﻿72 
  PALEONTOLOGY 
  OF 
  ILLINOI- 
  

  

  coronal 
  ridge 
  and 
  the 
  somewhat 
  greater 
  obliquity 
  of 
  the 
  postero- 
  

   lateral 
  border. 
  As 
  in 
  the 
  above 
  example, 
  the 
  antero-laterai 
  border 
  

  

  has 
  a 
  moderately 
  oblique 
  course 
  from 
  the 
  obtuse 
  inner 
  angle 
  out- 
  

   ward 
  and 
  forward, 
  and 
  is 
  similarly 
  marked 
  by 
  the 
  produced 
  basal 
  

   rim; 
  the 
  posterior 
  depression, 
  however, 
  is 
  quite 
  obsolete, 
  the 
  slope 
  

   from 
  the 
  summit 
  of 
  the 
  coronal 
  ridge 
  to 
  the 
  rounded 
  fold 
  along 
  the 
  

   postero-lateral 
  border 
  showing 
  scarcely 
  the 
  leaM 
  tl 
  on- 
  

  

  cavity; 
  on 
  the 
  other 
  hand, 
  while 
  the 
  gentler 
  declivity 
  in 
  front 
  is 
  

   faintly 
  depressed, 
  it 
  is 
  destitute 
  of 
  the 
  impressed 
  thread-like 
  line 
  

   and 
  narrow 
  belt 
  parallel 
  with 
  the 
  anterior 
  border 
  ol 
  

   larger 
  tooth. 
  The 
  surface 
  punctation 
  of 
  the 
  smaller 
  specin 
  

   appreciably 
  coarser 
  and 
  more 
  like 
  that 
  of 
  the 
  associated 
  teeth 
  of 
  

   Psephodus, 
  and 
  in 
  both 
  the 
  remnant 
  of 
  coronal 
  enamel 
  along 
  the 
  

   inner 
  margin 
  is 
  traversed 
  by 
  similar 
  faint 
  parallel 
  lines 
  of 
  growth. 
  

   In 
  the 
  process 
  of 
  the 
  preliminary 
  distribution 
  of 
  the 
  materials 
  of 
  

   the 
  collections 
  for 
  study, 
  the 
  teeth 
  upon 
  which 
  the 
  foregoing 
  not! 
  

   are 
  based 
  were 
  referred 
  to 
  Psephadw 
  oUiqwu, 
  a 
  relationship 
  

   which 
  may 
  yet 
  prove 
  to 
  be 
  well 
  founded— 
  the 
  Bmaller 
  of 
  the 
  exam] 
  

   above 
  referred 
  to 
  possibly 
  representing 
  the 
  young 
  stage 
  of 
  the 
  la 
  

   teeth 
  described 
  under 
  the 
  latter 
  designation. 
  The 
  latter 
  Bpecim< 
  

   however, 
  shows 
  the 
  inroHed 
  extremity 
  entire, 
  instead 
  of 
  the 
  oblique 
  

   truncation 
  such 
  as 
  distinguishes 
  all 
  mature 
  individuals 
  of 
  Puphod 
  

   while 
  the 
  strong 
  inrollmenl 
  and 
  consequent 
  strongly 
  arch, 
  d 
  longi- 
  

   tudinal 
  profile 
  offer 
  marked 
  contrast 
  with 
  the 
  forms 
  of 
  Psephodu* 
  

   with 
  which 
  the 
  present 
  teeth 
  were 
  associated. 
  Th< 
  larger 
  example 
  

   bear- 
  a 
  striking 
  resemblance 
  to 
  the 
  mandibular 
  posterior 
  form 
  ol 
  

  

  Cochtiodtu; 
  but 
  of 
  the 
  latter 
  genus 
  no 
  other 
  remains 
  have 
  thus 
  far 
  

  

  been 
  discovered 
  in 
  Kinderhook 
  horizons 
  affording 
  the 
  teeth 
  arx 
  

   noticed. 
  

  

  logical 
  position 
  and 
  locality: 
  Kinderhook 
  formation; 
  Burling- 
  

   ton, 
  Iowa. 
  

  

  PSBFHODl 
  s 
  i 
  \n 
  -, 
  St. 
  .1. 
  and 
  YY. 
  

   PL 
  11. 
  l 
  Iff. 
  i. 
  B. 
  

  

  i.tli 
  small. 
  Mandibular 
  median 
  (?) 
  form 
  sub-triangular 
  in 
  out- 
  

   line. 
  mo,|. 
  arched 
  in 
  the 
  direction 
  of 
  inrollment. 
  Ante 
  

   lateral 
  border 
  nearly 
  straight, 
  undulated, 
  the 
  orenulated 
  coronal 
  fold 
  

   § 
  harplj 
  inbeveled 
  to 
  the 
  ohanneled 
  basal 
  portion; 
  postei 
  l 
  or 
  

  

  iqm 
  border 
  rapidly 
  oom 
  towards 
  the 
  outer 
  extremity, 
  mal 
  

  

  