﻿SPONGIIDA. 
  

  

  383 
  

  

  and 
  the 
  greater 
  number 
  of 
  cored 
  primaries. 
  Sponr/ia 
  cavernosa, 
  

   Esper, 
  differs 
  from 
  both 
  iu 
  having 
  the 
  surface 
  between 
  the 
  canals 
  

   echinated 
  with 
  tufts. 
  

  

  The 
  pecuharly 
  smooth 
  and 
  unbroken 
  character 
  of 
  the 
  surface 
  of 
  

   the 
  skeleton 
  between 
  the 
  openings 
  of 
  the 
  excretory 
  canals 
  appears 
  

   to 
  be 
  due 
  mainly 
  to 
  the 
  remarkable 
  modification 
  of 
  the 
  usual 
  position 
  

   of 
  the 
  uncored 
  primary 
  fibres, 
  by 
  which, 
  instead 
  of 
  running 
  parallel 
  

   to 
  the 
  cored 
  primaries, 
  and 
  so 
  meeting 
  the 
  general 
  surface 
  at 
  right 
  

   angles 
  and 
  (as 
  is 
  usually 
  the 
  case) 
  by 
  a 
  superficial 
  projection, 
  they 
  

   run 
  approximately 
  at 
  right 
  angles 
  to 
  the 
  very 
  scanty 
  cored 
  fibres, 
  

   and 
  so 
  parallel 
  to 
  the 
  general 
  surface 
  of 
  the 
  sponge 
  ; 
  the 
  very 
  close 
  

   interstitial 
  network 
  further 
  adds 
  to 
  its 
  density 
  and 
  evenness 
  of 
  the 
  

   texture. 
  

  

  STELOSPONGUS. 
  

  

  Stelospongos, 
  Schmidt, 
  Atl. 
  Geb. 
  p. 
  29 
  ; 
  Hyatt, 
  Mem. 
  Bost. 
  Soc. 
  ii. 
  

  

  pt. 
  3, 
  p. 
  528. 
  

   Polyfibrospongia, 
  BouvrbcDiJi, 
  P. 
  Z. 
  S. 
  1877, 
  p. 
  459. 
  

   Stelospongia, 
  F. 
  E. 
  Schnlzc, 
  Zeitsch. 
  wiss. 
  Zool. 
  xxxii. 
  p. 
  613. 
  

   Stellospongia, 
  Marshall, 
  Zeitsch. 
  wiss. 
  Zool. 
  xxxv. 
  pp. 
  90, 
  118. 
  

  

  I 
  cannot 
  see 
  any 
  sufficient 
  reason 
  for 
  Marshall's 
  mode 
  of 
  writing 
  

   the 
  name 
  of 
  this 
  genus. 
  The 
  first 
  part 
  of 
  the 
  word 
  appears 
  to 
  be 
  

   based 
  on 
  (rrz/'X/j, 
  a 
  column, 
  from 
  the 
  frequency 
  with 
  which 
  Schmidt 
  

   alludes 
  to 
  the 
  columns 
  (" 
  Siiulen 
  ") 
  formed 
  by 
  the 
  main 
  fibres 
  of 
  the 
  

   skeleton. 
  

  

  6. 
  Stelospongus 
  excavatus. 
  (Plate 
  XXXIX. 
  fig. 
  A.) 
  

  

  A 
  small 
  spirit- 
  specimen, 
  obtained 
  at 
  Port 
  MoUe, 
  Queensland, 
  has 
  

   a 
  head 
  which 
  arises 
  from 
  a 
  short 
  pedicel, 
  is 
  broad 
  and 
  semitruncate 
  

   above, 
  and 
  cup-like, 
  being 
  excavated 
  on 
  its 
  upper 
  surface 
  by 
  four 
  

   pits, 
  the 
  deepest 
  occupying 
  a 
  great 
  part 
  of 
  the 
  thickness 
  of 
  the 
  sponge 
  ; 
  

   each 
  pit 
  contains 
  a 
  vent 
  ; 
  the 
  vents 
  vaiy 
  in 
  size 
  from 
  about 
  '25 
  to 
  3 
  

   millim. 
  The 
  colour 
  in 
  spirit 
  is 
  greyish 
  white 
  (putty 
  colour) 
  ; 
  the 
  

   dermis 
  conceals 
  all 
  the 
  skeleton 
  but 
  the 
  ends 
  of 
  the 
  primary 
  fibres, 
  

   which 
  appear 
  as 
  low 
  points 
  over 
  the 
  whole 
  of 
  the 
  outer 
  surface 
  

   and 
  just 
  inside 
  the 
  margins 
  of 
  the 
  pits. 
  

  

  The 
  skeleton-liues 
  measure 
  about 
  "38 
  millim. 
  in 
  diameter, 
  the 
  

   individual 
  fibres 
  of 
  primary 
  lines 
  from 
  "018 
  to 
  •028 
  millim. 
  in 
  

   diameter, 
  those 
  of 
  the 
  large 
  secondary 
  lines 
  -07 
  millim. 
  lioth 
  the 
  

   secondary 
  and 
  primary 
  fibres 
  enclose 
  more 
  or 
  less 
  foreign 
  matter, 
  

   which 
  also 
  occurs 
  on 
  the 
  outside 
  of 
  the 
  primary 
  fibres 
  and 
  dermis, 
  

   forming 
  a 
  kind 
  of 
  mosaic. 
  Greatest 
  height 
  and 
  breadth 
  of 
  the 
  

   single 
  specimen 
  31 
  and 
  25 
  millim. 
  respectively. 
  Several 
  large 
  nu- 
  

   cleated 
  and 
  unsegmented 
  ova 
  are 
  discernible 
  in 
  the 
  tissues, 
  scattered 
  

   or 
  aggregated 
  in 
  groups 
  of 
  two 
  or 
  three 
  ; 
  the 
  diameter 
  of 
  the 
  largest 
  

   is 
  about 
  -06 
  millim. 
  ; 
  one 
  was 
  also 
  observed 
  which 
  had 
  apparently 
  

   divided 
  into 
  four 
  segments. 
  

  

  A 
  fine 
  dry 
  specimen, 
  300 
  millim. 
  in 
  gross 
  height 
  by 
  95 
  iu 
  the 
  maxi- 
  

   mum 
  diameter 
  of 
  the 
  cup, 
  provided 
  with 
  a 
  slender 
  pedicel 
  150 
  millim. 
  

   long, 
  breaking 
  up 
  below 
  into 
  a 
  number 
  of 
  long 
  stringy 
  rooting 
  

  

  