﻿620 
  COLLECTIONS 
  FROM 
  THE 
  WESTERN 
  INDIAN 
  OCEAN. 
  

  

  or 
  sarcodic 
  material, 
  and 
  a 
  single 
  form 
  of 
  spicule, 
  viz. 
  smooth 
  

   acuate 
  of 
  considerable 
  lougth, 
  and 
  by 
  the 
  presence 
  of 
  a 
  regular 
  

   dermal 
  skeleton 
  composed 
  of 
  spicules 
  laid 
  horizontally. 
  I 
  do 
  not 
  

   know 
  any 
  other 
  species 
  except 
  the 
  original 
  one, 
  L. 
  massalis, 
  Carter, 
  

   and 
  the 
  two 
  described 
  below. 
  

  

  42. 
  LeucopMceus 
  proteus. 
  (Plate 
  LIII. 
  fig. 
  B 
  ; 
  Plate 
  LIV, 
  

  

  fig. 
  A-.) 
  

  

  Massive, 
  suberect 
  ; 
  irregularly 
  columnar 
  near 
  base, 
  showing 
  a 
  ten- 
  

   dency 
  to 
  terminate 
  above 
  in 
  several 
  short 
  and 
  thin 
  membranous 
  or 
  

   prismatic 
  lobes, 
  which 
  by 
  anastomosis 
  inter 
  se 
  enclose 
  cellular 
  spaces, 
  

   within 
  which 
  the 
  chief 
  excretory 
  canals 
  open. 
  Surface 
  very 
  variable 
  

   in 
  character 
  in 
  different 
  specimens 
  ; 
  either 
  rough 
  or 
  even 
  and 
  

   glabrous 
  near 
  the 
  base, 
  towards 
  apex 
  longitudinally 
  ridged 
  and 
  

   grooved, 
  leading 
  up 
  into 
  the 
  membranous 
  expansions 
  just 
  described, 
  

   and 
  hispid 
  with 
  closely 
  set, 
  upwardly-directed 
  sharp 
  points, 
  1-2 
  

   millim. 
  high, 
  tending 
  to 
  coalesce 
  into 
  ridges, 
  and 
  terminated 
  by 
  

   single 
  projecting 
  spicules. 
  Vents 
  opening 
  either 
  upwards 
  at 
  the 
  

   bottom 
  of 
  the 
  spaces 
  enclosed 
  between 
  the 
  terminal 
  lobes, 
  or 
  

   laterally 
  between 
  the 
  larger 
  lateral 
  ridges, 
  1-3 
  millim. 
  in 
  diameter. 
  

   Consistence 
  in 
  spirit 
  — 
  that 
  of 
  solid 
  basal 
  part 
  firm, 
  rather 
  elastic, 
  

   that 
  of 
  upper 
  laciniate 
  parts 
  compressible, 
  elastic 
  ; 
  colour, 
  surface 
  

   reddish 
  purple, 
  interior 
  dull 
  palo 
  brown. 
  Main 
  skeleton 
  formed 
  of 
  

   very 
  loose 
  spicular 
  tracts, 
  5-10 
  spicules 
  broad, 
  passing 
  outwards 
  from 
  

   the 
  centre 
  of 
  the 
  sponge, 
  at 
  distances 
  of 
  about 
  -28 
  to 
  '6 
  millim. 
  from 
  

   each 
  other, 
  branching 
  at 
  acute 
  angles, 
  but 
  maintaining 
  a 
  direction 
  

   subparallel 
  to 
  each 
  other, 
  and 
  not 
  crossing. 
  No 
  visible 
  horny 
  

   uniting 
  substance 
  ; 
  spicules 
  connected 
  by 
  a 
  yellowish 
  sarcode, 
  

   rather 
  darker 
  than 
  the 
  interstitial 
  sarcode. 
  The 
  terminal 
  spicules 
  

   of 
  the 
  fibres 
  either 
  penetrate 
  or 
  support 
  the 
  dermal 
  membrane. 
  

   Dermal 
  skeleton 
  consisting 
  of 
  irregular 
  tracts 
  of 
  spicules 
  laid 
  obliquely 
  

   or 
  vertically 
  along 
  the 
  ends 
  of 
  the 
  main-skeleton 
  fibres. 
  Sarcode 
  

   subtransparent, 
  yellowish 
  brown 
  in 
  centre, 
  bright 
  reddish 
  purple 
  at 
  

   surface. 
  Spicules 
  smooth 
  acuate, 
  bluntly 
  rounded 
  at 
  base 
  and 
  

   tapering 
  gradually 
  to 
  sharp 
  points 
  from 
  about 
  the 
  middle 
  ; 
  size 
  about 
  

   2-5 
  by 
  -032 
  millim. 
  

  

  Hal. 
  Providence 
  Reef, 
  Mascarene 
  group, 
  24 
  fms. 
  ; 
  bottom, 
  sand 
  

   and 
  dead 
  coral. 
  

  

  Of 
  the 
  two 
  spirit-specimens 
  from 
  which 
  this 
  description 
  is 
  drawn 
  

   up, 
  the 
  largest 
  has 
  the 
  variable 
  surface 
  characters 
  above 
  described, 
  

   and 
  must 
  have 
  been 
  50 
  millim. 
  (2 
  inches) 
  high 
  by 
  25 
  millim. 
  

   broad 
  when 
  perfect 
  ; 
  its 
  basal 
  portion 
  is 
  very 
  irregularly 
  formed, 
  

   being 
  curved 
  to 
  one 
  side 
  and 
  ending 
  in 
  a 
  cup-shaped 
  depression, 
  by 
  

   which 
  it 
  was 
  perhaps 
  attached 
  to 
  a 
  shell 
  or 
  other 
  foreign 
  body 
  : 
  

   the 
  smaller 
  specimen 
  has 
  lost 
  its 
  base. 
  The 
  specific 
  name, 
  proteus, 
  

   is 
  intended 
  to 
  commemorate 
  the 
  variability 
  of 
  the 
  outward 
  form. 
  

  

  The 
  general 
  habit 
  is 
  that 
  of 
  L. 
  massalis 
  and 
  fenestratHS 
  ; 
  but 
  the 
  

   spicules 
  diff'er 
  from 
  those 
  of 
  the 
  former 
  in 
  being 
  about 
  five 
  times 
  as 
  

  

  