﻿inl 
  PAL 
  EONTOLOGY 
  OF 
  ILLINOIS. 
  

  

  Teeth 
  supposed 
  to 
  represent 
  the 
  median 
  form 
  of 
  the 
  mandibles, 
  

   small, 
  trapezoidal 
  in 
  outline, 
  strongly 
  arched 
  from 
  within 
  outward. 
  

   lateral 
  (?) 
  border 
  nearly 
  straight, 
  with 
  Blight 
  obliquity 
  in 
  

   its 
  outward 
  and 
  slightly 
  forward 
  course, 
  basal 
  portion 
  evidently 
  

   shallow, 
  channeled, 
  and 
  defined 
  ahove 
  by 
  the 
  relatively 
  Btrong, 
  

   rounded 
  enamel 
  fold; 
  anterolateral 
  or 
  oblique 
  border 
  converging 
  

   from 
  the 
  suh-acute 
  inner 
  angle 
  to 
  point 
  of 
  Enrollment 
  at 
  an 
  an 
  

   of 
  about 
  20 
  with 
  the 
  opposite 
  border, 
  the 
  strong, 
  rounded 
  enamel 
  

   fold 
  projecting 
  beyond 
  the 
  comparatively 
  shallow, 
  channeled 
  basal 
  

   rim; 
  inner 
  margin 
  somewhat 
  abruptly 
  rounded 
  from 
  the 
  obtuse 
  

   posterior 
  angle, 
  thence 
  nearly 
  straight 
  to 
  the 
  anterior 
  angle, 
  usually 
  

   inbeveled 
  inferiorly. 
  Coronal 
  surface 
  showing 
  a 
  wide, 
  gently 
  depressed 
  

   acclivity 
  very 
  gradually 
  rising 
  from 
  the 
  antero-lateraJ 
  border 
  culmi- 
  

   nating 
  in 
  a 
  rounded 
  ridge, 
  the 
  posterior 
  slope 
  of 
  which 
  abruptly 
  

   descends 
  to 
  the 
  posterolateral 
  border 
  fold, 
  from 
  which 
  it 
  is 
  del':! 
  

   by 
  b 
  narrow 
  parallel 
  depression. 
  The 
  latter 
  feature 
  may 
  become 
  

   obsolete 
  in 
  worn 
  specimens- 
  indeed 
  the 
  whole 
  outer 
  half 
  of 
  the 
  

   coronal 
  surface 
  usually 
  bears 
  evidences 
  of 
  excessive 
  wear 
  from 
  D 
  

   The 
  inner 
  margin 
  of 
  the 
  crown 
  preserves 
  the 
  enamel 
  coating, 
  through 
  

   which 
  the 
  Bomewhai 
  irregular 
  orifices 
  of 
  the 
  tubular 
  structure 
  are 
  

   distinctly 
  discernible, 
  worn 
  surfaces 
  showing 
  a 
  iim 
  pitted 
  BtructUTC 
  

   with 
  t. 
  itudinally 
  elongate 
  pui 
  aotly 
  as 
  remarked 
  in 
  

  

  the 
  before 
  mentioned 
  form-. 
  A 
  medium 
  sized 
  tooth 
  n 
  m 
  

  

  greatest 
  diameter 
  between 
  the 
  inner 
  angles 
  7..". 
  mm: 
  length 
  along 
  

   postero-lateral 
  border 
  to 
  point 
  of 
  inrollmenl 
  nearly 
  l 
  mm. 
  

  

  In 
  assigning 
  the 
  las! 
  above 
  described 
  form 
  to 
  - 
  Uu, 
  we 
  

  

  pave 
  been 
  guided 
  chiefly 
  by 
  the 
  marked 
  resemblance 
  of 
  the 
  surface 
  

   punotation 
  to 
  that 
  observe! 
  in 
  the 
  posterior 
  forms 
  of 
  the 
  up] 
  

   lower 
  jaws 
  with 
  which 
  it 
  is 
  associated 
  in 
  the 
  same 
  deposits. 
  Bui 
  

  

  while 
  the 
  above 
  forms 
  are 
  represented 
  bj 
  l 
  individuals 
  each, 
  

  

  the 
  collections 
  contain 
  only 
  three 
  examples 
  ol 
  the 
  presenl 
  form, 
  and 
  

   two 
  of 
  these 
  are 
  proportionately 
  much 
  smaller 
  than 
  any 
  of 
  the 
  

   unplea 
  of 
  the 
  mandibular 
  posterior 
  teeth 
  with 
  which 
  it 
  i- 
  Bup- 
  

   thifl 
  form 
  waa 
  Bpeoifioally 
  associated; 
  but 
  Mr. 
  col- 
  

  

  lection 
  contains 
  a 
  Bingle 
  imperfect 
  en 
  of 
  i 
  larger 
  individual 
  

  

  whioh 
  corresponds 
  in 
  relal 
  the 
  ordinary 
  dimensions 
  of 
  the 
  

  

  mandibular 
  post) 
  riot 
  to 
  th. 
  

   In 
  general 
  outline 
  and 
  coronal 
  contour 
  the* 
  lome 
  

  

  emblanoes 
  in 
  common 
  with 
  the 
  forms 
  provisionall] 
  identified 
  with 
  

  

  