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  Blackwelder 
  — 
  Little 
  known 
  Paleozoic 
  Faunas. 
  

  

  echinoderms, 
  etc. 
  The 
  other 
  is 
  an 
  assemblage 
  of 
  mollusks, 
  

   with 
  a 
  few 
  brachiopods. 
  The 
  former 
  occurs 
  in 
  the 
  blackish 
  to 
  

   drab-gray 
  limestones 
  mentioned 
  above, 
  while 
  the 
  latter 
  was 
  

   found 
  at 
  the 
  horizon 
  about 
  60 
  feet 
  lower 
  in 
  a 
  dense, 
  olive-gray 
  

   limestone 
  mottled 
  with 
  purple. 
  It 
  is 
  thus 
  evident 
  that 
  the 
  

   environment 
  of 
  the 
  two 
  faunules 
  in 
  life 
  was 
  somewhat 
  differ- 
  

   ent. 
  In 
  the 
  upper, 
  or 
  brachiopod 
  faunule, 
  the 
  most 
  character- 
  

   istic 
  species 
  are 
  Productus 
  cora, 
  Composita 
  subtilita, 
  and 
  

   Chonetes 
  geinitzianus. 
  The 
  lower 
  or 
  mollusk 
  faunule 
  is 
  char- 
  

   acterized 
  especially 
  by 
  Composita 
  subtilita, 
  /Spirifer 
  rocky 
  - 
  

   montanus, 
  and 
  a 
  number 
  of 
  small 
  gastropods 
  and 
  pelecypods. 
  

   The 
  full 
  quota 
  of 
  species 
  recognized 
  in 
  each 
  zone 
  is 
  given 
  

   below 
  : 
  

  

  Fossils 
  of 
  the 
  upper 
  or 
  brachiopod 
  zone. 
  

  

  Fchinocrinus 
  sp. 
  Schizophoria 
  aff. 
  resupinoides. 
  

  

  Crinoidal 
  plates. 
  Chonetes 
  Geinitzianus. 
  

  

  Batostomella 
  sp. 
  Chonetes 
  granidifer. 
  

  

  Batostomella 
  ? 
  sp. 
  Productus 
  cora. 
  

   Rhombopora 
  lepidodendroides 
  ? 
  Productus 
  semireticulatus. 
  

  

  JStenopora 
  sp. 
  Productus 
  nebraskensis. 
  

  

  Lingula 
  umbonata 
  ? 
  Spirifer 
  rockymontanus. 
  

  

  Lingula 
  carbonaria. 
  Composita 
  subtilita. 
  

  

  IAngulidiscina 
  sp. 
  Conocardium 
  sp. 
  

  

  Derbya 
  robusta. 
  • 
  Fish 
  plate. 
  

  

  Fossils 
  of 
  the 
  lovier 
  or 
  mollusk 
  zone. 
  

  

  Large 
  crinoid 
  stems. 
  Pleurophorus 
  2 
  sp. 
  

  

  Spirifer 
  robkymontanus 
  ? 
  Bucanopsis 
  ? 
  sp. 
  

  

  Squamidaria 
  perplexa 
  ? 
  Fuphemus 
  ? 
  sp, 
  

  

  Composita 
  subtilita 
  ? 
  Pleurotomaria 
  sp. 
  

  

  Myalina 
  sp. 
  Naticopsis 
  sp. 
  

  

  Cypricardinia 
  sp. 
  Euomphalus 
  sp. 
  

  

  With 
  reference 
  to 
  the 
  age 
  and 
  correlation 
  of 
  these 
  faunules, 
  

   Dr. 
  Girty 
  says 
  that 
  the 
  upper 
  zone 
  is 
  il 
  pretty 
  clearly 
  of 
  Penn- 
  

   sylvanian 
  age. 
  They 
  are 
  also 
  probably 
  early 
  Pennsylvanian." 
  

   The 
  lower 
  faunule 
  "evidently 
  presents 
  a 
  different 
  fades 
  . 
  . 
  . 
  

   The 
  preservation 
  of 
  most 
  of 
  the 
  species 
  is 
  poor 
  and 
  none 
  of 
  

   them 
  are 
  very 
  diagnostic, 
  but 
  there 
  is 
  at 
  least 
  a 
  possibility 
  that 
  

   this 
  collection 
  may 
  prove 
  to 
  be 
  of 
  Upper 
  Mississippian 
  age." 
  

   The 
  remark 
  may 
  be 
  added 
  here, 
  however, 
  that 
  both 
  faunules 
  

   occur 
  in 
  a 
  single 
  formation 
  of 
  distinctive 
  and 
  unified 
  character, 
  

   separated 
  from 
  the 
  known 
  lower 
  Mississippian 
  limestone 
  by 
  a 
  

   distinct 
  unconformity. 
  Therefore, 
  unless 
  there 
  is 
  strong 
  evi- 
  

   dence 
  to 
  the 
  contrary, 
  it 
  seems 
  probable 
  that 
  both 
  faunules 
  

   belong 
  to 
  the 
  same 
  period. 
  

  

  