﻿198 
  

  

  PROCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  

  

  [Mar. 
  9, 
  

  

  2. 
  On 
  some 
  Remains 
  of 
  Bothriolepis 
  from 
  the 
  Upper 
  Devonian 
  

   Sandstones 
  of 
  Elgin. 
  By 
  George 
  E. 
  Roberts, 
  Esq. 
  

  

  [Communicated 
  by 
  Prof. 
  J. 
  Morris, 
  F.G.S.] 
  

  

  [The 
  publication 
  of 
  this 
  paper 
  is 
  unavoidably 
  deferred.] 
  

   [Abstract.] 
  

  

  Remains 
  of 
  a 
  large 
  Dendrodoid 
  Coelacanth, 
  obtained 
  by 
  the 
  author 
  

   in 
  Elgin, 
  were 
  referred 
  by 
  him 
  to 
  the 
  genus 
  Bothriolepis. 
  These 
  

   consisted 
  of 
  two 
  large 
  casts 
  of 
  a 
  central 
  head-plate, 
  with 
  portions 
  of 
  

   the 
  test 
  ; 
  a 
  natural 
  cast 
  considered 
  by 
  him 
  to 
  represent 
  the 
  parietal, 
  

   squamosal, 
  scapular, 
  and 
  coracoid 
  boces 
  ; 
  casts 
  of 
  the 
  nasal 
  bones, 
  

   and 
  teeth 
  of 
  the 
  upper 
  jaw 
  ; 
  together 
  with 
  tooth-like 
  bodies, 
  which 
  

   were 
  suggested 
  to 
  be 
  teeth 
  originally 
  situated 
  in 
  the 
  posterior 
  

   region 
  of 
  the 
  mouth. 
  

  

  The 
  ornament 
  borne 
  upon 
  the 
  head-plate 
  was 
  next 
  described 
  by 
  

   the 
  author; 
  and, 
  in 
  conclusion, 
  the 
  affinities 
  between 
  the 
  genera 
  

   Bothriolepis, 
  Asterolepis, 
  Pteraspis, 
  and 
  Cephalaspis 
  were 
  discussed. 
  

  

  3. 
  On 
  Missing 
  Sedimentary 
  Formations, 
  from 
  Suspension 
  or 
  Re- 
  

   moval 
  of 
  Deposits. 
  By 
  J. 
  J. 
  Bigsby, 
  M.D., 
  F.G.S., 
  formerly 
  

   British 
  Secretary 
  to 
  the 
  Canadian 
  Boundary 
  Commission. 
  

  

  Contents. 
  

  

  I. 
  Introduction. 
  

  

  II. 
  Instances 
  of 
  Blanks 
  or 
  Gaps 
  *. 
  

  

  1 
  . 
  With 
  a 
  Quaternary 
  Roof. 
  

  

  2. 
  With 
  a 
  Tertiary 
  Eoof. 
  

  

  3. 
  With 
  a 
  Cretaceous 
  Roof. 
  

  

  a. 
  Chalk. 
  

  

  b. 
  Upper 
  Greensand. 
  

  

  c. 
  Gault 
  and 
  Neocomian. 
  

  

  4. 
  Witli 
  a 
  Jurassic 
  Roof. 
  

  

  a. 
  Oolite. 
  

  

  b. 
  Lias. 
  

  

  5. 
  With 
  a 
  Triassic 
  Roof. 
  

  

  6. 
  With 
  a 
  Permian 
  Roof. 
  

  

  7. 
  With 
  a 
  Carboniferous 
  Roof. 
  

  

  8. 
  With 
  a 
  Devonian 
  Roof. 
  

  

  9. 
  With 
  a 
  Silurian 
  Roof. 
  

  

  III. 
  Conclusion. 
  

  

  1. 
  General 
  Considerations. 
  

  

  2. 
  Summary. 
  

  

  3. 
  Inferences. 
  

  

  I. 
  Introduction. 
  

   Although 
  it 
  has 
  been 
  long 
  known 
  that 
  formations 
  or 
  parts 
  of 
  forma- 
  

   tions 
  are 
  frequently 
  absent 
  from 
  their 
  places 
  * 
  in 
  the 
  vertical 
  series 
  

   of 
  sedimentary 
  rocks, 
  little 
  notice 
  has 
  been 
  hitherto 
  taken 
  of 
  this 
  

   absence, 
  except 
  in 
  single 
  unconnected 
  cases 
  ; 
  and 
  that 
  little 
  con- 
  

   sists 
  almost 
  entirely 
  of 
  a 
  few 
  remarks 
  in 
  Mr. 
  Jukes's 
  excellent 
  

   ' 
  Manual 
  ' 
  and 
  an 
  allusion 
  or 
  two 
  in 
  the 
  writings 
  of 
  Sir 
  R. 
  I. 
  Mur- 
  

   chison, 
  Mr. 
  Darwin, 
  and 
  Prof. 
  J. 
  Hall, 
  of 
  New 
  York. 
  

  

  As 
  circumstances, 
  relations, 
  processes, 
  and 
  purposes 
  well 
  worthy 
  of 
  

   our 
  attention 
  are 
  here 
  concerned, 
  it 
  is 
  proposed 
  now 
  to 
  open 
  out 
  and 
  

   examine 
  this 
  subject 
  as 
  well 
  as 
  it 
  can 
  be 
  done 
  in 
  a 
  first 
  attempt. 
  

  

  The 
  progress 
  of 
  geological 
  knowledge, 
  as 
  of 
  all 
  science, 
  is 
  usually 
  

  

  * 
  As 
  Lias 
  from 
  between 
  Oolite 
  and 
  Trias 
  ; 
  Upper 
  Silurian 
  from 
  between 
  

   Devonian 
  and 
  Lower 
  Silurian 
  : 
  the 
  roof 
  being 
  the 
  upper, 
  and 
  the 
  floor 
  the 
  lower 
  

   side 
  of 
  the 
  place 
  which 
  the 
  missing 
  rock 
  should 
  have 
  occupied; 
  thus 
  occasioning 
  

   a 
  blank. 
  

  

  