﻿PALEONTOLOGY 
  OF 
  ILLINOIS. 
  

  

  the 
  lateral 
  surface 
  of 
  this 
  side 
  the 
  tubercles 
  consist 
  of 
  simple, 
  invg- 
  

   alarly-conical, 
  radiately-soalptared 
  prominenoes, 
  their 
  apices 
  din 
  

   apward, 
  sometimes 
  coalescing 
  in 
  the 
  ohlique 
  rows, 
  forming 
  irregular, 
  

   sharp 
  crests 
  spanning 
  two 
  or 
  more 
  of 
  the 
  obscure 
  costs). 
  Similarly 
  

   confluent, 
  larger 
  tubercles 
  are 
  met 
  with 
  in 
  either 
  border, 
  where 
  tiny 
  

   form 
  uymmetrically-oblique 
  rows, 
  with 
  indications 
  of 
  a 
  curving 
  up- 
  

   ward 
  oil 
  gaining 
  the 
  left 
  side, 
  but 
  presenting 
  individual 
  variation 
  in 
  

   the 
  latter 
  respect 
  — 
  no 
  two 
  Bpeeimena 
  actually 
  agreeing. 
  

  

  In 
  regard 
  to 
  the 
  correspondence 
  of 
  the 
  characters 
  of 
  opp 
  

   Hanks 
  of 
  these 
  spines, 
  the 
  fine 
  example 
  described 
  by 
  Dr. 
  Leidy 
  offers 
  

   most 
  conclusive 
  evidence 
  bearing 
  on 
  their 
  dissimilarity, 
  and 
  which 
  

   might 
  readily 
  confuse 
  identifications 
  based 
  on 
  unique 
  specimens, 
  

   showing 
  opposite 
  Bides 
  of 
  the 
  spine. 
  The 
  latter 
  shows 
  an 
  individual 
  

   of 
  about 
  the 
  same 
  dimensions 
  as 
  the 
  example 
  abov< 
  alluded 
  to, 
  free 
  

   from 
  the 
  matrix 
  of 
  "iron-gray 
  limestone," 
  revealing 
  both 
  sides 
  of 
  

   the 
  spine, 
  the 
  anterior 
  border 
  of 
  which, 
  unfortunately, 
  fa 
  

   worn 
  smooth 
  obliterating 
  the 
  tuberoolation. 
  Compared 
  with 
  tbj 
  

   Louis 
  specimen, 
  the 
  right-side 
  tuberculatum 
  shows 
  approximately 
  

   the 
  same 
  disposition 
  in 
  oblique 
  rows 
  ascending 
  from 
  either 
  border 
  

   and 
  meeting 
  in 
  the 
  middle 
  where 
  their 
  continuity 
  is 
  intern;: 
  

  

  In 
  the 
  left 
  side 
  "the 
  tubercles 
  are 
  arranged 
  more 
  regularly 
  in 
  lon- 
  

   gitudinal 
  rows, 
  and 
  they 
  evince 
  a 
  tendency 
  to 
  become 
  continent 
  in 
  

   short 
  transverse 
  rows, 
  which 
  pursue 
  an 
  irregular 
  waving 
  course 
  

   acros> 
  thi 
  ray."' 
  with 
  a 
  general 
  alight 
  obliquity 
  ascending 
  from 
  near 
  

   the 
  anterior 
  border 
  where 
  the 
  large 
  confluent 
  tubercles 
  are 
  rather 
  

   suddenly 
  deflected 
  apward 
  and 
  cross 
  th< 
  bliquely, 
  diminishing 
  

  

  as 
  they 
  approach 
  the 
  right 
  flank, 
  precisely 
  as 
  shown 
  in 
  the 
  fragment 
  

   originally 
  described 
  by 
  the 
  authors 
  1. 
  VI, 
  PL 
  \\1I. 
  

  

  f. 
  Ufa). 
  The 
  posterior 
  border 
  is 
  occupied 
  by 
  three 
  or 
  more 
  

   tudinal 
  rows 
  of 
  tubercles, 
  laterally 
  oomproaoed, 
  the 
  margin 
  in 
  the 
  

   left 
  side 
  being 
  occupied 
  by 
  a 
  row 
  of 
  oonflnent 
  tubercles 
  obliquely 
  

  

  curved 
  upward 
  exactly 
  in 
  the 
  opposite 
  direction 
  to 
  the 
  similar 
  row 
  

   in 
  the 
  same 
  side 
  at 
  the 
  anterior 
  border. 
  The 
  SXampll 
  1 
  bj 
  

  

  Dr. 
  Leidy 
  is 
  reported 
  as 
  having 
  been 
  derived 
  from 
  the 
  Carboniferous 
  

   Limestone 
  of 
  Missouri 
  Territory; 
  the 
  exaol 
  formation 
  and 
  locality. 
  

  

  however, 
  are 
  unknown. 
  

  

  It 
  may 
  Well 
  be 
  questioned 
  whether 
  these 
  spines 
  a 
  

   rather 
  than 
  a 
  lateral 
  DOSitiOD 
  on 
  th. 
  body 
  Of 
  the 
  ti-h. 
  Their 
  thinks. 
  

  

  id 
  of 
  pressnting 
  that 
  absolnte 
  symmetry 
  oharaoteristie 
  of 
  <l 
  

  

  to 
  Qm 
  taberoulose 
  ornamentation. 
  

   ihow 
  in 
  Miiiin 
  t 
  r 
  i 
  . 
  • 
  : 
  1 
  1 
  features 
  which 
  may 
  be 
  mor. 
  m 
  a. 
  

  

  