﻿Blackwelder 
  — 
  Little 
  known 
  Paleozoic 
  Faunas. 
  175 
  

  

  In 
  June, 
  1912, 
  the 
  writer, 
  while 
  on 
  a 
  brief 
  visit 
  to 
  this 
  local- 
  

   ity, 
  was 
  fortunate 
  enough 
  to 
  find 
  a 
  zone 
  of 
  black 
  slates 
  which 
  

   are 
  crowded 
  with 
  well-preserved 
  specimens 
  of 
  graptolites. 
  

   Owing 
  to 
  the 
  lack 
  of 
  time 
  and 
  facilities 
  only 
  a 
  small 
  collection 
  

   was 
  obtained, 
  but 
  in 
  this 
  material 
  Mr. 
  E. 
  O. 
  Ulrich 
  has 
  identified 
  

   the 
  following 
  list 
  of 
  species 
  : 
  

  

  Didymograptus 
  extensus 
  Hall. 
  

   Didymograptus 
  cf. 
  nitidas 
  Hall. 
  

   Didymograptus 
  cf. 
  planus 
  E. 
  and 
  W. 
  

   Didymograptus 
  cf. 
  tornquisti 
  Rued. 
  

   Didymograptus 
  caducens 
  (Salter) 
  Rued. 
  

   Didymograptus 
  nanus 
  Lapw. 
  

   Didymograptus 
  bifidus 
  Hall. 
  

   Tetragraptus 
  similis 
  Hall. 
  

   Dichograptus 
  cf. 
  octobrachiatus 
  Hall. 
  

   Phyllograptus 
  n. 
  sp. 
  aff. 
  P. 
  ang 
  ustifolius 
  Hall. 
  

   Lingula 
  sp. 
  undet. 
  

   Hexactinellid 
  sponge 
  spicules. 
  

  

  Of 
  this 
  collection 
  he 
  says 
  : 
  " 
  It 
  probably 
  represents 
  an 
  horizon 
  

   intermediate 
  between 
  the 
  Tetragraptus 
  and 
  the 
  Didymograptus 
  

   bifidus 
  zones 
  of 
  the 
  ' 
  Canadian 
  ' 
  as 
  worked 
  out 
  by 
  Dr. 
  R. 
  Ruede- 
  

   mann, 
  in 
  New 
  York." 
  This 
  seems 
  to 
  prove 
  that 
  there 
  are 
  rocks 
  

   of 
  Lower 
  Ordovician 
  age 
  in 
  this 
  part 
  of 
  Idaho. 
  The 
  fossils 
  were 
  

   found 
  about 
  a 
  mile 
  south 
  of 
  the 
  pass 
  on 
  the 
  Trail 
  Creek 
  /road 
  

   northeast 
  of 
  Ketchum. 
  The 
  detailed 
  stratigraphy 
  and 
  the 
  

   relations 
  of 
  the 
  strata 
  in 
  which 
  they 
  were 
  found 
  still 
  remain 
  

   to 
  be 
  worked 
  out. 
  

  

  Fossils 
  from 
  the 
  Amsden 
  formation 
  in 
  the 
  Gros 
  Ventre 
  

   Range, 
  Wyoming. 
  — 
  The 
  series 
  of 
  soft 
  sandstones, 
  shales, 
  and 
  

   limestones 
  which 
  overlie 
  the 
  well-known 
  Madison 
  limestone, 
  

   have 
  been 
  given 
  the 
  name 
  Amsden 
  formation 
  by 
  Darton.* 
  It 
  

   can 
  be 
  followed 
  with 
  more 
  or 
  less 
  confidence 
  clear 
  across 
  the 
  

   state 
  from 
  the 
  Black 
  Hills 
  to 
  Idaho. 
  Yery 
  few 
  fossils 
  have 
  

   been 
  found 
  therein, 
  and 
  the 
  majority 
  even 
  of 
  those 
  were 
  poorly 
  

   preserved 
  or 
  of 
  doubtful 
  significance. 
  Some 
  of 
  them 
  indicated 
  

   Pennsylvanian 
  age, 
  while 
  others 
  were 
  doubtfully 
  referred 
  to 
  

   the 
  Mississippian. 
  

  

  In 
  1911 
  fossils 
  were 
  found 
  by 
  the 
  writer 
  and 
  C. 
  W. 
  Tomlin- 
  

   son 
  at 
  several 
  horizons 
  in 
  the 
  Amsden 
  formation 
  along 
  the 
  

   crest 
  of 
  the 
  Gros 
  Yentre 
  Range, 
  and 
  were 
  later 
  submitted 
  to 
  

   Dr. 
  G. 
  H. 
  Girty 
  for 
  study. 
  Nearly 
  all 
  the 
  specimens 
  were 
  

   found 
  in 
  a 
  thin 
  group 
  of 
  limestone 
  beds 
  a 
  little 
  below 
  the 
  

   middle 
  of 
  the 
  formation. 
  Dr. 
  Girty 
  has 
  recognized 
  two 
  some- 
  

   what 
  unlike 
  faunules. 
  The 
  more 
  widespread 
  of 
  the 
  two 
  con- 
  

   sists 
  . 
  almost 
  entirely 
  of 
  brachiopods, 
  with 
  a 
  few 
  bryozoans, 
  

  

  *Darton, 
  N. 
  H., 
  U. 
  S. 
  Geol. 
  Survey, 
  Prof. 
  Paper 
  51, 
  Geology 
  of 
  the 
  Big 
  

   Horn 
  Mts., 
  Wyoming 
  ; 
  and 
  other 
  papers. 
  

  

  