﻿1864.] 
  POWRIE 
  FORFARSHIRE 
  FOSSILS. 
  425 
  

  

  fins 
  ; 
  their 
  outer 
  surface 
  is 
  not 
  preserved 
  in 
  any 
  of 
  my 
  Fishes, 
  but 
  a 
  

   specimen 
  belonging 
  to 
  Mr. 
  Mitchell 
  clearly 
  shows 
  that 
  this 
  surface, 
  

   like 
  that 
  of 
  all 
  the 
  other 
  genera, 
  is 
  smooth 
  and 
  slightly 
  raised 
  in 
  the 
  

   centre 
  ; 
  the 
  inner 
  surface 
  is 
  undoubtedly 
  sculptured, 
  but 
  too 
  indis- 
  

   tinctly 
  to 
  admit 
  of 
  correct 
  description. 
  The 
  head 
  is 
  protected 
  by 
  

   very 
  large 
  strong 
  scales 
  ; 
  the 
  scales 
  covering 
  the 
  head 
  of 
  this 
  genus 
  

   and 
  also 
  of 
  Climatius 
  seem 
  rather 
  to 
  have 
  been 
  bony 
  plates 
  than 
  

   true 
  scales 
  ; 
  they 
  are 
  somewhat 
  hexagonal 
  in 
  shape, 
  and 
  appear 
  to 
  me 
  

   to 
  partake 
  a 
  good 
  deal 
  of 
  the 
  character 
  of 
  the 
  dermal 
  scutes 
  of 
  some 
  

   of 
  our 
  Reptiles. 
  

  

  The 
  spine 
  figured 
  by 
  Agassiz 
  *, 
  the 
  original 
  of 
  which 
  is 
  also 
  in 
  

   the 
  collection 
  at 
  Rossie 
  Priory, 
  is 
  considerably 
  curved, 
  and 
  has 
  the 
  

   longitudinal 
  ridges 
  smooth, 
  differing 
  in 
  these 
  respects 
  from 
  the 
  anterior 
  

   dorsal 
  of 
  the 
  above-described 
  Fish 
  ; 
  it 
  appears 
  to 
  be 
  the 
  anterior 
  

   dorsal 
  of 
  another 
  and, 
  as 
  yet, 
  unknown 
  species 
  of 
  this 
  genus. 
  

  

  EuTHACAETHTTS, 
  Powrie. 
  

  

  Head 
  small, 
  rather 
  compressed, 
  ovate; 
  body 
  rather 
  elongated, 
  

   slightly 
  compressed 
  laterally 
  ; 
  branchial 
  arches 
  numerous, 
  exposed 
  ; 
  

   tail 
  heterocercal 
  ; 
  fins 
  membranous, 
  preceded 
  by 
  conical 
  spines 
  ; 
  two 
  

   dorsals, 
  two 
  pectorals, 
  two 
  ventrals, 
  one 
  anal 
  ; 
  several 
  pairs 
  of 
  inter- 
  

   mediate 
  dermal 
  spines 
  ; 
  spines 
  straight, 
  ridged 
  longitudinally 
  ; 
  scales 
  

   minute. 
  

  

  EuTHACAXTnus 
  McjSTicoli, 
  Powrie. 
  

  

  Posterior 
  dorsal 
  spine 
  rather 
  longer 
  than 
  the 
  anterior, 
  both 
  having 
  

   smooth, 
  bold, 
  rounded, 
  longitudinal 
  ridges, 
  very 
  large 
  at 
  the 
  anterior 
  

   margin, 
  small 
  at 
  the 
  posterior; 
  dorsal 
  fins 
  very 
  large; 
  scales 
  very 
  

   small, 
  smooth 
  externally, 
  inner 
  surface 
  having 
  four 
  or 
  five 
  striae 
  ex- 
  

   tending 
  from 
  the 
  anterior 
  margin. 
  

  

  This 
  elegantly 
  formed 
  Fish 
  existed 
  in 
  great 
  numbers 
  in 
  these 
  

   olden 
  waters. 
  Its 
  remains, 
  consisting 
  generally 
  of 
  detached 
  spines 
  

   and 
  masses 
  of 
  scales, 
  are 
  frequently 
  to 
  be 
  met 
  with. 
  Good 
  speci- 
  

   mens 
  are, 
  however, 
  very 
  scarce, 
  only 
  one 
  complete 
  specimen 
  having 
  

   as 
  yet 
  been 
  found. 
  It 
  had 
  attained 
  a 
  considerable 
  size 
  ; 
  the 
  speci- 
  

   men 
  referred 
  to 
  is 
  seven 
  inches 
  in 
  length 
  ; 
  fragments, 
  however, 
  in- 
  

   dicate 
  a 
  length 
  of 
  at 
  least 
  eighteen 
  inches. 
  

  

  The 
  head 
  has 
  not 
  been 
  found 
  well 
  preserved; 
  it 
  is 
  small, 
  elliptical, 
  

   and 
  compressed 
  laterally, 
  and 
  appears 
  to 
  have 
  been 
  covered 
  partly 
  

   with 
  scales 
  similar 
  to 
  but 
  smaller 
  than 
  those 
  of 
  the 
  body, 
  and 
  partly 
  

   with 
  hexagonal 
  scales 
  or 
  plates. 
  The 
  eye-orbit 
  is 
  obscure, 
  but 
  appears 
  

   to 
  have 
  been 
  moderately 
  large, 
  and 
  placed 
  rather 
  back. 
  The 
  branchial 
  

   apparatus 
  consists 
  of 
  many 
  exposed 
  arches, 
  extending 
  backwards 
  and 
  

   downwards 
  from 
  the 
  eye-orbit. 
  The 
  body, 
  slightly 
  compressed 
  late- 
  

   rally, 
  gradually 
  increases 
  in 
  depth 
  to 
  the 
  insertion 
  of 
  the 
  anterior 
  

   dorsal 
  spine 
  ; 
  here 
  the 
  depth 
  is 
  about 
  equal 
  to 
  two-ninths 
  of 
  the 
  

   entire 
  length 
  ; 
  from 
  this 
  point 
  it 
  gradually 
  tapers 
  backwards 
  to 
  the 
  

   commencement 
  of 
  the 
  tail, 
  which 
  is 
  heterocercal, 
  exceedingly 
  

   graceful 
  in 
  form, 
  and 
  occupies 
  not 
  much 
  less 
  than 
  one-fourth 
  of 
  the 
  

   * 
  ' 
  Vieux 
  Gres 
  Rouge/ 
  pi. 
  xxxiii. 
  fig. 
  26. 
  

  

  