﻿HUDSON 
  RIVER 
  BEDS 
  NEAR 
  ALBANY 
  497 
  

  

  The 
  most 
  interesting 
  discovery 
  of 
  Whitfield's 
  is 
  that 
  of 
  the 
  

   presence 
  of 
  shales 
  of 
  Trenton 
  age 
  among 
  the 
  shales 
  of 
  the 
  Hudson 
  

   valley. 
  The 
  writer 
  has 
  carefully 
  compared 
  specimens 
  of 
  the 
  grap- 
  

   tolite 
  in 
  question 
  found 
  at 
  the 
  arsenal 
  yard 
  and 
  preserved 
  in 
  the 
  

   state 
  museum 
  with 
  the 
  D. 
  amplexicaulis 
  found 
  in 
  the 
  

   Trenton 
  limestone 
  at 
  Middleville 
  and 
  is 
  convinced 
  of 
  their 
  iden- 
  

   tity. 
  Besides 
  this 
  graptolite 
  other 
  fossils 
  have 
  been 
  found 
  in 
  the 
  

   shales 
  and 
  calcareous 
  sandstones 
  (not 
  limestone) 
  of 
  south 
  Troy 
  

   and 
  the 
  neighborhood 
  of 
  the 
  arsenal 
  which 
  more 
  firmly 
  establish 
  

   Prof. 
  Whitfield's 
  discovery. 
  

  

  The 
  supposed 
  homotaxy 
  of 
  the 
  Normans 
  kill 
  fauna 
  with 
  that 
  

   of 
  the 
  Utica 
  shale 
  is 
  based 
  on 
  the 
  occurrence 
  of 
  four 
  graptolites 
  

   in 
  both 
  faunas. 
  Of 
  these 
  the 
  presence 
  of 
  Didymograptus 
  

   serratulus 
  in 
  the 
  Utica 
  beds 
  has 
  not 
  been 
  verified 
  by 
  other 
  

   collectors 
  and 
  is 
  doubted 
  by 
  Lapworth 
  and 
  Gurley; 
  Hall's 
  

   Diplograptus 
  pristis, 
  however, 
  is 
  partly 
  identical 
  with 
  

   Hall's 
  D. 
  quadrimucronatus, 
  which 
  is 
  very 
  common 
  at 
  

   Fort 
  Plain 
  as 
  everywhere 
  in 
  the 
  Utica 
  shale, 
  and 
  which 
  at 
  that 
  

   time 
  was 
  considered 
  also 
  by 
  Hall 
  as 
  occurring 
  only 
  at 
  the 
  locality 
  

   from 
  which 
  it 
  was 
  first 
  made 
  known 
  (Lake 
  St 
  John, 
  Canada), 
  

   and 
  partly 
  identical 
  with 
  Diplograptus 
  foliaceus, 
  

   Murchison. 
  1 
  

  

  The 
  two 
  forms, 
  D. 
  foliaceus 
  and 
  D. 
  q 
  u 
  adrim 
  u- 
  

   cronatus, 
  are 
  not 
  always 
  easy 
  of 
  separation, 
  when 
  com- 
  

   pletely 
  flattened 
  in 
  the 
  shales; 
  and 
  the 
  writer 
  also 
  has, 
  follow- 
  

   ing 
  Hall's 
  example 
  and 
  identification, 
  'described 
  colonies 
  of 
  D. 
  

   quadrimucronatus 
  as 
  belonging 
  to 
  D. 
  pristis 
  Hall. 
  

   Fritz 
  Freeh 
  (54:626) 
  supposes 
  this 
  large 
  mucronate 
  form 
  of 
  the 
  

   Utica 
  shale 
  to 
  be 
  D. 
  w 
  h 
  i 
  t 
  f 
  i 
  e 
  1 
  d 
  i, 
  Hall. 
  A 
  detailed 
  account 
  of 
  

   all 
  these 
  forms 
  will 
  be 
  given 
  by 
  the 
  writer 
  in 
  another 
  paper. 
  

  

  Olimacograptus 
  bicornis 
  and 
  Dicranograp- 
  

   tus 
  ramosus 
  are, 
  indeed, 
  common 
  to 
  the 
  Normans 
  kill 
  and 
  

  

  'Diplograptus 
  quadrimucronatus 
  is 
  restricted 
  to 
  the 
  Utica 
  

   shale, 
  and 
  for 
  this 
  reason, 
  can 
  not 
  be 
  adduced 
  as 
  connecting 
  the 
  Utica 
  and 
  

   Normans 
  kill 
  shales; 
  Diplograptus 
  foliaceus, 
  which 
  is 
  more 
  

   common 
  in 
  the 
  Normans 
  kill 
  shale, 
  ranges 
  from 
  the 
  Chazy 
  to 
  the 
  Lorraine 
  

   beds 
  and 
  hence 
  is 
  of 
  no 
  taxonomic 
  value. 
  

  

  