﻿:;-! 
  PALEONTOLOGY 
  OF 
  ILL1N< 
  

  

  Orthocebas 
  Okawi 
  DOV. 
  

  

  Bhell 
  elongate, 
  slender, 
  very 
  gradually 
  tapering 
  to 
  the 
  ape: 
  

   oonoave, 
  about 
  l 
  of 
  them 
  usually 
  in 
  the 
  diameti 
  

  

  Biphunele 
  subcentral, 
  Bnrface 
  markings 
  unknown. 
  

  

  This 
  Bhell 
  has 
  a 
  general 
  resemblance 
  to 
  0. 
  1 
  I 
  th< 
  0] 
  

  

  Coal 
  Measures, 
  but 
  differs 
  from 
  that 
  in 
  the 
  position 
  of 
  the 
  aiphun- 
  

   ole, 
  which 
  in 
  our 
  Bpeeies 
  is 
  deoidedly 
  Bubcentral. 
  

  

  tion 
  and 
  locality: 
  Chester 
  limestone, 
  vicinity 
  of 
  th< 
  

   bluffs, 
  near 
  Bed 
  Bud, 
  Randolph 
  county, 
  Olinois. 
  

  

  No. 
  -J. 
  I 
  s 
  -". 
  of 
  the 
  Illinois 
  State 
  collection. 
  

  

  Obthxh 
  5p. 
  nov. 
  

  

  Bhell 
  small, 
  gradually 
  tapering. 
  Surface 
  ornamented 
  with 
  tr 
  

   verse 
  ridges 
  or 
  elevations; 
  situated 
  at 
  irregular 
  dil 
  ioh 
  

  

  other, 
  and 
  with 
  delicate 
  thread-like 
  Btria 
  which 
  cover 
  thetrai 
  

   ridges 
  as 
  well 
  as 
  the 
  Bpaoes 
  between 
  them. 
  The 
  ridges 
  an 
  

   wil] 
  to 
  distinguish 
  this 
  species 
  from 
  any 
  hitherto 
  found 
  in 
  the 
  

  

  1 
  Measures, 
  its 
  ornamentation 
  resembling 
  that 
  of 
  the 
  (>. 
  u> 
  

   latum 
  of 
  the 
  Niagara 
  limestone 
  more 
  closely 
  than 
  any 
  other 
  known 
  

   American 
  The 
  fragment 
  belong 
  t.. 
  the 
  

  

  non-septate 
  portion 
  of 
  the 
  sh. 
  11. 
  

  

  Mm 
  and 
  locality: 
  Roof 
  of 
  the 
  middle 
  coal, 
  LaSalle, 
  HI. 
  

   2,486, 
  "f 
  the 
  Illinois 
  State 
  collection. 
  

  

  Plbubotomabia 
  Mi 
  Bp. 
  m 
  

  

  This 
  line 
  shell 
  is 
  only 
  Known 
  from 
  an 
  imperfect 
  east 
  of 
  the 
  lasl 
  

  

  whorl, 
  which 
  may 
  l» 
  d< 
  Boribed 
  as 
  folli 
  

  

  Bhell 
  attaining 
  a 
  broadrj 
  J 
  in 
  outline; 
  * 
  

  

  three 
  or 
  more, 
  rapidly 
  rtiminighin 
  

   whorl 
  obliquely 
  flattened, 
  Bhowu 
  about 
  I 
  

  

  ,„ 
  breadth, 
  which 
  is 
  traversed 
  by 
  abont 
  eight 
  rather 
  sfa 
  

   „,. 
  baUon 
  depn 
  i 
  :'»""' 
  t 
  i 
  " 
  f 
  "» 
  

  

  inoh 
  wide 
  near 
  the 
  aperture. 
  Th( 
  of 
  this 
  whorl 
  i 
  

  

  ,, 
  v 
  nun 
  about 
  half 
  as 
  far 
  a 
  

  

  ,1, 
  d 
  thi 
  ap] 
  • 
  hut 
  their 
  nun., 
  

  

  ,,, 
  ... 
  band, 
  

   the 
  whorl 
  ind 
  of 
  : 
  ' 
  »*hei 
  leep 
  

  

  ll.llblll. 
  

  

  