﻿in 
  a 
  Section 
  of 
  the 
  Morrison 
  Formation. 
  193 
  

  

  their 
  belief 
  that 
  it 
  is 
  of 
  Cenornanian 
  age. 
  Berry 
  places 
  

   it 
  without 
  qualification 
  in 
  the 
  Upper 
  Cretaceous. 
  A 
  

   very 
  large 
  Cheyenne 
  flora 
  is 
  known, 
  and 
  although 
  it 
  has 
  

   not 
  been 
  thoroughly 
  studied, 
  Berry 
  and 
  I 
  have 
  looked 
  

   it 
  over 
  with 
  some 
  care 
  and 
  agree 
  perfectly 
  that 
  its 
  

   affinity 
  is 
  undoubtedly 
  with 
  the 
  Upper 
  Cretaceous. 
  

   Whatever 
  may 
  be 
  ultimately 
  decided 
  as 
  to 
  the 
  relation 
  

   between 
  the 
  Cheyenne 
  and 
  the 
  type 
  Dakota 
  or 
  with 
  the 
  

   so-called 
  Dakota 
  of 
  the 
  Denver 
  Basin, 
  I 
  do 
  not 
  think 
  

   there 
  is 
  any 
  doubt 
  about 
  the 
  "Morrison" 
  plants 
  being 
  

   in 
  the 
  Upper 
  Cretaceous 
  flora. 
  

  

  A 
  further 
  word 
  may 
  be 
  said 
  on 
  the 
  interpretation 
  to 
  

   be 
  given 
  the 
  stratigraphic 
  position 
  of 
  the 
  plant-bearing 
  

   strata 
  of 
  the 
  type 
  Morrison. 
  The 
  floras 
  previously 
  

   known 
  from 
  beds 
  regarded 
  as 
  of 
  Morrison 
  age, 
  or 
  in 
  the 
  

   approximate 
  position 
  of 
  the 
  Morrison, 
  are 
  without 
  

   dicotyledons 
  and 
  there 
  is 
  no 
  hesitation 
  in 
  referring 
  them 
  

   to 
  the 
  Lower 
  Cretaceous. 
  It 
  is 
  difficult 
  to 
  reconcile 
  these 
  

   floras 
  with 
  the 
  dicotyledonous 
  flora 
  from 
  the 
  type 
  sec- 
  

   tions 
  of 
  the 
  Morrison. 
  Is 
  it 
  not 
  within 
  the 
  limits 
  of 
  

   possibility 
  that 
  certain 
  beds 
  that 
  have 
  been 
  identified 
  

   elsewhere 
  as 
  of 
  Morrison 
  age 
  may 
  not 
  be 
  the 
  same 
  age 
  

   as 
  the 
  Morrison 
  in 
  its 
  type 
  section? 
  

  

  A 
  hasty 
  review 
  of 
  the 
  Dinosaur 
  fauna 
  of 
  the 
  type 
  Mor- 
  

   rison, 
  which 
  includes 
  some 
  five 
  or 
  six 
  species, 
  shows 
  that 
  

   several 
  of 
  the 
  species 
  have 
  been 
  reported 
  elsewhere, 
  but 
  

   according 
  to 
  C. 
  W. 
  Gilmore, 
  of 
  the 
  U. 
  S. 
  National 
  

   Museum, 
  not 
  a 
  single 
  one 
  of 
  these 
  species 
  has 
  with 
  cer- 
  

   tainty 
  been 
  identified 
  outside 
  the 
  type 
  area. 
  

  

  Conclusion. 
  

  

  The 
  conclusion 
  is 
  reached 
  that 
  the 
  dicotyledonous 
  

   flora 
  discussed 
  in 
  this 
  paper 
  from 
  the 
  type 
  section 
  of 
  the 
  

   Morrison 
  formation, 
  finds 
  its 
  closest 
  affinity 
  with 
  the 
  

   so-called 
  Dakota 
  flora 
  of 
  the 
  Denver 
  Basin, 
  a 
  flora 
  that 
  

   is 
  known 
  to 
  come 
  in 
  whole 
  or 
  in 
  part 
  from 
  what 
  is 
  classed 
  

   as 
  the 
  Purgatoire 
  formation, 
  and 
  not 
  from 
  the 
  Dakota 
  

   as 
  at 
  present 
  delimited. 
  Under 
  the 
  classification 
  which 
  

   places 
  the 
  Purgatoire 
  formation, 
  — 
  the 
  so-called 
  lower 
  

   Dakota 
  at 
  Morrison 
  — 
  in 
  the 
  Lower 
  Cretaceous 
  series, 
  

   the 
  "Morrison 
  flora" 
  occurs 
  below 
  the 
  base 
  of 
  this 
  

   series. 
  The 
  suggested 
  classification 
  makes 
  Purgatoire 
  

   include 
  the 
  plant-bearing 
  part 
  of 
  the 
  original 
  Morrison, 
  

  

  