﻿PALEONTOLOGY 
  OF 
  ILLINOIS. 
  

  

  of 
  variable 
  depth, 
  which 
  is 
  due 
  to 
  abrasion 
  while 
  in 
  use. 
  The 
  

   corona] 
  surface 
  is 
  enveloped 
  in 
  a 
  thin 
  layer 
  of 
  enamel, 
  beneath 
  

   which 
  as 
  also 
  in 
  the 
  worn 
  areas 
  the 
  punctate 
  structure 
  is 
  clearly 
  

   discernible, 
  the 
  puncts 
  inclosed 
  in 
  vertical 
  prisms, 
  as 
  also 
  observed 
  

   in 
  relation 
  to 
  the 
  superficial 
  structural 
  features 
  of 
  Ptamnuxhu. 
  

  

  The 
  foregoing 
  diagnosis 
  applies 
  to 
  a 
  form 
  which, 
  from 
  the 
  moder- 
  

   ate 
  anWo-posterior 
  convexity 
  of 
  the 
  crown, 
  and 
  which 
  was 
  com- 
  

   municated 
  to 
  the 
  series 
  of 
  teeth, 
  evidently 
  pertains 
  to 
  the 
  maxillary. 
  

   Usociated 
  with 
  the 
  above 
  form. 
  Mr. 
  VanHome 
  has 
  die 
  la 
  

  

  fragment 
  of 
  a 
  tooth, 
  exhibiting 
  precisely 
  the 
  same 
  structural 
  feat- 
  

   ures 
  above 
  noticed, 
  which 
  we 
  are 
  led 
  to 
  regard 
  as 
  the 
  representa- 
  

   tive 
  of 
  the 
  opposed 
  form 
  belonging 
  to 
  the 
  lower 
  jaw. 
  

  

  The 
  latter 
  or 
  mandibular 
  form, 
  in 
  a 
  general 
  

   way 
  agreeing 
  in 
  outline 
  with 
  the 
  maxillary 
  teeth, 
  

   is 
  distinguished 
  by 
  its 
  relatively 
  greater 
  trai 
  

   verse 
  diameter 
  as 
  compared 
  to 
  the 
  length. 
  Btrongly 
  

   arched 
  longitudinally, 
  with 
  a 
  narrow 
  depressed 
  

   belt 
  parallel 
  with 
  the 
  lateral 
  borders 
  of 
  the 
  

   crown 
  which 
  form 
  a 
  Blightly 
  upraised 
  fold. 
  1 
  

   yond 
  which 
  the 
  basal 
  border 
  extends 
  in 
  a 
  prom- 
  

   inent 
  rim. 
  The 
  anterior 
  and 
  posterior 
  walls 
  of 
  

   the 
  base, 
  as 
  also 
  the 
  inferior 
  surface 
  enveloped 
  

   in 
  the 
  dense 
  layer 
  protect 
  ing 
  the 
  coarser 
  cellular 
  

   structure 
  composing 
  the 
  greater 
  portion 
  of 
  its 
  

   thickness, 
  are 
  precisely 
  as 
  observed 
  in 
  the 
  ah 
  

   described 
  form 
  of 
  the 
  upper 
  jaw. 
  

  

  The 
  last 
  noticed 
  form 
  is 
  comparable 
  to 
  the 
  

   " 
  / 
  oopobob. 
  teeth 
  to 
  which 
  ProfesSOZ 
  Agassi/, 
  gave 
  the 
  name 
  

  

  PiE'ffitSratSgsur- 
  Labodut, 
  of 
  which 
  two 
  Bp< 
  flies 
  are 
  indicated, 
  

   Transvereftpro- 
  /,. 
  protatjfpus, 
  Agass.. 
  and 
  /.. 
  j>l<u<iis. 
  

   W^TontfOTn.! 
  from 
  the 
  mountain 
  limestone 
  of 
  Ireland. 
  But 
  in 
  

   profile. 
  , 
  ■ 
  i 
  

  

  . 
  ,,i 
  instance 
  all 
  the 
  foots 
  Beem 
  to 
  point 
  to 
  generic 
  identitj 
  

   with 
  the 
  first 
  described 
  form, 
  which 
  is 
  unmistakably 
  congeneric 
  with 
  

   the 
  teeth 
  designated 
  by 
  Professor 
  \ 
  the 
  above 
  generic 
  

  

  appellation, 
  as 
  to 
  the 
  homologioal 
  relations 
  of 
  tin 
  two 
  forms 
  al- 
  

   laded 
  ,,, 
  above, 
  to 
  briefly 
  recapitulate: 
  The 
  slight 
  longitudinal 
  

   oonvexitj 
  of 
  the 
  first 
  described 
  form, 
  indicating 
  for 
  the 
  aeri 
  

   teeth 
  associated 
  in 
  the 
  Bame 
  ro* 
  a 
  vers 
  moderatelj 
  arohed 
  

   tudinal 
  contour; 
  and 
  in 
  the 
  oaa 
  of 
  the 
  latter 
  for,,, 
  th< 
  

  

  the 
  crown 
  from 
  behind 
  forwards, 
  indicatini 
  a 
  corresponding 
  

   utronglj 
  roUed 
  outline 
  for 
  th< 
  "f 
  two 
  e 
  individuals, 
  in 
  

  

  both 
  onsonant 
  With 
  what 
  actually 
  

  

  