﻿452 
  COLLECTIONS 
  FROM 
  MELAXE.SIA. 
  

  

  fibre. 
  (4) 
  Equianchorate 
  ; 
  navicular, 
  shaft 
  almost 
  straight, 
  pointed 
  

   at 
  each 
  end 
  ; 
  length 
  "OIG-'OIS 
  millim. 
  

  

  Hah. 
  Port 
  Darwin, 
  7-12 
  fms. 
  ; 
  bottom 
  sand, 
  mud, 
  and 
  shells. 
  

  

  The 
  above 
  diagnosis 
  is 
  based 
  on 
  a 
  large 
  specimen. 
  A 
  small 
  

   specimen 
  (which 
  is 
  perhaps 
  the 
  apes 
  of 
  a 
  larger 
  one), 
  36 
  millim. 
  

   high, 
  also 
  occurs 
  from 
  the 
  same 
  place 
  and 
  same 
  depth, 
  differing 
  

   from 
  it 
  in 
  having 
  no 
  perceptible 
  horny 
  fibre, 
  in 
  being, 
  in 
  consequence, 
  

   soft 
  and 
  fiaccid, 
  and 
  in 
  having 
  the 
  spined 
  acuate 
  confined 
  to 
  a 
  

   central 
  axis 
  which 
  contains 
  a 
  large 
  quantity 
  of 
  sand 
  ; 
  it 
  is 
  probably 
  

   identical 
  with 
  the 
  large 
  specimen, 
  its 
  diff'erences 
  being 
  partly 
  in- 
  

   dividual, 
  partly 
  due 
  to 
  youth 
  ; 
  it 
  contains 
  the 
  parasite 
  Spongio- 
  

   phagus, 
  Carter. 
  This 
  very 
  fine 
  species 
  appears 
  to 
  be 
  referable 
  to 
  

   Rliaplikloplilus 
  by 
  possessing 
  a 
  distinct 
  dermal 
  crust 
  composed 
  mainly 
  

   of 
  smooth 
  spinulate 
  spicules 
  with 
  their 
  points 
  projected 
  outwards, 
  

   but 
  adds 
  to 
  this 
  the 
  presence 
  in 
  this 
  crust 
  of 
  the 
  spined 
  echinating 
  

   spicules, 
  a 
  feature 
  in 
  which 
  it 
  resembles 
  Dlrrhopalum. 
  The 
  crust 
  

   is 
  thin, 
  but 
  appears 
  to 
  represent 
  the 
  correspondingly 
  situated 
  struc- 
  

   ture 
  in 
  R. 
  cratitius, 
  Esper 
  (Ehlers). 
  Its 
  root-like 
  base 
  recalls 
  the 
  

   horizontal 
  meshwork 
  figured 
  by 
  Esper, 
  and 
  here, 
  as 
  there, 
  the 
  erect 
  

   portion 
  appears 
  to 
  have 
  no 
  real 
  tendency 
  to 
  form 
  branches 
  ; 
  but, 
  

   besides 
  the 
  differences 
  in 
  the 
  dermis, 
  the 
  skeleton 
  and 
  echinating 
  

   spicules 
  are 
  both 
  much 
  longer 
  than 
  in 
  the 
  type 
  and 
  hitherto 
  only 
  

   recognized 
  species 
  of 
  the 
  genus. 
  The 
  height 
  of 
  the 
  perfect 
  and 
  

   well-preserved 
  spirit-specimen 
  is 
  470 
  millim. 
  (18^ 
  inches). 
  The 
  

   arborescent 
  form, 
  the 
  strongly 
  horny 
  fibre, 
  the 
  slenderness 
  of 
  the 
  

   skeletal 
  and 
  echinating 
  spicules, 
  the 
  replacement 
  of 
  the 
  spinulate 
  

   for 
  the 
  most 
  part 
  by 
  the 
  spined 
  acuate 
  in 
  the 
  main-skeleton 
  fibre, 
  

   and 
  the 
  thickness 
  of 
  the 
  dermal 
  crust, 
  distinguish 
  R. 
  arborescens 
  from 
  

   R, 
  procerus. 
  

  

  81. 
  RhaphidopMus, 
  sp. 
  

  

  The 
  following 
  appears 
  to 
  be 
  distinct 
  from 
  all 
  known 
  species 
  of 
  

   the 
  genus, 
  but 
  more 
  material 
  is 
  necessary 
  for 
  full 
  description 
  : 
  — 
  

  

  A 
  small 
  dry 
  specimen 
  of 
  subramose 
  cylindrical 
  growth, 
  45 
  millim. 
  

   long 
  by 
  12 
  millim. 
  in 
  greatest 
  diameter, 
  the 
  surface 
  proliferating 
  

   into 
  ridges 
  and 
  processes 
  2-3 
  millim. 
  high, 
  giving 
  it 
  a 
  fiocculent 
  

   appearance. 
  Colour 
  pale 
  dusky 
  brown. 
  Skeleton 
  UTCgularly 
  rect- 
  

   angular 
  in 
  arrangement 
  ; 
  spicules 
  united 
  in 
  the 
  fibre 
  by 
  a 
  small 
  

   amount 
  of 
  very 
  pale 
  horny 
  substance, 
  which 
  is 
  only 
  occasionally 
  

   seen 
  outside 
  the 
  spicules 
  ; 
  primary 
  fibres 
  about 
  8 
  to 
  10, 
  secondary 
  

   6 
  to 
  8 
  spicules 
  broad. 
  Dermal 
  skeleton 
  a 
  single 
  layer 
  of 
  smooth 
  

   subspinulates 
  in 
  tufts 
  radiating 
  outwards. 
  

  

  Spicules 
  : 
  — 
  (1) 
  Smooth 
  acuate, 
  tapering 
  gradually 
  to 
  sharp 
  point 
  ; 
  

   size 
  -23 
  by 
  -0095 
  to 
  -0127 
  millim. 
  : 
  in 
  fibre. 
  (2) 
  Smooth 
  sub- 
  

   spinulate, 
  forming 
  dermal 
  layer 
  ; 
  head 
  very 
  slight, 
  larger 
  than 
  shaft 
  ; 
  

   tapering 
  gradually 
  to 
  sharp 
  point 
  ; 
  size 
  -25 
  by 
  '0095 
  to 
  -0127 
  millim, 
  

   (3) 
  Spined 
  cylindrical, 
  tapering 
  gradually 
  from 
  well-rounded, 
  very 
  

   slightly 
  dilated 
  base 
  to 
  rounded 
  apex, 
  which 
  is 
  about 
  one 
  third 
  

   the 
  diameter 
  of 
  the 
  base; 
  spines 
  prominent, 
  sharp, 
  distal 
  ones 
  

  

  