﻿266 
  D. 
  K. 
  Greger 
  — 
  Devonian 
  of 
  Central 
  Missouri. 
  

  

  three 
  species 
  (rare), 
  Spirifer 
  euruteines 
  Owen 
  

   (rare). 
  

  

  Thickness 
  48 
  inches. 
  

  

  Zone 
  No. 
  4. 
  Yellow, 
  soft, 
  limy 
  shale, 
  very 
  f 
  ossilif 
  erons 
  ; 
  Zaph- 
  

   rentis 
  sp. 
  (common), 
  Spirifer 
  euruteines 
  Owen 
  

   (exceedingly 
  abundant), 
  Camarotozchia 
  sp. 
  (rare), 
  

   Atrypa 
  reticularis 
  (rare), 
  Schizophoria 
  striatula 
  

   iowensis 
  (rare), 
  Cyrtina 
  triquetra 
  (rare). 
  

  

  Thickness 
  20 
  inches. 
  

  

  Zone 
  No. 
  5. 
  Iron-stained, 
  gray, 
  shaly 
  limestone, 
  made 
  np 
  almost 
  

   entirely 
  of 
  fragmentary 
  Schizophoria 
  striatula 
  

   iowensis. 
  This 
  layer 
  is 
  harder 
  and 
  breaks 
  down 
  in 
  

   large 
  blocks 
  which 
  do 
  not 
  weather 
  nearly 
  so 
  rapidly 
  

   as 
  the 
  beds 
  above 
  and 
  below 
  ; 
  Schizophoria 
  striatula 
  

   iowensis 
  (qnite 
  abundant), 
  Stropheodonta 
  callaway- 
  

   ensis 
  Swallow 
  (common), 
  Camarotoechia 
  sp. 
  (rare), 
  

   Orbiculoidea 
  sp. 
  (rare), 
  Aulopora 
  sp. 
  (rare), 
  Zaph- 
  

   rentis 
  sp. 
  (rare). 
  

  

  Thickness 
  10 
  inches. 
  

  

  Zone 
  No. 
  6. 
  Fine-grained, 
  bluish, 
  limy 
  shale, 
  fossils 
  abundant; 
  

   pelecypods, 
  14 
  species, 
  mostly 
  undescribed 
  forms, 
  

   Orthoceras 
  sp. 
  (rare), 
  Spirifer 
  iowensis 
  Owen 
  

   (rare), 
  Atrypa 
  reticularis, 
  large 
  form 
  (rare). 
  

  

  Thickness 
  10 
  feet 
  to 
  creek 
  bed. 
  

  

  Of 
  the 
  abundant 
  pelecypods 
  from 
  zone 
  No. 
  6, 
  the 
  fol- 
  

   lowing 
  genera 
  are 
  identified, 
  those 
  most 
  abundant 
  being 
  

   given 
  first: 
  Paracyclas, 
  Palceoneilo, 
  Schizodus, 
  Edmon- 
  

   dia, 
  Grammy 
  sia, 
  Actinopteria, 
  Pterinopecten, 
  Gonio- 
  

   pliora. 
  Brachiopods 
  are 
  quite 
  rare 
  in 
  this 
  zone, 
  but 
  the 
  

   two 
  species 
  recorded 
  are 
  forms 
  that 
  occur 
  only 
  in 
  the 
  

   uppermost 
  layers 
  of 
  the 
  shale, 
  in 
  the 
  type 
  locality. 
  

   However, 
  with 
  the 
  evidence 
  offered 
  by 
  the 
  pelecypods 
  

   alone, 
  the 
  correlation 
  of 
  this 
  zone 
  with 
  the 
  top 
  of 
  the 
  

   Craghead 
  Creek 
  exposure 
  can 
  scarcely 
  be 
  questioned, 
  

   especially 
  when 
  the 
  very 
  similar 
  lithologic 
  character 
  of 
  

   the 
  beds 
  is 
  taken 
  into 
  consideration. 
  

  

  It 
  is 
  interesting 
  to 
  note 
  in 
  this 
  connection 
  that 
  ten 
  spe- 
  

   cies 
  from 
  the 
  upper 
  beds 
  of 
  the 
  Craghead 
  Creek 
  shale 
  

   are 
  seemingly 
  identical 
  with 
  forms 
  described 
  by 
  Doctor 
  

   Cleland 
  in 
  Bulletin 
  No. 
  21 
  of 
  the 
  Wisconsin 
  Geological 
  

   and 
  Natural 
  History 
  Survey, 
  as 
  follows: 
  Orbiculoidea 
  

   teller 
  i 
  Cleland, 
  Liorhynchus 
  greeni 
  Cleland, 
  Camarotoe- 
  

   chia 
  scitulus 
  Cleland, 
  Crancena 
  iowensis 
  (Calvin) 
  (figs. 
  

   8 
  and 
  9 
  only), 
  Edmondia 
  fragilis 
  Cleland, 
  Goniophora 
  

   obtusiloba 
  Cleland, 
  Pterinopecten 
  telleri 
  Cleland, 
  Gram- 
  

   mysia 
  nodocostata 
  Hall, 
  Ptyctodus 
  calceolus 
  N. 
  & 
  W., 
  and 
  

   Ptyctodus 
  ferox 
  Eastman. 
  

  

  Fulton, 
  Mo. 
  

  

  