﻿442 
  COLLECTIONS 
  FROM 
  MELANESIA. 
  

  

  has, 
  however, 
  done 
  good 
  service 
  in 
  pointing 
  out 
  an 
  essential 
  differ- 
  

   ence 
  between 
  the 
  two 
  groups 
  into 
  which 
  he 
  divides 
  the 
  Chalino- 
  

   psidinae, 
  viz. 
  in 
  the 
  way 
  in 
  which 
  their 
  echinating 
  spicules 
  are 
  

   attached. 
  It 
  must, 
  however, 
  be 
  remarked 
  ihnt 
  Echinodict>jum, 
  mihi, 
  

   as 
  now 
  understood, 
  approaches 
  Axinella 
  decidedly 
  in 
  this 
  point. 
  

  

  The 
  presence 
  of 
  spined 
  echinating 
  spicules 
  is 
  not 
  (see 
  liaspailia, 
  

   infra) 
  distinctive 
  of 
  the 
  family 
  as 
  here 
  constituted. 
  

  

  The 
  absence 
  or 
  slightly 
  pronounced 
  tendency 
  to 
  difference 
  in 
  size 
  

   and 
  form 
  between 
  the 
  corresponding 
  spicules 
  of 
  allied 
  species, 
  when 
  

   the 
  outward 
  form 
  of 
  the 
  sponge 
  differs 
  unmistakably, 
  is 
  a 
  most 
  

   characteristic 
  feature 
  of 
  this 
  family, 
  and 
  is 
  especially 
  well 
  exhibited 
  

   in 
  the 
  genera 
  Echinonema, 
  Clathria, 
  Echinodicti/um, 
  and 
  liaspailia 
  

   (s. 
  str.), 
  whereas 
  in 
  Axinellid;e 
  the 
  relative 
  thickness 
  of 
  the 
  spicules 
  

   usually 
  gives 
  good 
  characters 
  (see 
  Acanthella, 
  sp., 
  p. 
  463, 
  where 
  the 
  

   external 
  form 
  differs 
  little 
  from 
  A. 
  ohtusum). 
  

  

  OPHLITISPONGIA. 
  

  

  Ophlitaspongia, 
  Boioerbank, 
  Mon. 
  Brit. 
  Spong. 
  ii. 
  p. 
  14. 
  

  

  Vosmaer 
  (Family 
  Desmacid. 
  p. 
  107) 
  places 
  0. 
  seriata, 
  Bowerbank, 
  

   the 
  typical 
  species 
  of 
  this 
  genus, 
  under 
  Bc'smacodes, 
  and 
  says 
  [1. 
  c. 
  

   p. 
  155) 
  of 
  0. 
  papilla, 
  id., 
  which 
  seems 
  to 
  me 
  not 
  to 
  be 
  specifically 
  

   distinct 
  from 
  it, 
  that 
  it 
  is 
  probably 
  a 
  Clathria, 
  but 
  that 
  no 
  ancho- 
  

   rate 
  spicules 
  have 
  been 
  described 
  in 
  it 
  ; 
  I 
  have 
  examined 
  the 
  

   original 
  slides 
  (Bowerbankian) 
  without 
  finding 
  anchors. 
  The 
  sponge 
  

   which 
  I 
  am 
  about 
  to 
  describe 
  from 
  the 
  present 
  collection 
  agi-ees 
  

   with 
  these 
  British 
  O^Mitisiionijia' 
  (but 
  not 
  with 
  the 
  foreign 
  ones) 
  of 
  

   Bowerbank 
  in 
  their 
  fibre 
  and 
  spiculation, 
  except 
  that 
  the 
  fibre 
  is 
  

   cored 
  by 
  a 
  cylindrical 
  spicule 
  which 
  is 
  wanting 
  in 
  0. 
  seriata 
  and 
  

   painlla. 
  I 
  am 
  inclined 
  to 
  believe 
  that 
  we 
  have 
  here 
  a 
  natural 
  

   genus, 
  differing 
  from 
  Clathria 
  mainly 
  in 
  the 
  absence 
  of 
  anchorate 
  

   spicules. 
  I 
  do 
  not 
  see 
  how 
  these 
  species 
  can 
  be 
  placed 
  under 
  

   Desmacodes, 
  when 
  they 
  have 
  echinating 
  spicules, 
  but 
  no 
  skeleton 
  

   acerates 
  (except 
  tricurvates) 
  and 
  no 
  bihamates. 
  

  

  73. 
  Oplilitispongia 
  australiensis. 
  (Plate 
  XLII. 
  figs, 
  c, 
  c'.) 
  

  

  Habit 
  of 
  Clathria 
  frondifera 
  ; 
  spiculation 
  of 
  C. 
  coralloidcs 
  and 
  

   allied 
  species. 
  Massive 
  ; 
  structure 
  cellular, 
  i. 
  e. 
  interior 
  and 
  surface 
  

   broken 
  up 
  into 
  angular 
  cells 
  by 
  walls 
  of 
  tough 
  denser 
  sponge 
  - 
  

   substance, 
  projecting 
  at 
  surface 
  in 
  low 
  ridges 
  and 
  slight 
  points 
  ; 
  

   between 
  them 
  are 
  extended 
  thin 
  membranous 
  expansions. 
  Texture 
  

   in 
  dry 
  state 
  firm, 
  tough, 
  subelastic 
  ; 
  colour 
  pale 
  dirty 
  brown. 
  

  

  Main 
  skeleton 
  — 
  meshes 
  rounded, 
  narrow 
  ; 
  primary 
  fibres 
  stout, 
  

   amber-yellow, 
  cored 
  with 
  about 
  one 
  third 
  their 
  thickness 
  of 
  spicules, 
  

   proceeding 
  straight 
  to 
  surface, 
  diameter 
  about 
  -1 
  to 
  -14 
  millim. 
  ; 
  

   secondary 
  fibres 
  abundant, 
  irregular 
  in 
  direction, 
  amber-yellow. 
  

  

  