﻿FISHES. 
  

  

  233 
  

  

  Family 
  GASTEROSTEID^E. 
  

  

  Genus 
  GASTEROSTEUS, 
  Artedu 
  

  

  Gasterosteus 
  aculeatus, 
  Linn. 
  Stickleback. 
  

  

  After 
  a 
  few 
  years' 
  collecting 
  of 
  this 
  family, 
  and 
  the 
  

   examination 
  of 
  several 
  hundred 
  individuals, 
  I 
  am 
  driven 
  to 
  

   the 
  conclusion 
  that 
  there 
  is 
  but 
  one 
  species 
  in 
  our 
  district, 
  

   and 
  also 
  that 
  the 
  number, 
  presence, 
  or 
  absence 
  of 
  lateral 
  

   plates 
  is 
  of 
  no 
  value 
  in 
  the 
  determination 
  of 
  species 
  ; 
  for 
  I 
  

   find 
  that 
  in 
  some 
  of 
  our 
  lochs 
  and 
  streams 
  these 
  creatures 
  are 
  

   pretty 
  constant 
  in 
  the 
  appearance 
  and 
  number 
  of 
  their 
  

   armature, 
  whilst 
  in 
  others, 
  by 
  one 
  sweep 
  of 
  a 
  hand-net, 
  a 
  

   batch 
  can 
  be 
  taken 
  with 
  a 
  number 
  of 
  plates 
  varying 
  so 
  that 
  

   they 
  represent 
  every 
  so-called 
  species 
  that 
  has 
  been 
  recorded 
  

   as 
  British. 
  Nor 
  does 
  the 
  number 
  of 
  plates 
  indicate 
  age, 
  for 
  I 
  

   have 
  often 
  found 
  individuals 
  not 
  over 
  one 
  inch 
  in 
  length 
  

   possessed 
  of 
  nine 
  to 
  twelve 
  such 
  plates 
  ; 
  whilst 
  others 
  of 
  full 
  

   size 
  have 
  not 
  more 
  than 
  three 
  or 
  four. 
  It 
  is 
  also 
  noticeable 
  

   that 
  the 
  number 
  of 
  plates 
  on 
  each 
  side 
  is 
  not 
  the 
  same, 
  

   there 
  frequently 
  being 
  one 
  to 
  four 
  more 
  on 
  one 
  side 
  than 
  upon 
  

   the 
  other. 
  

  

  Day, 
  British 
  Fishes, 
  vol. 
  i., 
  p. 
  237, 
  says 
  : 
  " 
  It 
  is 
  in 
  the 
  ocean, 
  

   more 
  than 
  in 
  fresh 
  waters, 
  that 
  we 
  must 
  seek 
  the 
  spiny-rayed 
  

   fishes 
  ; 
  and, 
  similarly, 
  it 
  is 
  on 
  the 
  sea-boards, 
  or 
  skirts 
  of 
  the 
  

   ocean, 
  that 
  we 
  must 
  look 
  for 
  Sticklebacks 
  in 
  which 
  the 
  

   armature 
  of 
  the 
  side 
  is 
  most 
  developed, 
  as 
  in 
  the 
  variety 
  

   trachurus 
  ; 
  while 
  such 
  as 
  have 
  the 
  free 
  portion 
  of 
  the 
  tail 
  

   unarmed 
  are 
  furthest 
  inland 
  or 
  on 
  elevated 
  plateaus." 
  

  

  It 
  is 
  quite 
  true 
  that 
  the 
  development 
  is 
  greatest 
  and 
  most 
  

   constant 
  along 
  the 
  sea-board, 
  the 
  only 
  variation 
  I 
  find 
  in 
  

   these 
  being 
  the 
  want 
  of 
  one 
  of 
  the 
  dorsal 
  spines. 
  But 
  I 
  

   occasionally 
  meet 
  with 
  specimens 
  from 
  pools 
  in 
  the 
  interior 
  of 
  

   our 
  district 
  with 
  an 
  equally 
  great 
  development 
  of 
  lateral 
  

   plates, 
  and 
  the 
  keel 
  upon 
  the 
  tail 
  quite 
  as 
  well 
  marked. 
  This 
  

   keel, 
  again, 
  in 
  inland 
  water 
  specimens, 
  is 
  subject 
  to 
  consider- 
  

   able 
  variation 
  ; 
  sometimes 
  it 
  is 
  formed 
  by 
  an 
  elevation 
  of 
  the 
  

   skin 
  only 
  — 
  in 
  others, 
  it 
  is 
  composed 
  of 
  one 
  continuous 
  horny 
  

   plate 
  ; 
  while, 
  again, 
  it 
  may 
  be 
  formed 
  by 
  a 
  series 
  of 
  obtuse 
  

   spines 
  ; 
  and, 
  lastly, 
  of 
  a 
  number 
  of 
  small 
  plates 
  with 
  a 
  high 
  

   ridge 
  along 
  the 
  centre 
  of 
  each. 
  All 
  things 
  considered, 
  it 
  

  

  