﻿lis 
  PALEONTOLOGY 
  OF 
  ILLINOIS. 
  

  

  line 
  uniting 
  the 
  inner/ 
  anterior 
  and 
  posterior 
  angles, 
  basal 
  portion 
  

   ohanneled, 
  coronal 
  enamel 
  forming 
  a 
  narrow 
  inbeveled 
  fold 
  along 
  

   the 
  upper 
  edge; 
  postero-lateral 
  border 
  very 
  oblique, 
  forming 
  an 
  

   angle 
  of 
  Id 
  to 
  50 
  with 
  the 
  opposite 
  border, 
  in 
  respect 
  to 
  basal 
  

   portion 
  and 
  shallow 
  enamel 
  fold, 
  presenting 
  the 
  usual 
  generic 
  char- 
  

   acteristics; 
  inner 
  margin 
  strongly 
  arched 
  from 
  the 
  subacute 
  posterior 
  

   extremity 
  round 
  the 
  base 
  of 
  the 
  posterior 
  lobe, 
  in 
  front 
  of 
  which 
  it 
  

   forms 
  a 
  rather 
  deep 
  broad 
  sinus, 
  and 
  again 
  broadly 
  arched 
  in 
  pi 
  

   ing 
  the 
  anterior 
  coronal 
  prominence 
  to 
  the 
  obtuse 
  anterior 
  angle. 
  

   Coronal 
  region 
  nearly 
  centrally 
  divided 
  by 
  the 
  median 
  depression; 
  

   posterior 
  lobe 
  prominent, 
  anterior 
  face 
  steeply 
  rising 
  into 
  the 
  

   rounded 
  crest, 
  whence 
  the 
  broader 
  slope 
  more 
  gradually 
  and 
  regu- 
  

   larly 
  descends 
  with 
  slight 
  transverse 
  convexity 
  to 
  the 
  postero- 
  

   lateral 
  border, 
  just 
  above 
  which 
  lies 
  a 
  faint 
  depressed 
  parallel 
  bell 
  ; 
  

   median 
  depression 
  occupying 
  less 
  than 
  one-fourth 
  the 
  lateral 
  area 
  

   of 
  the 
  surface, 
  rather 
  deeply 
  excavated 
  and 
  usually 
  well 
  defined 
  ; 
  

   crest 
  of 
  anterior 
  lobe 
  near 
  the 
  posterior 
  side, 
  the 
  broad 
  slope 
  de- 
  

   scending 
  in 
  regular 
  convexity 
  to 
  the 
  antero-lateral 
  border. 
  Sur- 
  

   face 
  marked 
  by 
  transverse 
  rugsa 
  or 
  imbrications 
  over 
  the 
  less 
  

   abraded 
  portion 
  of 
  the 
  posterior 
  lobe, 
  and 
  which 
  on 
  reaching 
  the 
  

   median 
  depression 
  are, 
  in 
  some 
  instances, 
  rather 
  strongly 
  d< 
  

   from 
  a 
  direct 
  course 
  downwards 
  and 
  forward, 
  becoming 
  obsolete 
  in 
  

   the 
  region 
  of 
  the 
  anterior 
  lobe, 
  which 
  is 
  occupied 
  by 
  irregular 
  prom- 
  

   inences, 
  producing 
  an 
  elegant 
  verrucose 
  ornamentation, 
  irregular 
  

   ridges 
  sometimes 
  taking 
  the 
  place 
  of 
  the 
  verrucose 
  promii 
  

   surface 
  punctsa 
  line, 
  spared 
  by 
  little 
  more 
  than 
  their 
  own 
  diameter. 
  

   A 
  mature 
  specimen 
  measures 
  in 
  greatest 
  diameter 
  between 
  the 
  im 
  

   angles 
  K) 
  nun.; 
  length 
  of 
  antero-lateral 
  border 
  to 
  p. 
  nut 
  of 
  inroll- 
  

   ment 
  about 
  15 
  mm. 
  

  

  Mandibular 
  posterior 
  teeth 
  Bub-trapezoidal 
  in 
  outline. 
  Btrongly 
  

   arched 
  and 
  inrolled. 
  antero-lateral 
  border 
  moderately 
  oblique 
  in 
  

   its 
  outward 
  ami 
  forward 
  course 
  from 
  the 
  very 
  obtuse 
  inner 
  angle, 
  

   ohanneled 
  and 
  limited 
  above 
  by 
  the 
  narrow 
  enameled 
  fold 
  ; 
  postero- 
  

   lateral 
  border 
  converging 
  toward 
  point 
  of 
  inroUmenl 
  at 
  an 
  angl< 
  of 
  

   50 
  . 
  or 
  less, 
  with 
  the 
  inner 
  margin 
  presenting 
  the 
  canal 
  ohanneled 
  

   condition 
  and 
  enamel 
  fold 
  above; 
  inner 
  mi 
  arched 
  

  

  round 
  lli. 
  bass 
  of 
  the 
  median 
  ridge, 
  with 
  a 
  broad 
  CUrva- 
  

  

  tnre 
  behind 
  in 
  passing 
  into 
  the 
  product 
  d 
  subacute 
  i 
  n 
  mity. 
  

  

  Median 
  lobi 
  of 
  orown 
  oulminating 
  in 
  a 
  sharply 
  rounded 
  

  

  and 
  nor 
  of 
  a 
  lim 
  through 
  the 
  centre 
  of 
  tiie 
  tooth, 
  steeply 
  sloping 
  

   and 
  in. 
  ■>;>> 
  tin 
  mo, 
  I, 
  lately 
  depressed 
  anterior 
  belt, 
  the 
  Op] 
  

  

  