﻿1 
  94 
  jS. 
  Welter 
  — 
  Succession 
  of 
  Fossil 
  Faunas 
  in 
  Missouri. 
  

  

  sions 
  in 
  the 
  chert, 
  the 
  finest 
  detail 
  of 
  the 
  surface 
  markings 
  of 
  

   the 
  shells 
  are 
  preserved. 
  The 
  limestone 
  is 
  coarsely 
  crystalline 
  

   and 
  is 
  largely 
  composed 
  of 
  crinoid 
  remains. 
  On 
  the 
  decomposi- 
  

   tion 
  of 
  the 
  limestone, 
  the 
  chert 
  remains 
  in 
  the 
  soil, 
  often 
  form- 
  

   ing 
  regular 
  strata 
  in 
  the 
  residual 
  clay 
  beds. 
  Much 
  of 
  the 
  

   fossiliferous 
  chert, 
  so 
  abundant 
  in 
  the 
  soil 
  of 
  this 
  region, 
  is 
  

   from 
  this 
  horizon. 
  

  

  The 
  fauna 
  collected 
  at 
  Station 
  7 
  is 
  as 
  follows. 
  

  

  Agaricocrinus 
  americanus 
  Roemer. 
  

   Spiriferina 
  sp. 
  

   Terebratula 
  sacculus 
  Martin. 
  

   Athyris 
  incrassatus 
  Hall. 
  

   Platycrinus 
  saffordi 
  Troost. 
  

   Eretmocrinus 
  originarius 
  Wachsmuth. 
  

   Spirifer 
  logani 
  Kail. 
  

   Orthis 
  dubia 
  Hall. 
  

   Batocrinus 
  biturbinatus 
  Hall. 
  

   Pentremites 
  conoideus 
  Hall. 
  

   Spirifer 
  pseudolineata 
  Hall. 
  

  

  | 
  Derbyia 
  keokuk 
  Hall. 
  

   Batocrinus 
  sp. 
  

   Granatocrinus 
  granulosus 
  Meek 
  and 
  

  

  Worthen. 
  

   Spirifer 
  tenuicostatus 
  Hall. 
  

   Spirifer 
  neglectus 
  Hall. 
  

   Spirifer 
  suborbicidaris 
  Hall. 
  

   Productus 
  seligerus 
  Hall. 
  

   Eumetria 
  vemeuilana 
  Hall. 
  

   Batocrinus 
  nashvillm 
  Troost. 
  

   Platyceras 
  fisurella 
  Hall. 
  

  

  Derbyia 
  keokuk 
  Hall. 
  

   Rhynchonella 
  mutata 
  Hall. 
  

   Chonetes 
  illinoisensis 
  Hall. 
  

   Orthis 
  dubia 
  Hall. 
  

  

  This 
  is 
  decidedly 
  a 
  Keokuk 
  fauna, 
  and 
  here 
  we 
  find 
  the 
  first 
  

   appearance 
  of 
  a 
  large 
  number 
  of 
  new 
  forms. 
  Crinoids 
  are 
  

   abundant, 
  but 
  only 
  the 
  more 
  delicate 
  Keokuk 
  forms 
  are 
  present. 
  

   The 
  crinoidal 
  fauna 
  does 
  not 
  assume 
  the 
  grotesque 
  character 
  so 
  

   noticeable 
  among 
  the 
  crinoids 
  of 
  the 
  Keokuk 
  Group 
  in 
  Iowa. 
  

   The 
  tuberosus 
  variety 
  of 
  Agaricocrinus 
  americanus 
  is 
  the 
  only 
  

   representative 
  of 
  these 
  large 
  forms. 
  

  

  Zone 
  YI11. 
  — 
  The 
  upper 
  chert 
  bed 
  is 
  succeeded 
  by 
  beds 
  of 
  

   crinoidal 
  limestone 
  similar 
  to 
  those 
  which 
  precede 
  it. 
  These 
  

   strata 
  may 
  be 
  seen 
  at 
  Station 
  8, 
  and 
  the 
  fauna 
  collected 
  there 
  is 
  

   as 
  follows 
  : 
  

  

  Spirifer 
  logani 
  Hall. 
  

   Phillipsia 
  bufo 
  Meek 
  and 
  Worthen. 
  

   Zaphrentis 
  centralis 
  Worthen. 
  

   Productus 
  punctatus 
  Martin. 
  

  

  At 
  Station 
  9 
  the 
  same 
  horizon 
  is 
  exposed 
  and 
  the 
  following 
  

   species 
  were 
  collected. 
  

  

  Spirifer 
  logani 
  Hall. 
  Camarophoria 
  subtrigona 
  Meek 
  and 
  

  

  Spirifer 
  suborbicularis 
  Hall. 
  Worthen. 
  

  

  Productus 
  punctatus 
  Martin. 
  Derbyia 
  keokuk 
  Hall. 
  

  

  Terebratula 
  sacculus 
  Martin. 
  

  

  The 
  fauna 
  of 
  this 
  zone 
  is 
  Keokuk, 
  though, 
  many 
  species 
  

   which 
  were 
  common 
  in 
  the 
  chert 
  zone, 
  apparently 
  are 
  absent 
  

   here. 
  The 
  reappearance 
  of 
  Chonetes 
  illinoisensis 
  is 
  interest- 
  

   ing, 
  it 
  being 
  a 
  form 
  especially 
  abundant 
  in 
  the 
  Burlington 
  beds 
  

   below. 
  Among 
  the 
  specimens 
  of 
  Spirifer 
  logani 
  the 
  character 
  

   of 
  a 
  lengthened 
  hinge 
  line 
  is 
  more 
  exaggerated 
  than 
  in 
  the 
  

   beds 
  below, 
  but 
  above 
  this 
  zone 
  it 
  is 
  a 
  rare 
  species. 
  

  

  Zone 
  IX. 
  — 
  This 
  zone, 
  as 
  well 
  as 
  the 
  three 
  succeeding 
  ones, 
  

   with 
  the 
  exception 
  of 
  Zone 
  XI, 
  have 
  only 
  been 
  seen 
  in 
  Mackey's 
  

  

  