﻿136 
  Verrill 
  — 
  Changes 
  in 
  the 
  colors 
  of 
  certain 
  fishes, 
  etc. 
  

  

  It 
  is 
  well 
  known 
  that 
  trout, 
  flounders, 
  and 
  some 
  other 
  fishes 
  

   are 
  able 
  to 
  change 
  their 
  colors, 
  even 
  in 
  the 
  daytime, 
  according 
  

   to 
  the 
  color 
  of 
  their 
  surroundings. 
  Therefore 
  a 
  darkening 
  of 
  

   the 
  colors 
  at 
  night 
  is 
  to 
  be 
  expected, 
  even 
  if 
  not 
  asleep. 
  But 
  

   in 
  all 
  the 
  cases 
  mentioned 
  above 
  the 
  nocturnal 
  change 
  of 
  color 
  is 
  

   of 
  a 
  protective 
  character, 
  as 
  explained 
  in 
  the 
  preceding 
  article. 
  

  

  Other 
  fishes, 
  however, 
  show 
  much 
  more 
  remarkable 
  changes. 
  

   Among 
  these 
  the 
  scup 
  or 
  porgy 
  {Stenotomus 
  chrysops) 
  is 
  one 
  

   of 
  the 
  best 
  examples. 
  This 
  fish, 
  when 
  active 
  in 
  the 
  daytime, 
  

   usually 
  has 
  a 
  bright 
  silvery 
  color 
  with 
  iridescent 
  tints. 
  But 
  at 
  

   night, 
  when 
  asleep, 
  it 
  has 
  a 
  dull 
  bronzy 
  ground-color 
  and 
  the 
  

   body 
  is 
  crossed 
  by 
  about 
  six 
  transverse 
  black 
  bands. 
  When 
  

   one 
  of 
  these 
  fishes, 
  with 
  this 
  coloration, 
  was 
  awakened 
  by 
  sud- 
  

   denly 
  turning 
  up 
  the 
  gas, 
  it 
  immediately 
  assumed 
  the 
  bright 
  

   silvery 
  colors 
  belonging 
  to 
  its 
  daytime 
  dress. 
  This 
  experiment 
  

   was 
  repeated 
  many 
  times, 
  on 
  different 
  individuals, 
  with 
  the 
  

   same 
  result. 
  As 
  this 
  fish 
  naturally 
  rests 
  among 
  eel-grass 
  and 
  sea- 
  

   weeds, 
  the 
  protective 
  character 
  of 
  its 
  nocturnal 
  colors 
  is 
  obvious. 
  

  

  A 
  common 
  file-fish 
  {Monacanthus, 
  sp.) 
  was 
  observed 
  that 
  

   presents 
  a 
  very 
  decided 
  change 
  in 
  color 
  pattern. 
  This 
  species, 
  

   in 
  the 
  daytime, 
  is 
  mottled 
  with 
  brown 
  and 
  dark 
  olive 
  green, 
  

   and 
  the 
  fins 
  and 
  tail 
  are 
  a 
  little 
  darker 
  than 
  the 
  body, 
  but 
  

   when 
  asleep, 
  at 
  night, 
  its 
  body 
  becomes 
  pallid 
  gray 
  or 
  nearly 
  

   white, 
  while 
  the 
  fins 
  and 
  tail 
  become 
  decidedly 
  black. 
  These 
  

   colors 
  are 
  decidedly 
  protective 
  at 
  night, 
  or 
  in 
  a 
  feeble 
  light, 
  

   among 
  rocks 
  and 
  weeds, 
  where 
  it 
  lives. 
  This 
  and 
  other 
  species 
  

   of 
  file-fishes, 
  when 
  sleeping, 
  would 
  usually 
  rest 
  on 
  the 
  bottom 
  

   with 
  the 
  back 
  leaning 
  against 
  the 
  glass 
  of 
  the 
  aquarium 
  or 
  

   against 
  a 
  stone 
  at 
  a 
  considerable 
  angle. 
  

  

  The 
  common 
  tautog 
  or 
  black 
  fish 
  (Tautoga 
  onitis) 
  has 
  the 
  

   curious 
  habit 
  of 
  resting 
  upon 
  one 
  side, 
  half 
  buried 
  among 
  

   gravel, 
  or 
  partly 
  under 
  stones, 
  and 
  is 
  often 
  curved 
  in 
  strange 
  

   positions. 
  It 
  is 
  easy 
  to 
  imagine 
  that 
  the 
  flounders 
  originated 
  

   from 
  some 
  symmetrical 
  ancestral 
  form 
  that 
  acquired, 
  like 
  the 
  

   tautog, 
  the 
  habit 
  of 
  resting 
  upon 
  one 
  side, 
  at 
  first 
  only 
  when 
  

   sleeping, 
  but 
  afterwards 
  continually, 
  owing 
  to 
  the 
  greater 
  pro- 
  

   tection 
  that 
  this 
  habit 
  and 
  its 
  imitative 
  coloration 
  afforded. 
  

   The 
  one-sided 
  coloration 
  and 
  the 
  changes 
  in 
  the 
  position 
  of 
  the 
  

   eyes, 
  etc., 
  would 
  gradually 
  follow 
  in 
  accordance 
  with 
  well 
  

   known 
  laws 
  of 
  evolution. 
  

  

  The 
  common 
  squid 
  (Loligo 
  Pealei) 
  was 
  observed 
  sleeping 
  

   on 
  several 
  occasions. 
  At 
  such 
  times 
  it 
  rests 
  in 
  an 
  inclined 
  

   position, 
  on 
  the 
  tip 
  of 
  its 
  tail 
  and 
  on 
  the 
  basal 
  parts 
  of 
  the 
  

   arms, 
  which 
  are 
  bunched 
  together 
  and 
  extended 
  forward, 
  so 
  

   that 
  the 
  head 
  and 
  anterior 
  part 
  of 
  the 
  body 
  are 
  raised 
  from 
  

   the 
  bottom, 
  so 
  as 
  to 
  give 
  room 
  for 
  breathing. 
  The 
  siphon 
  

   tube 
  is 
  then 
  turned 
  to 
  one 
  side. 
  Under 
  these 
  circumstances 
  

   the 
  color 
  is 
  darker 
  and 
  the 
  spots 
  more 
  distinct 
  than 
  when 
  it 
  is 
  

   active, 
  owing 
  to 
  the 
  expansion 
  of 
  the 
  brown 
  and 
  purple 
  chro- 
  

   matophores. 
  

  

  