﻿430 
  

  

  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  

  

  been 
  warmer 
  as 
  a 
  whole, 
  the 
  environmental 
  contrasts 
  between 
  the 
  two 
  

   areas 
  must 
  have 
  been 
  as 
  great 
  then 
  as 
  they 
  are 
  now, 
  and 
  it 
  is 
  permissible 
  

   to 
  expect 
  these 
  contrasts 
  to 
  find 
  as 
  much 
  expression 
  in 
  faunal 
  differ- 
  

   ences, 
  particularly 
  among 
  the 
  small, 
  nonvolant 
  manmials, 
  as 
  they 
  do 
  

   today. 
  A 
  comparison 
  of 
  the 
  Lower 
  Oligocene 
  faunas 
  of 
  the 
  two 
  areas 
  

   (table 
  3) 
  shows 
  that 
  faunal 
  differences 
  did 
  exist. 
  By 
  analogy 
  with 
  

   Recent 
  faunas 
  the 
  differences 
  appear 
  to 
  be 
  correlated 
  with 
  environ- 
  

   mental 
  differences. 
  It 
  is 
  expected 
  that 
  further 
  explorations 
  will 
  

   modify 
  the 
  faunal 
  differences 
  somewhat; 
  but, 
  in 
  view 
  of 
  the 
  extensive 
  

   explorations 
  in 
  both 
  areas, 
  radical 
  changes 
  are 
  not 
  anticipated. 
  

  

  Table 
  3. 
  — 
  Distribution 
  of 
  Lower 
  Oligocene 
  fauna 
  

  

  For 
  purposes 
  of 
  discussion, 
  the 
  fauna 
  of 
  the 
  Mountain 
  Province 
  as 
  

   here 
  used 
  is 
  the 
  combined 
  faunas 
  of 
  Pipestone 
  Springs 
  and 
  the 
  Lower 
  

   Oligocene 
  of 
  Canyon 
  Ferry. 
  These 
  two 
  areas 
  were 
  chosen 
  deliberately 
  

   because 
  they 
  are 
  separated 
  from 
  the 
  plains 
  by 
  more 
  than 
  one 
  range 
  of 
  

   mountains 
  and 
  cannot 
  possibly 
  be 
  interpreted 
  as 
  having 
  been 
  in 
  the 
  

  

  