﻿130 
  COLLECTIONS 
  FROM 
  MELANESIA. 
  

  

  determine 
  to 
  some 
  extent 
  its 
  range 
  of 
  variation 
  : 
  this, 
  as 
  we 
  might 
  

   have 
  expected, 
  is 
  most 
  markedly 
  presented 
  by 
  the 
  characters 
  of 
  the 
  

   spinous 
  protuberances 
  formed 
  by 
  the 
  hypertrophy 
  of 
  some 
  of 
  the 
  

   granules 
  on 
  the 
  abactinal 
  surface 
  ; 
  the 
  smallest 
  specimen 
  is 
  without 
  

   any 
  special 
  spines. 
  Of 
  three 
  larger 
  and 
  subequal 
  specimens, 
  that 
  

   which 
  is 
  a 
  little 
  the 
  smallest 
  has 
  a 
  more 
  prominent 
  granule 
  deve- 
  

   loped 
  here 
  and 
  there 
  along 
  the 
  middle 
  lines 
  of 
  the 
  rays, 
  and 
  some 
  

   six, 
  still 
  more 
  prominent, 
  at 
  the 
  centre 
  of 
  the 
  dislv 
  ; 
  the 
  other 
  two 
  

   have 
  much 
  more 
  prominent 
  spinous 
  granules 
  at 
  what 
  may 
  be 
  called 
  

   the 
  base 
  of 
  the 
  rays, 
  and 
  some 
  smaller 
  protuberances 
  around 
  the 
  

   centre 
  of 
  the 
  disk 
  ; 
  these 
  latter 
  are, 
  in 
  the 
  largest 
  specimen 
  of 
  all, 
  

   quite 
  inconspicuous. 
  E. 
  is 
  about 
  equal 
  to 
  2 
  r; 
  R=72, 
  58 
  ; 
  r—34, 
  27. 
  

   Arms 
  29 
  or 
  26 
  millim. 
  wide 
  at 
  the 
  base, 
  narrowing 
  hardly 
  at 
  all 
  

   till 
  quite 
  near 
  their 
  end 
  ; 
  marginal 
  plates 
  very 
  well 
  developed, 
  equal 
  

   in 
  either 
  series, 
  and 
  13 
  or 
  14 
  in 
  number 
  ; 
  pedicellarise 
  scarce. 
  

  

  The 
  central 
  region 
  of 
  the 
  disk 
  is 
  not 
  distinctly 
  elevated 
  ; 
  with 
  

   increase 
  in 
  size 
  the 
  ossicles 
  of 
  the 
  abactinal 
  surface 
  become 
  less 
  

   closely 
  packed 
  than 
  in 
  the 
  smaller 
  forms 
  ; 
  and 
  three 
  rows 
  of 
  ossicles 
  

   can 
  be 
  quite 
  distinctly 
  made 
  out 
  ; 
  the 
  investing 
  granulation 
  is 
  not 
  

   especially 
  coarse 
  ; 
  the 
  intervening 
  pores 
  may 
  be 
  set 
  singly 
  or 
  dis- 
  

   posed 
  in 
  groups 
  of 
  three 
  or 
  four. 
  With 
  increase 
  in 
  size, 
  likewise, 
  

   the 
  boundary 
  line 
  between 
  the 
  two 
  sets 
  of 
  marginal 
  plates 
  becomes 
  

   more 
  distinct 
  ; 
  from 
  the 
  angle 
  of 
  the 
  arm 
  outwards 
  the 
  supero- 
  

   marginals 
  increase 
  in 
  breadth 
  till 
  the 
  last 
  two 
  or 
  three, 
  but 
  they 
  are 
  

   always 
  at 
  least 
  twice 
  as 
  long 
  as 
  they 
  are 
  broad 
  ; 
  the 
  terminal 
  two 
  

   or 
  three 
  touch 
  in 
  the 
  middle 
  line. 
  The 
  infero-marginals 
  are 
  a 
  little 
  

   stouter, 
  but 
  have 
  otherwise 
  much 
  the 
  same 
  proj)ortions 
  as 
  the 
  upper 
  

   series. 
  

  

  The 
  intermediate 
  plates 
  are 
  distinct 
  from 
  one 
  another 
  and 
  are 
  

   covered 
  by 
  large 
  distinct 
  granules. 
  The 
  innermost 
  row 
  of 
  adambu- 
  

   lacral 
  spines 
  are 
  6 
  or 
  7 
  in 
  number, 
  and 
  are 
  more 
  delicate 
  than 
  the 
  two 
  

   stouter 
  ones 
  which 
  are 
  placed 
  outside 
  them 
  ; 
  those 
  of 
  the 
  outermost 
  

   row 
  are 
  smaller 
  and 
  more 
  irregular, 
  and 
  are 
  not 
  easily 
  distinguished 
  

   from 
  the 
  granules 
  of 
  the 
  ventral 
  plates. 
  

  

  Madreporic 
  plate 
  rather 
  large, 
  distinct, 
  g 
  to 
  ^ 
  r 
  distant 
  from 
  the 
  

   centre 
  ; 
  the 
  anus 
  often 
  distinguished 
  by 
  its 
  periphery 
  of 
  eight 
  or 
  

   ten 
  small 
  plates. 
  

  

  The 
  dried 
  specimens 
  are 
  yellowish 
  or 
  light 
  slate-coloured 
  ; 
  but 
  

   there 
  is 
  no 
  information 
  as 
  to 
  what 
  is 
  their 
  colour 
  when 
  alive 
  or 
  

   fresh. 
  

  

  The 
  species 
  is 
  verj-^ 
  distinct 
  from 
  P. 
  dilafatiis 
  of 
  Perrier, 
  which 
  

   species 
  has 
  perhaps 
  been 
  founded 
  on 
  forms 
  which 
  were 
  only 
  varieties 
  

   of 
  the 
  Astrof/onium 
  miliare 
  of 
  Gray. 
  

  

  Thursday 
  Island, 
  Torres 
  Straits, 
  3-5 
  fms. 
  ; 
  sand. 
  

  

  19. 
  Dorigona 
  longimana. 
  

  

  Pentagonaster 
  longimanus, 
  Perrier, 
  p. 
  228. 
  

   Percy 
  Island, 
  Queensland 
  ; 
  Prince 
  of 
  Wales 
  Channel, 
  Aug. 
  1881, 
  

   7 
  fms. 
  

  

  