﻿192 
  S. 
  Welter 
  — 
  Succession 
  of 
  Fossil 
  Faunas 
  in 
  Missouri. 
  

  

  grained 
  limestone 
  of 
  Zone 
  I. 
  The 
  chert, 
  when 
  subjected 
  to 
  

   the 
  influence 
  of 
  weathering, 
  slacks 
  to 
  a 
  fine 
  white 
  powder. 
  In 
  

   many 
  cases 
  the 
  chert 
  masses 
  surround 
  a 
  nucleus 
  of 
  limestone, 
  

   the 
  passage 
  from 
  the 
  one 
  material 
  to 
  the 
  other 
  being 
  very 
  

   gradual. 
  Often 
  fossils 
  retaining 
  their 
  calcareous 
  condition 
  are 
  

   found 
  embedded 
  in 
  the 
  chert. 
  Like 
  the 
  limestone 
  below, 
  this 
  

   also 
  is 
  largely 
  made 
  up 
  of 
  crinoidal 
  remains, 
  but 
  perfectly 
  pre- 
  

   served 
  bodies 
  are 
  much 
  more 
  common. 
  

  

  At 
  Station 
  12 
  the 
  following 
  fauna 
  was 
  collected. 
  

  

  Spirifer 
  grimesi 
  Hall. 
  

   Athyris 
  incrassatus 
  Hall. 
  

   Dorycrinus 
  parvus 
  Shumard. 
  

   Physetocrinus 
  ventricosus 
  Hall. 
  

   Orthis 
  sivallovi 
  Hall. 
  

  

  Agaricocrinus 
  americanus 
  Eoemer. 
  

   Platyceras 
  sp. 
  

  

  Actinocrinus 
  verrucosus 
  Hall. 
  

   Terebratula 
  cf. 
  hastata 
  Sowerby. 
  

  

  At 
  Station 
  6 
  very 
  few 
  fossils 
  were 
  collected 
  from 
  this 
  zone, 
  

   but 
  Athyris 
  lamellosa 
  was 
  seen 
  in 
  addition 
  to 
  those 
  mentioned. 
  

   However 
  at 
  this 
  locality 
  we 
  have 
  the 
  chert 
  bed, 
  with 
  the 
  same 
  

   character 
  of 
  chert 
  and 
  limestone, 
  lying 
  in 
  the 
  same 
  position 
  as 
  

   regards 
  the 
  fauna 
  with 
  the 
  great 
  development 
  of 
  Spirifer 
  

   grimesi, 
  and 
  there 
  can 
  be 
  no 
  doubt 
  as 
  to 
  the 
  equivalence 
  of 
  the 
  

   beds 
  at 
  the 
  two 
  localities. 
  

  

  In 
  the 
  Gulf 
  R.R. 
  section 
  this 
  chert 
  bed 
  is 
  exposed 
  at 
  two 
  

   other 
  localities 
  besides 
  Station 
  6. 
  At 
  Station 
  3 
  about 
  eight 
  

   feet 
  of 
  this 
  stratum 
  is 
  exposed. 
  Only 
  two 
  species 
  of 
  fossils 
  

   were 
  collected 
  here, 
  though 
  others 
  are 
  present. 
  

  

  Spirifer 
  grimesi 
  Hall. 
  

  

  Dorycrinus 
  parvus 
  Shumard. 
  

  

  At 
  Station 
  4 
  this 
  bed 
  is 
  again 
  exposed. 
  No 
  fossils 
  were 
  col- 
  

   lected 
  here, 
  but 
  in 
  the 
  face 
  of 
  the 
  quarry 
  Spirifer 
  grimesi 
  and 
  

   Athyris 
  incrassatus 
  appear 
  to 
  be 
  common. 
  

  

  This 
  zone 
  may 
  be 
  considered 
  as 
  the 
  upper 
  limit 
  of 
  the 
  true 
  

   Burlington, 
  and 
  can 
  be 
  recognized 
  by 
  the 
  peculiar 
  character 
  of 
  

   the 
  limestone 
  and 
  chert, 
  as 
  well 
  as 
  by 
  its 
  fauna. 
  In 
  this 
  region 
  

   Dorycrinus 
  parvus 
  is 
  characteristic 
  of 
  the 
  horizon. 
  

  

  Zone 
  VI. 
  — 
  Lying 
  above 
  the 
  lower 
  chert 
  bed 
  is 
  an 
  horizon 
  of 
  

   rather 
  coarsely 
  crystalline 
  limestone, 
  much 
  like 
  that 
  which 
  

   also 
  occurs 
  below 
  the 
  chert. 
  Nearly 
  all 
  the 
  quarries 
  along 
  the 
  

   south 
  bank 
  of 
  Wilson 
  Creek, 
  in 
  Springfield, 
  are 
  in 
  strata 
  of 
  

   this 
  zone. 
  The 
  beds 
  however, 
  dip 
  to 
  the 
  west, 
  and 
  being 
  car- 
  

   ried 
  below 
  the 
  surface, 
  higher 
  beds 
  are 
  exposed 
  in 
  the 
  quarries 
  

   near 
  the 
  Gulf 
  R.R. 
  shops. 
  

  

  At 
  Station 
  3 
  the 
  base 
  of 
  this 
  zone 
  may 
  be 
  seen 
  resting 
  

   directly 
  upon 
  the 
  chert 
  beds 
  below. 
  Fossils 
  are 
  abundant 
  at 
  

   this 
  locality 
  and 
  the 
  following 
  species 
  were 
  collected. 
  

  

  