﻿HUDSON 
  RIVER 
  BEDS 
  NEAR 
  ALBANY 
  563 
  

  

  to 
  Europe 
  was 
  already 
  opened 
  in 
  the 
  younger 
  Trenton 
  per- 
  

   iod 
  ; 
  for 
  Isotelus 
  g 
  i 
  g 
  a 
  s 
  and 
  Trinucleus 
  concen- 
  

   tric 
  u 
  s 
  (=o 
  r 
  n 
  a 
  t 
  u 
  s 
  Stbg.) 
  appear 
  already 
  in 
  the 
  Caradoc 
  and 
  

   its 
  equivalents. 
  Triarthrus 
  becki, 
  the 
  most 
  characteris- 
  

   tic 
  form 
  of 
  the 
  Utica 
  shale, 
  seems 
  to 
  occur 
  already 
  in 
  the 
  Chas- 
  

   mops 
  limestone 
  of 
  Sweden. 
  In 
  the 
  later 
  Utica 
  age 
  the 
  Lorraine 
  

   fauna 
  from 
  the 
  western 
  part 
  of 
  the 
  state 
  seemed 
  to 
  gain 
  the 
  

   ascendancy, 
  as 
  indicated 
  by 
  the 
  fauna 
  discovered 
  by 
  Beecher 
  near 
  

   the 
  old 
  Dudley 
  observatory 
  at 
  Albany 
  and 
  by 
  the 
  writer 
  on 
  Green. 
  

   Island. 
  

  

  The 
  Lorraine 
  fauna, 
  with 
  its 
  close 
  relationship 
  to 
  the 
  Trenton 
  

   fauna 
  in 
  identical 
  or 
  vicarious 
  forms 
  (a 
  relationship 
  which 
  be- 
  

   comes 
  still 
  more 
  emphasized 
  toward 
  the 
  interior 
  of 
  the 
  continent 
  

   in 
  the 
  overlying 
  Richmond 
  beds) 
  is 
  again 
  evidently 
  an 
  epicontin- 
  

   ental 
  fauna 
  derived 
  from 
  the 
  Trenton 
  fauna. 
  

  

  To 
  state 
  it 
  more 
  concisely, 
  the 
  writer 
  believes 
  that 
  the 
  Trenton 
  

   fauna 
  and 
  its 
  derivative, 
  the 
  Lorraine 
  fauna, 
  are 
  of 
  epicontinental 
  

   origin, 
  and 
  entered 
  the 
  Hudson 
  valley 
  region 
  from 
  the 
  west, 
  while 
  

   the 
  Dicellograptus 
  fauna 
  and 
  its 
  derivative, 
  the 
  Utica 
  fauna, 
  are 
  

   foreign 
  to 
  the 
  continent, 
  and 
  entered 
  it 
  from 
  the 
  Atlantic 
  ocean 
  

   by 
  way 
  of 
  the 
  Canadian 
  basin. 
  This 
  follows 
  from 
  the 
  necessary 
  

   assumption 
  of 
  the 
  presence 
  of 
  a 
  Paleo-Appalachian 
  continent 
  

   (see 
  Freeh, 
  54) 
  to 
  the 
  east 
  of 
  North 
  America. 
  The 
  former 
  assump- 
  

   tion 
  seems 
  to 
  be 
  supported 
  by 
  the 
  indications 
  of 
  the 
  presence 
  of 
  a 
  

   ne 
  — 
  sw 
  current 
  in 
  the 
  Mohawk 
  region 
  during 
  the 
  Utica 
  epoch, 
  

   found 
  by 
  the 
  writer 
  in 
  the 
  prevailing 
  arrangement 
  of 
  the 
  grap- 
  

   tolites, 
  cephalopod 
  shells, 
  sponge 
  spicules, 
  etc. 
  in 
  the 
  shales 
  (55). 
  

   Lapworth, 
  followed 
  by 
  Walther, 
  maintains 
  (53) 
  that 
  the 
  grapto- 
  

   lites 
  were 
  planktonic 
  or 
  rather 
  pseudo-planktonic 
  animals 
  which, 
  

   drifting 
  along 
  the 
  coasts, 
  left 
  their 
  remains 
  in 
  the 
  quieter 
  waters 
  

   at 
  a 
  certain 
  distance 
  from 
  the 
  coast. 
  This 
  view 
  would 
  also 
  sug- 
  

   gest 
  that 
  the 
  Trenton 
  and 
  Utica 
  shales 
  were 
  formed 
  along 
  the 
  

   continental 
  shelf 
  under 
  the 
  influence 
  of 
  currents 
  entering 
  from 
  

   northeast. 
  The 
  alternations 
  of 
  coarse, 
  mostly 
  barren 
  sandstones 
  

   with 
  fine 
  grained, 
  muddy 
  graptolite-bearing 
  deposits 
  indicate 
  the 
  

   changing 
  conditions 
  along 
  this 
  coast 
  shelf, 
  which, 
  on 
  the 
  whole, 
  

  

  