﻿462 
  COLLECTIONS 
  FROM 
  MELANESIA. 
  

  

  frond, 
  though 
  only 
  curved 
  somewhat 
  to 
  one 
  side 
  in 
  the 
  plane 
  of 
  

   expansion, 
  was 
  in 
  life 
  decumbent, 
  so 
  that 
  the 
  terminal 
  branches 
  

   were 
  then 
  in 
  contact 
  with 
  the 
  sea-bottom. 
  The 
  species 
  differs 
  from 
  

   R. 
  australlensis 
  in 
  the 
  branching 
  and 
  anastomosing 
  habit 
  and 
  the 
  

   flattened 
  knife-edged 
  branches, 
  and 
  in 
  having 
  the 
  longitudinally 
  

   arranged 
  spicules 
  not 
  confined 
  to 
  the 
  axis, 
  but 
  extending 
  to 
  the 
  

   cortex. 
  From 
  R. 
  syringella, 
  Schmidt, 
  it 
  also 
  differs 
  in 
  its 
  growth 
  

   (though 
  Schmidt 
  mentions 
  that 
  the 
  branches 
  of 
  R. 
  sj/ringella 
  some- 
  

   times 
  unite) 
  and 
  in 
  the 
  absence 
  of 
  heads 
  to 
  the 
  acuate 
  spicules. 
  

  

  AXINELLID^. 
  

  

  Axinellida, 
  Carter, 
  An7i. 
  ^ 
  Mag. 
  N. 
  H. 
  1875, 
  xvi. 
  p. 
  133. 
  

  

  This 
  family 
  differs 
  from 
  the 
  Ectyonida) 
  in 
  the 
  much 
  greater 
  

   importance 
  of 
  size 
  of 
  spicule 
  as 
  a 
  factor 
  of 
  specific 
  distinction. 
  The 
  

   relations 
  of 
  the 
  two 
  families, 
  however, 
  require 
  readjustment 
  on 
  

   more 
  satisfactory 
  bases 
  than 
  at 
  present. 
  

  

  90. 
  Axinella 
  echidnsea. 
  (Plate 
  XLIII. 
  fig. 
  a.) 
  

   ? 
  Spongia 
  echidnaja, 
  Lamarck, 
  Ann. 
  Mus. 
  Hist. 
  Nat. 
  xx. 
  p. 
  448. 
  

  

  It 
  seems 
  likely 
  that 
  this 
  will 
  prove 
  to 
  be 
  Lamarck's 
  species. 
  

   That 
  author 
  refers 
  (?. 
  c.) 
  to 
  Seba 
  (Thesaurus, 
  iii. 
  pi. 
  xcix. 
  fig. 
  7) 
  in 
  

   illustration 
  of 
  his 
  sponge. 
  This 
  figure 
  has 
  a 
  strong 
  resemblance 
  to 
  

   the 
  present 
  species, 
  but 
  does 
  not 
  show 
  the 
  same 
  tendency 
  to 
  lateral 
  

   junction 
  between 
  the 
  branches, 
  and 
  has 
  most 
  of 
  the 
  latter 
  somewhat 
  

   enlarged 
  at 
  the 
  tips, 
  whereas 
  in 
  these 
  specimens 
  they 
  usually, 
  though 
  

   not 
  invariably, 
  are 
  either 
  of 
  about 
  the 
  same 
  diameter 
  throughout 
  

   or 
  else 
  taper 
  to 
  points. 
  The 
  dark 
  reddish-brown 
  colour 
  of 
  these 
  

   specimens 
  and 
  the 
  peculiar 
  echination 
  of 
  their 
  surface 
  by 
  angular 
  

   wedge- 
  or 
  knife-shape 
  processes 
  about 
  2 
  to 
  4 
  millim. 
  high, 
  projecting 
  

   outwards 
  and 
  somewhat 
  upwards, 
  are 
  decidedly 
  indicated 
  in 
  the 
  

   figure. 
  In 
  texture 
  the 
  specimens 
  are 
  tough, 
  elastic, 
  harsh 
  to 
  the 
  

   touch 
  in 
  the 
  dry 
  state 
  ; 
  the 
  surface- 
  processes 
  are 
  flexible, 
  almost 
  

   soft, 
  in 
  spirit. 
  In 
  structure 
  it 
  is 
  a 
  true 
  Axinella, 
  and 
  thus 
  does 
  

   not 
  support 
  Lamarck's 
  surmise 
  that 
  it 
  might 
  be 
  identical 
  with 
  

   Spongia 
  muricata 
  of 
  Esper 
  (Pallas, 
  sp.), 
  which 
  is 
  Tricentrium 
  muri- 
  

   catum 
  of 
  Ehlers. 
  The 
  main 
  skeleton 
  exhibits 
  the 
  usual 
  longitudi- 
  

   nally 
  elongated 
  meshes 
  of 
  loose 
  spiculo-fibre, 
  which 
  in 
  the 
  stem 
  is 
  

   composed 
  in 
  part 
  of 
  a 
  transparent 
  and 
  almost 
  colourless 
  horny 
  uniting 
  

   material, 
  which 
  seems 
  to 
  be 
  wanting 
  in 
  the 
  surface-tufts 
  ; 
  distance 
  

   between 
  longitudinal 
  lines 
  of 
  axis 
  "07 
  to 
  "1 
  millim. 
  Surface 
  covered 
  

   with 
  a 
  fuscous-brown 
  subopaque 
  pigment, 
  which 
  penetrates 
  to 
  a 
  

   slight 
  distance 
  below. 
  Sarcode 
  transparent, 
  almost 
  colourless, 
  very 
  

   pale 
  reddish 
  brown. 
  Spicules 
  : 
  — 
  (1) 
  Smooth, 
  slightly 
  curved 
  acerate, 
  

   tapering 
  gradually 
  to 
  sharp 
  points, 
  or 
  more 
  or 
  less 
  blunted 
  at 
  

   one 
  or 
  both 
  ends 
  ; 
  size 
  -3 
  by 
  '0095 
  to 
  -44 
  by 
  •0127 
  millim. 
  : 
  these 
  

  

  