﻿A 
  MONOGEAPH 
  OF 
  THE 
  VICTORIAN 
  SPONGES. 
  , 
  61 
  

  

  which 
  attach 
  the 
  sponge 
  to 
  the 
  substratum 
  on 
  which 
  it 
  grows. 
  The 
  colour 
  in 
  spirit 
  

   is 
  white 
  and 
  the 
  texture 
  of 
  the 
  sponge 
  is 
  characteristically 
  harsh 
  and 
  unyielding 
  to 
  

   the 
  touch. 
  

  

  The 
  canal 
  system 
  conforms 
  to 
  type 
  D, 
  and 
  is 
  described 
  in 
  detail 
  on 
  pp. 
  30, 
  81, 
  

   and 
  illustrated 
  in 
  Fig. 
  4, 
  Plate 
  IV. 
  

  

  (b.) 
  Arrangement 
  of 
  the 
  Skeleton. 
  — 
  The 
  skeleton 
  consists 
  of 
  triradiate, 
  quadri- 
  

   radiate 
  and 
  oxeote 
  spicules. 
  The 
  triradiates 
  form 
  nearly 
  the 
  entire 
  skeleton 
  and 
  are 
  

   arranged 
  in 
  an 
  irregular 
  layer 
  in 
  the 
  walls 
  of 
  the 
  Ascon 
  -tubes 
  and 
  in 
  an 
  especially 
  

   dense 
  layer 
  of 
  especially 
  large 
  spicules 
  mixed 
  with 
  smaller 
  ones 
  in 
  the 
  pseudoderm. 
  

   The 
  quadriradiates 
  are 
  relatively 
  few 
  but 
  easily 
  discoverable 
  and 
  even 
  abundant 
  in 
  

   some 
  specimens, 
  they 
  occur 
  in 
  the 
  walls 
  of 
  the 
  Ascon-tubes, 
  witli 
  the 
  apical 
  ray 
  

   projecting 
  into 
  the 
  gastral 
  cavity, 
  and 
  in 
  the 
  lining 
  membrane 
  of 
  the 
  pseudogaster 
  

   with 
  the 
  apical 
  ray 
  projecting 
  into 
  the 
  latter. 
  The 
  oxeote 
  spicules 
  vary 
  greatly 
  as 
  to 
  

   the 
  numbers 
  in 
  which 
  they 
  occur 
  in 
  different 
  specimens. 
  Their 
  position, 
  however, 
  

   appears 
  to 
  be 
  constant. 
  They 
  have 
  one 
  end 
  embedded 
  in 
  the 
  margin 
  of 
  the 
  

   pseudopore, 
  while 
  the 
  greater 
  part 
  of 
  the 
  spicule 
  projects 
  freely, 
  sometimes 
  singly 
  

   and 
  sometimes 
  in 
  dense 
  tufts, 
  towards 
  the 
  centre 
  of 
  the 
  pseudopore. 
  In 
  some 
  

   specimens 
  the 
  pseudopores 
  literally 
  bristle 
  with 
  these 
  tufts 
  of 
  oxeotes 
  converging 
  

   towards 
  but 
  not 
  reaching 
  the 
  centre 
  of 
  the 
  space, 
  in 
  others 
  only 
  a 
  few 
  oxeotes 
  can 
  be 
  

   found. 
  

  

  (c.) 
  The 
  spicules 
  (PI. 
  X., 
  Fig. 
  4). 
  

  

  (1.) 
  Triradiates. 
  — 
  Dermal. 
  Regular; 
  rays 
  conical 
  or 
  subfusiform, 
  gradually 
  

   sharp-pointed, 
  very 
  stout, 
  measuring 
  about 
  0-35 
  by 
  0-050 
  nnn. 
  

   (Numerous 
  smaller 
  spicules 
  occur 
  mixed 
  with 
  these.) 
  Deep. 
  Ilegular 
  ; 
  

   rays 
  conical 
  or 
  subfusiform, 
  gradually 
  sharp-pointed, 
  measuring 
  

   0-17 
  l)y 
  0-014 
  mm. 
  Numerous 
  intermediate 
  sizes 
  occur. 
  

  

  (2.) 
  Quadriradiates. 
  — 
  Of 
  tlie 
  same 
  shape 
  and 
  size 
  as 
  tlie 
  smaller 
  triradiates, 
  

   but 
  with 
  a 
  sliort, 
  slender, 
  curved 
  and 
  sharply 
  pointed 
  apical 
  ray. 
  

  

  Sometimes 
  the 
  smaller 
  spicules 
  in 
  tlie 
  pseudoscular 
  membrane 
  

   become 
  strongly 
  sagittal, 
  the 
  oral 
  rays 
  being 
  curved 
  backwards 
  

   towards 
  the 
  basal. 
  

  

  (3.) 
  Oxeotes. 
  — 
  Short, 
  slender, 
  straight, 
  gradually 
  sharply 
  pointed 
  at 
  both 
  

   ends, 
  measuring 
  about 
  0-lC 
  by 
  0-003 
  mm. 
  

  

  {d.) 
  Affinities. 
  — 
  This 
  species, 
  which 
  Mr. 
  Carter 
  characterises 
  as 
  " 
  by 
  far 
  ihv 
  

   largest 
  and 
  most 
  abundant 
  in 
  specimens 
  of 
  all 
  Mr. 
  Wilson's 
  calcanuins 
  sjiongcs 
  " 
  is 
  

   easily 
  recognisable 
  by 
  both 
  general 
  appearance 
  and 
  si)iculation. 
  Mr. 
  Carter 
  makes 
  no 
  

  

  