﻿L80 
  PALEONTOLOGY 
  OF 
  tLLINi 
  

  

  arched 
  backward, 
  the 
  whole 
  tooth 
  moderately 
  arched 
  vertically 
  and 
  

   the 
  crown-face 
  vertically 
  convex: 
  the 
  outer 
  face 
  Blightly 
  concave 
  

   vertically, 
  swollen 
  in 
  front 
  of 
  the 
  summit, 
  round 
  which 
  the 
  1 
  

   line 
  arches 
  from 
  its 
  slightly 
  concave 
  course 
  near 
  the 
  lateral 
  extremi- 
  

   ties, 
  which 
  latter 
  are 
  somewhat 
  angularly 
  rounded. 
  The 
  inner 
  and 
  

   outer 
  coronal 
  margins 
  are 
  sharply 
  inbeveled 
  to 
  the 
  coarsely-pitted 
  

   basal 
  plate, 
  which 
  behind 
  forms 
  a 
  wide 
  area 
  nearly 
  in 
  the 
  plai 
  

   the 
  inner 
  crown-face. 
  The 
  surface 
  punctation 
  is 
  fine, 
  rather 
  widely 
  

   spaced, 
  much 
  after 
  the 
  same 
  style 
  described 
  in 
  the 
  other 
  fori 
  

   the 
  species. 
  The 
  mature 
  inner 
  tooth 
  of 
  the 
  Beries 
  measun 
  

   lateral 
  diameter, 
  8 
  mm.; 
  greatest 
  width 
  from 
  behind 
  outward, 
  8 
  

   mm.; 
  height 
  of 
  inner 
  crown-face 
  2.6 
  mm. 
  The 
  outer 
  or 
  fourth 
  

   tooth 
  of 
  the 
  same 
  series 
  is 
  (i 
  mm. 
  in 
  lateral 
  extent, 
  the 
  other 
  dimen- 
  

   sions 
  proportionately 
  diminished. 
  

  

  The 
  above 
  described 
  forms 
  embraced 
  under 
  one 
  and 
  the 
  88 
  

   specific 
  designation, 
  are 
  well 
  represented 
  in 
  the 
  collections 
  accessible 
  

   to 
  us 
  from 
  the 
  Chester 
  formation. 
  The 
  species 
  is 
  Ultimately 
  allied 
  

   to 
  that 
  described 
  from 
  the 
  subjacent 
  St. 
  Louis 
  limeston 
  iodus 
  

  

  Van 
  Hornii, 
  of 
  which 
  it 
  constitutes 
  a 
  fine 
  example 
  of 
  a 
  repn 
  

   tativc 
  species. 
  As 
  distinguished 
  from 
  the 
  St. 
  Louis 
  species, 
  the 
  

   mandibular 
  terminal 
  tooth 
  is 
  relatively 
  narrower 
  in 
  lateral 
  diam 
  

   stronger 
  and 
  more 
  compactly 
  built, 
  the 
  alation 
  proportionately 
  nar- 
  

   rower 
  and 
  the 
  median-lobe 
  correspondingly 
  wider; 
  the 
  narrow 
  

   dian 
  tooth 
  is 
  apparently 
  more 
  elevated 
  along 
  the 
  crest 
  ; 
  the 
  maxillary 
  

   posterior 
  teeth, 
  on 
  the 
  other 
  hand, 
  are 
  proportionately 
  more 
  elo 
  

   transversely, 
  posterior 
  lobe 
  more 
  prominent, 
  and 
  the 
  median 
  depres- 
  

   sion 
  more 
  deeply 
  excavated 
  and 
  defined 
  by 
  steeper 
  walls: 
  in 
  n 
  

  

  to 
  the 
  distinctions 
  observable 
  in 
  the 
  serial 
  teeth, 
  those 
  supposed 
  to 
  

  

  pertain 
  to 
  the 
  present 
  species 
  are 
  perceptibly 
  less 
  elongate 
  laterally. 
  

  

  with 
  less 
  abrupt 
  inner 
  coronal 
  fact 
  . 
  and 
  generally 
  more 
  robus( 
  pro- 
  

   portion-, 
  as 
  compared 
  with 
  the 
  normally 
  developed 
  individuals 
  of 
  

  

  C. 
  Van 
  Hornii, 
  which, 
  as 
  has 
  bees 
  pointed 
  out, 
  vary 
  to 
  a 
  verj 
  

   markable 
  degree 
  in 
  tin 
  ir 
  coronal 
  a 
  

  

  logical 
  i>"siti<>>i 
  and 
  localitie$: 
  (duster 
  limestone; 
  Chester 
  and 
  

   Evansville, 
  (Randolph 
  county.' 
  Prairie 
  du 
  Long, 
  (Monroe 
  co 
  

  

  IlllllOl-. 
  

  

  

  