﻿171 
  PALEONTOLOGY 
  OF 
  ILLINOIS. 
  

  

  outer 
  extremity, 
  enamel 
  fold 
  relatively 
  deep 
  and 
  strongly 
  inbeveled 
  

   to 
  the 
  channeled 
  basal 
  rim, 
  which 
  is 
  also 
  beveled, 
  in 
  the 
  worn 
  ex- 
  

   ample 
  to 
  the 
  obtuse 
  inferior 
  edge; 
  poatero-lateral 
  or 
  oblique 
  border 
  

   similarly 
  gently 
  arched, 
  somewhat 
  undulated, 
  converging 
  at 
  an 
  angle 
  

   of 
  about 
  30° 
  with 
  the 
  opposite 
  border, 
  enamel 
  fold 
  rounded 
  and 
  

   inbeveled 
  to 
  the 
  shallow-channeled 
  basal 
  border; 
  inner 
  margin 
  

   gently 
  arched 
  round 
  the 
  base 
  of 
  the 
  coronal 
  prominence, 
  with 
  slight 
  

   concavity 
  in 
  passing 
  the 
  coronal 
  depression 
  to 
  the 
  sub-acute 
  post 
  

   rior 
  angle, 
  inbeveled 
  below. 
  Coronal 
  ridge 
  occupying 
  nearly 
  ball 
  the 
  

   anterior 
  coronal 
  area, 
  prominent, 
  gently 
  convex 
  along 
  the 
  broad 
  

   crest, 
  steeply 
  sloped 
  into 
  the 
  posterior 
  depression, 
  where 
  it 
  is 
  

   denned 
  by 
  a 
  slight 
  impressed 
  angulation, 
  posterior 
  alation 
  bc 
  

   elevated 
  along 
  the 
  outer 
  border. 
  Surface 
  punetatioo 
  comparatively 
  

   coarse, 
  irregular, 
  the 
  surface 
  toward 
  the 
  inner 
  margin 
  being 
  trai 
  

   versely 
  undulated 
  and 
  enveloped 
  in 
  the 
  dense 
  enamel 
  layer. 
  Infe- 
  

   rior 
  surface 
  gently 
  concave, 
  smooth. 
  Breadth 
  margin, 
  

   5 
  mm 
  ; 
  greatest 
  length, 
  10 
  mm. 
  

  

  The 
  unique 
  example 
  furnishing 
  the 
  foregoing 
  description 
  Bhoi 
  

   nearly 
  entire, 
  though 
  somewhat 
  worn, 
  tooth, 
  representing, 
  perhs 
  

   the 
  posterior 
  form 
  of 
  the 
  left 
  ramus 
  of 
  the 
  upper 
  jaw. 
  lt> 
  relati 
  

   appear 
  to 
  be 
  near 
  XystrodtU, 
  from 
  which, 
  however, 
  it 
  widely 
  departs 
  

   in 
  the 
  rounded 
  condition 
  of 
  the 
  enamel 
  fold 
  along 
  the 
  straight 
  bor- 
  

   der, 
  and 
  especially 
  in 
  the 
  coarse, 
  irregular 
  puneta, 
  which 
  show 
  no 
  

   sign 
  of 
  arrangement 
  in 
  parallel 
  transverse 
  row.-,. 
  There 
  ala 
  

   some 
  likeness 
  to 
  the 
  teeth 
  mentioned 
  under 
  the 
  head 
  of 
  Dtltod 
  

   eonvobthu, 
  from 
  the 
  same 
  formation, 
  so 
  far 
  a- 
  relates 
  to 
  the 
  chai 
  

   ter 
  of 
  the 
  puneta' 
  and 
  appearance 
  of 
  the 
  Burface 
  enamel: 
  but 
  the 
  

   tooth 
  in 
  question 
  is 
  not 
  homologous 
  with 
  the 
  supposed 
  maxilJ 
  

   posterior 
  form 
  of 
  typical 
  a 
  evidenced 
  by 
  the 
  qi 
  

  

  different 
  character 
  of 
  the 
  anterior 
  articular 
  border. 
  In 
  outline, 
  the 
  

   tooth 
  equally 
  resembles 
  Tomodua, 
  as 
  rep 
  1 
  by 
  authentic 
  

  

  ample* 
  oi 
  /• 
  eonvextu, 
  kg., 
  and 
  this 
  resemblance 
  

   to 
  the 
  coronal 
  contour; 
  but 
  we 
  are 
  not 
  sufficiently 
  familiar 
  with 
  the 
  

   character 
  of 
  the 
  articular 
  border 
  m 
  the 
  latter 
  genu 
  

  

  ine 
  its 
  exact 
  relations 
  with 
  the 
  form 
  lure 
  particularly 
  i 
  

  

  to, 
  r 
  . 
  therefore, 
  with 
  no 
  certain 
  convictions 
  as 
  to 
  th< 
  

  

  eric 
  relations 
  that 
  this 
  example 
  is 
  provisionally 
  placed 
  in 
  the 
  al 
  

  

  logical 
  p 
  rition 
  and 
  locality: 
  Upper 
  Burlington 
  lin 
  Bah- 
  

  

  it 
  Grove. 
  hesMoincs 
  county, 
  [owa. 
  

  

  