﻿432 
  COLLECTIONS 
  FROM 
  MELANESIA. 
  

  

  the 
  Indo-Pacific 
  region, 
  agrees 
  well 
  with 
  the 
  typical 
  form 
  of 
  the 
  

   genus, 
  only 
  presenting 
  its 
  peculiarities, 
  both 
  external 
  and 
  internal, 
  

   under 
  a 
  decidedly 
  more 
  striking 
  form 
  than 
  in 
  the 
  Atlantic 
  and 
  

   Mediterranean 
  species. 
  Halichondria 
  hifreqmns, 
  Carter, 
  differs 
  from 
  

   it 
  in 
  having 
  the 
  spined 
  acerate 
  skeletou-spicule 
  which 
  occurs 
  in 
  

   some 
  of 
  the 
  Atlantic 
  species, 
  but 
  agrees 
  with 
  it 
  in 
  having 
  a 
  biha- 
  

   mate 
  ; 
  its 
  external 
  characters 
  are 
  unknown, 
  but 
  it 
  will 
  almost 
  

   certainly 
  prove 
  to 
  be 
  a 
  Crella. 
  

  

  66. 
  Crella 
  schmidti. 
  (Plate 
  XLI. 
  fig. 
  a 
  a.) 
  

  

  Massive, 
  sending 
  up 
  moderately 
  thick 
  lobes 
  pierced 
  by 
  passages 
  

   1 
  to 
  4 
  millira. 
  in 
  diameter, 
  lined 
  by 
  smooth 
  surfaces 
  bearing 
  the 
  

   pores. 
  General 
  surface 
  covered 
  with 
  narrow 
  longitudinal 
  ridges 
  

   about 
  1 
  millim. 
  broad, 
  5 
  millim. 
  high, 
  and 
  1 
  millim. 
  apart, 
  rough 
  ; 
  

   dermal 
  membrane 
  between 
  ridges 
  smooth, 
  transparent. 
  Vents 
  few, 
  

   in 
  depressions 
  1 
  to 
  3 
  millim. 
  deep. 
  Texture 
  in 
  spirit 
  like 
  crumb 
  of 
  

   bread 
  ; 
  colour 
  dirty 
  yellowish 
  white. 
  Main 
  skeleton 
  somewhat 
  irre- 
  

   gular, 
  spiculo-fibre 
  devoid 
  of 
  horny 
  matter 
  ; 
  in 
  deep 
  parts 
  spicules 
  

   1- 
  or 
  2-serial, 
  fibres 
  very 
  irregular 
  in 
  direction; 
  towards 
  the 
  periphery 
  

   primary 
  fibres, 
  with 
  spicules 
  2- 
  to 
  4-serial, 
  run 
  towards 
  the 
  surface, 
  

   generally 
  at 
  an 
  obtuse 
  angle 
  to 
  it 
  ; 
  they 
  terminate 
  between 
  the 
  

   intermarginal 
  chambers 
  in 
  tufts 
  of 
  the 
  tibiella 
  spicule, 
  12 
  to 
  15 
  

   spicules 
  broad, 
  the 
  distal 
  ends 
  of 
  the 
  tibiellas 
  spreading 
  out 
  upon 
  the 
  

   dermal 
  membrane 
  and 
  forming 
  its 
  only 
  skeleton. 
  Sarcode 
  pale' 
  

   brown, 
  rather 
  granular. 
  Spicules: 
  — 
  (1) 
  Skeleton 
  acerate, 
  smooth, 
  

   straight 
  or 
  slightly 
  curved, 
  tapering 
  to 
  sharp 
  points 
  from 
  near 
  

   centre 
  ; 
  size 
  -22 
  by 
  '0063 
  millim. 
  (2) 
  Tibiella 
  of 
  dermal 
  tufts, 
  

   straight, 
  smooth, 
  heads 
  of 
  same 
  thickness 
  as 
  centre 
  of 
  shaft 
  ; 
  shaft 
  

   tapering 
  to 
  necks 
  below 
  heads, 
  necks 
  tapering 
  gradually 
  to 
  the 
  oval 
  

   heads 
  ; 
  size 
  '22 
  by 
  •0063 
  millim. 
  (3) 
  Equiauchorate 
  of 
  flesh, 
  tri- 
  

   dentate, 
  the 
  shaft 
  stout, 
  strongly 
  . 
  curved 
  ; 
  the 
  teeth 
  strong, 
  well 
  

   curved 
  inwards, 
  sharp, 
  the 
  two 
  lateral 
  ones 
  united 
  to 
  shaft 
  by 
  falcate 
  

   expansions 
  ; 
  length 
  of 
  spicule 
  '037 
  millim., 
  that 
  of 
  each 
  head 
  "013 
  

   millim., 
  thickness 
  of 
  shaft 
  -0044 
  millim. 
  [(4) 
  Bihamate 
  of 
  flesh, 
  

   contort, 
  curve 
  moderate, 
  ends 
  bent 
  sharply 
  inwards 
  ; 
  size 
  -037 
  by 
  

   •0()21 
  millim. 
  Possibly 
  foreign 
  to 
  the 
  sponge, 
  but 
  not 
  uncommon 
  

   in 
  both 
  the 
  deeper 
  and 
  superficial 
  parts 
  of 
  the 
  sarcode.] 
  

  

  Hub. 
  Port 
  Jackson, 
  0-5 
  fms. 
  

  

  The 
  only 
  specimen 
  is 
  in 
  spirit 
  and 
  well 
  preserved, 
  but 
  small 
  ; 
  

   the 
  external 
  characters 
  peculiar 
  to 
  the 
  genus 
  are, 
  however, 
  well 
  

   marked. 
  Whereas 
  the 
  head 
  of 
  the 
  tibiella 
  is 
  scarcely 
  defined 
  as 
  

   such 
  in 
  any 
  of 
  Schmidt's 
  species 
  (of 
  which 
  two 
  are 
  fz'oni 
  the 
  Adriatic 
  

   and 
  two 
  from 
  the 
  West-Indian 
  seas), 
  here 
  it 
  is 
  quite 
  a 
  striking 
  

   feature 
  of 
  the 
  dermal 
  membrane 
  when 
  seen 
  in 
  section 
  ; 
  in 
  HaUchon- 
  

   dria 
  infrequent, 
  Carter, 
  above 
  referred 
  to, 
  the 
  head 
  of 
  the 
  tibiella 
  is 
  

   similarly 
  well 
  defined. 
  The 
  spicules 
  are 
  generally 
  stouter 
  than 
  

   those 
  of 
  Schmidt's 
  species, 
  and 
  none 
  of 
  the 
  skeleton 
  forms 
  are 
  spined, 
  

   as 
  appears 
  to 
  be 
  the 
  case 
  in 
  C. 
  elegans 
  and 
  pajjillosa, 
  if 
  not 
  in 
  ho'^pi- 
  

   talis. 
  I 
  associate 
  this 
  species 
  with 
  the 
  name 
  of 
  the 
  distinguished 
  

  

  