﻿142 
  COLLECTIONS 
  FROM 
  MELANESIA. 
  

  

  become 
  less 
  conspicuous 
  and 
  much 
  reduced 
  ; 
  the 
  white 
  lines 
  along 
  

   the 
  arm 
  are 
  broken 
  into 
  by 
  blue 
  patches, 
  much 
  less 
  extensively 
  de- 
  

   veloped 
  than 
  in 
  the 
  dark 
  form 
  ; 
  on 
  the 
  lower 
  surface 
  of 
  the 
  arm 
  

   the 
  blue 
  lines 
  may 
  be 
  present 
  as 
  continuous" 
  tracts, 
  or 
  they 
  may 
  here 
  

   and 
  there 
  be 
  interrupted 
  by 
  white. 
  

  

  Port 
  Curtis 
  ; 
  Thursday 
  Island 
  ; 
  Port 
  Darwin. 
  

  

  16. 
  Ophiothrix 
  striolata. 
  

   Lyman, 
  p. 
  36. 
  

  

  Thursday 
  Island. 
  

  

  17. 
  Ophiothrix 
  galatesB. 
  

   Lyman, 
  p. 
  36. 
  

  

  Port 
  Darwin. 
  

  

  18. 
  Ophiothrix 
  ciliaris. 
  

  

  Lyman, 
  p. 
  85. 
  

   Port 
  Jackson, 
  0-5 
  fms. 
  ; 
  Port 
  MoUe. 
  

  

  „ 
  19. 
  Ophiothrix 
  rotata. 
  

  

  Martens, 
  Arch.f. 
  Nat. 
  1870, 
  p. 
  258. 
  

  

  A 
  single 
  specimen, 
  without 
  doubt 
  referred 
  to 
  this 
  species, 
  differs 
  

   in 
  one 
  or 
  two 
  points 
  from 
  tbat 
  described 
  by 
  Dr. 
  von 
  Martens. 
  In 
  

   the 
  Berlin-Museum 
  specimen 
  the 
  diameter 
  of 
  the 
  disk 
  is 
  7 
  millim., 
  

   and 
  the 
  length 
  of 
  the 
  arras 
  35 
  millim. 
  In 
  our 
  specimen 
  the 
  arms 
  

   must 
  have 
  been 
  nearly 
  150 
  millim. 
  long, 
  while 
  the 
  diameter 
  of 
  the 
  

   disk 
  is 
  12 
  millim. 
  The 
  upper 
  spines 
  are 
  not 
  more 
  than 
  twice 
  the 
  

   width 
  of 
  the 
  arm, 
  instead 
  of 
  four 
  times. 
  The 
  original 
  describer 
  

   makes 
  two 
  statements 
  with 
  regard 
  to 
  the 
  colour 
  of 
  the 
  oral 
  shields 
  : 
  

   — 
  " 
  Unterseite 
  der 
  Bcheibe 
  mit 
  den 
  Muudschildern 
  und 
  die 
  Arm- 
  

   stacheln 
  blass 
  " 
  ; 
  and 
  " 
  Das 
  der 
  Madreporenplatte 
  zi;gehorige 
  Mund- 
  

   schild 
  ist 
  merklich 
  grosser, 
  an 
  den 
  Heiten 
  nicht 
  eingebuchtet 
  und 
  

   weiss, 
  nicht 
  wie 
  die 
  andern 
  violett." 
  In 
  the 
  specimen 
  now 
  under 
  

   examination 
  there 
  is 
  some 
  violet 
  marking 
  on 
  each 
  one 
  of 
  the 
  mouth- 
  

   shields. 
  

  

  Thursday 
  Island, 
  3-4 
  fms. 
  

  

  So 
  far 
  as 
  the 
  present 
  collection 
  allows 
  me 
  to 
  form 
  any 
  ideas 
  with 
  

   regard 
  to 
  the 
  range 
  of 
  variation 
  within 
  the 
  limits 
  of 
  a 
  " 
  species," 
  and 
  

   the 
  value 
  of 
  the 
  colour-markings 
  on 
  which 
  previous 
  investigators 
  have 
  

   laid, 
  and, 
  as 
  it 
  seemed, 
  justifiably, 
  very 
  considerable 
  stress, 
  I 
  am 
  in- 
  

   clined 
  to 
  the 
  view 
  that 
  the 
  variation 
  is 
  very 
  much 
  greater 
  than 
  was 
  

   supposed, 
  and 
  that, 
  after 
  all, 
  colour-marking, 
  though 
  an 
  important 
  

   aid 
  in 
  the 
  discrimination 
  of 
  the 
  species, 
  can 
  hardly 
  be 
  said 
  to 
  have 
  

   the 
  value 
  which 
  has 
  been 
  attached 
  to 
  it. 
  The 
  doubts 
  first 
  raised 
  

   by 
  a 
  study 
  of 
  0. 
  martensi 
  (vide 
  supra) 
  are 
  not 
  a 
  little 
  strengthened 
  

   by 
  the 
  three 
  specimens 
  now 
  lying 
  before 
  me, 
  which, 
  I 
  have 
  little 
  

  

  