﻿454 
  COLLECTIONS 
  FROM 
  MELAHESIA, 
  

  

  ECHINODICTYUM. 
  

  

  Echinodictyum, 
  Ridlcfj, 
  Journ. 
  Linn. 
  Soc, 
  Zool. 
  xv. 
  p. 
  493. 
  

   Dictjocylindrus, 
  Carter, 
  pars, 
  nee 
  Boicerbanh. 
  

  

  There 
  can 
  be 
  no 
  doubt 
  that 
  Schmidt 
  is 
  right 
  in 
  identifying 
  his 
  

   (Nardo's) 
  genus 
  Easpailia 
  with 
  Dictyocylindrus 
  of 
  Bowerbank, 
  and 
  

   in 
  superseding 
  the 
  latter 
  name 
  on 
  grounds 
  of 
  priority 
  (the 
  dates 
  are, 
  

   Nardo, 
  1833, 
  Schmidt, 
  1862, 
  Bowerbank, 
  1864). 
  The 
  spiculation, 
  

   outward 
  form, 
  and 
  skeleton-arrangement 
  of 
  the 
  type 
  species 
  of 
  the 
  

   two 
  genera 
  (-K. 
  vimiaalis, 
  Schmidt, 
  and 
  B. 
  liispidus, 
  Montagu) 
  agree 
  

   essentially, 
  Bowerbank 
  has 
  placed 
  in 
  his 
  genus, 
  besides 
  typical 
  

   Raspailuf, 
  species 
  of 
  Axos 
  {D. 
  dentatus) 
  and 
  Axinella 
  (D. 
  sctosus). 
  

   Carter 
  has 
  placed 
  in 
  the 
  genus 
  species 
  (D. 
  Ictciniatus 
  and 
  pylcei) 
  of 
  an 
  

   erect 
  branching 
  habit, 
  somewhat 
  like 
  some 
  Kasjxtilice, 
  but 
  with 
  a 
  

   spiued 
  cf/Iindrical 
  instead 
  of 
  a 
  spined 
  aeuate 
  echinating 
  spicule, 
  as 
  

   in 
  EcMnodictyum, 
  which 
  is 
  thus 
  further 
  approximated 
  to 
  Raspailia. 
  

   A 
  slight 
  enlargement 
  of 
  this 
  genus, 
  by 
  admitting 
  species 
  which 
  have 
  

   the 
  setaceous 
  aeuate, 
  will, 
  I 
  believe, 
  meet 
  the 
  requirements 
  : 
  it 
  will 
  

   then 
  be 
  distinguished 
  from 
  Raspailia 
  only 
  by 
  a 
  more 
  robust 
  habit 
  

   and 
  by 
  having 
  the 
  fibre 
  exclusively 
  composed 
  of 
  acerate 
  spicules 
  : 
  — 
  

  

  EcHiNODiCTTrM, 
  diagn. 
  emend. 
  Sponges 
  erect, 
  cup-shaped 
  or 
  

   ramose. 
  Skeleton 
  formed 
  of 
  spicules 
  united 
  into 
  distinct 
  fibres. 
  

   From 
  the 
  fibres 
  project 
  at 
  right 
  angles 
  short, 
  strongly 
  spined, 
  

   cylindrical 
  spicules, 
  tapering 
  from 
  their 
  attached 
  ends 
  ; 
  long, 
  

   slender, 
  smooth 
  aeuate 
  (single-pointed) 
  spicules 
  may 
  also 
  be 
  inserted 
  

   upon 
  the 
  fibre, 
  projecting 
  from 
  it 
  at 
  acute 
  angles. 
  Spicules 
  com- 
  

   posing 
  fibre 
  exclusively 
  smooth, 
  acerate 
  (doubly 
  pointed). 
  No 
  

   special 
  flesh-spicules. 
  

  

  Distribution. 
  Indo-Pacific 
  region. 
  

  

  Echinonema 
  vasiplicatum, 
  Carter, 
  Ann. 
  & 
  Mag. 
  Nat. 
  Hist. 
  1882, 
  ix. 
  

   p. 
  114, 
  S.W. 
  Australia, 
  and 
  iJictyocylindrus 
  laciniatus 
  and 
  p?/^-a, 
  id., 
  

   must 
  be 
  referred 
  to 
  this 
  genus. 
  

  

  83. 
  EcMnodictyum 
  bilamellatum. 
  

  

  Spongia 
  bilamellata, 
  Lamarck, 
  Ann. 
  Mus. 
  Hist. 
  Nat. 
  xx. 
  p. 
  434. 
  

   Echinodictyum 
  bilamellatum, 
  Ridley, 
  Journ. 
  Linn. 
  8oc., 
  Zool. 
  xv. 
  

   p. 
  493, 
  pi. 
  xxviii. 
  figs. 
  1-6. 
  

  

  A 
  dry 
  specimen, 
  very 
  closely 
  resembling 
  in 
  its 
  external 
  characters 
  

   the 
  one 
  which 
  I 
  described 
  {I. 
  c.) 
  from 
  N.AV. 
  Australia, 
  but 
  not 
  so 
  well 
  

   preserved. 
  It 
  diff'ers 
  somewhat 
  from 
  previously 
  known 
  specimens 
  

   in 
  the 
  proportions, 
  though 
  not 
  in 
  the 
  form, 
  of 
  its 
  spicules, 
  viz. 
  : 
  — 
  

   Larger 
  acerate, 
  about 
  -35 
  by 
  "018 
  millim.; 
  smaller 
  acerate, 
  about 
  

   •17 
  to 
  -24 
  by 
  '0095 
  millim. 
  ; 
  spined 
  echinating 
  cylindrical, 
  -099 
  to 
  

  

  Indian 
  species 
  Ectyon 
  sjjarsus, 
  appears 
  to 
  me 
  to 
  be 
  specifically 
  distinct 
  both 
  from 
  

   Dr. 
  Gray's 
  and 
  the 
  present 
  species 
  for 
  two 
  reasons, 
  viz. 
  (1) 
  the 
  presence 
  in 
  it 
  

   of 
  a 
  smaller 
  grapnel-spicule 
  with 
  spined 
  shaft 
  ; 
  and 
  (2) 
  the 
  apparent 
  absence 
  

   of 
  the 
  tibiella. 
  I 
  propose 
  the 
  name 
  Acarnus 
  cartcri 
  for 
  the 
  West-Indian 
  form. 
  

  

  