﻿120 
  PALEONTOLOGY 
  OF 
  ILLINOI 
  

  

  antero-lateral 
  border 
  to 
  point 
  of 
  inrollment 
  a 
  tritle 
  less 
  than 
  5 
  mm., 
  

   in 
  outline 
  showing 
  the 
  usual 
  quadrilateral 
  figure. 
  The 
  antero-lat- 
  

   eral 
  border 
  is 
  very 
  ohlique 
  in 
  its 
  course 
  forward 
  and 
  backward, 
  

   coronal 
  enamel 
  forming 
  a 
  strong, 
  rounded 
  fold 
  iabeveled 
  to 
  the 
  

   channeled 
  basal 
  portion; 
  inner 
  margin 
  gently 
  arched 
  round 
  the 
  base 
  

   of 
  the 
  anterior 
  coronal 
  prominence 
  with 
  a 
  slight 
  concavity 
  forward, 
  

   and 
  a 
  broader 
  one 
  in 
  the 
  region 
  of 
  the 
  median 
  depression; 
  post 
  

   lateral 
  horder 
  unknown. 
  Anterior 
  portion 
  of 
  the 
  crown 
  occupied 
  by 
  

   a 
  pair 
  of 
  low, 
  regularly 
  transversely 
  arched 
  ri 
  ited 
  by 
  a 
  

  

  shallow, 
  well-defined 
  furrow, 
  and 
  posteriorly 
  defined 
  by 
  a 
  broader 
  

   median 
  depression 
  intervening 
  between 
  the 
  anterior 
  and 
  post 
  

   lobes. 
  Surface 
  more 
  or 
  less 
  regularly 
  marked 
  by 
  Btrong, 
  cl< 
  

   arranged 
  transverse 
  imbrications 
  parallel 
  with 
  the 
  inner 
  margin, 
  

   and 
  apparently 
  extending 
  over 
  the 
  entire 
  coronal 
  region, 
  bet 
  

   showing 
  a 
  relatively 
  coarse, 
  crowded 
  punctate 
  structure. 
  

  

  The 
  species 
  indicated 
  by 
  the 
  fragment 
  of 
  tooth 
  abo 
  ribed 
  

  

  apparently 
  constitutes 
  a 
  typical 
  representative 
  of 
  the 
  genus 
  Cliiion- 
  

   mlus, 
  of 
  which 
  it 
  is 
  the 
  latest 
  that 
  has. 
  as 
  yet, 
  been 
  made 
  

   known. 
  It 
  exhibits 
  intimate 
  relations 
  with 
  the 
  Keokuk 
  C. 
  m 
  : 
  

   but 
  is 
  distinguished 
  by 
  its 
  small 
  size, 
  the 
  greater 
  outward 
  and 
  

   backward 
  obliquity 
  of 
  the 
  antero-lateral 
  border, 
  and 
  the 
  double* 
  

   Dbed 
  broad 
  anterior 
  prominence; 
  the 
  transverse 
  imbricated 
  orna- 
  

   u 
  entation 
  markedly 
  partakes 
  of 
  the 
  generic 
  oharaofa 
  

   with 
  Bpeoiee 
  of 
  the 
  genus. 
  

  

  Geological 
  position 
  and 
  locality; 
  St. 
  Louis 
  limestone: 
  Alton. 
  Illi- 
  

   nois. 
  

  

  <,, 
  sua 
  COCIi^IODUS, 
  

  

  COOHLIODUS 
  Van 
  Hoi. 
  mi. 
  St. 
  J. 
  and 
  W, 
  

  

  PL 
  vn. 
  ii". 
  

  

  ill 
  below 
  medium 
  sue, 
  repw 
  entatr?ea 
  of 
  the 
  mandibular 
  

   nor 
  and 
  median, 
  and 
  maxillary 
  are 
  lei 
  

  

  Mandibular 
  rior 
  teeth 
  in 
  the 
  outline 
  and 
  of 
  the 
  

  

  triturating 
  surfs 
  markabl< 
  

  

  oharactt 
  t 
  y 
  inrolled 
  at 
  the 
  • 
  

  

  Lntero-lateraJ 
  border 
  with 
  a 
  slightly 
  curved 
  outline, 
  the 
  enamel 
  

   fold 
  occupying 
  aboul 
  one-third 
  of 
  the 
  vertical 
  space 
  ana 
  

  

  