﻿212 
  H. 
  S. 
  Williams 
  — 
  Devonian-Silur 
  

  

  ian 
  boundary 
  

  

  Tilestone. 
  Chapman 
  sandstone. 
  

  

  Zone 
  D, 
  Arisaig. 
  

  

  19. 
  Orthoceras 
  semipartitum 
  "] 
  

  

  f 
  0. 
  punctostriatnm 
  

  

  20. 
  0. 
  ? 
  ! 
  A 
  . 
  , 
  . 
  

  

  21. 
  0. 
  striatum 
  \ 
  A 
  sm 
  §' 
  le 
  fra 
  S 
  ment 
  

  

  1 
  0. 
  nummulara 
  Sow 
  

   j 
  0. 
  ibex 
  Sow. 
  

  

  22. 
  0. 
  tract) 
  eale 
  J 
  

  

  1 
  0. 
  exornatum 
  

  

  23. 
  Bellerophon 
  carinatus 
  B. 
  carinatus 
  

  

  B. 
  carinatus 
  

  

  24. 
  B. 
  striatus 
  ? 
  

  

  B. 
  striatus 
  

  

  25. 
  B. 
  trilobatus 
  B. 
  trilobatus 
  

  

  B. 
  trilobatus 
  

  

  26. 
  B. 
  globatus 
  ? 
  

  

  B. 
  globatus 
  

  

  27. 
  Tentaculites 
  scalaris 
  ? 
  B. 
  cf. 
  elongatus 
  

  

  T. 
  distans. 
  

  

  28. 
  Battus 
  tuberculatus 
  Beyrichia 
  tuberculata 
  

  

  j 
  B. 
  pustulosa 
  Hall 
  

   \ 
  B. 
  equilatera 
  

  

  

  In 
  addition 
  to 
  the 
  above, 
  Homalonotus 
  Knightii 
  Konig 
  is 
  

   reported 
  from 
  the 
  Upper 
  Ludlow, 
  and 
  also 
  from 
  Zone 
  D, 
  

   Arisaig 
  ; 
  and 
  an 
  undetermined 
  representative 
  of 
  the 
  same 
  

   genus 
  appears 
  among 
  the 
  Chapman 
  specimens. 
  

  

  The 
  presence 
  of 
  plants 
  is 
  further 
  significant. 
  In 
  the 
  Chap- 
  

   man 
  sandstone 
  a 
  specimen 
  of 
  P 
  silophyton, 
  which 
  is 
  probably 
  P. 
  

   princeps, 
  appears 
  in 
  the 
  midst 
  of 
  the 
  marine 
  fossils, 
  giving 
  

   evideuce 
  of 
  proximity 
  of 
  land, 
  and 
  also 
  of 
  the 
  transition 
  con- 
  

   dition 
  leading 
  up 
  to 
  the 
  Old 
  Red 
  sandstone 
  type 
  of 
  Devonian. 
  

   " 
  Psilophyton 
  (?)" 
  is 
  also 
  reported 
  from 
  the 
  Upper 
  Arisaig,* 
  

   and 
  it 
  is 
  the 
  " 
  Tilestone 
  " 
  of 
  Wales 
  (= 
  Upper 
  Ludlow 
  and 
  

   Downton 
  sandstone), 
  in 
  which 
  the 
  earliest 
  known 
  traces 
  of 
  

   land 
  plants 
  appear 
  in 
  the 
  Welsh 
  succession. 
  f 
  

  

  The 
  above 
  evidence 
  leads 
  directly 
  to 
  the 
  conclusion 
  that 
  the 
  

   fauna 
  of 
  the 
  Chapman 
  sandstone 
  of 
  Maine 
  is 
  the 
  equivalent 
  of 
  

   the 
  Tilestone 
  fauna 
  of 
  Wales 
  and 
  of 
  the 
  uppermost 
  Arisaig 
  

   fauna 
  of 
  Nova 
  Scotia. 
  The 
  latter 
  has 
  already 
  been 
  authentic- 
  

   ally 
  identified 
  with 
  the 
  " 
  Ludlow 
  Tilestone 
  " 
  by 
  Salter, 
  and 
  

   the 
  general 
  fauna 
  of 
  the 
  Upper 
  Arisaig 
  has 
  been 
  identified 
  with 
  

   the 
  Lower 
  Helderberg 
  by 
  all 
  those 
  who 
  have 
  studied 
  the 
  spe- 
  

   cies. 
  

  

  The 
  Nictaux 
  iron-ore 
  fossils 
  indicate 
  a 
  somewhat 
  younger 
  

   fauna, 
  which 
  has 
  been 
  recognized 
  by 
  Dawson 
  and 
  other 
  

   paleontologists 
  as 
  approximately 
  equivalent 
  to 
  the 
  Oriskany 
  

   sandstone 
  of 
  the 
  New 
  York 
  section. 
  

  

  In 
  the 
  Gaspe 
  series 
  the 
  place 
  of 
  transition 
  from 
  the 
  G-aspe 
  

   limestones 
  to 
  the 
  sandstones 
  is 
  very 
  near 
  to 
  the 
  horizon 
  of 
  the 
  

   Oriskany 
  sandstone 
  further 
  west. 
  The 
  stratigraphic 
  and 
  

   petrographic 
  evidence 
  in 
  the 
  Maine 
  series 
  points 
  to 
  the 
  

   equivalency 
  of 
  the 
  Chapman 
  sandstone 
  with 
  the 
  base 
  of 
  

   the 
  Gaspe 
  sandstone. 
  The 
  particular 
  fauna 
  of 
  the 
  Chap- 
  

   man 
  sandstone 
  is 
  not 
  known, 
  at 
  present, 
  in 
  the 
  Gaspe 
  series. 
  

   But 
  if 
  this 
  correlation 
  with 
  the 
  Gaspe 
  series 
  be 
  correct, 
  

   the 
  relations 
  of 
  the 
  several 
  known 
  faunas 
  of 
  the 
  Maine 
  

  

  * 
  Ami. 
  Catalogue 
  of 
  Silurian 
  Fossils 
  from 
  Arisaig, 
  Nova 
  Scotia, 
  Nova 
  Scotia 
  

   Inst. 
  Sci., 
  Ser. 
  2, 
  vol. 
  i, 
  p. 
  185 
  (1892). 
  

   f 
  H. 
  B. 
  Woodward, 
  The 
  Geology 
  of 
  England 
  and 
  Wales, 
  pp. 
  104, 
  105 
  (1887). 
  

  

  