﻿224 
  PALEONTOLOGY 
  OF 
  ILLINOIS. 
  

  

  the 
  upper 
  jaw 
  of 
  the- 
  above 
  speeiee 
  agnized 
  in 
  the 
  teeth 
  which 
  

  

  Messrs. 
  Newberry 
  and 
  Worthen 
  identified 
  with 
  Psamirwdm 
  por, 
  

   of 
  A 
  ■<■' 
  »« 
  evidently 
  most 
  intii 
  related, 
  so 
  

  

  far 
  as 
  may 
  be 
  judged 
  from 
  th 
  rity 
  in 
  I 
  [La 
  of 
  their 
  - 
  

  

  ficial 
  coronal 
  structure, 
  which 
  is. 
  indeed, 
  identical 
  in 
  both 
  of 
  I 
  

   forms. 
  We 
  aiv. 
  therefore, 
  convinced 
  that 
  they 
  . 
  | 
  

  

  one 
  and 
  the 
  same 
  Bp< 
  si. 
  a, 
  presenting 
  the 
  same 
  combination 
  of 
  .! 
  

   tal 
  apparatus 
  observed 
  in 
  the 
  several 
  species 
  described 
  in 
  the 
  fore- 
  

   es. 
  

  

  The 
  latter 
  form 
  is 
  distinguished 
  by 
  its 
  transversely 
  elongate 
  tra- 
  

   pezoidal 
  outline, 
  the 
  course 
  of 
  the 
  lateral 
  , 
  and 
  g 
  

  

  tour 
  of 
  the 
  coronal 
  region 
  intimately 
  repeal 
  

  

  in 
  Pgammodus 
  plenus, 
  of 
  the 
  St. 
  Louis 
  formation. 
  The 
  inner 
  I 
  

  

  which 
  is 
  similarly 
  marked 
  by 
  a 
  slight 
  angulation 
  a 
  little 
  in 
  a 
  

  

  the 
  middle, 
  shows 
  a 
  distinct 
  truncation 
  of 
  the 
  posterior 
  ai 
  

   with 
  a 
  narrow 
  articular 
  facet. 
  In 
  the 
  character 
  of 
  tl 
  „,] 
  

  

  posterior 
  margins, 
  also, 
  intimafe 
  

  

  above 
  Bpeeies. 
  lint 
  the 
  examples 
  of 
  the 
  ; 
  form 
  an 
  jia- 
  

  

  bly 
  of 
  greater 
  depth 
  and 
  more 
  solid 
  or 
  massive 
  p 
  an 
  d 
  the 
  

  

  punctffi 
  of 
  the 
  coronal 
  surf 
  . 
  fi'mer 
  

  

  numerous 
  even 
  than 
  remarked 
  in 
  th< 
  iponding 
  teeth 
  o( 
  p. 
  

  

  A 
  maturt 
  tooth 
  c 
  . 
  lliall;i 
  

  

  across 
  the 
  inner 
  margin 
  39 
  mm. 
  ; 
  length 
  along 
  inn. 
  

   greatest 
  depth 
  of 
  tooth 
  10 
  mm. 
  

  

  fber 
  with 
  the 
  i 
  form, 
  both 
  i 
  ;,, 
  the 
  

  

  " 
  horizon, 
  the 
  species 
  is 
  readily 
  ushed 
  

  

  which 
  it 
  has 
  already 
  been 
  eompan 
  d. 
  and 
  of 
  which 
  it 
  is 
  an 
  i: 
  

  

  ( 
  ' 
  x;l, 
  "l' 
  lr 
  " 
  f 
  a 
  n 
  'i 
  ,li 
  rds 
  their 
  relatit 
  

  

  with 
  the 
  Europ< 
  an 
  t< 
  eth 
  originally 
  d< 
  Bcribed 
  by 
  Prol 
  d< 
  r 
  

  

  the 
  name 
  of 
  Psammodus 
  p, 
  it 
  hardly 
  probable 
  that 
  

  

  that 
  B] 
  bo 
  variabli 
  

  

  logical 
  position 
  and 
  locality: 
  I 
  : 
  | 
  

  

  PSAMMOm 
  - 
  \. 
  and 
  \Y. 
  

  

  I'l 
  M\ 
  | 
  

  

  i 
  and 
  Woi 
  pi 
  XI 
  

  

  the 
  type 
  Bpeoimen, 
  the 
  from 
  il 
  .. 
  

  

  mtain 
  other 
  h 
  

  

  to 
  the 
  a] 
  

   jaws, 
  which 
  are 
  believed 
  to 
  .ally 
  id< 
  with 
  th< 
  

  

  