﻿1864.] 
  POWRIE— 
  FORFARSHIRE 
  FOSSILS. 
  427 
  

  

  intermediate 
  dermal 
  spines, 
  their 
  ridges 
  in 
  some 
  seeming 
  to 
  be 
  

   smooth, 
  in 
  others 
  crenate, 
  and 
  some 
  appearing 
  to 
  have 
  more 
  than 
  

   four 
  pairs 
  of 
  them. 
  No 
  specimens 
  sufficiently 
  perfect 
  have 
  hitherto 
  

   been 
  obtained 
  to 
  prove 
  this. 
  

  

  Fragments 
  belonging 
  to 
  other 
  distinct 
  species, 
  if 
  not 
  genera, 
  of 
  

   Acanthodian 
  Fishes 
  occasionally 
  turn 
  up, 
  but 
  as 
  yet 
  these 
  are 
  all 
  

   very 
  imperfect. 
  

  

  Family 
  CEPHALASPIM]. 
  

  

  Of 
  this 
  family 
  the 
  genus 
  Cephalaspis 
  is 
  very 
  widely 
  and 
  rather 
  

   abundantly 
  distributed 
  through 
  all 
  the 
  fossiliferous 
  strata 
  yet 
  exa- 
  

   mined 
  in 
  Forfarshire. 
  Pteraspis 
  has 
  never 
  yet 
  been 
  found 
  in 
  For- 
  

   farshire; 
  but, 
  having 
  been 
  detected 
  in 
  sandstones 
  belonging 
  to 
  the 
  

   same 
  epoch 
  in 
  the 
  neighbouring 
  county 
  of 
  Perth, 
  it 
  may 
  here 
  be 
  classed 
  

   amongst 
  our 
  Fishes. 
  As, 
  however, 
  I 
  intend, 
  unless 
  some 
  one 
  more 
  

   competent 
  undertake 
  the 
  task, 
  in 
  a 
  future 
  communication 
  to 
  de- 
  

   scribe 
  our 
  Forfarshire 
  Cephalaspidee, 
  I 
  shall 
  here 
  merely 
  remark 
  that 
  

   the 
  Scottish 
  Old 
  Red 
  Sandstones 
  seem 
  as 
  yet 
  to 
  have 
  yielded 
  only 
  

   one 
  species 
  of 
  Cephalaspis 
  — 
  C. 
  Lyelli. 
  Only 
  one 
  species 
  of 
  Pte- 
  

   raspis 
  also 
  has 
  as 
  yet 
  been 
  found, 
  which 
  I 
  propose 
  to 
  name 
  P. 
  

   Mitchelli. 
  In 
  the 
  spring 
  of 
  1861 
  I 
  procured 
  three 
  tolerably 
  com- 
  

   plete 
  heads 
  of 
  this 
  Fish, 
  with 
  several 
  other 
  fragments, 
  from 
  a 
  quarry 
  

   near 
  Bridge 
  of 
  Allan, 
  in 
  Perthshire. 
  In 
  this 
  quarry 
  the 
  rocks 
  be- 
  

   long 
  to 
  the 
  same 
  geological 
  horizon 
  as 
  the 
  Forfarshire 
  flaggy 
  beds. 
  

   That 
  this 
  is 
  the 
  case 
  may 
  be 
  readily 
  proved 
  by 
  tracing 
  their 
  strati- 
  

   graphical 
  connexion, 
  and 
  also 
  from 
  their 
  organic 
  remains. 
  In 
  the 
  

   same 
  bed 
  in 
  which 
  I 
  discovered 
  Pteraspis, 
  I 
  at 
  the 
  same 
  time 
  found 
  

   a 
  fine 
  head 
  of 
  Cephalaspis 
  Lyelli. 
  The 
  Rev. 
  Hugh 
  Mitchell 
  had, 
  

   considerably 
  prior 
  to 
  this 
  date, 
  procured 
  specimens 
  of 
  this 
  same 
  

   species 
  also 
  from 
  Perthshire 
  ; 
  to 
  him, 
  therefore, 
  belongs 
  the 
  merit 
  

   of 
  being 
  the 
  first 
  to 
  discover 
  Pteraspis 
  in 
  the 
  Scottish 
  Old 
  Red 
  Sand- 
  

   stones 
  ; 
  and 
  as 
  it 
  appears 
  to 
  me 
  to 
  be 
  undoubtedly 
  specifically 
  dis- 
  

   tinct 
  from 
  any 
  known 
  Pteraspis, 
  I 
  propose 
  adding 
  the 
  name 
  of 
  its 
  

   original 
  discoverer 
  as 
  a 
  specific 
  affix. 
  

  

  The 
  intermediate 
  position 
  in 
  the 
  Old 
  Red 
  Sandstone 
  series 
  as- 
  

   signed 
  by 
  the 
  late 
  Hugh 
  Miller 
  to 
  the 
  Forfarshire 
  and 
  other 
  sand- 
  

   stones 
  containing 
  remains 
  of 
  Cephalaspis, 
  Pterygotus 
  Anglicus, 
  &c, 
  

   was, 
  until 
  very 
  recently, 
  the 
  classification 
  adopted 
  by 
  our 
  leading 
  

   geologists 
  ; 
  it 
  is 
  that 
  given 
  by 
  Sir 
  Charles 
  Lyell 
  in 
  the 
  last 
  edition 
  of 
  

   his 
  admirable 
  ' 
  Manual 
  of 
  Geology 
  ' 
  (5th 
  edit., 
  1855). 
  Dr. 
  Slimon's 
  

   discovery 
  in 
  the 
  Upper 
  Silurian 
  shales 
  of 
  Lanarkshire 
  of 
  Crustacean 
  

   remains 
  very 
  similar 
  to 
  those 
  of 
  Forfarshire 
  led 
  Mr. 
  Page 
  to 
  adopt 
  

   the 
  true 
  view 
  of 
  the 
  position 
  of 
  these 
  formations, 
  namely, 
  that 
  they 
  

   form 
  the 
  lowest 
  members 
  of 
  the 
  Old 
  Red 
  Sandstone 
  series, 
  as 
  exhi- 
  

   bited 
  in 
  Scotland 
  (see 
  'Advanced 
  Text-Book,' 
  chap. 
  xi. 
  ; 
  also 
  paper 
  

   read 
  at 
  the 
  Meeting 
  of 
  the 
  British 
  Association 
  in 
  Glasgow, 
  1856). 
  

   This 
  is 
  also 
  the 
  position 
  assigned 
  to 
  the 
  Forfarshire 
  sandstones 
  by 
  Sir 
  

   R. 
  I. 
  Murchison 
  in 
  ' 
  Siluria' 
  (see 
  2nd 
  edit. 
  pp. 
  275-285). 
  The 
  only 
  

   point 
  in 
  which 
  my 
  observations 
  lead 
  me 
  to 
  differ 
  from 
  the 
  descriptions 
  

   there 
  so 
  fully 
  and 
  clearly 
  given 
  is 
  that, 
  instead 
  of 
  the 
  Forfarshire 
  beds 
  

  

  