﻿254 
  PALAEONTOLOGY 
  OF 
  ILLINOIS. 
  

  

  walls, 
  and 
  in 
  which 
  respects 
  intimate 
  relationship 
  with 
  Botacomihu 
  

   is 
  disclosed. 
  The 
  lateral 
  surfaces 
  display 
  numerous 
  narrow 
  longitu- 
  

   dinal 
  ridges, 
  spaed 
  by 
  intervening 
  shallow 
  sulci, 
  in 
  width 
  a 
  little 
  

   more 
  than 
  the 
  diamefa 
  r 
  of 
  the 
  ridges, 
  and 
  irregularly, 
  coarsely 
  pitted. 
  

   The 
  costs 
  apparently 
  occupy 
  tin 
  entire 
  surface, 
  saw 
  a 
  belt 
  extend- 
  

   ing 
  along 
  either 
  side 
  of 
  the 
  posterioz 
  angle, 
  where 
  they 
  are 
  obeolete, 
  

   or 
  at 
  least 
  less 
  marked. 
  Perhaps 
  the 
  most 
  interesting 
  feature 
  is 
  

   that 
  observed 
  in 
  connection 
  with 
  the 
  tuberculatum: 
  The 
  carina 
  along 
  

   the 
  a 
  1 
  1 
  1 
  • 
  rior 
  edge 
  sends 
  of! 
  at 
  irregular, 
  alternate 
  intervals 
  a 
  strong 
  

   low 
  tubercle, 
  which 
  tills 
  the 
  adjacent 
  sulcus, 
  even 
  crowding 
  

   upon 
  or 
  enveloping 
  the 
  next 
  parallel 
  ridge; 
  similar, 
  somewhat 
  

   smaller 
  tumid 
  tubercles 
  are 
  dispersed 
  with 
  greater 
  or 
  less 
  irregular- 
  

   ity 
  over 
  the 
  body 
  of 
  the 
  spine, 
  where, 
  in 
  the 
  worn 
  condition 
  of 
  the 
  

   specimen, 
  they 
  often 
  have 
  the 
  appearance 
  of 
  occupying 
  tin 
  sulci, 
  

   and 
  toward 
  tin 
  ap< 
  \ 
  becoming 
  continent 
  and 
  stretching 
  aoross 
  two 
  

   or 
  more 
  costae. 
  The 
  tubercles 
  in 
  the 
  belt 
  along 
  the 
  posterior 
  edge 
  

   are 
  relatively 
  large, 
  irregularly 
  subconical, 
  and 
  ranged 
  in 
  ti 
  

   three 
  irregular 
  rows; 
  they 
  are 
  mostly 
  worn 
  quite 
  smooth, 
  hut 
  there 
  

   are 
  vestiges 
  of 
  radiate 
  ornamentation 
  still 
  visible. 
  

  

  spared 
  with 
  previously 
  described 
  spines, 
  the 
  present 
  form, 
  per- 
  

   haps, 
  finds 
  its 
  nearest 
  ally 
  in 
  the 
  Bataeanthut 
  tUttatnu, 
  of 
  t 
  lie 
  Keo- 
  

   kuk 
  limestone. 
  It 
  is 
  distinguished, 
  however, 
  from 
  that 
  Bpeeies 
  by 
  its 
  

   moro 
  compressed 
  lenticular 
  transverse 
  section 
  and 
  the 
  distinct 
  an- 
  

   gulation 
  of 
  the 
  anterior 
  and 
  posterior 
  edges; 
  also, 
  the 
  distinct 
  char- 
  

  

  and 
  disposition 
  of 
  the 
  tuberculatum 
  ; 
  th< 
  anterior 
  edge, 
  

  

  does 
  not 
  preserve 
  the 
  large, 
  claw-like 
  /entioles 
  that 
  appear 
  in 
  the 
  

   above 
  Bpeeies, 
  bat 
  these 
  may 
  have 
  beet 
  a 
  off, 
  and 
  even 
  their 
  

  

  bases 
  obliterated 
  by 
  abrasion. 
  The 
  distinct 
  angulation 
  of 
  the 
  ant' 
  

   and 
  especially 
  the 
  posterioz 
  sdgi 
  nts 
  an 
  anomalous 
  ohara 
  

  

  m 
  contrast 
  with 
  the 
  rounded 
  borders 
  of 
  H,it<ir,iull,u.<, 
  as 
  r. 
  | 
  

  

  by 
  the 
  specM 
  B. 
  itettatut 
  (N. 
  and 
  \\\. 
  Bp.,) 
  and 
  B. 
  taemij 
  

  

  and 
  W.j 
  but 
  the 
  unique 
  example 
  before 
  u 
  is 
  not 
  sufficiently 
  entire 
  

  

  to 
  permit 
  comparisons 
  Deeessary 
  in 
  order 
  to 
  determine 
  

  

  generic 
  relationship, 
  while 
  such 
  oharaei 
  are 
  discernible 
  

  

  marked 
  resemblance 
  to 
  those 
  attributed 
  to 
  Batooemthu. 
  

  

  logical 
  position 
  and 
  locality: 
  Keokuk 
  linn 
  stone. 
  upp. 
  r 
  in 
  ds 
  : 
  K. 
  o- 
  

  

  kuk, 
  Iowa. 
  

  

  