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  32 
  Spencer 
  — 
  Devonian 
  Strata 
  in 
  Colorado. 
  

  

  In 
  the 
  Gunnison 
  region 
  the 
  following 
  forms 
  were 
  found 
  : 
  

  

  Streptelasma 
  sp. 
  Spirifer 
  disjunctus 
  var. 
  Ani- 
  

   Ghmtetes 
  sp. 
  masensis. 
  

  

  Monotrypella 
  sp. 
  b. 
  Atliyris 
  Coloradcensis. 
  

  

  Schizophoria 
  striatida. 
  Gamarotoechia 
  (Rhynconella) 
  

   Orthis 
  sp. 
  Midlichi. 
  

  

  Orthothetes 
  Ghemungensis 
  var. 
  Gamarotoechia 
  contracta 
  f 
  

  

  Ghonetes 
  sp. 
  JS 
  T 
  aticopsis? 
  humilis. 
  

   Productella 
  semiglobosa. 
  

  

  Other 
  localities 
  which 
  are 
  represented 
  in 
  the 
  collections 
  of 
  

   the 
  U. 
  S. 
  National 
  Museum 
  have 
  yielded 
  some 
  of 
  the 
  forms 
  

   listed 
  above. 
  The 
  labels 
  are 
  not 
  definite, 
  but 
  show 
  the 
  occur- 
  

   rence 
  of 
  the 
  fauna 
  over 
  a 
  wider 
  area 
  than 
  that 
  in 
  which 
  the 
  

   section 
  has 
  been 
  studied 
  in 
  detail. 
  They 
  are 
  as 
  follows 
  : 
  Mass- 
  

   ive 
  limestone 
  of 
  White 
  river, 
  Colorado 
  ; 
  Canon 
  of 
  Cement 
  

   creek, 
  Colorado; 
  Northwestern 
  Colorado; 
  Southwestern 
  Colo- 
  

   rado. 
  

  

  After 
  a 
  comparison 
  of 
  the 
  fossils 
  from 
  the 
  various 
  localities, 
  

   Dr. 
  Girty 
  says 
  : 
  " 
  The 
  strata 
  from 
  which 
  these 
  forms 
  have 
  been 
  

   collected 
  are 
  without 
  doubt 
  of 
  Devonian 
  age. 
  As 
  they 
  have 
  

   essentially 
  the 
  same 
  fauna, 
  I 
  refer 
  them 
  to 
  the 
  same 
  horizon, 
  

   which 
  I 
  take 
  to 
  be 
  well 
  up 
  in 
  the 
  Devonian. 
  In 
  my 
  opinion, 
  

   it 
  probably 
  belongs 
  below 
  the 
  Chemung, 
  at 
  about 
  the 
  base 
  of 
  

   the 
  Upper 
  or 
  near 
  the 
  top 
  of 
  the 
  Lower 
  Devonian. 
  While 
  

   this 
  fauna 
  is 
  clearly 
  related 
  to 
  other 
  fossil 
  assemblages 
  of 
  our 
  

   western 
  Devonian, 
  it 
  cannot 
  be 
  said 
  to 
  be 
  strictly 
  identical 
  with 
  

   any 
  one 
  of 
  them, 
  for 
  its 
  common 
  forms, 
  Spirifer 
  disjunctus 
  

   var. 
  Animasensis, 
  Athyris 
  Color 
  adwnsis, 
  and 
  Gamarotoechia 
  

   Endlichi, 
  which, 
  so 
  far 
  as 
  I 
  am 
  aware, 
  have 
  not 
  been 
  found 
  

   elsewhere, 
  give 
  it 
  considerable 
  individuality. 
  Of 
  the 
  faunas 
  

   with 
  which 
  I 
  am 
  familiar, 
  it 
  most 
  closely 
  resembles 
  that 
  

   described 
  by 
  Whiteaves 
  from 
  Hay 
  river, 
  Canada, 
  and 
  from 
  

   other 
  parts 
  of 
  the 
  Mackenzie 
  region." 
  

  

  Correlation.— 
  The 
  combined 
  evidence 
  furnished 
  by 
  paleon- 
  

   tology 
  and 
  stratigraphy, 
  as 
  set 
  forth 
  in 
  the 
  preceding 
  para- 
  

   graphs, 
  is 
  thought 
  to 
  be 
  sufficient 
  to 
  establish 
  the 
  practical 
  

   equivalency 
  of 
  formations 
  of 
  Devonian 
  age 
  occurring 
  in 
  widely 
  

   separated 
  localities 
  of 
  Colorado, 
  Utah 
  and 
  Arizona. 
  The 
  

   "Farting 
  Quartzite 
  " 
  has 
  been 
  a 
  datum 
  of 
  reference 
  in 
  all 
  the 
  

   geological 
  investigations 
  iu 
  the 
  Central 
  region 
  of 
  Colorado. 
  

   With 
  the 
  discovery 
  of 
  its 
  age 
  as 
  Devonian 
  its 
  equivalence 
  with 
  

   strata 
  of 
  that 
  age 
  in 
  the 
  Grand 
  Canon 
  district 
  was 
  established, 
  

   and 
  now 
  it 
  is 
  found 
  to 
  be 
  represented 
  in 
  the 
  San 
  Juan 
  region 
  

   of 
  Colorado. 
  The 
  evidence 
  upon 
  which 
  this 
  correlation 
  rests, 
  

   is 
  the 
  occurrence 
  of 
  fish 
  remains 
  of 
  similar 
  types 
  in 
  the 
  three 
  

   regions, 
  and 
  the 
  corresponding 
  position 
  which 
  the 
  siliceous 
  

  

  