﻿302 
  PALEONTOLOGY 
  OK 
  ILLINOIS. 
  

  

  ition 
  ami 
  /<-.-,)/;///: 
  The 
  specimen 
  originally 
  descrn 
  

   obtained 
  from 
  the 
  Burlington 
  limestone, 
  near 
  Hamburg, 
  in 
  Calhoun 
  

   county, 
  and 
  the 
  one 
  figured 
  from 
  tin 
  Bame 
  horizon 
  at 
  Ifontesuma, 
  

  

  in 
  Pike 
  COUnty, 
  Illinois. 
  

  

  The 
  latter 
  is 
  number 
  1. 
  171 
  of 
  the 
  mini 
  - 
  Lotion. 
  

  

  Genus 
  ZBACRINU8, 
  Ti 
  

  

  V.\ 
  . 
  \( 
  i;;m 
  s 
  Coxani 
  a, 
  Worthen. 
  

   pl 
  xxyiii. 
  ri«L 
  

  

  /■ 
  i.i 
  mr, 
  February, 
  1882. 
  

  

  Bulletin 
  No. 
  I, 
  ol 
  the 
  Ulli 
  

  

  Body 
  of 
  medium 
  size, 
  basin-shaped, 
  more 
  than 
  twice 
  as 
  wia\ 
  

   high 
  to 
  the 
  top 
  of 
  the 
  radial 
  Bast 
  depressed, 
  and 
  the 
  ba 
  

  

  which 
  are 
  Bmall, 
  are 
  concealed 
  by 
  the 
  tirst 
  columnar 
  joints. 
  Bub- 
  

   radials 
  hexagonal, 
  once 
  and 
  a 
  half 
  as 
  wide 
  as 
  their 
  height 
  above 
  the 
  

   basal 
  concavity, 
  which 
  is 
  in 
  part 
  formed 
  by 
  the 
  upward 
  curvature 
  of 
  

   their 
  lower 
  angles, 
  their 
  upper 
  ang 
  ding 
  up 
  nearly 
  one-hall 
  

  

  the 
  length 
  of 
  the 
  radial 
  Beries. 
  

  

  Badiala 
  nearly 
  twice 
  as 
  wide 
  as 
  long, 
  pentagonal, 
  and 
  trun< 
  

   Bquarely 
  across 
  their 
  n 
  j 
  >i 
  »« 
  r 
  marginB 
  for 
  the 
  Bupport 
  of 
  the 
  brachial 
  

   I 
  he 
  anterior 
  ray 
  has 
  two 
  brachials, 
  the 
  lir.-t 
  one 
  quadran- 
  

   gular, 
  once 
  and 
  a 
  half 
  as 
  wide 
  as 
  long, 
  and 
  tL- 
  i 
  Bhort, 
  pent* 
  

   angular, 
  and 
  supporting 
  the 
  first 
  divisions 
  of 
  the 
  ray. 
  Each 
  dn 
  

   of 
  this 
  ray 
  bifurcates 
  again 
  on 
  fourteenth 
  or 
  th 
  plate, 
  the 
  

   outer 
  division 
  dividing 
  again 
  about 
  the 
  same 
  distance 
  above, 
  making 
  

  

  Bil 
  arms 
  to 
  thifl 
  ray. 
  

  

  The 
  other 
  rays, 
  so 
  far 
  as 
  can 
  he 
  seen 
  from 
  the 
  only 
  D 
  We 
  

  

  d, 
  bav( 
  only 
  a 
  Bingle 
  brachial 
  plate, 
  which 
  is 
  a 
  litl 
  

   than 
  the 
  radial 
  hi 
  low. 
  pentagonal, 
  and 
  Bupporta 
  on 
  its 
  upper 
  angles 
  

   two 
  stout 
  arms, 
  which 
  divide 
  iir>t 
  on 
  the 
  sixth 
  or 
  seventh 
  plate, 
  the 
  

   inner 
  division 
  continuing 
  simple 
  I 
  while 
  • 
  

  

  Mr. 
  nioi-, 
  on 
  the 
  tenth 
  to 
  the 
  twelfth 
  plate, 
  making 
  

   arms 
  to 
  each 
  of 
  tin 
  -> 
  rays, 
  or 
  thirty-eight 
  to 
  the 
  entire 
  indi- 
  

   \hh 
  

  

  \ 
  rni- 
  oomposod 
  of 
  short 
  quadrangular 
  joints, 
  rounded 
  exl 
  

   kher 
  delicate 
  pinnules 
  from 
  their 
  inner 
  mar 
  

   unknown. 
  Column 
  rather 
  Blender, 
  composed 
  of 
  round 
  pli 
  

  

  