﻿016 
  COLLECTIONS 
  FROM 
  THE 
  WESTERN 
  INDIAN 
  OCEAN. 
  

  

  mentioned 
  by 
  Carter, 
  II. 
  cc.) 
  of 
  a 
  fine 
  tricurvate 
  acerate 
  flesh-spicule 
  

   in 
  addition 
  to 
  an 
  equianchorate. 
  A 
  third 
  species, 
  E. 
  vasipliccda., 
  

   assigned 
  by 
  Carter 
  {op. 
  at. 
  1882, 
  x. 
  p. 
  114) 
  to 
  the 
  genus 
  belongs, 
  

   as 
  I 
  have 
  stated 
  in 
  my 
  report 
  on 
  the 
  Australian 
  collections 
  (Part 
  I. 
  

   p. 
  454), 
  not 
  to 
  this 
  genus, 
  but 
  to 
  EcMnodictyum, 
  mihi. 
  The 
  genus 
  

   was 
  not 
  met 
  with 
  by 
  the 
  ' 
  Alert 
  ' 
  on 
  the 
  north 
  and 
  east 
  of 
  Australia, 
  

   although 
  it 
  is 
  common 
  on 
  the 
  south 
  and 
  south-west 
  (Carter) 
  ; 
  it 
  is 
  

   a 
  little 
  strange 
  therefore 
  to 
  find 
  the 
  following 
  two 
  species 
  in 
  the 
  

   western 
  part 
  of 
  the 
  Indian 
  Ocean. 
  

  

  38. 
  Echinonema, 
  sp. 
  

  

  A 
  small, 
  irregularly-grown 
  specimen 
  in 
  spirit, 
  consisting 
  of 
  an 
  

   extended 
  coating 
  base 
  and 
  three 
  low 
  lobes, 
  more 
  or 
  less 
  flattened,, 
  

   two 
  of 
  them 
  uniting 
  with 
  each 
  other. 
  Surface 
  corrugated 
  by 
  low 
  

   mseandering 
  ridges, 
  giving 
  an 
  irregularly 
  dimpled 
  aspect 
  to 
  the 
  sur- 
  

   face 
  ; 
  dermal 
  membrane 
  upon 
  the 
  ridges 
  glabrous. 
  Vents 
  small, 
  

   scattered, 
  oval 
  or 
  circular, 
  "6 
  to 
  1*0 
  millim. 
  in 
  diameter, 
  generally 
  

   placed 
  on 
  margins 
  or 
  in 
  depressions 
  rather 
  than 
  in 
  the 
  middle 
  of 
  

   surfaces. 
  Consistence 
  in 
  spirit 
  firm, 
  very 
  tough, 
  elastic 
  ; 
  colour 
  duU 
  

   umber-brown. 
  

  

  Main 
  skeleton 
  approximately 
  rectangular 
  in 
  arrangement, 
  the 
  pri- 
  

   mary 
  fibres 
  being 
  set 
  vertically 
  to 
  the 
  surface, 
  and 
  the 
  secondaries 
  

   parallel 
  to 
  it, 
  but 
  with 
  their 
  ends 
  curved 
  round 
  to 
  meet 
  the 
  primaries 
  ; 
  

   fibre 
  very 
  strong, 
  pale 
  to 
  dark 
  amber-yellow 
  in 
  colour 
  : 
  the 
  primary 
  

   fibres 
  about 
  "14 
  millim. 
  thick, 
  and 
  cored 
  for 
  one 
  to 
  two 
  thirds 
  of 
  their 
  

   thickness 
  by 
  subspinulate 
  spicules 
  ; 
  secondary 
  fibre 
  "07 
  to 
  "14 
  millim. 
  

   thick, 
  either 
  devoid 
  of 
  spicules 
  or 
  cored 
  by 
  at 
  most 
  two 
  series. 
  

   Dermal 
  skeleton 
  formed 
  by 
  a 
  set 
  of 
  radiating 
  tufts 
  of 
  subspinulate 
  

   spicules, 
  the 
  bases 
  of 
  the 
  tufts 
  being 
  placed 
  about 
  '25 
  millim. 
  apart, 
  

   and 
  the 
  ends 
  of 
  the 
  spicules 
  of 
  the 
  different 
  tufts 
  intercrossing. 
  8ar- 
  

   code 
  pale 
  yellowish 
  brown, 
  subtransparent. 
  Spicules 
  : 
  — 
  (1) 
  Skeletal 
  

   and 
  dermal 
  subspinulate 
  ; 
  head 
  slight, 
  oval, 
  provided 
  with 
  a 
  few 
  

   very 
  fine 
  terminal 
  spines 
  ; 
  head 
  of 
  about 
  the 
  same 
  diameter 
  as 
  middle 
  

   of 
  shaft; 
  tapering 
  gradually 
  to 
  sharp 
  point; 
  size 
  '26 
  by 
  -008 
  millim. 
  

   (2) 
  Echinating 
  spiued 
  subspinulate 
  ; 
  the 
  head 
  and 
  distal 
  two 
  thirds 
  

   well 
  spined 
  ; 
  spines 
  strong, 
  sharp, 
  projecting 
  at 
  right 
  angles 
  to 
  

   surface 
  ; 
  size 
  of 
  spicule 
  -1 
  by 
  '0085 
  millim. 
  (3) 
  Tricurvate 
  acerate 
  

   of 
  sarcode, 
  median 
  curve 
  rather 
  sharp 
  ; 
  size 
  "04 
  by 
  '001 
  millim. 
  

   (4) 
  Equianchorate, 
  navicular, 
  shaft 
  slightly 
  curved 
  ; 
  length 
  of 
  spicule 
  

   •012 
  millim. 
  

  

  Hah. 
  Etoile 
  Island, 
  Amirante 
  group, 
  13 
  fms. 
  ; 
  attached 
  to 
  dead 
  

   coral. 
  

  

  This 
  species 
  is 
  evidently 
  nearly 
  related 
  to 
  E. 
  typicimi 
  and 
  E. 
  an- 
  

   cJioratum 
  of 
  Carter, 
  from 
  its 
  resemblance 
  in 
  external 
  form 
  and 
  in 
  

   spiculation. 
  The 
  structure 
  of 
  the 
  dermal 
  " 
  crust 
  " 
  is 
  essentially 
  the 
  

   same 
  as 
  that 
  described 
  by 
  me 
  in 
  the 
  nearly 
  allied 
  genus 
  JRha- 
  

   phiflopMus 
  (see 
  R. 
  arborescens 
  and 
  B. 
  procerus, 
  Part 
  I. 
  pp. 
  450-1, 
  of 
  

   this 
  Report). 
  

  

  