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  THE 
  VERTEBRATE 
  FAUNA 
  OF 
  "DEE." 
  

  

  those 
  that 
  hold 
  the 
  two 
  forms 
  to 
  be 
  the 
  same) 
  : 
  What 
  becomes 
  

   of 
  the 
  excess 
  of 
  males 
  in 
  what 
  some 
  writers 
  are 
  pleased 
  to 
  

   call 
  its 
  immature 
  state 
  ? 
  It 
  may 
  also 
  be 
  asked 
  : 
  Why 
  is 
  there 
  

   such 
  a 
  paucity 
  of 
  males 
  when 
  the 
  fish 
  is 
  in 
  what 
  they 
  term 
  

   its 
  adult 
  state 
  ? 
  And 
  further 
  : 
  At 
  what 
  stage 
  of 
  their 
  exis- 
  

   tence 
  does 
  the 
  change 
  take 
  place 
  in 
  the 
  form, 
  external 
  colour, 
  

   and 
  markings 
  of 
  the 
  two 
  forms 
  ? 
  Besides 
  this, 
  circularis 
  is 
  

   quite 
  abundant, 
  and 
  breeds 
  freely 
  in 
  Aberdeen 
  Bay 
  and 
  along 
  

   the 
  coast 
  both 
  north 
  and 
  south, 
  while 
  radula 
  is 
  entirely 
  absent 
  

   from 
  that 
  ground, 
  and 
  is 
  not 
  to 
  be 
  found 
  until 
  we 
  reach 
  deep 
  

   water 
  to 
  the 
  north 
  of 
  Wick. 
  Again, 
  if 
  circularis 
  is 
  the 
  young 
  

   of 
  radula, 
  how 
  is 
  it 
  that 
  not 
  a 
  single 
  example 
  of 
  it 
  is 
  caught 
  

   in 
  company 
  with 
  radula 
  ? 
  One 
  would 
  naturally 
  expect 
  that 
  

   the 
  immature 
  stage 
  would 
  occasionally 
  be 
  found 
  with 
  the 
  

   adult. 
  

  

  The 
  nature 
  and 
  distribution 
  of 
  the 
  spines 
  of 
  the 
  two 
  

   forms 
  differ, 
  radula 
  having 
  a 
  few 
  strong 
  irregularly-placed 
  

   spines 
  upon 
  the 
  nose, 
  and 
  three 
  rows 
  of 
  from 
  seventeen 
  to 
  

   eighteen 
  spines 
  on 
  each 
  " 
  wing," 
  and 
  the 
  anterior 
  end 
  of 
  

   these 
  rows 
  does 
  not 
  come 
  nearer 
  the 
  edge 
  of 
  the 
  fin 
  than 
  

   inches. 
  On 
  the 
  other 
  hand, 
  circularis 
  has 
  no 
  strong 
  spines 
  

   upon 
  the 
  nose, 
  and 
  those 
  on 
  the 
  "wings" 
  come 
  right 
  up 
  to, 
  

   and 
  extend 
  along, 
  the 
  anterior 
  edge, 
  the 
  spines 
  becoming 
  

   less 
  as 
  they 
  advance 
  towards 
  the 
  front. 
  There 
  are 
  sometimes 
  

   four 
  rows 
  of 
  these 
  spines, 
  and 
  they 
  form 
  a 
  triangular 
  patch, 
  

   the 
  long 
  end 
  of 
  which 
  points 
  posteriorly. 
  

  

  In 
  reference 
  to 
  the 
  spinulation 
  of 
  the 
  Rays, 
  Dr. 
  Gunther, 
  

   in 
  his 
  Introduction 
  to 
  the 
  Study 
  of 
  Fishes, 
  says 
  : 
  " 
  The 
  males 
  

   of 
  all 
  are 
  armed 
  with 
  patches 
  of 
  claw-like 
  spines, 
  retractile 
  

   in 
  grooves 
  of 
  the 
  integument, 
  and 
  serially 
  arranged, 
  occupying 
  

   a 
  space 
  on 
  the 
  upper 
  side 
  of 
  the 
  pectoral 
  fin 
  near 
  the 
  angle 
  

   of 
  the 
  disc, 
  and 
  frequently 
  also 
  the 
  sides 
  of 
  the 
  head." 
  

   These 
  spines 
  are 
  certainly 
  not 
  retractile 
  in 
  the 
  British 
  forms. 
  

   They 
  are 
  firmly 
  set 
  by 
  broad 
  bases 
  into 
  the 
  skin, 
  and 
  are 
  

   immovable. 
  

  

  Taking 
  all 
  things 
  into 
  consideration, 
  there 
  seems 
  to 
  be 
  

   no 
  doubt 
  but 
  that 
  Baia 
  radula 
  must 
  stand 
  as 
  a 
  distinct 
  

   species. 
  This 
  opinion 
  I 
  have 
  held 
  from 
  the 
  first, 
  but 
  refrained 
  

   from 
  expressing 
  it 
  until 
  such 
  time 
  as 
  a 
  series 
  of 
  each 
  in 
  

   all 
  their 
  stages 
  could 
  be 
  obtained. 
  This 
  has, 
  within 
  the 
  

   past 
  two 
  years, 
  come 
  to 
  hand, 
  and 
  I 
  have 
  now 
  an 
  unbroken 
  

  

  