﻿86 
  PALAEONTOLOGY 
  OF 
  ILLINOIS. 
  

  

  tlic 
  downward 
  and 
  slightly 
  outward 
  produced 
  basal 
  rim. 
  A 
  medium 
  

   sized 
  tooth 
  measures 
  between 
  the 
  angles 
  of 
  the 
  inner 
  margin 
  ~> 
  

   m 
  m, 
  and 
  about 
  the 
  same 
  as 
  the 
  length 
  along 
  the 
  antero-lateral 
  

   border. 
  

  

  Geological 
  position 
  and 
  localities: 
  St. 
  Louis 
  formation: 
  St 
  Louis, 
  

   Mo., 
  Alton, 
  111., 
  Pella, 
  Iowa. 
  

  

  Vaticinodus? 
  similis, 
  St. 
  J. 
  and 
  \Y. 
  

  

  PL 
  IV. 
  Fitf. 
  17-19. 
  

  

  Maxillary 
  posterior 
  teeth 
  very 
  small, 
  subspatulate 
  in 
  outline, 
  very 
  

   obliquely 
  inrolled. 
  Antero-lateral 
  border 
  with 
  moderate 
  obliquity 
  

   outward 
  and 
  forward, 
  coronal 
  fold 
  very 
  narrow 
  and 
  inbeveled 
  to 
  the 
  

   shallow, 
  channeled 
  basal 
  rim; 
  postero-lateral 
  border 
  slightly 
  arched, 
  

   basal 
  portion 
  channeled 
  and 
  limited 
  above 
  by 
  the 
  inbeveled 
  coronal 
  

   fold, 
  posteriorly 
  expanding 
  beyond 
  the 
  coronal 
  border 
  terminating 
  

   in 
  the 
  sharply-rounded 
  posterior 
  extremity; 
  inner 
  margin 
  abruptly 
  

   and 
  deeply 
  arched 
  from 
  the 
  posterior 
  angle 
  round 
  the 
  base 
  of 
  the 
  

   coronal 
  prominence, 
  thence 
  more 
  gently 
  curved 
  to 
  the 
  obtuse 
  

   anterior 
  angle. 
  Coronal 
  prominence 
  occupying 
  about 
  half 
  the 
  

   entire 
  area 
  of 
  the 
  crown, 
  moderately 
  and 
  regularly 
  arched 
  trans- 
  

   versely, 
  culminating 
  in 
  the 
  low 
  rounded 
  crest 
  near 
  the 
  anterior 
  

   side 
  where 
  it 
  is 
  more 
  or 
  less 
  well 
  defined 
  from 
  the 
  plain 
  anterior 
  

   area 
  into 
  which 
  the 
  slope 
  merges. 
  Surface 
  olosely 
  and 
  finely 
  punc- 
  

   tate, 
  the 
  anterior 
  region 
  showing 
  faint 
  revolving 
  plica. 
  Breadth 
  

   between 
  the 
  angles 
  of 
  the 
  inner 
  margin 
  about 
  '.» 
  m 
  m. 
  : 
  length 
  

   along 
  antero-lateral 
  border 
  probably 
  8 
  mm. 
  A 
  large 
  tooth 
  

   measures 
  22 
  m 
  m. 
  across 
  the 
  inner 
  margin, 
  and 
  6 
  DQ 
  in. 
  at 
  the 
  

   antero-lateral 
  bord< 
  r. 
  

  

  With 
  the 
  above 
  described 
  form 
  occur 
  teeth 
  referable 
  to 
  the 
  opp 
  

  

  position 
  on 
  the 
  lower 
  jaw. 
  and 
  which 
  may 
  have 
  been 
  B 
  

  

  with 
  tin 
  in. 
  These 
  teeth 
  might 
  readily 
  be 
  mistaken 
  for 
  

   examples 
  of 
  the 
  mandibular 
  posterior 
  teeth 
  of 
  Deltoptyckius, 
  which 
  

  

  they 
  olosely 
  resemble 
  in 
  outline 
  and 
  contour 
  of 
  ti.' 
  

  

  The 
  specimen 
  figured 
  presents 
  the 
  usual 
  appearand 
  »'f 
  the 
  form. 
  

   which 
  bas 
  a 
  triangular 
  outline, 
  the 
  antero-lateral 
  border 
  Blightly 
  

  

  curved, 
  with 
  abrupt 
  mural 
  face, 
  half 
  or 
  more 
  of 
  

  

  Oped 
  in 
  the 
  cuaind 
  licit 
  which 
  is 
  distinctly 
  defined 
  from 
  thi 
  

  

  flaring 
  basal 
  rim; 
  inner 
  margin 
  nearly 
  a' 
  with 
  the 
  

  

  anterior 
  border, 
  broadly 
  arched 
  in 
  a 
  Blight 
  Bigmoidal 
  course 
  pi 
  

  

  