﻿OF 
  THE 
  MORAY 
  FIRTH 
  AREA. 
  

  

  249 
  

  

  Incertce 
  sedis. 
  

   Order 
  PLACODERMATA. 
  

  

  Genus 
  COCCOSTEUS, 
  Agassiz. 
  

   Coccosteus 
  decipiens, 
  Agassiz, 
  1844. 
  

  

  Syn. 
  C. 
  cuspidatus, 
  Ag. 
  ; 
  C. 
  oblongus, 
  Ag. 
  ; 
  C. 
  microspondylus, 
  M'Coy 
  ; 
  

   C. 
  trigonaspis, 
  M'Coy; 
  C. 
  latus 
  (Ag.), 
  M'Coy; 
  C. 
  pusillus, 
  M'Coy 
  ; 
  

   C. 
  Milleri, 
  Egert. 
  

  

  (Restored 
  figure 
  of 
  skeleton, 
  PI. 
  iv. 
  fig. 
  1.) 
  

   There 
  can 
  be 
  no 
  doubt 
  that 
  there 
  is 
  but 
  one 
  species 
  of 
  Coccosteus 
  in 
  the 
  

   Orcadian 
  beds 
  of 
  the 
  Moray 
  Firth, 
  namely, 
  C. 
  decipiens 
  of 
  Agassiz, 
  

   which 
  includes 
  also 
  the 
  Coccostean 
  remains 
  from 
  this 
  region, 
  to 
  

   which 
  the 
  names 
  cuspidatus, 
  oblongus, 
  and 
  Milleri 
  have 
  been 
  given. 
  

   It 
  is 
  also 
  the 
  only 
  species 
  known 
  from 
  the 
  Orkney 
  beds, 
  M 
  'Coy's 
  

   microspondylus, 
  trigonaspis, 
  and 
  pusillus 
  being 
  certainly 
  synonymous. 
  

   The 
  latter 
  seems 
  to 
  be 
  only 
  a 
  young 
  form 
  of 
  C. 
  decipiens, 
  and 
  must 
  

   not 
  be 
  confounded, 
  as 
  has 
  been 
  the 
  case, 
  with 
  C. 
  minor, 
  H. 
  Miller, 
  

   from 
  the 
  Thurso 
  district. 
  

  

  Coccosteus 
  decipiens 
  is 
  one 
  of 
  the 
  commonest 
  fishes 
  in 
  the 
  Orcadian 
  

   series 
  of 
  rocks, 
  being 
  abundant 
  in 
  all 
  the 
  fish-bearing 
  localities 
  of 
  

   this 
  horizon 
  in 
  the 
  Moray 
  Firth 
  area, 
  in 
  Orkney, 
  and 
  also 
  through- 
  

   out 
  Caithness, 
  except 
  in 
  the 
  John 
  o' 
  Groat's 
  beds. 
  

  

  In 
  PI. 
  iv. 
  fig. 
  1, 
  I 
  have 
  given 
  a 
  restored 
  outline 
  of 
  the 
  skeleton 
  

   of 
  this 
  species, 
  nearly 
  the 
  same 
  as 
  that 
  which 
  I 
  have 
  previously 
  

   published 
  (46, 
  PI. 
  x. 
  fig. 
  1), 
  and 
  without 
  any 
  attempt 
  to 
  delineate 
  

   the 
  outline 
  of 
  the 
  body 
  and 
  dermal 
  fins, 
  as 
  has 
  been 
  done 
  by 
  Mr. 
  

   Smith 
  Woodward 
  in 
  a 
  drawing 
  given 
  in 
  his 
  'Catalogue' 
  (47, 
  p. 
  

   282, 
  fig. 
  44). 
  Mr. 
  Woodward 
  has 
  in 
  his 
  figure 
  represented 
  Coc- 
  

   costeus 
  with 
  a 
  hypothetical 
  caudal 
  fin 
  of 
  a 
  regular 
  heterocercal 
  

   form, 
  but 
  I 
  venture 
  to 
  think 
  that 
  he 
  is 
  not 
  justified 
  in 
  this 
  by 
  the 
  

   condition 
  of 
  the 
  vertebral 
  column 
  as 
  we 
  find 
  it. 
  Had 
  Coccosteus 
  

   possessed 
  such 
  a 
  heterocercal 
  tail 
  we 
  should 
  expect 
  to 
  find 
  the 
  

   apophyses 
  at 
  the 
  commencement 
  of 
  the 
  fin 
  on 
  the 
  hajmal 
  aspect 
  

   becoming 
  suddenly 
  much 
  elongated, 
  and 
  the 
  vertebral 
  axis 
  per- 
  

   manently 
  directed 
  upwards 
  at 
  this 
  part, 
  whereas, 
  though 
  these 
  

   apophyses 
  are 
  indeed 
  slightly 
  longer 
  and 
  more 
  vertical 
  on 
  the 
  

   haemal 
  than 
  on 
  the 
  neural 
  aspect, 
  they 
  show 
  no 
  sudden 
  or 
  great 
  elon- 
  

   gation, 
  nor 
  does 
  the 
  notochordal 
  axis 
  present 
  any 
  constant 
  upward 
  

   bend. 
  That 
  Coccosteus 
  possessed 
  a 
  vertical 
  caudal 
  fin-fold, 
  which 
  was 
  

  

  