﻿PPONGIIDA, 
  601 
  

  

  its 
  wall 
  about 
  •05 
  millim. 
  thick, 
  of 
  a 
  fine 
  transparent 
  pnrple 
  colour, 
  

   and 
  is 
  composed 
  of 
  a 
  transparent 
  matrix 
  containing 
  closely 
  packed 
  

   subglobiilar 
  transparent 
  cells 
  -008 
  to 
  -013 
  millim. 
  in 
  diameter, 
  pro- 
  

   vided 
  with 
  small 
  opaque 
  refringent 
  nuclei 
  ; 
  the 
  laminae 
  composing 
  

   the 
  wall 
  of 
  the 
  fibre 
  are 
  readily 
  separated. 
  The 
  dermal 
  membrane 
  

   is 
  not, 
  as 
  in 
  A. 
  membranosa, 
  traversed 
  by 
  raised 
  thickenings 
  which 
  

   radiate 
  from 
  the 
  tij)S 
  of 
  the 
  conuli, 
  but 
  is 
  externally 
  homogeneous 
  

   and 
  subtransparent 
  ; 
  it 
  is 
  pale 
  purple 
  in 
  colour 
  and 
  quite 
  thin 
  ; 
  

   under 
  the 
  microscope 
  it 
  is 
  subtransparent, 
  granular 
  and 
  speckled 
  

   in 
  parts 
  with 
  the 
  less 
  transparent 
  and 
  darker 
  purple 
  nuclei 
  or 
  con- 
  

   densed 
  pigment-masses, 
  about 
  '005 
  millim. 
  in 
  diameter, 
  which 
  occupy 
  

   the 
  centres 
  of 
  large 
  cells. 
  

  

  Hah. 
  Mario 
  Louise 
  Island, 
  Amirante 
  group, 
  16 
  and 
  17 
  fms. 
  ; 
  Provi- 
  

   dence 
  Island, 
  Mascarene 
  group, 
  19 
  fms. 
  

  

  The 
  species 
  appears 
  to 
  be 
  most 
  nearly 
  related 
  to 
  A. 
  carnosa, 
  

   Schmidt 
  (Spong. 
  Adr. 
  Meer. 
  p. 
  26, 
  pi. 
  iii. 
  fig. 
  3), 
  from 
  the 
  Adriatic, 
  

   and 
  A. 
  cauUformis, 
  Carter 
  (Ann. 
  & 
  Mag. 
  N. 
  H. 
  1882, 
  ix. 
  p. 
  270), 
  from 
  

   the 
  West 
  Indies 
  ; 
  but 
  differs 
  from 
  the 
  former 
  in 
  its 
  far 
  more 
  loosely 
  

   reticulate 
  skeleton, 
  and 
  from 
  the 
  latter 
  in 
  not 
  having 
  the 
  surface 
  

   nearly 
  even. 
  It 
  is 
  perhaps 
  identical 
  with 
  the 
  elongated 
  specimens 
  

   described 
  by 
  Pallas 
  (I. 
  c.) 
  under 
  Spongia 
  membranosa. 
  It 
  difters 
  

   superficially 
  from 
  the 
  tj^pical 
  form 
  of 
  that 
  species 
  in 
  the 
  closer 
  

   approximation 
  of 
  the 
  conuli, 
  the 
  more 
  slender 
  habit 
  of 
  the 
  sponge, 
  

   the 
  smoothness 
  of 
  the 
  dermal 
  membrane, 
  in 
  its 
  minute 
  structure, 
  

   and 
  in 
  the 
  simple, 
  not 
  compound, 
  character 
  of 
  the 
  skeleton-fibre. 
  

  

  The 
  larger 
  specimens 
  are 
  slightly 
  compressed 
  laterally, 
  and 
  both 
  

   measure 
  about 
  60 
  millim. 
  (2^ 
  inches) 
  in 
  height 
  ; 
  four 
  spirit-speci- 
  

   mens 
  form 
  the 
  series. 
  

  

  17. 
  lanthella 
  flabelliformis. 
  

  

  Spongia 
  flabelliformis, 
  Tallas, 
  Elench. 
  ZoojyJi. 
  p. 
  380. 
  

  

  A 
  macerated 
  fragment 
  agreeing 
  in 
  outward 
  form, 
  so 
  far 
  as 
  it 
  goes, 
  

   and 
  in 
  the 
  proportions 
  and 
  character 
  of 
  its 
  fibre 
  with 
  the 
  above 
  

   species. 
  The 
  places 
  in 
  the 
  fibres 
  originally 
  occupied 
  by 
  the 
  purple 
  

   cells 
  are 
  chiefly 
  represented 
  by 
  vacant 
  spaces, 
  giving 
  a 
  honeycombed 
  

   appearance 
  to 
  the 
  skeleton-fibre 
  in 
  some 
  parts. 
  

  

  Hah. 
  Providence 
  Reef, 
  Mascarene 
  Islands, 
  24 
  fms. 
  

  

  Distribution. 
  See 
  Part 
  I., 
  p. 
  392, 
  of 
  this 
  Report. 
  

  

  SILICEA. 
  

  

  MONA 
  CTINELLIDA 
  . 
  

  

  The 
  great 
  abundance 
  of 
  Ceratosa 
  has 
  for 
  its 
  complement 
  a 
  corre- 
  

   sponding 
  comparative 
  scarcity 
  of 
  Monactinellid 
  Silicca 
  ; 
  this 
  defi- 
  

   ciency 
  is 
  largely 
  accounted 
  for 
  by 
  the 
  few 
  Ectyoriida; 
  collected 
  here 
  

   as 
  compared 
  with 
  the 
  Northern 
  Australian 
  waters. 
  

  

  