﻿176 
  PAL/EONTOLOGY 
  OF 
  ILLINOI 
  

  

  illation. 
  Antero-lateral 
  border 
  Blightly 
  carved 
  Bigmoidally, 
  present- 
  

   ing 
  an 
  alu-upt 
  declivity 
  from 
  the 
  angularly 
  rounded 
  apper 
  edj 
  

   beneath 
  which 
  the 
  coronal 
  enamel 
  forms 
  a 
  well 
  defined 
  belt, 
  sharply 
  

   limited 
  hy 
  the 
  basal 
  portion, 
  which 
  latter 
  projects 
  downward, 
  form- 
  

   ing 
  a 
  narrow 
  rim 
  along 
  the 
  inferior 
  edge; 
  postero-lateral 
  border 
  

   rapidly 
  diverging 
  from 
  the 
  outer 
  extremity, 
  terminating 
  in 
  the 
  mi 
  

   or 
  less 
  produced 
  posterior 
  angle, 
  the 
  apper 
  edge 
  enveloped 
  in 
  the 
  

   narrow 
  enamel 
  fold, 
  which 
  is 
  distinctly 
  defined 
  from 
  the 
  inferior 
  

   basal 
  border; 
  inner 
  margin 
  making 
  a 
  moderate 
  Bigmoidal 
  curvature, 
  

   varying 
  in 
  obliquity 
  to 
  the 
  antero-lateral 
  border, 
  with 
  which 
  it 
  may 
  

   form 
  a 
  right-angle. 
  

  

  Maxillary 
  posterior 
  teeth 
  characterized 
  hy 
  the 
  relatively 
  narrow 
  

   transverse 
  diameter 
  at 
  the 
  inner 
  margin, 
  and 
  consequent 
  wed 
  

   shaped 
  outline. 
  General 
  contour 
  of 
  the 
  coronal 
  region 
  resembling 
  

   that 
  of 
  the 
  opposed 
  mandibular 
  teeth, 
  the 
  principal 
  prominence 
  

   tending 
  along 
  the 
  antero-lateral 
  border, 
  slightly 
  convex 
  or 
  plane 
  

   transversely, 
  more 
  or 
  less 
  steeply 
  sloping 
  into 
  the 
  Longitudinal 
  

   median 
  depression, 
  which 
  is 
  bordered 
  on 
  the 
  opposite 
  side 
  by 
  the 
  

   upraised 
  narrow 
  wing 
  expansion 
  terminating 
  in 
  the 
  posterior 
  angle; 
  

   antero-lateral 
  holder 
  gently 
  curved 
  Bigmoidally, 
  more 
  or 
  less 
  abruptly, 
  

   sometimes 
  vertically, 
  sloping 
  from 
  the 
  angular 
  superior 
  edge 
  at 
  the 
  

   junction 
  with 
  the 
  crown, 
  the 
  enamel 
  forming 
  a 
  belt 
  well 
  defined 
  

   from 
  the 
  basal 
  border 
  which 
  terminates 
  interiorly 
  in 
  a 
  thin 
  rim; 
  

   the 
  opposite 
  Bide 
  gradually 
  converges 
  from 
  the 
  posterior 
  angle 
  toward 
  

   the 
  outer 
  extremity, 
  the 
  apper 
  edge 
  enveloped 
  in 
  a 
  distinot, 
  narrow 
  

   enamel 
  fold, 
  and 
  defined 
  by 
  a 
  Blight 
  channel 
  from 
  the 
  equally 
  shal- 
  

   low 
  basal 
  border; 
  inner 
  margin 
  oblique 
  in 
  one 
  or 
  other 
  direction 
  to 
  

   antero-lateral 
  border, 
  with 
  which 
  it 
  also 
  sometimes 
  forms 
  a 
  right- 
  

  

  a 
  iiL.de. 
  

  

  The 
  triturating 
  surface 
  in 
  the 
  typical 
  of 
  both 
  the 
  above 
  

  

  d( 
  -criiicd 
  forma 
  presents 
  a 
  line 
  transversi 
  striated 
  appearance, 
  pro- 
  

   duced 
  by 
  the 
  arrangement 
  of 
  the 
  pnnotn 
  in 
  more 
  or 
  lees 
  parallel 
  

   rows, 
  conforming 
  in 
  direction 
  to 
  the 
  course 
  of 
  the 
  inner 
  margin. 
  

   However, 
  the 
  latter 
  feature 
  is 
  no! 
  observed 
  as 
  a 
  persisted 
  one 
  over 
  

  

  the 
  entire 
  extent 
  of 
  the 
  coronal 
  region, 
  even 
  in 
  the 
  typical 
  

   while 
  in 
  others 
  it 
  is 
  hut 
  obscurely 
  apparent, 
  and 
  in 
  BOme 
  

  

  presumably 
  otherwise 
  -with 
  the 
  typical 
  forms, 
  the 
  

  

  ,,,, 
  e 
  of 
  the 
  tran-. 
  nation, 
  on 
  the 
  contrary 
  ex- 
  

  

  hibiting 
  the 
  usual 
  den-,' 
  panel 
  common 
  t" 
  the 
  

  

  nli!\ 
  ,,f 
  the 
  Coohliodonts. 
  

  

  