﻿K. 
  F. 
  Mather 
  — 
  Pottsville 
  Formations 
  and 
  Jfraunas. 
  137 
  

  

  Aclisina 
  ? 
  sp. 
  

  

  Orthoceras 
  sp. 
  

  

  Metacoceras 
  sp. 
  

  

  Pronorites 
  cyclolobus 
  var. 
  arkansasensis 
  Smith 
  

  

  Gastrioceras 
  listeri 
  (Martin) 
  

  

  Gastrioceras 
  hyattianum 
  Girty 
  

  

  Gastrioceras 
  angulatum 
  Girty 
  

  

  Gastrioceras 
  carbonarium 
  von 
  Buch 
  

  

  Gastrioceras 
  kesslerense 
  Mather 
  

  

  The 
  Atoka 
  fauna 
  as 
  thus 
  made 
  known 
  includes 
  six 
  forms 
  not 
  

   specifically 
  identifiable 
  and 
  three 
  new 
  .species, 
  so 
  that 
  there 
  

   remain 
  thirty-three 
  species 
  known 
  to 
  occur 
  elsewhere. 
  Twenty 
  

   of 
  these 
  have 
  been 
  described 
  among 
  the 
  Morrow 
  fauna 
  of 
  the 
  

   Boston 
  Mountains. 
  One 
  additional 
  form, 
  Pronorites 
  cyclolo- 
  

   bus 
  var. 
  arkansasensis, 
  is 
  known 
  elsewhere 
  only 
  from 
  the 
  

   upper 
  strata 
  of 
  the 
  Morrow 
  group 
  in 
  Carroll 
  County, 
  Arkansas. 
  

   Another 
  species, 
  Strop 
  hostylus 
  remex, 
  occurs 
  in 
  the 
  Lower 
  

   Aubrey 
  group 
  of 
  Utah, 
  a 
  horizon 
  which 
  may 
  be 
  closely 
  corre- 
  

   lated 
  with 
  the 
  Morrow. 
  The 
  remaining 
  forms 
  are 
  present 
  in 
  

   somewhat 
  higher 
  strata 
  in 
  this 
  and 
  adjoining 
  regions. 
  

  

  Four 
  of 
  the 
  Atoka 
  species, 
  Prismopora 
  concava, 
  Myalina 
  

   cuneiformis 
  f 
  , 
  Worthenia 
  tabulata, 
  and 
  Gastrioceras 
  kessler- 
  

   ense, 
  are 
  especially 
  characteristic 
  of 
  the 
  Kessler 
  member 
  of 
  

   the 
  Morrow 
  as 
  distinct 
  from 
  the 
  lower 
  fossiliferous 
  beds 
  of 
  

   that 
  group. 
  The 
  last 
  named 
  of 
  these 
  four 
  is 
  the 
  most 
  com- 
  

   mon 
  species 
  in 
  the 
  Atoka 
  fauna. 
  On 
  the 
  other 
  hand, 
  two 
  

   species, 
  P 
  seudomonotis 
  precursor 
  and 
  Parallelodon 
  pergib- 
  

   bosus, 
  are 
  noteworthy 
  as 
  representative 
  Brentwood 
  forms. 
  

  

  The 
  evidence 
  is 
  quite 
  conclusive 
  that 
  this 
  fossiliferous 
  por- 
  

   tion 
  of 
  the 
  Atoka 
  formation 
  cannot 
  be 
  much, 
  if 
  any, 
  younger 
  

   than 
  the 
  upper 
  beds 
  of 
  the 
  Morrow 
  group. 
  The 
  deposition 
  of 
  

   the 
  Atoka 
  sediments 
  must, 
  therefore, 
  have 
  begun 
  in 
  early 
  

   Pottsville 
  time. 
  

  

  The 
  age 
  of 
  the 
  Caney, 
  Jackfork, 
  and 
  Stanley 
  formations. 
  

  

  The 
  proper 
  correlation 
  of 
  the 
  Caney 
  shale, 
  the 
  Jackfork 
  

   sandstone, 
  and 
  the 
  Stanley 
  shale 
  present 
  unusual 
  difficulties 
  

   because 
  of 
  the 
  somewhat 
  conflicting 
  nature 
  of 
  the 
  data 
  avail- 
  

   able. 
  G. 
  H. 
  Girty 
  in 
  his 
  description 
  of 
  the 
  Caney 
  fauna* 
  has 
  

   presented 
  all 
  phases 
  of 
  the 
  problems 
  involved. 
  There 
  have 
  

   been 
  found 
  in 
  the 
  Stanley 
  shale 
  obscure 
  plant 
  remains 
  which 
  

   David 
  White 
  states 
  are 
  of 
  Carboniferous 
  age 
  ; 
  he 
  concludes 
  

   that 
  " 
  it 
  is 
  probable 
  that 
  they 
  belong 
  either 
  in 
  the 
  upper 
  part 
  

   of 
  the 
  Mississippian 
  or 
  in 
  the 
  lower 
  Pottsville, 
  but 
  this 
  point 
  

  

  * 
  Girty, 
  G. 
  H., 
  The 
  fauna 
  of 
  the 
  Caney 
  shale 
  of 
  Oklahoma, 
  U. 
  S. 
  Geol. 
  

   Survey, 
  Bull. 
  377, 
  1909. 
  

  

  Am. 
  Jour. 
  Sci. 
  — 
  Fourth 
  Series, 
  Vol. 
  XLIIT, 
  No. 
  254. 
  — 
  February, 
  1917. 
  

   10 
  

  

  