﻿86 
  Mr. 
  A. 
  Dendy 
  on 
  Sjionges 
  from 
  

  

  tions 
  being 
  frequently 
  rilled 
  up 
  by 
  delicate 
  membranous 
  

   tissue. 
  

  

  The 
  arrangement 
  of 
  the 
  horny 
  skeleton 
  agrees 
  very 
  well 
  

   with 
  that 
  in 
  Clathria 
  indica, 
  but 
  the 
  spicular 
  element 
  is 
  more 
  

   strongly 
  developed, 
  though 
  scarcely 
  at 
  the 
  expense 
  of 
  the 
  

   horny 
  fibre. 
  There 
  are 
  an 
  abundance 
  of 
  smooth 
  styli 
  enclosed 
  

   in 
  the 
  primary 
  lines 
  of 
  the 
  skeleton. 
  

  

  Spicules. 
  — 
  (a). 
  Megasclera 
  : 
  — 
  (1) 
  Smooth 
  styli 
  (fig. 
  8, 
  a, 
  

   b, 
  c), 
  straight 
  or 
  slightly 
  curved, 
  gradually 
  sharp-pointed, 
  

   and 
  of 
  two 
  principal 
  sizes 
  — 
  (a) 
  stout 
  and 
  relatively 
  short, 
  

   averaging 
  about 
  0'175 
  by 
  0*008 
  millim., 
  abundant 
  and 
  

   occurring 
  principally 
  in 
  the 
  choanosome 
  ; 
  (/3) 
  long 
  and 
  slender, 
  

   sometimes 
  becoming 
  slightly 
  tylostylote, 
  averaging 
  about 
  

   0*22 
  by 
  - 
  005 
  millim., 
  occurring 
  principally 
  in 
  the 
  dermal 
  

   membrane. 
  (2) 
  The 
  echinating 
  spicules 
  (tig. 
  8, 
  d) 
  ; 
  these 
  

   are 
  short 
  and 
  relatively 
  stout 
  spined 
  tylostyli, 
  gradually 
  and 
  

   very 
  sharply 
  pointed 
  at 
  the 
  apex, 
  and 
  narrowing 
  somewhat 
  

   towards 
  the 
  base, 
  which 
  is 
  commonly 
  expanded 
  into 
  a 
  slight 
  

   head 
  ; 
  the 
  spines 
  are 
  scarce 
  or 
  absent 
  for 
  a 
  short 
  distance 
  

   above 
  the 
  base 
  ; 
  size 
  of 
  spicule 
  about 
  0'056 
  by 
  0'006 
  millim. 
  

  

  (b). 
  Microsclera 
  : 
  — 
  A 
  few 
  very 
  minute 
  slender 
  isochelas 
  of 
  

   the 
  usual 
  Clathria 
  type, 
  about 
  0'014 
  millim. 
  long. 
  In 
  an 
  

   embryo 
  enclosed 
  in 
  the 
  sponge 
  there 
  are 
  also 
  some 
  small 
  and 
  

   exceedingly 
  slender 
  toxa, 
  and 
  it 
  is 
  not 
  unlikely 
  that 
  such 
  may 
  

   also 
  exist 
  in 
  the 
  adult 
  sponge, 
  where 
  they 
  might 
  escape 
  

   detection 
  amongst 
  the 
  mass 
  of 
  larger 
  spicules. 
  

  

  This 
  species 
  is 
  represented 
  in 
  the 
  collection 
  by 
  five 
  speci- 
  

   mens 
  and 
  a 
  piece 
  in 
  spirit. 
  

  

  Rhap>hidop>hlus 
  spicuhsus, 
  n. 
  sp. 
  (PI. 
  IV. 
  fig. 
  4.) 
  

  

  There 
  is 
  in 
  the 
  collection 
  a 
  single 
  dry 
  specimen 
  and 
  a 
  

   piece 
  in 
  spirit. 
  The 
  dry 
  specimen 
  forms 
  a 
  flattened 
  clathrous 
  

   mass 
  of 
  branching 
  and 
  anastomosing 
  flattened 
  trabecular 
  *. 
  

   It 
  seems 
  to 
  be 
  a 
  good 
  deal 
  shrunk 
  up 
  and 
  measures 
  in 
  its 
  

   present 
  condition 
  108 
  millim. 
  in 
  length 
  and 
  72 
  millim. 
  in 
  

   breadth, 
  while 
  the 
  thickness 
  of 
  the 
  trabecular 
  averages 
  about 
  

   5 
  millim. 
  It 
  is 
  impossible 
  to 
  say 
  whether 
  the 
  species 
  is 
  erect 
  

   or 
  decumbent 
  in 
  life. 
  

  

  The 
  colour 
  of 
  the 
  living 
  sponge 
  was 
  vermilion 
  ; 
  when 
  dry 
  

   it 
  is 
  light 
  brownish 
  yellow, 
  with 
  occasional 
  red 
  tinges, 
  and 
  in 
  

   spirit 
  it 
  is 
  darker 
  greyish 
  yellow. 
  

  

  The 
  texture 
  in 
  spirit 
  is 
  compact 
  and 
  cork-like. 
  Theoscula 
  

   are 
  minute 
  and 
  scattered, 
  mostly 
  on 
  or 
  near 
  the 
  margins 
  of 
  

  

  * 
  That 
  this 
  flattening 
  is 
  normal 
  is 
  shown 
  by 
  the 
  spirit 
  specimen. 
  

  

  