﻿614 
  COLLECTIONS 
  FROM 
  THZE 
  WESTERN 
  INDIAN 
  OCEAN. 
  

  

  Clathrias, 
  except 
  perhaps 
  C. 
  elegans, 
  Vosmaer 
  (habit 
  unknown), 
  and 
  

   C. 
  (DlcU/ocylindrus) 
  anchorata, 
  Carter. 
  The 
  latter 
  is 
  only 
  known 
  

   from 
  small 
  shapeless 
  masses, 
  and 
  has 
  the 
  skeleton-spicule 
  stout, 
  

   smooth, 
  and 
  strongly 
  curved; 
  otherwise 
  the 
  spicular 
  complement 
  

   is 
  essentially 
  the 
  same. 
  In 
  the 
  present 
  species 
  the 
  two 
  kinds 
  of 
  

   anchorates 
  appear 
  to 
  be 
  distinct, 
  the 
  smaller 
  form 
  being 
  very 
  

   abundant, 
  the 
  larger, 
  though 
  evidently 
  normally 
  present, 
  much 
  less 
  

   common 
  ; 
  the 
  occurrence 
  of 
  a 
  larger 
  and 
  smaller 
  anchorate 
  in 
  some 
  

   Esperice, 
  as 
  pointed 
  out 
  by 
  Carter 
  (Ann. 
  & 
  Mag. 
  N. 
  H. 
  1882, 
  ix. 
  

   pp. 
  298, 
  299), 
  is 
  an 
  analogous 
  circumstance. 
  

  

  36. 
  Clathria 
  mseandrina. 
  (Plate 
  LIU. 
  fig. 
  I 
  ; 
  Plate 
  LIV. 
  

   figs. 
  7i-h".) 
  

  

  Sponge 
  only 
  known 
  as 
  an 
  incrusting, 
  widely-spreading 
  mass, 
  

   consisting 
  of 
  a 
  thin 
  basal 
  lamina 
  not 
  exceeding 
  1 
  millim. 
  in 
  thickness, 
  

   from 
  which 
  arise 
  vertically, 
  at 
  intervals 
  of 
  1 
  to 
  3 
  millim., 
  parallel- 
  walled 
  

   ridges, 
  or 
  triangular 
  masses, 
  about 
  "5 
  to 
  1'5 
  millim. 
  in 
  diameter 
  and 
  

   2—1 
  miUim. 
  in 
  height, 
  usually 
  united 
  laterally 
  to 
  form 
  a 
  series 
  of 
  

   meandrine 
  ridges, 
  generally 
  2-3 
  millim. 
  apart, 
  at 
  the 
  surface 
  of 
  the 
  

   sponge. 
  Surface 
  of 
  basal 
  lamina 
  very 
  uneven 
  under 
  lens, 
  honey- 
  

   combed 
  with 
  round 
  openings 
  "25 
  to 
  -75 
  miUim. 
  in 
  diameter 
  ; 
  the 
  

   trabecula 
  between 
  the 
  openings 
  is 
  hirsute 
  with 
  projecting 
  spicules 
  ; 
  

   surface 
  of 
  vertical 
  ridges 
  uneven, 
  densely 
  hirsute 
  with 
  projecting 
  

   spicules 
  and 
  skeleton-fibres, 
  towards 
  the 
  base 
  it 
  has 
  a 
  honeycombed 
  

   appearance 
  similar 
  to 
  that 
  of 
  the 
  basal 
  lamina. 
  Consistence 
  in 
  spirit 
  

   slightly 
  resistent, 
  but 
  soft, 
  compressible, 
  elastic. 
  Colour 
  in 
  spirit 
  

   buflf-yellow. 
  

  

  Main 
  skeleton 
  — 
  arrangement 
  subrectangular 
  ; 
  fibre 
  dense, 
  pale 
  

   amber-yellow, 
  echiuated 
  sparsely 
  below 
  surface 
  of 
  sponge 
  by 
  spicule 
  

   no. 
  2, 
  set 
  at 
  right 
  angles 
  to 
  fibre. 
  Primary 
  fibres 
  approximately 
  verti- 
  

   cal 
  to 
  surface, 
  terminating 
  on 
  it 
  in 
  short 
  horny 
  points 
  densely 
  clothed 
  

   with 
  spicule 
  no. 
  1, 
  which 
  are 
  directed 
  outwards, 
  parallel 
  to 
  the 
  axis 
  

   of 
  the 
  fibre 
  ; 
  diameter 
  of 
  fibre 
  about 
  -05 
  to 
  -1 
  millim. 
  ; 
  cored 
  with 
  

   proper 
  spicules, 
  usually 
  biserially 
  arranged, 
  to 
  a 
  variable 
  distance, 
  

   not 
  exceeding 
  •? 
  millim., 
  below 
  surface 
  ; 
  distance 
  of 
  fibres 
  apart 
  

   about 
  -17 
  to 
  '35 
  millim. 
  Secondary 
  fibres 
  uucored, 
  •()35-'07 
  millim. 
  

   thick, 
  placed 
  at 
  intervals 
  of 
  about 
  '17 
  millim., 
  approximately 
  vertical 
  

   to 
  primaries. 
  Dermal 
  skeleton 
  composed 
  of 
  a 
  rather 
  close 
  rect- 
  

   angularly-meshed 
  reticulation 
  ; 
  fibres 
  about 
  •04--07 
  millim. 
  thick, 
  

   apparently 
  covered 
  in 
  parts 
  by 
  a 
  thick 
  incrustation 
  of 
  foreign 
  

   bodies. 
  Sarcode 
  transparent, 
  very 
  pale 
  yellow-brown. 
  

  

  Spicules 
  : 
  — 
  (1) 
  Acuate, 
  or 
  with 
  slightly 
  constricted 
  base, 
  either 
  

   smooth 
  or 
  with 
  the 
  base 
  minutely 
  spined, 
  moderately 
  curved, 
  tapering 
  

   gradually 
  from 
  base 
  to 
  sharp 
  point 
  ; 
  size 
  -023 
  by 
  -01 
  1 
  to 
  "013 
  millim. 
  

   (echinating 
  the 
  apices 
  of 
  primary 
  fibres). 
  (2) 
  Spined 
  acuate, 
  straight 
  ; 
  

   a 
  head 
  slightly 
  indicated 
  by 
  a 
  subterminal 
  neck, 
  spines 
  minute 
  to 
  

   moderate-sized, 
  placed 
  at 
  right 
  angles 
  to 
  long 
  axis 
  ; 
  size 
  of 
  spicule 
  

   •075 
  by 
  -0063 
  millim. 
  (echinating 
  fibres 
  of 
  main 
  skeleton). 
  (3) 
  Sub- 
  

   spinulate 
  or 
  acuate, 
  smooth, 
  almost 
  straight, 
  tapering 
  gradually 
  from 
  

  

  