﻿ECHINODEBMATA. 
  145 
  

  

  by 
  the 
  fact 
  that 
  two 
  successive 
  plates 
  are 
  so 
  marked, 
  and 
  that 
  then 
  

   there 
  is 
  an 
  interval 
  of 
  two 
  or 
  more 
  not 
  so 
  distinguished. 
  Three 
  or 
  

   four 
  blackish 
  dots 
  are 
  to 
  be 
  found 
  on 
  the 
  radial 
  shields, 
  along 
  the 
  

   line 
  of 
  the 
  vertical 
  side 
  ; 
  by 
  pairs 
  or 
  threes 
  the 
  upper 
  arm-plates 
  are 
  

   faint 
  pink 
  or 
  light 
  green, 
  and 
  the 
  pink 
  ones 
  are 
  distinguished 
  by 
  

   each 
  having 
  a 
  black 
  dot. 
  

  

  I 
  have 
  taken 
  advantage 
  of 
  the 
  locplity 
  of 
  this 
  Avell-marked 
  and 
  

   really 
  beautiful 
  species 
  to 
  associate 
  with 
  it 
  a 
  name 
  honoured 
  by 
  

   us 
  all. 
  

  

  Port 
  Darwin, 
  7-12 
  fms., 
  mud 
  and 
  sand. 
  

  

  24. 
  Ophiothrix 
  melanogramma. 
  

  

  Disk 
  pentagonal 
  in 
  appearance, 
  completely 
  covered 
  with 
  fine 
  

   spinules, 
  which 
  are 
  a 
  good 
  deal 
  longer 
  and 
  rarer 
  on 
  the 
  actinal 
  sur- 
  

   face. 
  Arms 
  4-5 
  times 
  the 
  diameter 
  of 
  the 
  disk, 
  tapering 
  very 
  deli- 
  

   cately 
  ; 
  the 
  upper 
  surface 
  marked 
  by 
  a 
  black 
  line, 
  which 
  extends 
  a 
  

   good 
  way 
  on 
  to, 
  but 
  does 
  not 
  reach, 
  the 
  centre 
  of 
  the 
  disk. 
  

  

  The 
  radial 
  shields 
  are 
  almost 
  completely 
  obscured 
  by 
  the 
  spinu- 
  

   lation, 
  which 
  is 
  very 
  delicate 
  ; 
  mouth-shields 
  broader 
  than 
  long, 
  the 
  

   inner 
  sides 
  meeting 
  at 
  an 
  acute 
  angle, 
  the 
  outer 
  edge 
  rather 
  evenly 
  

   rounded, 
  the 
  l^ridge 
  between 
  the 
  genital 
  slits 
  very 
  narrow 
  ; 
  seven 
  or 
  

   eight 
  arm-spines, 
  the 
  two 
  lowest 
  very 
  small, 
  the 
  upper 
  one 
  as 
  long 
  

   as 
  five 
  or 
  six 
  upper 
  arm-plates, 
  but 
  the 
  uppermost 
  of 
  all 
  is 
  not 
  the 
  

   longest 
  ; 
  the 
  upper 
  spines 
  are 
  richly 
  and 
  delicately 
  echinulated, 
  and, 
  

   owing 
  to 
  the 
  great 
  encroachment 
  of 
  the 
  side 
  arm-plates 
  on 
  the 
  upper 
  

   surface 
  of 
  the 
  arm, 
  the 
  spines 
  of 
  either 
  side 
  come 
  to 
  lie 
  very 
  close 
  to 
  

   one 
  another, 
  and 
  soon 
  obscure 
  the 
  arm 
  itself. 
  One 
  small 
  tentacle- 
  

   scale. 
  The 
  lower 
  arm-plates 
  have 
  a 
  concave 
  notch 
  on 
  their 
  adoral 
  

   edge, 
  have 
  a 
  short 
  side 
  passing 
  into 
  the 
  short 
  lateral 
  edge, 
  and 
  are 
  

   three-sided 
  on 
  their 
  aboral 
  face, 
  so 
  that 
  they 
  form 
  an 
  irregular 
  

   hexagon 
  which 
  is 
  broader 
  than 
  long. 
  Owing 
  to 
  the 
  size 
  of 
  the 
  side 
  

   arm-plates, 
  the 
  upper 
  arm-plates 
  are 
  lozenge-shaped. 
  

  

  This 
  species 
  has 
  a 
  most 
  elegant 
  appearance, 
  the 
  black 
  band 
  already 
  

   spoken 
  of 
  relieving 
  the 
  whiteness 
  of 
  all 
  the 
  other 
  parts, 
  while 
  a 
  kind 
  

   of 
  feathery 
  appearance 
  is 
  given 
  to 
  the 
  arms 
  by 
  the 
  delicate 
  plates 
  

   and 
  long 
  glassy 
  spines. 
  

  

  Prince 
  of 
  AVales 
  Channel. 
  

  

  25. 
  Ophiomaza 
  cacaotica. 
  

   Li/man, 
  p. 
  37. 
  

  

  The 
  coloration 
  of 
  these 
  specimens 
  is 
  very 
  far 
  from 
  the 
  chocolate 
  

   of 
  Mr. 
  Lyman's 
  type 
  ; 
  but 
  three 
  specimens 
  collected 
  in 
  one 
  locality 
  

   (Gulf 
  of 
  Suez) 
  are 
  — 
  one 
  chocolate-coloured, 
  one 
  quite 
  light, 
  and 
  one 
  

   intermediate. 
  A 
  discussion, 
  however, 
  of 
  the 
  characters 
  of 
  the 
  

   variations 
  of 
  this 
  species 
  will 
  be 
  more 
  profitable 
  when 
  our 
  series 
  is 
  

   larger. 
  

  

  Port 
  Mollc 
  ; 
  Prince 
  of 
  Wales 
  Channel. 
  

  

  I. 
  

  

  