspicuously 
  above 
  the 
  level 
  of 
  the 
  

   summit 
  ; 
  the 
  fifth, 
  the 
  one 
  containing 
  the 
  anal 
  orifice, 
  is 
  a 
  little 
  

   lower 
  and 
  truncate. 
  Ambulacra, 
  placed 
  at 
  the 
  bottom 
  of 
  a 
  deep 
  

   sinus; 
  curving 
  gently 
  in 
  an 
  upward 
  direction. 
  The 
  gi 
  widtfa 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  