﻿172 
  PAL/EONTOLOGY 
  OF 
  ILLINOIS. 
  

  

  Enniskillen, 
  for 
  the 
  opportunity 
  to 
  examine 
  sketches 
  of 
  the 
  two 
  

   forms 
  of 
  the 
  type 
  species, 
  from 
  tin- 
  Mountain 
  limestone 
  of 
  Bi 
  

   England, 
  belonging 
  to 
  the 
  Musi 
  urn 
  at 
  Florence 
  Court, 
  whirl), 
  bo 
  far 
  

   Lates 
  to 
  general 
  outline 
  and 
  coronal 
  contour, 
  convey 
  a 
  tolerably 
  

   distinct 
  impression 
  of 
  the 
  peculiarities 
  distinguishing 
  the 
  

  

  The 
  latter 
  sketches 
  exhibit 
  examples 
  of 
  two 
  forms, 
  the 
  one 
  and 
  

   apparently 
  that 
  occurring 
  most 
  abundantly, 
  represents 
  an 
  elongate 
  

   tooth 
  below 
  medium 
  size, 
  trapezoidal 
  in 
  outline, 
  with 
  very 
  gradually 
  

   converging 
  lateral 
  borders, 
  and 
  moderate 
  convexity 
  from 
  within 
  out- 
  

   ward. 
  The 
  straight 
  or 
  anterolateral 
  border 
  presents 
  an 
  abrupt 
  face 
  

   with 
  a 
  sharp 
  angulation 
  above, 
  and 
  which 
  seems 
  to 
  be 
  envel 
  

   by 
  an 
  enamel 
  belt; 
  the 
  oblique 
  border 
  appears 
  to 
  be 
  denned 
  by 
  a 
  

   narrow 
  rounded 
  enamel 
  fold 
  inbeveled 
  to 
  the 
  basal 
  rim. 
  which 
  

   expands 
  somewhat 
  beyond 
  the 
  limits 
  of 
  the 
  coronal 
  border, 
  termi- 
  

   nating 
  'in 
  the 
  subacute 
  posterior 
  angle; 
  the 
  inner 
  margin 
  is 
  appa- 
  

   rently 
  very 
  ^mtly 
  ^igmoi 
  dalK^cjiived^ 
  between 
  the 
  obtuse 
  anterior 
  

   angle 
  and 
  the 
  posterior 
  extremity, 
  or 
  nearly 
  at 
  right 
  angles 
  with 
  

   the 
  anterolateral 
  border. 
  The 
  crown 
  shows 
  moderate 
  trans 
  

   convexity 
  of 
  the 
  principal 
  prominence 
  along 
  the 
  straight 
  border, 
  the 
  

   slope 
  somewhat 
  steeply 
  descending 
  into 
  the 
  posterior 
  depression, 
  

  

  which 
  is 
  bordered 
  by 
  the 
  narrow 
  upraised 
  alation. 
  . 
  ondform 
  

  

  of 
  teeth 
  alluded 
  to 
  under 
  the 
  same 
  specific 
  designation, 
  i- 
  repre- 
  

   sented 
  by 
  medium-sized 
  example-, 
  trigonal 
  in 
  outline, 
  and 
  Btrongly 
  

   arched 
  longitudinally. 
  The 
  antero-lateral 
  or 
  straight 
  border 
  is 
  

   abruptly 
  truncated, 
  apparently 
  vertical, 
  and 
  bordered 
  by 
  a 
  1 
  ■ 
  

   coronal 
  enamel, 
  basal 
  rim 
  pot 
  clearly 
  definable: 
  the 
  oblique 
  1 
  

   is 
  gently 
  curved, 
  rapidly 
  converging 
  toward 
  the 
  outer 
  extremity, 
  

   character 
  of 
  enamel 
  fold 
  and 
  basal 
  rim 
  not 
  discernible; 
  inner 
  mar* 
  

   gin 
  broadly 
  and 
  regularly 
  arched 
  between 
  the 
  inner 
  angles, 
  appa- 
  

   rently 
  nearly 
  at 
  right 
  angles 
  with 
  the 
  straight 
  border. 
  Corona] 
  

  

  u 
  occupied 
  by 
  the 
  very 
  prominent 
  anterior 
  ridge, 
  which 
  forms 
  

  

  a 
  alight 
  convexity 
  extending 
  from 
  the 
  sharp 
  angulation 
  along 
  the 
  

   straighl 
  border 
  posteriorly 
  over 
  two-thirds 
  and 
  more 
  of 
  the 
  b 
  

  

  ana 
  of 
  the 
  CTOWn, 
  where 
  the 
  slope 
  abruptly 
  descends 
  to 
  the 
  

  

  oblique 
  posterolateral 
  border, 
  which 
  shows 
  a 
  very 
  narrow. 
  . 
  

  

  denned 
  alation. 
  In 
  both 
  of 
  the 
  forms 
  above 
  DOticed 
  the 
  .clonal 
  

   surface 
  is 
  minutely 
  punctate, 
  the 
  puncU 
  not 
  arraii: 
  stinel 
  

  

  \ 
  specimen 
  of 
  the 
  narrow 
  elongate 
  form 
  measures 
  

   in 
  length 
  along 
  the 
  straighl 
  border 
  about 
  17 
  mm.: 
  breadt 
  

   oner 
  margin 
  n 
  mm.: 
  lateral 
  l- 
  inverge 
  toward 
  the 
  < 
  

  

  