﻿•211 
  PALKoNTOLOGY 
  OF 
  ILLINOIS. 
  

  

  ACONDYLACANTHCS 
  ? 
  MuDGIANl 
  ~. 
  St. 
  J. 
  1111(1 
  W. 
  

   PL 
  XXIV. 
  Fig. 
  8. 
  

  

  A 
  fragment 
  from 
  the 
  Upper 
  Coal 
  Measures 
  of 
  Kansas 
  represent. 
  

   ing 
  a 
  medium-size 
  ichthyodorulite 
  is 
  provisionally 
  referred 
  to 
  the 
  

   above 
  genus. 
  The 
  Bpeeimen 
  prea 
  rvea 
  a 
  length 
  of 
  about 
  7 
  centi- 
  

   metres, 
  apparently 
  of 
  the 
  middle 
  or 
  lower 
  portion 
  of 
  the 
  spine, 
  of 
  

   which 
  the 
  entire 
  anterior 
  border 
  is 
  hrokcn 
  away, 
  revealing 
  the 
  deeply 
  

   avated 
  posterior 
  face 
  or 
  the 
  pulp 
  cavity, 
  bordered 
  by 
  a 
  strip 
  of 
  

   the 
  thick 
  lateral 
  walls 
  mar 
  the 
  pustero-lati 
  ral 
  angles. 
  The 
  trans- 
  

   V< 
  rse 
  section 
  of 
  the 
  spine 
  is 
  subtriangular, 
  moderately 
  arched 
  along 
  

   the 
  anterior 
  edge, 
  lateral 
  surfaces 
  evidently 
  gently 
  convex 
  trai 
  

   v. 
  rselv, 
  and, 
  so 
  far 
  as 
  revealed 
  by 
  the 
  remaining 
  walls, 
  o 
  rn 
  a 
  ment 
  ed 
  

   by 
  simple, 
  angularly 
  rounded 
  longitudinal 
  costa, 
  separated 
  by 
  do 
  

   narrow 
  intercostal 
  grooves; 
  the 
  costa 
  enveloped 
  in 
  the 
  smooth 
  

   enamel 
  layer 
  throughout. 
  Beyond 
  this 
  the 
  superficial 
  features 
  are 
  

   not 
  disclosed, 
  and 
  so 
  little 
  remains 
  thai 
  the 
  moderately 
  rapid 
  taper- 
  

   ing 
  of 
  the 
  spine 
  is 
  hardly 
  more 
  than 
  an 
  infer. 
  

  

  While 
  the 
  generic 
  relations 
  of 
  the 
  specimm 
  above 
  referred 
  to 
  are 
  

   by 
  no 
  means 
  satisfactorily 
  authenticated 
  bj 
  the 
  meagre 
  oharaefc 
  

   that 
  remain, 
  its 
  specific 
  distinctness 
  from 
  any 
  form 
  OOOUrring 
  in 
  

   the 
  Coal 
  Measures 
  as 
  yet 
  diaoovered 
  is 
  unmistakable. 
  Th< 
  ipeeiifl 
  

   designation 
  is 
  given 
  in 
  honor 
  of 
  the 
  late 
  Profi 
  min 
  l 
  

  

  Hodge, 
  the 
  distinguished 
  educationist 
  and 
  director 
  of 
  the 
  firai 
  State 
  

   ilogical 
  survey 
  of 
  Kansas. 
  

  

  logical 
  position 
  and 
  locality: 
  Upper 
  Coal 
  Measures; 
  Rook 
  Gn 
  

   Pottawattamie 
  county, 
  Kansas. 
  

  

  A. 
  ONOYLH 
  wiin 
  B? 
  \iiui\s. 
  St. 
  .1. 
  and 
  \V. 
  

  

  pi 
  w\i 
  ris. 
  i. 
  

  

  1 
  1,, 
  „,. 
  ample 
  here 
  red 
  rred 
  to 
  pn 
  rtion 
  

  

  of 
  a 
  large 
  dorsal 
  Bpine, 
  probably 
  between 
  20 
  and 
  28 
  oentimetres 
  in 
  

   length, 
  of 
  which 
  perhaps 
  6 
  oentimetres 
  of 
  tl 
  transit} 
  

  

  broken 
  ahorl 
  off, 
  while 
  ti 
  ted 
  portion 
  shows 
  evidences 
  of 
  cur- 
  

  

  iin.nt 
  in 
  the 
  rounded 
  anterior 
  margin. 
  , 
  th< 
  rarfaoi 
  

  

  ,l 
  i( 
  ,| 
  portion 
  of 
  the 
  spin.- 
  i- 
  evidently 
  much 
  worn, 
  the 
  001 
  

  

  f 
  or 
  t| 
  ; 
  . 
  part 
  .1. 
  stitufa 
  Of 
  I 
  nanirl. 
  (US 
  

  

  a, 
  mi. 
  in 
  .oimiion 
  with 
  that 
  of 
  the 
  bflfe 
  

  

  . 
  that 
  it 
  is 
  impossible 
  to 
  

  

  of 
  the 
  superficial 
  ornamentation, 
  upon 
  wh 
  

  

  