﻿8P0NGIIDA. 
  473 
  

  

  101. 
  Stelletta 
  purpurea. 
  

   (Plate 
  XL. 
  fig. 
  E 
  ; 
  Plate 
  XLIII. 
  figs, 
  j, 
  /.) 
  

  

  Free, 
  subspherical 
  or 
  suboval. 
  A 
  single 
  circular 
  vent 
  (about 
  2 
  

   millim. 
  in 
  diameter 
  in 
  moderate-sized 
  specimens) 
  often 
  present 
  ; 
  it 
  

   leads 
  deeply 
  into 
  the 
  sponge. 
  Surface 
  subpapillose, 
  i. 
  e. 
  embossed 
  

   with 
  small 
  semiglobular 
  elevations, 
  visible 
  most 
  readily 
  under 
  a 
  

   lateral 
  light. 
  Colour 
  purple 
  in 
  spirit, 
  when 
  well 
  preserved. 
  A 
  

   distinct 
  cortical 
  layer 
  with 
  sarcode 
  of 
  the 
  same 
  consistency 
  as 
  that 
  

   of 
  the 
  central 
  part 
  of 
  the 
  sponge, 
  about 
  '7 
  millim. 
  broad, 
  containing 
  

   the 
  subcortical 
  crypts, 
  and 
  formed 
  (in 
  adult 
  specimens) 
  by 
  the 
  space 
  

   intervening 
  between 
  the 
  heads 
  of 
  the 
  superficial 
  zoue-spicules 
  ; 
  

   a 
  subcortical 
  zone 
  of 
  anchors 
  and 
  smaller 
  zone-spicules. 
  Deep 
  

   sarcode 
  transparent, 
  brownish 
  yellow 
  ; 
  that 
  of 
  surface 
  purplish 
  

   red, 
  rather 
  granular. 
  

  

  Spicules: 
  — 
  (1) 
  Zone-spicule 
  ; 
  shaft 
  stout, 
  tapering 
  gradually 
  to 
  

   sharp 
  point, 
  1'4 
  to 
  1-6 
  by 
  -045 
  to 
  -06 
  millim. 
  ; 
  arms 
  strong, 
  

   tapering 
  gradually 
  to 
  sharp 
  points, 
  projectiug 
  somewhat 
  forward 
  

   at 
  the 
  commencement, 
  and 
  then 
  curving 
  backwards 
  slightly, 
  "27 
  

   by 
  -043 
  to 
  '06 
  millim. 
  in 
  length 
  and 
  breadth 
  respectively, 
  (2) 
  

   Anchor, 
  long, 
  tapering 
  to 
  sharp 
  point 
  ; 
  head 
  almost 
  flat 
  above 
  ; 
  

   arms 
  turning 
  rather 
  abruptly 
  back 
  to 
  form 
  an 
  angle 
  of 
  about 
  45° 
  

   with 
  shaft, 
  tapering 
  to 
  sharp 
  points 
  ; 
  expanse 
  of 
  arms 
  at 
  their 
  

   points 
  •! 
  millim. 
  ; 
  diameter 
  of 
  shaft 
  about 
  •035 
  millim. 
  : 
  length 
  of 
  

   shaft 
  about 
  2 
  millim., 
  of 
  arms 
  about 
  '07 
  millim. 
  Head 
  usually 
  lying 
  

   below 
  the 
  zone 
  of 
  " 
  chones. 
  " 
  (3) 
  Body 
  acerate, 
  long, 
  slender, 
  

   tapering 
  very 
  gradually 
  from 
  centre 
  to 
  sharp 
  points 
  ; 
  size 
  about 
  1*5 
  

   to 
  2 
  by 
  -037 
  millim. 
  (4) 
  Minute 
  stellate 
  of 
  flesh; 
  about 
  7 
  to 
  

   10 
  arms 
  ; 
  no 
  percex^tible 
  body 
  ; 
  arms 
  straight, 
  very 
  slender, 
  viz. 
  

   about 
  -0008 
  millim. 
  in 
  diameter, 
  apparently 
  smooth, 
  terminated 
  

   by 
  minute 
  head 
  ; 
  diameter 
  of 
  spicule 
  across 
  arms 
  -02 
  to 
  -025 
  

   millim. 
  : 
  distributed 
  throughout 
  all 
  parts 
  of 
  the 
  sarcode. 
  

  

  JIab. 
  Prince 
  of 
  Wales 
  Channel, 
  Thursday 
  Island, 
  and 
  West 
  

   Island, 
  Torres 
  Straits, 
  4-9 
  fms. 
  ; 
  bottom 
  sand 
  or 
  sand 
  and 
  coral. 
  

   Port 
  Darwin, 
  7-12 
  fms. 
  ; 
  bottom 
  sand 
  and 
  mud. 
  Arafura 
  Sea 
  oflf 
  

   N.W. 
  coast 
  of 
  Australia, 
  32-36 
  fms. 
  ; 
  sand, 
  mud, 
  and 
  shells. 
  

  

  Specimens 
  not 
  abundant 
  at 
  any 
  of 
  the 
  stations. 
  The 
  single 
  

   specimen 
  from 
  West 
  Island 
  is 
  remarkable 
  for 
  being 
  half 
  covered 
  

   by 
  specimens 
  of 
  lotrocliota 
  purpurea, 
  RMzocJialina 
  sinr/aj)orensis, 
  

   Cladochalina 
  niida, 
  and 
  a 
  coralline. 
  

  

  Stelletta 
  purpurea, 
  var. 
  retroflexa. 
  (Plate 
  XLIII. 
  fig. 
  h.) 
  

  

  This 
  name 
  may 
  be 
  applied 
  to 
  a 
  specimen 
  which 
  has 
  the 
  expanse 
  

   of 
  the 
  arms 
  of 
  the 
  zone-spicule 
  somewhat 
  greater 
  than 
  in 
  the 
  typical 
  

   form, 
  while 
  their 
  diameter 
  is 
  less, 
  and 
  one 
  or 
  more 
  of 
  the 
  arms 
  

   generally 
  has 
  the 
  point 
  bent 
  backwards 
  abruptly, 
  so 
  as 
  to 
  form 
  an 
  

   angle 
  of 
  about 
  135° 
  with 
  the 
  rest 
  of 
  the 
  arm. 
  The 
  specimen 
  is 
  

   globular, 
  and 
  has 
  a 
  vent 
  about 
  1-5 
  millim. 
  in 
  diameter. 
  The 
  bend 
  

  

  