﻿144 
  PAL2E0NT0L0GI 
  OF 
  ILLINOI8. 
  

  

  although 
  in 
  outline 
  and 
  general 
  appearance 
  they 
  are 
  bo 
  markedly 
  

   different 
  one 
  from 
  the 
  other. 
  A 
  comparison 
  of 
  the 
  forms 
  reveals 
  

   the 
  same 
  depressed 
  or 
  sulcated 
  anterior 
  slope- 
  of 
  tin 
  principal 
  

   coronal 
  prominence, 
  very 
  oblique 
  anterior 
  portion 
  of 
  the 
  inner 
  mar- 
  

   gin 
  and 
  ita 
  abrupt 
  deflection 
  in 
  passing 
  around 
  the 
  base 
  of 
  the 
  

   nal 
  ridge 
  into 
  the 
  posterior 
  extremity; 
  even 
  the 
  articular 
  edge 
  of 
  the 
  

   anterior 
  borders 
  in 
  the 
  two 
  forms 
  is 
  very 
  like, 
  but 
  in 
  the 
  posl 
  

   lateral 
  borders 
  there 
  is 
  marked 
  dissimilarity 
  between 
  them, 
  nor 
  have 
  

   we 
  been 
  able 
  to 
  identify 
  amongst 
  the 
  material 
  before 
  nc 
  • 
  with 
  

  

  which 
  the 
  maxillary 
  posterior 
  teeth 
  were 
  associated. 
  Whether 
  the 
  

   upper 
  jaw 
  was 
  terminated 
  by 
  a 
  series 
  of 
  teeth, 
  such 
  as 
  undoubtedly 
  

   occupied 
  the 
  anterior 
  portion 
  of 
  the 
  jaw 
  in 
  CochUodus, 
  it 
  is 
  in 
  

   sible 
  at 
  the 
  present 
  time 
  to 
  more 
  than 
  conjecture. 
  

  

  The 
  genus 
  is 
  represented 
  1 
  >y 
  Bpecies 
  thus 
  far 
  authentically 
  rep 
  

   only 
  in 
  lower 
  Carboniferous 
  formations 
  in 
  Europe, 
  where 
  it 
  was 
  the 
  

   eot. 
  mporary 
  of 
  CochUodus. 
  In 
  America, 
  however, 
  its 
  representatives 
  

   range 
  from 
  near 
  the 
  base 
  of 
  the 
  lower 
  Carboniferous 
  (Burlii 
  

   limestone), 
  thence 
  through 
  the 
  sue 
  formations 
  up 
  into 
  the 
  

  

  Coal 
  Measures. 
  The 
  following 
  is 
  a 
  list 
  of 
  the 
  Bpecies 
  at 
  the 
  pr 
  

   time 
  known, 
  the 
  affinities 
  of 
  the 
  forms 
  being 
  recognized 
  in 
  accord- 
  

   ance 
  with 
  the 
  characteristics 
  cited 
  in 
  tl 
  icriptions 
  and 
  

   observations 
  : 
  

  

  Deltodut 
  eubleevis, 
  Agass., 
  mountain 
  lin 
  Britain. 
  

  

  ( 
  — 
  Pcecilodus 
  paratteliu, 
  McCoy, 
  and 
  possibly 
  Mc- 
  

  

  1>. 
  8andalinu8, 
  de 
  Koninck, 
  I 
  am, 
  

  

  I>. 
  tpatulatus, 
  N. 
  and 
  W.. 
  0. 
  Burlington 
  limestone. 
  

  

  /*. 
  oecidentalia, 
  (Leidy 
  — 
  sp.) 
  Keokuk 
  limestone. 
  -D. 
  tteUohu, 
  V 
  

  

  and 
  W.i 
  

  

  l>. 
  undulotus, 
  N. 
  and 
  W. 
  Keokuk 
  Limestone. 
  

  

  D. 
  latior, 
  St. 
  .1. 
  and 
  W. 
  Keokuk 
  limestone. 
  

  

  D. 
  Littoni, 
  M. 
  and 
  W. 
  Warsaw 
  limesl 
  

  

  l>. 
  cinetuUu, 
  St. 
  J. 
  and 
  W. 
  Warsavi 
  Lim 
  

  

  l>. 
  trilobut, 
  St. 
  .1. 
  and 
  W. 
  Warsaw 
  I 
  

  

  /». 
  pai 
  .1. 
  and 
  W. 
  St. 
  Louis 
  limi 
  

  

  I>. 
  intermedial, 
  St. 
  J. 
  and 
  W. 
  St. 
  Louia 
  limestone. 
  

  

  /). 
  cingvdai 
  od 
  W 
  , 
  Ch< 
  rt< 
  c 
  lim 
  

  

  I 
  >. 
  m, 
  ,-. 
  . 
  \, 
  wb. 
  I. 
  urbonifei 
  

  

  h 
  PowtUU, 
  St. 
  .1. 
  and 
  W. 
  I 
  

  

  /». 
  propinquus, 
  St. 
  .1. 
  and 
  \\ 
  . 
  Coal 
  M 
  

  

  