﻿HUDSON 
  RIVER 
  BEDS 
  NEAR 
  ALBANY 
  571 
  

  

  the 
  center, 
  not 
  procumbent 
  in 
  any 
  direction; 
  pedicle-groove 
  begins 
  

   on 
  top 
  of 
  beak, 
  is 
  deepest 
  directly 
  behind 
  the 
  beak 
  and 
  becomes 
  

   shallower 
  toward 
  the 
  margin, 
  to 
  which 
  it 
  extends. 
  Surface 
  cov- 
  

   ered 
  by 
  very 
  fine, 
  regular, 
  concentric 
  growth 
  lines 
  which 
  are 
  not 
  

   interrupted 
  by 
  the 
  pedicle-groove. 
  Shell 
  apparently 
  quite 
  thick; 
  

   not 
  so 
  much 
  flattened 
  as 
  those 
  of 
  other 
  forms. 
  

  

  A 
  low 
  convex 
  shell 
  with 
  two 
  posteriorly 
  diverging 
  oval 
  mus- 
  

   cular 
  scars 
  may 
  represent 
  the 
  corresponding 
  brachial 
  valve. 
  

  

  Dimensions. 
  Length 
  of 
  type 
  specimen, 
  3 
  mm, 
  width 
  3.2 
  mm. 
  

  

  This 
  form 
  differs 
  from 
  S 
  c 
  h 
  . 
  o 
  v 
  a 
  1 
  i 
  s 
  , 
  Hall 
  and 
  Clarke, 
  of 
  

   the 
  Trenton, 
  by 
  its 
  subcircular 
  outline 
  and 
  more 
  central 
  position 
  

   of 
  the 
  beak 
  ; 
  from 
  Sch. 
  conica, 
  Dwight, 
  also 
  from 
  the 
  Tren- 
  

   ton, 
  by 
  its 
  smaller 
  convexity 
  and 
  equal 
  slope. 
  It 
  has 
  the 
  circular 
  

   outline 
  and 
  regular 
  concentric 
  striation 
  in 
  common 
  with 
  Sch. 
  

   p 
  e 
  1 
  o 
  p 
  e 
  a 
  , 
  Billings 
  sp., 
  from 
  the 
  Canadian 
  Trenton 
  and 
  Galena 
  

   shales 
  and 
  Salmon 
  river 
  (Hudson 
  river) 
  formation 
  of 
  Minnesota 
  

   (49: 
  365), 
  and 
  with 
  the 
  interesting 
  Sch. 
  minutula, 
  Schuch- 
  

   ert 
  and 
  Winchell 
  (p. 
  366). 
  The 
  latter 
  occurs 
  in 
  abundance 
  asso- 
  

   ciated 
  with 
  stems 
  of 
  D 
  i 
  p 
  1 
  o 
  g 
  r 
  a 
  p 
  t 
  u 
  s 
  in 
  the 
  " 
  lower 
  portion 
  

   of 
  the 
  Hudson 
  river 
  group 
  near 
  Granger 
  Minnesota 
  " 
  (=Utica 
  

   shale). 
  Sch. 
  papilliformis 
  differs 
  from 
  both 
  these 
  species 
  

   in 
  size, 
  the 
  more 
  central 
  position 
  and 
  more 
  abrupt 
  elevation 
  of 
  

   the 
  beak 
  or 
  apex, 
  and 
  in 
  the 
  presence 
  of 
  a 
  distinct 
  pedicle-groove 
  

   instead 
  of 
  the 
  apical 
  circular 
  pedicle 
  opening 
  of 
  the 
  others. 
  

  

  It 
  will 
  be 
  seen 
  that 
  these 
  minute 
  brachiopods 
  do 
  not 
  directly 
  

   determine 
  the 
  position 
  of 
  the 
  Normans 
  kill 
  graptolite 
  shales, 
  as 
  

   all 
  three 
  species 
  are 
  peculiar 
  to 
  this 
  horizon, 
  but 
  their 
  relation- 
  

   ship 
  to 
  Trenton 
  and 
  Utica 
  forms 
  of 
  the 
  genera 
  Leptobolus 
  

   and 
  S 
  c 
  h 
  i 
  z 
  o 
  t 
  r 
  e 
  t 
  a 
  , 
  would 
  certainly 
  suggest 
  the 
  Trenton- 
  

   Utica 
  age 
  of 
  the 
  shales 
  in 
  question. 
  

  

  It 
  is 
  certainly 
  peculiar 
  that 
  only 
  these 
  minute, 
  thin-shelled, 
  

   non-calcareous 
  brachiopod 
  valves 
  and 
  no 
  other 
  1'os.sils 
  occur 
  asso- 
  

   ciated 
  with 
  the 
  graptolites. 
  Their 
  size, 
  thinness 
  and 
  the 
  com- 
  

   position 
  of 
  their 
  shells 
  indicate 
  strongly 
  that 
  they 
  led 
  a 
  pseudo- 
  

   planktonic 
  life. 
  Winchell 
  and 
  Schuclici 
  t 
  suggesl 
  thai 
  Sch. 
  

  

  