﻿ECHIJSrODERMATA, 
  129 
  

  

  longer 
  in 
  the 
  median 
  line 
  of 
  each 
  ray, 
  where 
  they 
  form 
  a 
  remarkably 
  

   regular 
  series, 
  continued 
  on 
  to 
  the 
  disk, 
  but 
  they 
  become 
  more 
  or 
  

   less 
  ill-delined 
  on 
  the 
  raised 
  portion 
  ; 
  the 
  granules 
  on 
  the 
  rest 
  of 
  

   the 
  plates 
  present 
  no 
  peculiarities, 
  saving 
  that 
  they 
  are 
  a 
  little 
  

   longer 
  on 
  the 
  sides 
  of 
  the 
  raised 
  portion 
  of 
  the 
  disk. 
  The 
  respira- 
  

   tory 
  pores 
  on 
  this 
  surface 
  are 
  rather 
  large, 
  scattered, 
  and 
  simple. 
  

   The 
  supero-marginal 
  plates 
  are 
  as 
  much 
  as 
  7 
  millim. 
  high 
  in 
  the 
  

   widely 
  open 
  angle 
  of 
  the 
  arms 
  ; 
  they 
  are 
  narrow, 
  wider 
  above 
  than 
  

   below 
  ; 
  as 
  these 
  plates 
  pass 
  outwards 
  they 
  decrease 
  in 
  length 
  and 
  

   increase 
  in 
  breadth 
  ; 
  they 
  next 
  decrease 
  in 
  size 
  generally, 
  and 
  

   finally 
  they 
  are 
  again, 
  though 
  much 
  smaller, 
  of 
  the 
  same 
  general 
  

   form 
  as 
  those 
  of 
  the 
  angles 
  of 
  the 
  arm 
  ; 
  the 
  terminal 
  three 
  or 
  four 
  

   touch 
  in 
  the 
  middle 
  line 
  : 
  of 
  these 
  plates 
  there 
  are 
  about 
  23 
  on. 
  

   the 
  side 
  of 
  each 
  ray 
  ; 
  the 
  condition 
  of 
  their 
  armature 
  is, 
  perhaps, 
  

   best 
  described 
  by 
  saying 
  that 
  some 
  of 
  the 
  granules 
  elongate 
  to 
  form 
  

   small 
  spinous 
  tubercles. 
  The 
  madreporic 
  plate 
  is 
  situated 
  about 
  

   one 
  third 
  of 
  the 
  radius 
  from 
  the 
  centre 
  of 
  the 
  disk 
  ; 
  it 
  is 
  prominent, 
  

   5'5 
  millim. 
  long, 
  and 
  has 
  the 
  form 
  of 
  an 
  irregular 
  elongated 
  oval. 
  

   The 
  infero-marginal 
  plates 
  are 
  likewise 
  about 
  23 
  in 
  number, 
  and 
  

   their 
  form 
  in 
  different 
  regions 
  presents 
  very 
  much 
  the 
  same 
  varia- 
  

   tions 
  as 
  those 
  of 
  the 
  supero-marginal 
  series 
  ; 
  the 
  granules, 
  however, 
  

   do 
  not 
  present 
  the 
  same 
  tendency 
  to 
  become 
  spinous, 
  though 
  they 
  

   are 
  all 
  rather 
  longer 
  and 
  not 
  quite 
  so 
  closely 
  packed. 
  The 
  adam- 
  

   bulacral 
  spines 
  form 
  a 
  fringe 
  of 
  four 
  flattened 
  subequal 
  spines, 
  in 
  

   addition 
  to 
  which 
  two 
  smaller 
  outer 
  ones 
  may 
  be 
  attached 
  to 
  the 
  

   same 
  ossicle 
  ; 
  beyond 
  these 
  there 
  are 
  two 
  or 
  three 
  much 
  stouter 
  

   spines, 
  and 
  beyond 
  these 
  again 
  there 
  may 
  be 
  two 
  or 
  three 
  spines, 
  

   the 
  tips 
  of 
  which 
  may 
  be 
  pointed. 
  The 
  granulation 
  of 
  the 
  inter- 
  

   mediate 
  plates 
  presents 
  very 
  much 
  the 
  same 
  characters 
  as 
  that 
  of 
  

   the 
  infero-marginal 
  plates. 
  

  

  This 
  species 
  may 
  be 
  distinguished 
  from 
  P. 
  singularis 
  or 
  P. 
  mUiaris 
  

   by 
  the 
  length 
  of 
  its 
  arms, 
  and 
  the 
  shape 
  and 
  closer 
  packing 
  of 
  the 
  

   plates 
  of 
  the 
  abactinal 
  surface 
  ; 
  from 
  the 
  former 
  it 
  is 
  also 
  distinguished 
  

   by 
  having 
  the 
  adambulacral 
  spines 
  shorter 
  and 
  blunter, 
  though 
  they 
  

   are 
  by 
  no 
  means 
  as 
  blunt 
  as 
  in 
  P. 
  miUaris, 
  where 
  the 
  adambulacral 
  

   groove 
  is 
  so 
  wide. 
  

  

  Colour 
  : 
  the 
  specimen 
  whose 
  admeasurements 
  have 
  been 
  given 
  in 
  

   the 
  above 
  description 
  is 
  dark 
  slate; 
  another, 
  in 
  which 
  11 
  = 
  82 
  and 
  

   r 
  = 
  26, 
  is 
  light 
  stone- 
  coloured 
  ; 
  in 
  it 
  the 
  disk 
  is 
  not 
  elevated. 
  

   Port 
  Curtis, 
  5-11 
  fms. 
  ; 
  Prince 
  of 
  Wales 
  Channel, 
  3-5 
  fms. 
  

  

  18. 
  Pentagonaster 
  validus. 
  

  

  This 
  is 
  a 
  second 
  new 
  species 
  which 
  belongs 
  to 
  the 
  Astrorjonium 
  

   division 
  of 
  the 
  genus. 
  The 
  arms 
  are 
  distinct, 
  rounded, 
  and 
  stout, 
  

   the 
  anus 
  central 
  and 
  sometimes 
  very 
  distinct 
  ; 
  the 
  granulation 
  of 
  

   the 
  ossicles 
  is 
  rather 
  coarse, 
  and 
  only 
  a 
  few 
  larger 
  granules 
  are 
  

   found 
  scattered 
  over 
  the 
  abactinal 
  surface 
  ; 
  there 
  are 
  three 
  rows 
  of 
  

   adambulacral 
  spines. 
  

  

  As 
  five 
  specimens 
  of 
  this 
  form 
  were 
  collected 
  we 
  are 
  able 
  to 
  

  

  K 
  

  

  