﻿204 
  THE 
  VERTEBRATE 
  FAUNA 
  OF 
  " 
  DEE." 
  

  

  anxious 
  to 
  reach 
  some 
  definite 
  point 
  in 
  this 
  labyrinth 
  of 
  

   confusion. 
  I 
  have, 
  however, 
  been 
  forced 
  to 
  conclude 
  that 
  

   none 
  of 
  these 
  methods 
  can 
  be 
  taken 
  as 
  an 
  unfailing 
  guide 
  

   to 
  species, 
  because 
  external 
  form 
  and 
  colour 
  depend 
  upon 
  the 
  

   amount 
  of 
  food 
  and 
  the 
  nature 
  of 
  the 
  water 
  and 
  ground 
  in, 
  

   and 
  upon 
  which, 
  the 
  fish 
  has 
  lived. 
  It 
  is 
  a 
  well-known 
  fact 
  

   that 
  trout 
  living 
  in 
  a 
  stream 
  or 
  loch, 
  where 
  food 
  is 
  scanty, 
  

   are 
  long 
  and 
  lanky, 
  having 
  usually 
  a 
  large 
  unshapely 
  head 
  ; 
  

   and 
  if, 
  in 
  addition 
  to 
  this, 
  the 
  water 
  and 
  ground 
  are 
  of 
  a 
  

   dark 
  colour, 
  the 
  fish 
  will 
  be 
  correspondingly 
  black. 
  As 
  an 
  

   example, 
  I 
  caught 
  some 
  trout 
  in 
  a 
  small 
  mossy 
  burn 
  at 
  the 
  

   foot 
  of 
  Lochnagar 
  that 
  were 
  almost 
  black. 
  Had 
  it 
  not 
  been 
  

   that 
  the 
  edge 
  of 
  each 
  fin 
  had 
  a 
  thin 
  line 
  of 
  chalky 
  white, 
  

   it 
  would 
  have 
  been 
  almost 
  impossible 
  to 
  have 
  seen 
  the 
  

   fishes, 
  so 
  near 
  were 
  they 
  in 
  colour 
  to 
  the 
  surrounding 
  mossy 
  

   matter. 
  Yet, 
  farther 
  down 
  this 
  stream, 
  after 
  it 
  had 
  been 
  

   joined 
  by 
  others 
  of 
  a 
  less 
  peaty 
  character, 
  and 
  consequently 
  

   of 
  much 
  clearer 
  water 
  and 
  lighter 
  bottom, 
  the 
  fishes 
  there 
  

   were 
  correspondingly 
  lighter 
  in 
  colour. 
  Regarding 
  the 
  

   number 
  of 
  caecal 
  appendages 
  : 
  I 
  procured 
  for 
  special 
  exami- 
  

   nation 
  fifty 
  -five 
  trout, 
  taken 
  in 
  various 
  burns 
  and 
  rivers 
  

   throughout 
  the 
  counties 
  of 
  Kincardine, 
  Aberdeen, 
  and 
  Banff. 
  

   The 
  fishes 
  ranged 
  from 
  three-quarters 
  of 
  an 
  ounce 
  to 
  ten 
  

   and 
  three-quarter 
  ounces, 
  and 
  the 
  csecal 
  appendages 
  ranged 
  

   from 
  thirty 
  -eight 
  to 
  sixty 
  -nine, 
  the 
  two 
  extremes 
  being 
  

   found 
  in 
  the 
  same 
  stream. 
  It 
  will 
  thus 
  be 
  seen 
  that 
  the 
  

   number 
  of 
  cseca 
  cannot 
  be 
  taken 
  as 
  an 
  index 
  to 
  species. 
  

   The 
  number 
  of 
  vertebra?, 
  however, 
  seems 
  to 
  be 
  more 
  con- 
  

   stant, 
  ranging 
  from 
  fifty 
  - 
  eight 
  to 
  sixty. 
  All 
  things 
  

   considered, 
  it 
  seems 
  safe 
  to 
  conclude 
  that 
  our 
  trout, 
  one 
  

   and 
  all, 
  are 
  merely 
  varieties 
  one 
  of 
  another. 
  This 
  is 
  

   confirmed 
  in 
  no 
  small 
  degree 
  from 
  the 
  facts 
  pointed 
  out 
  

   by 
  Professor 
  Rasch 
  "that 
  the 
  ova 
  of 
  the 
  sea 
  and 
  river 
  

   trout 
  are 
  developed 
  regularly, 
  whichever 
  form 
  were 
  the 
  

   parent 
  ones, 
  and 
  that 
  the 
  offspring 
  were 
  fertile. 
  That 
  the 
  

  

  