﻿108 
  PAL 
  .K 
  ONTOLOGY 
  OF 
  ELLINOIB. 
  

  

  e 
  of 
  probability 
  as 
  pertaining 
  to 
  the 
  mandible 
  of 
  the 
  species. 
  

   The 
  latter 
  teeth 
  exhibit 
  in 
  a 
  marked 
  degree 
  homologous 
  relationship 
  

   to 
  Cochliodus, 
  possessing 
  the 
  same 
  general 
  outline 
  and 
  coronal 
  con- 
  

   tour 
  distinguishing 
  the 
  large 
  posterior 
  teeth 
  of 
  the 
  mandible 
  of 
  that 
  

   genns, 
  characterized, 
  however, 
  in 
  accordance 
  with 
  the 
  distinctive 
  

   peculiarities 
  appertaining 
  to 
  the 
  p 
  genns. 
  The 
  latter 
  form 
  

  

  is 
  trapezoidal 
  in 
  outline, 
  and 
  in 
  the 
  arching 
  and 
  inrollment 
  of 
  

   the 
  tooth 
  it 
  agrees 
  with 
  the 
  opposed 
  form; 
  posterior 
  wing 
  narrow, 
  

   basal 
  rim 
  extending 
  conspicuously 
  beyond 
  the 
  limits 
  of 
  the 
  shal- 
  

   low, 
  rounded, 
  inbeveled 
  enamel 
  fold; 
  median 
  lobe 
  situated* 
  a 
  little 
  

   posterior 
  of 
  the 
  middle, 
  broadly 
  and 
  regularly 
  arched 
  transverse- 
  

   ly, 
  culminating 
  in 
  a 
  tumid 
  crest, 
  the 
  slope 
  on 
  the 
  one 
  hand 
  

   ing 
  into 
  the 
  posterior 
  depression, 
  on 
  the 
  other 
  defined 
  by 
  a 
  

   Blight 
  angulation 
  from 
  the 
  anterior 
  area, 
  which 
  presents 
  a 
  broad 
  

   plane 
  or 
  gently-convex 
  surface, 
  with 
  faint 
  impressed 
  furrow 
  near 
  

   the 
  border 
  and 
  nearly 
  equal 
  in 
  breadth 
  to 
  the 
  median 
  lobe; 
  an- 
  

   terolateral 
  border 
  quite 
  obliquely 
  truncated 
  outward 
  and 
  back- 
  

   ward 
  from 
  the 
  sub-acute 
  inner 
  angle: 
  the 
  inner 
  margin 
  is 
  gently 
  

   arched 
  between 
  the 
  angles, 
  somewhat 
  more 
  strongly 
  arched 
  around 
  

   the 
  base 
  of 
  the 
  median 
  prominence, 
  and 
  slightly 
  deflected 
  on 
  nearing 
  

   the 
  posterior 
  extremity. 
  The 
  external 
  enamel 
  coating 
  investing 
  the 
  

   inner 
  portion 
  of 
  the 
  crown 
  shows 
  distinct 
  lines 
  of 
  growth 
  parallel 
  

   with 
  the 
  inner 
  margin, 
  the 
  worn 
  surface 
  regularly 
  and 
  minutely 
  

   punctate, 
  precisely 
  after 
  the 
  manner 
  observed 
  in 
  the 
  opposite 
  teeth 
  

   of 
  the 
  upper 
  jaw. 
  

  

  A 
  medium-size 
  posterior 
  tooth 
  of 
  the 
  upper 
  jaw 
  measures, 
  in 
  

   transverse 
  diameter 
  across 
  the 
  inner 
  margin, 
  L2.6 
  nun.: 
  length 
  

   along 
  antero-lateral 
  bonier 
  to 
  point 
  of 
  inrollment. 
  : 
  mm. 
  : 
  greatest 
  

   diameter 
  diagonal 
  to 
  the 
  Longitudinal 
  axis, 
  •"•"• 
  nun. 
  A 
  hi: 
  

   mandibular 
  posterior 
  tooth 
  measures 
  - 
  the 
  inner 
  margin, 
  L5.fi 
  

  

  nun. 
  : 
  Length 
  along 
  antero-lateral 
  border. 
  7 
  mm. 
  ; 
  Longitudinal 
  di- 
  

   ameter, 
  at 
  middle 
  '.» 
  mm. 
  

  

  Mr. 
  Vail 
  Home's 
  collection 
  contains 
  a 
  Bingle 
  mini;- 
  nnn 
  

  

  of 
  a 
  tooth 
  which 
  (dearly 
  belongs 
  to 
  the 
  form 
  which 
  we 
  h:i\c 
  

  

  already 
  i 
  •■! 
  from 
  the 
  Upper 
  Burlington 
  Ash-beds, 
  fro; 
  

  

  ample- 
  in 
  the 
  collection 
  of 
  Mr. 
  Springer, 
  and 
  which 
  is 
  re!' 
  

   to 
  the 
  mandibular 
  medium 
  form 
  iptcrodui. 
  Ph< 
  present 
  tooth 
  

  

  ante 
  the 
  Bami 
  resemblances 
  in 
  Burface 
  punctation, 
  as 
  com] 
  

   with 
  the 
  posterior 
  form 
  parvuhu, 
  as 
  in 
  the 
  former 
  ins! 
  

  

  noted 
  in 
  connection 
  with 
  this 
  form 
  and 
  S.ploKUt. 
  The 
  latter 
  

  

  Bpeoimen 
  attains 
  a 
  breadth 
  across 
  the 
  inner 
  margin 
  i 
  i 
  >lm^ 
  

  

  