﻿BPONGIIDA. 
  391 
  

  

  APLTSINID^. 
  

  

  Aplysinida, 
  Carter, 
  Ann. 
  S^- 
  Mag. 
  N. 
  II. 
  (o) 
  xvi. 
  p. 
  132. 
  

  

  This 
  name 
  is 
  used 
  in 
  a 
  wider 
  sense 
  than 
  that 
  to 
  which 
  Vosmaer 
  

   (Mitth. 
  Zool. 
  Neapel, 
  iv. 
  p. 
  444) 
  limits 
  it. 
  

  

  19. 
  Aplysina 
  membranosa. 
  

  

  Spongia 
  membranosa, 
  Pallas, 
  Elench. 
  Zooph. 
  p. 
  398. 
  

  

  Spongia 
  membranacea, 
  Esper, 
  Pflanzentlt. 
  ii. 
  p. 
  2-")G, 
  pi. 
  xxxiv. 
  

  

  ? 
  lauthella 
  conceiitvica, 
  Hijatt, 
  Mem. 
  Bost. 
  Soc. 
  ii. 
  p. 
  407. 
  

  

  ? 
  Aplysina 
  purpurea, 
  Carter, 
  Ann. 
  i^- 
  3Iaff. 
  iV. 
  H. 
  (o) 
  \i. 
  p. 
  36. 
  

  

  A 
  very 
  fine 
  species, 
  fortunately 
  preserved 
  in 
  spirit 
  as 
  well 
  as 
  in 
  the 
  

   dry 
  state. 
  It 
  forms 
  a 
  cylindrical 
  mass, 
  which 
  has 
  the 
  same 
  general 
  

   form 
  as 
  that 
  given 
  in 
  Esper 
  s 
  figure 
  (/. 
  c.) 
  ; 
  the 
  base 
  of 
  the 
  wet 
  

   specimen 
  is 
  about 
  40 
  millim. 
  (l-|iuch) 
  in 
  diameter. 
  The 
  dry 
  speci- 
  

   men, 
  which 
  is 
  much 
  the 
  largest 
  of 
  the 
  two, 
  is 
  580 
  millim. 
  (22^ 
  inches) 
  

   high, 
  and 
  the 
  maximum 
  diameter, 
  which 
  is 
  at 
  about 
  5 
  inches 
  above 
  

   the 
  base, 
  is 
  about 
  40 
  millim. 
  (13- 
  inch). 
  At 
  77 
  millim. 
  (3 
  inches) 
  

   above 
  the 
  base 
  a 
  branch 
  is 
  given 
  off, 
  22 
  millim. 
  (g 
  inch) 
  in 
  maximum 
  

   diameter 
  and 
  145 
  millim. 
  (9| 
  inches) 
  in 
  length, 
  and 
  on 
  the 
  same 
  

   side, 
  about 
  30 
  millim. 
  higher 
  up, 
  a 
  smaller 
  branch, 
  12 
  millim. 
  

   (^ 
  inch) 
  in 
  maximum 
  diameter 
  and 
  75 
  millim. 
  (3 
  inches) 
  in 
  height. 
  

   The 
  skeleton 
  consists 
  of 
  a 
  very 
  open 
  and 
  irregular 
  network 
  of 
  fibres, 
  

   1*5 
  to 
  2 
  millim. 
  in 
  thickness, 
  which 
  arise 
  at 
  the 
  base 
  of 
  the 
  sponge, 
  

   and 
  take 
  a 
  longitudinal 
  but 
  somewhat 
  sinuous 
  course 
  along 
  the 
  in- 
  

   terior 
  of 
  the 
  cylindrical 
  column 
  of 
  which 
  the 
  sponge 
  consists. 
  They 
  

   throw 
  out 
  branches 
  somewhat 
  freely 
  from 
  their 
  sides, 
  and 
  subdivide 
  

   terminally 
  into 
  ramifying 
  branches 
  ; 
  the 
  resulting 
  twigs 
  anastomose 
  

   freely, 
  the 
  superficial 
  ones 
  end 
  in 
  outwardly 
  and 
  upwardly 
  directed 
  

   points, 
  usually 
  bi- 
  or 
  tri-furcate, 
  which 
  are 
  just 
  covered 
  by 
  the 
  

   tough 
  dermis 
  ; 
  the 
  apices 
  are 
  -18 
  to 
  '28 
  millim. 
  in 
  diameter. 
  The 
  

   dermis 
  and 
  the 
  internal 
  membranes 
  consist 
  of 
  a 
  tough 
  membrane 
  

   of 
  a 
  puce 
  or 
  dull 
  purple 
  colour 
  in 
  spirit, 
  almost 
  black 
  in 
  the 
  dry 
  state. 
  

   The 
  membrane 
  is 
  seen 
  with 
  the 
  naked 
  eye 
  to 
  be 
  marked 
  with 
  nume- 
  

   rous 
  raised 
  thickened 
  lines, 
  which 
  radiate 
  from 
  the 
  projecting 
  apices 
  

   of 
  the 
  dermal 
  conuli 
  (formed 
  by 
  the 
  tension 
  of 
  the 
  dermis 
  over 
  the 
  

   points 
  of 
  the 
  skeleton, 
  as 
  mentioned 
  above), 
  and 
  branch 
  and 
  anasto- 
  

   mose 
  on 
  the 
  membranes. 
  Under 
  the 
  microscope 
  they 
  are 
  seen 
  not 
  to 
  

   be 
  special 
  fibre-structures, 
  but 
  to 
  consist 
  simply 
  of 
  thickened 
  mem- 
  

   brane. 
  The 
  membrane 
  is 
  coloured 
  by 
  purplish 
  cells, 
  which 
  are 
  about 
  

   •03 
  millim. 
  in 
  diameter, 
  and 
  are 
  crowded 
  with 
  scmiopaque 
  granules, 
  

   to 
  which 
  they 
  owe 
  their 
  colour. 
  The 
  fibres 
  of 
  the 
  skeleton 
  have 
  a 
  

   wide 
  central 
  cavity, 
  occupying 
  about 
  half 
  their 
  diameter, 
  and 
  filled, 
  

   or 
  almost 
  so, 
  witli 
  a 
  transparent 
  substance 
  coloured 
  diftusely 
  of 
  a 
  

   purplish-red 
  colour. 
  The 
  walls 
  of 
  the 
  fibre 
  are 
  composed 
  of 
  laminae 
  

   which 
  separate 
  readily, 
  and 
  may 
  then 
  be 
  seen 
  to 
  consist 
  of 
  a 
  dark 
  

   Bubstance, 
  rather 
  readily 
  torn, 
  thickly 
  set 
  with 
  fine 
  dark 
  purple-red 
  

  

  