﻿344 
  

  

  PROCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  [Apr. 
  27> 
  

  

  Calyniene, 
  different 
  from 
  Blumenbachii, 
  

  

  Brong. 
  

   Proetus 
  Stokesii 
  ? 
  

   Beyrichia 
  pustulosa, 
  Hall. 
  

   Beyrichia 
  equilatera, 
  Hall, 
  

   Beyrichia, 
  2 
  sp. 
  

   Leperditia 
  sinuata, 
  Hall. 
  

   Crinoidea. 
  

  

  Tentaculites. 
  

  

  Cornulites 
  serpularius. 
  

  

  Serpulites, 
  n. 
  sp. 
  (in 
  clusters 
  on 
  shell 
  

  

  of 
  Orthoceras). 
  

   Stenopora. 
  

   Heliopora 
  fragilis, 
  var. 
  Acadiensis, 
  

  

  Hall, 
  

  

  These 
  Silurian 
  strata 
  (see 
  fig. 
  4) 
  are 
  succeeded 
  by 
  Lower 
  Carboni- 
  

   ferous 
  conglomerate. 
  

  

  § 
  6. 
  Conclusion. 
  

  

  I 
  have 
  thus 
  directed 
  attention 
  to 
  the 
  results 
  of 
  a 
  detailed 
  examina- 
  

   tion 
  of 
  the 
  Silurian 
  strata 
  of 
  Arisaig. 
  This 
  being 
  the 
  undoubted 
  

   type 
  of 
  a 
  very 
  considerable 
  proportion 
  of 
  our 
  Nova-Scotian 
  Silurian 
  

   system, 
  and 
  bearing 
  so 
  striking 
  a 
  resemblance, 
  as 
  regards 
  its 
  fauna, 
  

   to 
  the 
  British 
  Upper 
  Silurian, 
  is 
  a 
  sufficient 
  reason 
  for 
  so 
  directing 
  

   attention 
  to 
  the 
  subject. 
  

  

  The 
  conclusion 
  thus 
  arrived 
  at 
  is, 
  that 
  the 
  members 
  of 
  the 
  series 
  

   are 
  respectively 
  the 
  approximate 
  equivalents 
  of 
  the 
  Mayhill 
  Sand- 
  

   stone, 
  Lower 
  Ludlow, 
  Aymestry 
  Limestone, 
  and 
  Upper 
  Ludlow. 
  

   Mr. 
  Salter 
  suggested 
  to 
  me 
  the 
  propriety 
  of 
  distinguishing 
  the 
  re- 
  

   spective 
  members 
  of 
  our 
  series 
  by 
  local 
  names. 
  I 
  have 
  not 
  been 
  

   able 
  to 
  act 
  on 
  the 
  suggestion, 
  on 
  account 
  of 
  the 
  mode 
  of 
  distribution 
  

   of 
  the 
  several 
  members 
  of 
  the 
  group. 
  I 
  have 
  therefore 
  distinguished 
  

   them 
  as 
  Arisaig 
  A, 
  B, 
  B', 
  C, 
  and 
  D. 
  I 
  have 
  not 
  yet 
  attempted 
  to 
  

   measure 
  the 
  entire 
  thickness 
  of 
  the 
  several 
  strata. 
  Supposing 
  Dr. 
  

   Dawson's 
  estimate 
  of 
  the 
  thickness 
  of 
  the 
  groups 
  B', 
  C, 
  D 
  to 
  be 
  

   correct, 
  although 
  I 
  consider 
  it 
  much 
  below 
  the 
  reality, 
  we 
  have 
  of 
  

   them 
  about 
  500 
  feet 
  ; 
  I 
  found 
  the 
  thickness 
  of 
  B 
  170 
  feet, 
  and 
  of 
  

   A 
  200 
  feet 
  ; 
  total, 
  870 
  feet. 
  

  

  I 
  have 
  observed 
  that 
  strata 
  A 
  have 
  a 
  fauna 
  well 
  developed, 
  too 
  

   much 
  so, 
  indeed, 
  to 
  warrant 
  the 
  supposition 
  that 
  while 
  there 
  are 
  

   sedimentary 
  rocks 
  in 
  other 
  parts 
  of 
  the 
  province, 
  which 
  we 
  have 
  

   every 
  reason 
  to 
  suppose 
  are 
  older 
  than 
  those 
  of 
  the 
  Arisaig 
  group, 
  

   our 
  A 
  fauna 
  is 
  the 
  first 
  one 
  represented 
  in 
  our 
  Nova-Scotian 
  geology. 
  

   Before 
  I 
  consulted 
  Sir 
  B. 
  I. 
  Murchison 
  and 
  Mr. 
  Salter, 
  I 
  supposed 
  

   that 
  certain 
  unaltered 
  strata 
  which 
  I 
  had 
  discovered 
  in 
  another 
  

   locality, 
  and 
  which 
  had, 
  as 
  their 
  only 
  fossils, 
  hundreds 
  of 
  Lingulce, 
  

   beautifully 
  preserved 
  in 
  small 
  spherical 
  and 
  elliptical 
  nodules, 
  might 
  

   be 
  our 
  Nova-Scotian 
  Primordial 
  zone. 
  These 
  appeared 
  undoubtedly 
  

   to 
  be 
  older 
  than 
  the 
  equivalent 
  in 
  this 
  locality 
  of 
  the 
  Arisaig 
  

   group 
  B', 
  or 
  the 
  Clinton 
  (U. 
  S.) 
  equivalent 
  of 
  Hall 
  and 
  Dawson. 
  So 
  

   that, 
  regarding 
  this 
  determination 
  as 
  correct, 
  I 
  considered 
  the 
  

   Lingula-bed 
  as 
  Middle 
  or, 
  possibly, 
  Lower 
  Silurian. 
  This 
  bed 
  

   appears 
  to 
  be 
  about 
  the 
  equivalent 
  of 
  the 
  bed 
  B 
  of 
  Arisaig, 
  and, 
  

   therefore, 
  is 
  not 
  Primordial. 
  I 
  believe, 
  then, 
  that 
  we 
  must 
  look 
  

   elsewhere 
  for 
  any 
  earlier 
  fauna 
  than 
  that 
  of 
  the 
  Arisaig 
  group 
  A. 
  

   The 
  older 
  slates 
  of 
  our 
  Gold-fields, 
  especially 
  in 
  the 
  Peninsula 
  of 
  

   Halifax, 
  bearing 
  a 
  striking 
  resemblance 
  to 
  the 
  Graptolitiferous 
  slates 
  

   of 
  Victoria, 
  in 
  Australia, 
  exhibited 
  by 
  Professor 
  M'Coy 
  in 
  the 
  Inter- 
  

  

  