﻿226 
  PALEONTOLOGY 
  OF 
  ILLINOIS. 
  

  

  fcioal 
  articular 
  wall, 
  which 
  latter 
  shows 
  a 
  Blight 
  concavity 
  betwei 
  

   the 
  angles, 
  the 
  anterior 
  angle 
  distinctly 
  truncated 
  for 
  the 
  narrow 
  

   oblique 
  articular 
  facet. 
  Anterior 
  and 
  posterior 
  margins 
  parallel, 
  

   nly 
  straight, 
  or 
  gently 
  arched 
  forward 
  with 
  a 
  slight 
  concavity 
  

   toward 
  the 
  inner 
  angle 
  in 
  front, 
  and 
  a 
  corresponding 
  convexity 
  in 
  

   the 
  posterior 
  margin, 
  inbeveled 
  to 
  the 
  basal 
  portion, 
  which 
  was 
  of 
  

   proportionate 
  vertical 
  depth. 
  The 
  basal 
  support 
  of 
  the 
  borders 
  is 
  

   not 
  preserved. 
  The 
  surface 
  of 
  unworn 
  teeth 
  exhibits 
  an 
  exceedingly 
  

   intricate 
  reticulated 
  ornamentation, 
  produced 
  by 
  the 
  rags 
  occupying 
  

   the 
  interspaces 
  between 
  the 
  punetffi, 
  the 
  prevalent 
  continuity 
  having 
  

   a 
  transverse 
  direction; 
  on 
  the 
  other 
  hand, 
  worn 
  sin- 
  

   rather 
  coarse, 
  crowded 
  puncta), 
  confluent 
  in 
  the 
  depressed 
  trai 
  

   belts. 
  Lateral 
  diameter 
  of 
  a 
  medium-size 
  smooth 
  tooth 
  across 
  the 
  

   posterior 
  margin, 
  37 
  mm.; 
  length 
  along 
  inner 
  border, 
  22 
  mm.; 
  

   depth 
  of 
  tooth, 
  at 
  least 
  B 
  mm. 
  

  

  Professor 
  Worthed 
  has 
  obtained 
  from 
  the 
  same 
  deposits, 
  ami 
  

   associated 
  with 
  the 
  foregoing 
  teeth, 
  a 
  single 
  imperfect 
  example 
  of 
  a 
  

   tooth 
  which 
  may 
  prove 
  to 
  be 
  identical 
  with 
  the 
  opposed 
  mandibular 
  

   form 
  of 
  the 
  present 
  species. 
  It 
  shows 
  a 
  medium 
  size 
  tooth, 
  quadri- 
  

   lateral 
  in 
  outline, 
  the 
  worn 
  anterior 
  margin 
  alightly 
  arcuate, 
  though 
  

   originally 
  probably 
  gently 
  arched, 
  corresponding 
  approximately 
  with 
  

   the 
  moderate 
  concavity 
  of 
  the 
  posterior 
  margin, 
  inner 
  border 
  making 
  

   nearly 
  a 
  right-angle 
  with 
  the 
  margins, 
  posterior 
  angle 
  truncated, 
  

   with 
  a 
  rather 
  prominent 
  angulation 
  about 
  one-third 
  the 
  distance 
  

   forward; 
  outer 
  border 
  unknown. 
  The 
  crown 
  i> 
  well 
  defined 
  all 
  

   round 
  from 
  the 
  deep, 
  slightly 
  excavated 
  hasal 
  walls, 
  which 
  arc 
  in- 
  

   beveled— 
  strongly 
  so 
  along 
  the 
  anterior 
  margin. 
  The 
  latter 
  

   accords 
  with 
  the 
  rather 
  marked 
  convexity 
  of 
  the 
  coronal 
  region 
  from 
  

   behind 
  forward, 
  giving 
  to 
  the 
  series 
  of 
  teeth 
  a 
  strongly 
  rolled 
  longi- 
  

   tudinal 
  section, 
  the 
  surface 
  showing 
  a 
  faint 
  transverse 
  furrow 
  in 
  the 
  

   anterior 
  half, 
  where, 
  as 
  also 
  in 
  the 
  slop, 
  bordering 
  the 
  posterior 
  

   margin, 
  the 
  Burface 
  presents 
  the 
  -aim 
  ornamentation 
  de- 
  

  

  scribed 
  in 
  connection 
  with 
  the 
  previously 
  mentioned 
  form, 
  the 
  n. 
  

   exposed 
  part- 
  showing 
  a 
  smooth, 
  densely 
  punet 
  

  

  corona] 
  area 
  is 
  nearly 
  plane, 
  or 
  faintly 
  d< 
  transversely, 
  with 
  

  

  :i 
  slight 
  depression 
  parallel 
  with 
  the 
  outer 
  border, 
  and 
  Bhowinj 
  

  

  full 
  in. 
  what 
  contrasting 
  with 
  the 
  opposed 
  maxillary 
  form. 
  

  

  Transverse 
  diameter 
  at 
  the 
  posterior 
  margin, 
  at 
  Last 
  10 
  mm.; 
  

   of 
  iiui.r 
  border, 
  22 
  mm.: 
  vertical 
  depth 
  of 
  tooth, 
  at 
  least 
  10 
  mm. 
  

   While 
  the 
  previously 
  noticed 
  maxillarj 
  form 
  hardly 
  requires 
  <1> 
  • 
  

   comparison 
  with 
  the 
  homologous 
  form 
  ol 
  I 
  

  

  