﻿the 
  Gulf 
  of 
  Manaar. 
  87 
  

  

  the 
  flattened 
  trabecular. 
  The 
  surface 
  of 
  the 
  sponge 
  is 
  very 
  

   uneven, 
  subglabrous 
  in 
  appearance 
  in 
  spirit, 
  rough 
  in 
  the 
  dry 
  

   condition. 
  

  

  The 
  main 
  skeleton 
  is 
  a 
  dense 
  irregular 
  reticulation 
  of 
  stout 
  

   horny 
  fibres, 
  with 
  rounded 
  meshes. 
  The 
  fibres 
  are 
  about 
  

   0*1 
  millim. 
  in 
  diameter, 
  but 
  variable 
  ; 
  they 
  are 
  abundantly 
  

   but 
  irregularly 
  cored 
  by 
  long 
  slender 
  tylostyli 
  and 
  sparsely 
  

   echinated 
  by 
  short 
  spined 
  tylostyli. 
  Between 
  the 
  fibres 
  of 
  

   the 
  skeleton 
  the 
  long 
  slender 
  tylostyli 
  are 
  very 
  thickly 
  but 
  

   irregularly 
  scattered 
  through 
  the 
  soft 
  tissues. 
  

  

  The 
  dermal 
  skeleton 
  is 
  well 
  developed 
  and 
  consists 
  of 
  

   dense, 
  close-set, 
  radiating 
  brushes 
  of 
  long 
  slender 
  tylostyli 
  

   with 
  their 
  points 
  projecting 
  outwards. 
  

  

  Spicules. 
  — 
  (a). 
  Megasclera 
  : 
  — 
  (1) 
  Long, 
  straight, 
  very 
  

   slender 
  tylostyli 
  (fig. 
  4, 
  a, 
  b, 
  c), 
  sharply 
  and 
  gradually 
  pointed 
  

   at 
  the 
  apex, 
  and 
  with 
  small 
  oval 
  heads 
  at 
  the 
  base, 
  which 
  is 
  

   sometimes 
  very 
  minutely 
  spined 
  ; 
  size 
  of 
  full-grown 
  examples 
  

   about 
  0*294 
  by 
  0*005 
  millim. 
  (2) 
  Short, 
  stout, 
  spined, 
  echi- 
  

   nating 
  tylostyli 
  (fig. 
  4, 
  d, 
  e), 
  with 
  rounded 
  heads 
  and 
  very 
  

   sharp 
  points 
  ; 
  the 
  spines 
  are 
  arranged 
  so 
  as 
  to 
  leave 
  the 
  apex 
  

   and 
  a 
  space 
  immediately 
  above 
  the 
  head 
  free 
  j 
  average 
  size 
  

   of 
  spicule 
  about 
  0*07 
  by 
  0*007 
  millim. 
  

  

  (b). 
  Microsclera 
  : 
  — 
  (1) 
  Very 
  minute 
  isochelte 
  of 
  the 
  usual 
  

   Clatliria 
  type, 
  about 
  0*014 
  millim. 
  long. 
  (2) 
  Very 
  small, 
  

   slender, 
  apparently 
  smooth 
  toxa, 
  about 
  0*056 
  millim. 
  long. 
  

  

  Hymeniacidon 
  (?) 
  foetida, 
  n. 
  sp. 
  (PI. 
  IV. 
  fig. 
  5.) 
  

  

  Sponge 
  massive, 
  sessile, 
  slightly 
  lobose. 
  The 
  single 
  speci- 
  

   men 
  in 
  the 
  collection 
  measures 
  143 
  millim. 
  in 
  greatest 
  breadth 
  

   and 
  60 
  millim. 
  in 
  height. 
  The 
  oscula 
  are 
  of 
  fair 
  size 
  and 
  

   situate 
  on 
  the 
  summits 
  of 
  the 
  low 
  lobes. 
  Surface 
  very 
  dis- 
  

   tinctly 
  reticulate. 
  Texture 
  in 
  the 
  dry 
  state 
  hard 
  and 
  incom- 
  

   pressible, 
  in 
  spirit 
  a 
  little 
  softer. 
  Colour 
  of 
  the 
  living 
  sponge 
  

   grey 
  ; 
  when 
  dry 
  or 
  in 
  spirit 
  the 
  colour 
  is 
  dull 
  blackish 
  grey 
  

   on 
  the 
  outside 
  and 
  lighter 
  internally. 
  

  

  The 
  main 
  skeleton 
  is 
  a 
  very 
  dense 
  irregular 
  reticulation 
  of 
  

   large 
  oxea, 
  sometimes 
  aggregated 
  in 
  thick 
  strands 
  or 
  fibres 
  ; 
  

   the 
  spongin 
  is 
  very 
  feebly, 
  if 
  at 
  all, 
  developed. 
  The 
  dermal 
  

   skeleton 
  is 
  a 
  very 
  close 
  reticulation 
  of 
  stout 
  bands 
  of 
  spicules. 
  

   The 
  meshes 
  of 
  the 
  reticulation 
  are 
  very 
  small 
  and 
  rounded, 
  

   and 
  the 
  bands 
  of 
  spicules 
  dividing 
  them 
  are 
  irregular, 
  but 
  so 
  

   strongly 
  developed 
  as 
  to 
  cover 
  a 
  greater 
  superficial 
  area 
  than 
  

   the 
  actual 
  meshes. 
  The 
  dermal, 
  like 
  the 
  main 
  skeleton, 
  is 
  

   composed 
  principally 
  of 
  large 
  oxea, 
  but 
  there 
  are 
  also 
  present 
  

  

  