﻿430 
  COLLECTIONS 
  FROM 
  MELANESIA. 
  

  

  others 
  the 
  secondaries 
  of 
  the 
  main 
  skeleton. 
  Sarcode 
  very 
  pale 
  

   brownish 
  yellow, 
  thin 
  and 
  transparent. 
  

  

  Spicules 
  : 
  — 
  ^(1) 
  Skeleton 
  acuate, 
  smooth, 
  straight 
  or 
  slightly 
  curved, 
  

   with 
  rounded 
  base 
  slightly 
  smaller 
  than 
  the 
  middle 
  of 
  the 
  shaft, 
  

   which 
  tapers 
  gradually 
  to 
  a 
  fine 
  point 
  from 
  near 
  the 
  middle 
  of 
  the 
  

   spicule 
  ; 
  size 
  of 
  spicule 
  '18 
  to 
  -2 
  by 
  -046 
  to 
  "0063 
  millim. 
  : 
  in 
  

   middle 
  of 
  fibre. 
  (2) 
  Flesh-spicule, 
  equianchorate, 
  navicular, 
  shaft 
  

   gradually 
  curved, 
  slender 
  ; 
  length 
  of 
  spicule 
  •013 
  to 
  'OlO 
  millim. 
  

  

  Hah. 
  Thursday 
  Island, 
  Torres 
  Straits, 
  3-6 
  fms. 
  (on 
  bivalve 
  shell 
  

   and 
  Hydroid). 
  

  

  Ptcpresented 
  by 
  a 
  dry 
  specimen 
  and 
  by 
  one 
  in 
  spirit 
  ; 
  the 
  larger 
  

   one 
  is 
  50 
  millim. 
  high 
  by 
  55 
  in 
  extreme 
  diameter. 
  The 
  species 
  

   is 
  distinguished 
  by 
  its 
  regularly 
  rectangular 
  main 
  skeleton 
  and 
  

   well-developed 
  homy 
  fibre. 
  

  

  65. 
  Myxilla 
  arborescens. 
  

   (Plate 
  XL. 
  fig. 
  G; 
  Plate 
  XLII. 
  figs, 
  a-ci' 
  .) 
  

  

  ? 
  Halichondria 
  plumosa, 
  Carter, 
  Phil. 
  Trans, 
  -vol. 
  168, 
  p. 
  287 
  (?2ec 
  

   Spougia 
  plumosa, 
  Montagu^ 
  Wern. 
  Mem. 
  ii. 
  p. 
  116). 
  

  

  Erect, 
  pedicellate, 
  branched, 
  branching 
  not 
  confined 
  to 
  one 
  plane, 
  

   forming 
  "heads" 
  by 
  the 
  aggregation 
  and 
  partial 
  anastomosis 
  of 
  

   many 
  different 
  pedicellate 
  branched 
  growths 
  arising 
  from 
  one 
  or 
  

   more 
  common 
  stems 
  ; 
  mode 
  of 
  branching 
  dieho- 
  to 
  pollacitomous 
  *. 
  

   Stems, 
  both 
  primary 
  and 
  secondary, 
  slender, 
  of 
  angulated 
  outline, 
  

   owing 
  to 
  the 
  lateral 
  projection 
  from 
  them 
  of 
  a 
  number 
  of 
  prominent, 
  

   jagged, 
  longitudinal 
  ridges. 
  Branches 
  palmate, 
  the 
  edges 
  sharp, 
  the 
  

   flat 
  surfaces 
  covered 
  with 
  longitudinal, 
  very 
  prominent 
  ridges 
  and 
  

   upwardly 
  projecting 
  points, 
  the 
  tips 
  of 
  the 
  branches 
  subtruncate. 
  

   Thickness 
  of 
  secondary 
  stems, 
  exclusive 
  of 
  surface-projections, 
  about 
  

   1-5 
  millim., 
  of 
  palmate 
  parts 
  of 
  branches 
  •25 
  to 
  '5 
  millim. 
  Minute 
  

   appearance 
  of 
  surface 
  in 
  spirit 
  granulated 
  (?'. 
  e. 
  covered 
  with 
  minute 
  

   rounded 
  elevations, 
  which 
  are 
  smooth 
  and 
  glabrous 
  in 
  spirit). 
  

   Texture 
  in 
  spirit 
  tough, 
  very 
  pliable, 
  of 
  very 
  imperfect 
  elasticity. 
  

   Vents 
  apparently 
  represented 
  by 
  round 
  or 
  oblong 
  apertures, 
  '25 
  

   to 
  1 
  millim. 
  in 
  maximum 
  diameter, 
  numerous, 
  placed 
  between 
  

   prominences 
  of 
  surface 
  of 
  branches. 
  Colour 
  in 
  spii'it 
  dull 
  pale 
  

   brown. 
  Sarcode 
  rather 
  granular, 
  pale 
  yellow-brown, 
  soft. 
  Skeleton 
  

   consisting 
  of 
  longitudinal 
  lines 
  of 
  loosely 
  aggregated 
  spicules 
  (nos. 
  

   1 
  and 
  2), 
  about 
  8 
  to 
  10 
  spicules 
  broad, 
  surrounded 
  by 
  some 
  loose 
  

   spicules 
  of 
  the 
  same 
  kind 
  and 
  echinated 
  by 
  spicule 
  no. 
  1 
  ; 
  the 
  

   lines 
  run 
  approximately 
  parallel 
  with 
  each 
  other, 
  occasionally 
  

   branching 
  and 
  anastomosing 
  at 
  acute 
  angles 
  ; 
  at 
  the 
  surface 
  these 
  

   primary 
  lines 
  either 
  become 
  loose 
  and 
  form 
  loose 
  tracts 
  of 
  skeleton- 
  

   spicules 
  running 
  along 
  the 
  surface, 
  or 
  they 
  remain 
  compact 
  and 
  

   project 
  as 
  surface-tufts. 
  

  

  Skeleton-spicules 
  : 
  — 
  (1) 
  Spined 
  acuate, 
  tapering 
  gradually 
  from 
  

   rounded 
  head 
  to 
  sharp 
  point, 
  generally 
  somewhat 
  curved 
  ; 
  spines 
  

  

  * 
  i. 
  e. 
  dividing 
  many 
  times 
  at 
  one 
  point 
  ; 
  from 
  ttoWukis. 
  

  

  