﻿406 
  G. 
  R. 
  Mansfield 
  — 
  Formations 
  of 
  S.E. 
  Idaho. 
  

  

  Pisidium 
  saginatum 
  White. 
  

  

  Plwnorbis, 
  resembling 
  P. 
  aequalis 
  White. 
  

  

  Lymnaea 
  of 
  the 
  type 
  of 
  L. 
  similis 
  Meek. 
  

  

  On 
  the 
  other 
  hand, 
  in 
  collections 
  from 
  Pliocene 
  ( 
  1 
  ) 
  

   beds 
  in 
  the 
  Fort 
  Hall 
  Indian 
  Reservation, 
  he 
  has 
  identi- 
  

   fied 
  the 
  following 
  forms 
  : 
  

  

  Succinea 
  f 
  or 
  Lymnaea 
  f 
  internal 
  casts, 
  not 
  otherwise 
  

   identifiable. 
  

  

  Oreohelix 
  (one 
  or 
  possibly 
  two 
  species) 
  internal 
  casts, 
  not 
  

   identifiable 
  further 
  

  

  Bifidaria, 
  internal 
  cast, 
  not 
  identifiable 
  further. 
  

  

  These 
  he 
  is 
  inclined 
  to 
  regard 
  as 
  Pliocene 
  ( 
  ?). 
  

  

  From 
  a 
  locality 
  in 
  the 
  SW.%, 
  SW.% 
  sec. 
  23, 
  T.7S., 
  

   R.33E., 
  in 
  the 
  western 
  part 
  of 
  the 
  Fort 
  Hall 
  Indian 
  Res- 
  

   ervation, 
  where 
  carbonaceous 
  shales 
  were 
  exposed 
  in 
  an 
  

   old 
  coal 
  prospect, 
  plant 
  remains 
  were 
  collected. 
  These 
  

   were 
  examined 
  by 
  F. 
  H. 
  Knowlton 
  and 
  proved 
  to 
  be 
  frag- 
  

   ments 
  of 
  stems 
  and 
  bark 
  not 
  determinable. 
  

  

  Most 
  of 
  the 
  fossils 
  thns 
  far 
  found 
  are 
  of 
  long-ranging 
  

   types, 
  but 
  some, 
  such 
  as 
  Oreohelix 
  from 
  the 
  Fort 
  Hall 
  

   Indian 
  Reservation, 
  suggest 
  later 
  rather 
  than 
  earlier 
  

   Tertiary 
  age, 
  while 
  others, 
  as 
  noted 
  above, 
  suggest 
  

   Eocene 
  age. 
  These 
  light 
  colored 
  beds 
  occur 
  at 
  suffi- 
  

   ciently 
  frequent 
  intervals 
  to 
  make 
  it 
  reasonably 
  certain 
  

   that 
  they 
  belong 
  together. 
  The 
  stratigraphic 
  position 
  

   of 
  the 
  beds 
  at 
  some 
  localities, 
  as 
  along 
  the 
  west 
  side 
  of 
  

   Bear 
  Lake 
  Valley, 
  indicates 
  that 
  they 
  are 
  of 
  later 
  age 
  

   than 
  the 
  Wasatch 
  formation. 
  They 
  were 
  regarded 
  as 
  

   Pliocene 
  by 
  Hayden 
  and 
  Peale. 
  10 
  In 
  view 
  of 
  the 
  unsatis- 
  

   factory 
  nature 
  of 
  the 
  evidence 
  it 
  seems 
  better 
  to 
  retain 
  

   tentatively 
  that 
  interpretation. 
  

  

  10 
  Peale, 
  A. 
  C: 
  U. 
  S. 
  Geol. 
  and 
  Geog. 
  Survey 
  Terr., 
  Eleventh 
  Ann. 
  Kept, 
  

   for 
  1877, 
  p. 
  640, 
  1879. 
  

  

  