﻿458 
  COLLECTION'S 
  FROM 
  MELANESIA, 
  

  

  the 
  present 
  form 
  provisionally 
  to 
  that 
  species, 
  with 
  which 
  it 
  agrees 
  

   much 
  better 
  than 
  the 
  form 
  which 
  I 
  named 
  E. 
  nervosum 
  (Journ. 
  Linn. 
  

   Soc, 
  Zool. 
  XV. 
  p. 
  496). 
  As 
  to 
  the 
  locality 
  at 
  which 
  S. 
  cancellata 
  

   was 
  obtained, 
  we 
  have 
  no 
  more 
  particular 
  knowledge 
  than 
  that 
  it 
  

   was 
  obtained 
  bj' 
  MM. 
  Peron 
  and 
  Lesueur. 
  As 
  these 
  travellers 
  seem 
  

   to 
  have 
  collected, 
  among 
  other 
  places, 
  on 
  the 
  north 
  coast 
  of 
  Australia, 
  

   this 
  fact 
  supports, 
  if 
  any 
  thing, 
  the 
  above 
  view 
  as 
  to 
  its 
  identity 
  with 
  

   the 
  present 
  species. 
  In 
  any 
  case 
  it 
  will 
  be 
  best 
  to 
  describe 
  the 
  latter 
  

   fully 
  : 
  — 
  Erect, 
  flabellato, 
  clathrous. 
  A 
  short 
  main 
  stem 
  gives 
  rise 
  

   to 
  a 
  clathrous 
  reticulation 
  lying 
  in 
  one 
  plane, 
  in 
  which 
  the 
  original 
  

   branches 
  are 
  only 
  distinguishable 
  near 
  the 
  base, 
  lleticulation 
  close, 
  

   regular 
  ; 
  meshes 
  oval, 
  the 
  longest 
  diameter 
  lying 
  in 
  direction 
  of 
  

   long 
  axis 
  of 
  sponge, 
  about 
  10 
  by 
  5 
  millim. 
  in 
  average 
  dimensions 
  ; 
  

   the 
  meshes 
  form 
  deep 
  cells, 
  occasionally 
  closed 
  by 
  a 
  septum 
  of 
  

   sponge-substance. 
  The 
  stem, 
  branches, 
  and 
  the 
  bars 
  which 
  com- 
  

   plete 
  the 
  reticulation 
  are 
  oblong 
  in 
  transverse 
  section, 
  with 
  rounded 
  

   margins 
  ; 
  hence 
  the 
  lateral 
  surfaces 
  are 
  flat 
  and 
  the 
  antero-posterior 
  

   ones 
  are 
  rounded. 
  Antero-posterior 
  diameter 
  of 
  stem 
  32 
  millim., 
  

   lateral 
  diameter 
  18 
  millim. 
  ; 
  antero-posterior 
  diameter 
  of 
  the 
  bars 
  

   which 
  form 
  the 
  ultimate 
  reticulation 
  about 
  10 
  millim., 
  lateral 
  di- 
  

   ameter 
  about 
  G 
  millim. 
  A 
  slight 
  tendency 
  to 
  proliferation 
  so 
  as 
  to 
  

   form 
  expansions 
  parallel 
  to 
  the 
  main 
  plane 
  of 
  the 
  sponge 
  is 
  shown 
  

   by 
  formation 
  of 
  a 
  few 
  meshes 
  on 
  the 
  surfaces 
  of 
  the 
  frond. 
  Termi- 
  

   nations 
  of 
  branches 
  either 
  united 
  by 
  connecting 
  bars 
  or 
  projecting 
  

   slightly 
  as 
  rounded 
  lobose 
  ends. 
  Surface 
  in 
  dry 
  (macerated) 
  state 
  

   quite 
  even, 
  appearing 
  minutely 
  reticulate. 
  Texture 
  firm, 
  that 
  of 
  

   stem 
  woody 
  ; 
  substance 
  of 
  branches 
  and 
  reticulation 
  rather 
  brittle, 
  

   slightly 
  compressible 
  ; 
  colour, 
  in 
  macerated 
  condition, 
  very 
  pale 
  

   yellow-brown. 
  

  

  Main 
  skeleton 
  rectangular 
  in 
  arrangement; 
  primary 
  fibres 
  only 
  pro- 
  

   jecting 
  from 
  surface 
  by 
  the 
  tuft 
  of 
  echinating 
  spicules 
  which 
  termi- 
  

   nates 
  them, 
  compact, 
  about 
  8 
  to 
  10 
  spicules 
  broad; 
  distance 
  between 
  

   them 
  at 
  surface 
  about 
  -4 
  millim. 
  ; 
  echinated 
  sparsely 
  in 
  interior, 
  

   abundantly 
  near 
  surface 
  of 
  sponge, 
  with 
  the 
  echinating 
  spicule 
  : 
  

   secondary 
  fibres 
  compact, 
  about 
  3 
  to 
  6 
  spicules 
  broad, 
  about 
  

   •3 
  millim, 
  apart, 
  echinated 
  abundantly 
  with 
  the 
  echinating 
  spicule. 
  

   Dermal 
  skeleton 
  consisting 
  of 
  an 
  irregular 
  network 
  with 
  rectangular 
  

   meshes, 
  the 
  meshes 
  generally 
  not 
  exceeding 
  -55 
  millim. 
  in 
  diameter; 
  

   fibre 
  compact, 
  about 
  10 
  spicules 
  broad, 
  well 
  echinated 
  with 
  the 
  

   echinating 
  spicule. 
  Horny 
  uniting 
  material 
  occasionally 
  distin- 
  

   guishable 
  outside 
  fibre 
  as 
  a 
  pale 
  yellow 
  transparent 
  substance. 
  

   Sarcode? 
  (absent). 
  Spicules: 
  — 
  (1) 
  Skeleton 
  acerate, 
  smooth, 
  slightly 
  

   curved, 
  tapering 
  to 
  sharp 
  points 
  from 
  within 
  about 
  four 
  diameters 
  of 
  

   the 
  ends 
  ; 
  size 
  '22 
  by 
  '0127 
  millim. 
  (2) 
  Echinating 
  cylindrical, 
  

   epined 
  ; 
  both 
  ends 
  well 
  rounded 
  ; 
  spicule 
  tapering 
  slightly 
  from 
  

   base 
  to 
  apex 
  ; 
  the 
  apex 
  about 
  half 
  the 
  diameter 
  of 
  the 
  base 
  ; 
  spines 
  

   distributed 
  all 
  over 
  the 
  spicule, 
  rather 
  more 
  abundantly 
  at 
  base 
  

   and 
  near 
  apex 
  than 
  elsewhere 
  ; 
  those 
  of 
  the 
  proximal 
  half 
  or 
  one 
  

   third 
  of 
  the 
  spicule 
  rather 
  small, 
  straight, 
  sharp, 
  the 
  remainder 
  

   longer, 
  curved 
  towards 
  base 
  ; 
  size 
  of 
  spicule 
  -15 
  by 
  "01 
  millim. 
  : 
  scat- 
  

  

  