﻿192 
  PALAEONTOLOGY 
  OF 
  ILLINOIS. 
  

  

  bo 
  far 
  as 
  the 
  meagre 
  materials 
  at 
  the 
  preseni 
  time 
  in 
  hands 
  per- 
  

   mit 
  of 
  being 
  determined. 
  

  

  The 
  earliest 
  representatives 
  of 
  the 
  genus 
  occurring 
  in 
  American 
  

   rocks 
  were 
  discovered 
  by 
  Mr. 
  Springer 
  in 
  Lower 
  Carboniferous 
  

  

  i, 
  probably 
  of 
  Chester 
  age, 
  of 
  New 
  Mexico; 
  the 
  typical 
  repre 
  

   sentative 
  species, 
  OrthopUurodus 
  oa/rbonaritu, 
  belongs 
  to 
  the 
  Upper 
  

  

  Carboniferous, 
  the 
  upper 
  division 
  of 
  which 
  has 
  afforded 
  the 
  majority 
  

   of 
  specimens 
  thus 
  far, 
  although 
  apparently 
  the 
  same 
  species 
  i- 
  

   unfrequently 
  met 
  with 
  in 
  deposits 
  near 
  the 
  base 
  of 
  the 
  

   Measures. 
  

  

  Ortiiopleurodus 
  carbonarhs, 
  (X. 
  and 
  W. 
  sp.) 
  pa 
  

  

  PL 
  XIII. 
  tig. 
  I 
  

   . 
  Newbbbbt 
  und 
  Wobthu, 
  1806, 
  111. 
  QeoL 
  Surv.. 
  n. 
  p. 
  i»4, 
  pL 
  X 
  

   f. 
  i. 
  :.. 
  

  

  Ins 
  angularit, 
  NbwBBBBT 
  and 
  Wokthen. 
  1889, 
  III. 
  QeoL 
  Surv.. 
  II. 
  p. 
  '.'7. 
  I'!. 
  IX. 
  f. 
  1 
  

  

  A 
  singularly 
  interesting 
  group 
  of 
  teeth 
  discovered 
  by 
  Mr. 
  L. 
  A. 
  

   Fuller 
  in 
  the 
  shales 
  over 
  Coal 
  No. 
  5 
  of 
  the 
  Illinois 
  General 
  Section 
  

   of 
  Coal 
  Measure 
  strata, 
  at 
  Floomington, 
  leaves 
  little 
  room 
  for 
  doubt 
  

   respecting 
  the 
  specific 
  identity 
  of 
  the 
  above 
  cited 
  forms, 
  and 
  with 
  

   which 
  is 
  associated 
  a 
  third 
  form 
  probably 
  holding 
  a 
  position 
  imme- 
  

   diately 
  in 
  advance 
  of 
  the 
  posterior 
  tooth 
  of 
  the 
  mandibles, 
  that 
  

   originally 
  described 
  under 
  the 
  name 
  ]>clt'>ilu.< 
  angularit. 
  This 
  

   "second" 
  or 
  median 
  tooth 
  of 
  the 
  mandible 
  is 
  distinguished 
  by 
  its 
  

   triangular 
  outline, 
  straight 
  postero-lateril 
  border 
  corresponding 
  in 
  

   ooadaptation 
  with 
  the 
  articular 
  border 
  of 
  the 
  above 
  mentioned 
  pos- 
  

   terior 
  tooth, 
  and 
  the 
  uniform 
  depressed 
  coronal 
  contour. 
  A 
  similar 
  

  

  tooth 
  has 
  been 
  obtained 
  from 
  the 
  Upper 
  Coal-Measure 
  strata 
  near 
  

  

  '.a. 
  Kansas, 
  where 
  individuals 
  of 
  the 
  long 
  posterior 
  teeth 
  of 
  the 
  

   upper 
  jaw 
  (Sandalodua 
  carbonarius) 
  have 
  also 
  been 
  found 
  : 
  and 
  only 
  

   recently 
  Professor 
  Worthen 
  has 
  brought 
  from 
  the 
  Upper 
  Coal 
  - 
  

   aSalle, 
  representatives 
  of 
  all 
  three 
  forms. 
  The 
  generic 
  dii 
  

   si-, 
  founded 
  on 
  the 
  typical 
  Bpecifio 
  form- 
  beloi 
  

   Bpeoies, 
  sufficiently 
  describes 
  the 
  individual 
  characteristics 
  of 
  the 
  

   various 
  dental 
  elements 
  here 
  ascribed 
  to 
  it. 
  

  

  Tlu 
  group 
  of 
  teeth 
  discovered 
  by 
  Mr. 
  Puller, 
  which 
  bear 
  i 
  

   appearnoe 
  of 
  having 
  belonged 
  to 
  one 
  and 
  the 
  same 
  individual, 
  pre- 
  

   the 
  following 
  proportionate 
  measurements: 
  Ma\r. 
  

  

  rved 
  length 
  along 
  the 
  der 
  18 
  mm. 
  ; 
  

  

  breadth 
  7 
  mm. 
  . 
  b 
  at 
  broki 
  i 
  itj 
  6 
  mm. 
  

  

  i.. 
  nth 
  ,,i 
  mandible, 
  I 
  l« 
  ngth 
  from 
  i 
  i 
  itren 
  

  

  