﻿190 
  8. 
  Welter 
  — 
  Succession 
  of 
  Fossil 
  Faunas 
  in 
  Missouri. 
  

  

  The 
  distinctive 
  character 
  of 
  this 
  zone 
  is 
  the 
  presence 
  in 
  

   large 
  numbers 
  of 
  8pirifer 
  grimesi 
  and 
  Syringothyris 
  plenus, 
  

   associated 
  with 
  Orthis 
  swallovi, 
  Productus 
  burlingtonensis,. 
  

   etc. 
  All 
  the 
  Chouteau 
  species 
  have 
  disappeared 
  and 
  the 
  fauna 
  

   is 
  typically 
  Burlington. 
  Exposures 
  of 
  the 
  intermediate 
  beds 
  

   between 
  this 
  zone 
  and 
  the 
  one 
  below, 
  have 
  not 
  been 
  observed, 
  

   but 
  the 
  change 
  from 
  one 
  fauna 
  to 
  the 
  other 
  is 
  probably 
  very 
  

   gradual, 
  8. 
  plenus, 
  8. 
  grimesi, 
  etc., 
  becoming 
  more 
  and 
  more 
  

   the 
  predominant 
  forms 
  and 
  replacing 
  the 
  smaller 
  species 
  which 
  

   were 
  abundaut 
  in 
  Zone 
  II. 
  

  

  Zone 
  IV. 
  — 
  At 
  Station 
  12, 
  three 
  distinct 
  beds 
  of 
  limestone 
  

   are 
  exposed. 
  The 
  lowest 
  of 
  these 
  is 
  very 
  similar 
  in 
  character 
  

   to 
  Zone 
  III 
  at 
  Station 
  13, 
  and 
  probably 
  lies 
  but 
  very 
  few 
  feet 
  

   above 
  it. 
  However, 
  there 
  is 
  a 
  decided 
  change 
  in 
  the 
  fauna. 
  

   8. 
  plenus 
  which 
  was 
  the 
  most 
  abundant 
  species 
  in 
  the 
  preced-. 
  

   ing 
  zone, 
  has 
  almost 
  entirely 
  disappeared. 
  

  

  At 
  Station 
  12, 
  the 
  following 
  species 
  were 
  collected 
  in 
  the 
  

   lowest 
  bed. 
  

  

  Spirifer 
  grimesi 
  Hall. 
  

   Orthis 
  sivallovi 
  Hall. 
  

   Orthis 
  burlingtonensis 
  Hall. 
  

   Athyris 
  incrassatus 
  Hall. 
  

   Productus 
  punctatus 
  Martin. 
  

  

  Metoptoma 
  umbella 
  Meek 
  and 
  Wor- 
  

  

  then. 
  

   Spirifer 
  lineatoides 
  Swallow. 
  

   Platyceras 
  quincyense 
  McChesney. 
  

   Platyceras 
  equilatera 
  Hall. 
  

  

  In 
  the 
  excavation 
  made 
  a 
  few 
  years 
  ago 
  at 
  Station 
  6, 
  the 
  

   same 
  three 
  beds 
  of 
  limestone 
  were 
  penetrated 
  as 
  are 
  seen 
  at 
  

   Station 
  12. 
  Some 
  fossils 
  were 
  obtained 
  from 
  here 
  at 
  the 
  time, 
  

   but 
  they 
  were 
  not 
  collected 
  with 
  reference 
  to 
  the 
  present 
  work. 
  

   In 
  the 
  bottom 
  of 
  the 
  excavation 
  a 
  coarse, 
  gray, 
  crystalline 
  

   limestone, 
  like 
  the 
  lower 
  bed 
  at 
  Station 
  12, 
  was 
  exposed, 
  and 
  a 
  

   great 
  number 
  of 
  large, 
  tine 
  specimens 
  of 
  8. 
  grimesi 
  were 
  col- 
  

   lected, 
  but 
  no 
  specimens 
  of 
  8. 
  plenus. 
  

  

  Northwest 
  of 
  Springfield, 
  in 
  a 
  large 
  sunk 
  hole 
  (Station 
  15), 
  a 
  

   stratum 
  of 
  gray, 
  crystalline 
  limestone 
  is 
  exposed, 
  with 
  numer- 
  

   ous 
  fossils. 
  Prominent 
  among 
  them 
  is 
  8. 
  grimesi, 
  but 
  not 
  a 
  

   specimen 
  of 
  8. 
  plenus 
  was 
  seen. 
  The 
  fauna 
  as 
  a 
  whole 
  is 
  very 
  

   similar 
  to 
  those 
  just 
  described 
  and 
  may 
  be 
  placed 
  with 
  them 
  in 
  

   Zone 
  LV. 
  The 
  species 
  collected 
  are 
  as 
  follows 
  : 
  

  

  Chonetes 
  illinoisensis 
  Worthen. 
  

   Spirifer 
  grimesi 
  Hall. 
  

   Orthis 
  burlingtonensis 
  Hall. 
  

   Spirifer 
  sp. 
  

  

  Athyris 
  incrassatus 
  Hall. 
  

   Productus 
  setigerus 
  Hall. 
  

   Platyceras 
  equilatera 
  Hall. 
  

   Athyris 
  lamellosa 
  L'Eveille. 
  

   Productus 
  punctatus 
  Martin. 
  

   Platyceras 
  quincyense 
  McChesney. 
  

  

  Spirifer 
  suborbicularis 
  Hall. 
  

   Orthis 
  swallovi 
  Hall. 
  

   Derbyia 
  keokuk 
  Hall. 
  

   Zaphrentis 
  centralis 
  Worthen. 
  

   Rhynchonella 
  cf. 
  pleurodon 
  Phillips. 
  

   Metoptoma 
  umbella, 
  Meek 
  and 
  Wor- 
  

   then. 
  

   Hadrophyllum 
  glans 
  White. 
  

   Phillipsia 
  bufo 
  Meek 
  and 
  Worthen. 
  ? 
  

  

  