﻿in 
  JSorth 
  America. 
  213 
  

  

  series 
  are 
  in 
  complete 
  harmony 
  with 
  the 
  known 
  succession 
  of 
  

   the 
  Gaspe* 
  faunas, 
  and 
  with 
  such 
  an 
  interpretation. 
  In 
  that 
  

   case, 
  the 
  Square 
  Lake 
  fauna 
  of 
  Maine 
  would 
  be 
  equivalent 
  to 
  

   the 
  fauna 
  of 
  the 
  upper 
  limestones 
  in 
  the 
  Gaspe 
  limestone 
  

   series, 
  aud 
  thus 
  correspond 
  with 
  the 
  known 
  sequence 
  of 
  faunas 
  

   in 
  the 
  Arisaig 
  series. 
  

  

  Reviewing 
  the 
  whole 
  evidence, 
  the 
  Chapman 
  fauna 
  must 
  be 
  

   regarded 
  as 
  the 
  equivalent 
  of 
  the 
  topmost 
  fauna 
  of 
  the 
  typical 
  

   Welch 
  Silurian 
  system 
  (— 
  Upper 
  Ludlow, 
  Tilestone 
  of 
  Mur- 
  

   chison, 
  or 
  Downton, 
  and 
  Ledbury 
  formations 
  of 
  later 
  authors). 
  

   This 
  places 
  the 
  Silurian-Devonian 
  boundary 
  for 
  North 
  America 
  

   at 
  the 
  place 
  where 
  it 
  was 
  determined 
  to 
  be 
  by 
  deYerneuil 
  in 
  

   18^7, 
  * 
  classifying 
  the 
  Lower 
  Helderberg 
  formation 
  in 
  the 
  

   Silurian 
  system. 
  The 
  special 
  Chapman 
  fauna, 
  I 
  am 
  at 
  present 
  

   inclined 
  to 
  think, 
  is 
  equivalent 
  to 
  the 
  Lower 
  Oriskany 
  fauna, 
  

   as 
  recognized 
  at 
  Becrat'ts, 
  and 
  farther 
  south 
  in 
  Virginia 
  and 
  

   Tennessee 
  ; 
  but, 
  however 
  the 
  precise 
  correlation 
  with 
  the 
  

   faunas 
  of 
  interior 
  America 
  may 
  be 
  settled, 
  the 
  place 
  of 
  the 
  

   Chapman 
  fauna 
  above 
  the 
  general 
  Lower 
  Helderberg 
  fauna 
  is 
  

   well 
  established 
  by 
  the 
  Gaspe 
  and 
  Arisaig 
  sections. 
  

  

  New 
  Haven, 
  Conn., 
  December, 
  1899. 
  

  

  * 
  Xote 
  sur 
  le 
  parallelisme 
  des 
  Depots 
  Paleozoiques 
  de 
  l'Amerique 
  septentri- 
  

   onale 
  avec 
  ceux 
  de 
  l'Europe. 
  Bull. 
  Soc. 
  Geol. 
  de 
  France, 
  2d 
  ser 
  , 
  t. 
  iv. 
  

  

  