﻿152 
  I'M. 
  1. 
  ONTOLOGY 
  OF 
  ILLINOIS. 
  

  

  anterior 
  border, 
  broadly 
  rounded 
  with 
  a 
  slight 
  sigrnoidal 
  curvature 
  

   on 
  nearing 
  the 
  slightly 
  produced 
  posterior 
  angle 
  of 
  the 
  alation 
  ; 
  

   postero-lateral 
  border 
  gradually 
  converging 
  toward 
  the 
  outer 
  margin 
  

   and 
  bordered 
  by 
  a 
  rather 
  strong 
  fold 
  of 
  the 
  coronal 
  enamel. 
  Crown 
  

   broadly 
  arched 
  over 
  the 
  principal 
  ridge, 
  which 
  occupies 
  two-thirds 
  

   or 
  more 
  of 
  the 
  entire 
  area, 
  posteriorly 
  rapidly 
  sloping 
  into 
  the 
  de- 
  

   pression 
  on 
  that 
  side, 
  which 
  is 
  bordered 
  by 
  the 
  relatively 
  narrow, 
  

   slightly 
  upraised 
  alate 
  expansion. 
  The 
  surface 
  is 
  interrupted 
  by 
  

   transverse 
  sulci, 
  especially 
  noticeable 
  near 
  the 
  border 
  in 
  the 
  ante- 
  

   rior 
  slope 
  and 
  in 
  the 
  posterior 
  depression, 
  and 
  minutely 
  and 
  uni- 
  

   formly 
  punctate. 
  A 
  worn 
  specimen 
  of 
  ordinary 
  size 
  measures 
  in 
  

   length 
  along 
  the 
  antero-lateral 
  border 
  about 
  7 
  mm. 
  ; 
  g] 
  readth 
  

  

  across 
  inner 
  margin, 
  8 
  mm. 
  

  

  Maxillary 
  posterior 
  teeth 
  trigonal 
  in 
  outline, 
  strongly 
  arched 
  and 
  

   spirally 
  inrolled. 
  Antero-lateral 
  border 
  describing 
  a 
  gentle 
  aigmoidal 
  

   curvature, 
  basal 
  portion 
  channeled 
  and 
  well 
  defined 
  from 
  the 
  strongly 
  

   inbeveled 
  coronal 
  fold, 
  which 
  constitutes 
  about 
  one-third 
  the 
  height 
  

   of 
  the 
  border; 
  postero-lateral 
  border 
  gently 
  arched, 
  approaching 
  

   point 
  of 
  inrollment 
  at 
  an 
  angle 
  of 
  about 
  70" 
  with 
  the 
  opposite 
  side. 
  

   relatively 
  deep, 
  basal 
  portion 
  slightly 
  inbeveled 
  to 
  the 
  inferior 
  edge 
  

   and 
  faintly 
  channeled, 
  enamel 
  fold 
  relatively 
  wide 
  and 
  sharply 
  

   rounded 
  above, 
  inbeveled 
  below; 
  inner 
  margin 
  making 
  an 
  angle 
  of 
  

   about 
  80° 
  with 
  the 
  anterior 
  border, 
  the 
  anterior 
  half 
  very 
  obliquely 
  

   produced 
  backward 
  from 
  the 
  very 
  obtuse 
  anterior 
  angle, 
  round, 
  d 
  

   and 
  sharply 
  deneofod 
  at 
  the 
  inner 
  angle 
  or 
  base 
  of 
  the 
  coronal 
  

   ridge 
  nearly 
  at 
  right 
  angles 
  to 
  the 
  anterior 
  course, 
  with 
  a 
  Blightly 
  

   concave 
  curvature 
  in 
  passing 
  the 
  posterior 
  depression 
  to 
  the 
  posterior 
  

   angle, 
  worn 
  specimens 
  showing 
  the 
  usual 
  inbeveled 
  infer). 
  

   Coronal 
  contour 
  Btrongly 
  marked, 
  principal 
  ridge 
  cul 
  min 
  at 
  in 
  g 
  in 
  the 
  

   rounded 
  creel 
  a 
  little 
  anterior 
  of 
  the 
  longitudinal 
  median 
  1. 
  

   anterior 
  slope 
  steep, 
  Blightly 
  depressed 
  near 
  the 
  articular 
  border, 
  

  

  where 
  it 
  flares 
  out 
  into 
  a 
  narrow 
  border 
  fold; 
  p 
  dope 
  fl 
  

  

  hirly 
  descending 
  with 
  moderate 
  concavity, 
  and 
  m< 
  

  

  posterior 
  depressed 
  belt, 
  which 
  is 
  bordered 
  by 
  the 
  narrow 
  and 
  but 
  

  

  Blightly 
  upraised 
  expansion 
  of 
  the 
  alate 
  posterior 
  border. 
  

  

  the 
  irregularly 
  elongated 
  pores, 
  the 
  Burfaee 
  Lb 
  

  

  Bulci 
  and 
  int. 
  r\. 
  oing 
  wid. 
  c 
  ridges 
  in 
  the 
  same 
  manner 
  noticed 
  in 
  the 
  

  

  mandibular 
  teeth. 
  \ 
  mature, 
  perfeol 
  tooth 
  mi 
  the 
  

  

  inner 
  margin 
  9 
  mm.; 
  length 
  along 
  antero-lateral 
  border 
  to 
  the 
  in- 
  

  

  ii. 
  7 
  nun. 
  ; 
  length 
  along 
  coronal 
  ;t\ 
  ni. 
  

  

  