﻿24 
  A 
  MONOGRAPH 
  OP 
  THE 
  VICTOBIAN 
  SPONGES. 
  

  

  liydroid 
  colony. 
  The 
  connection 
  between 
  the 
  individuals 
  which 
  compose 
  the 
  colony 
  

   is 
  a 
  far 
  more 
  intimate 
  one 
  than 
  in 
  any 
  other 
  colonial 
  metazoa. 
  The 
  entire 
  colony 
  

   now 
  behaves 
  as 
  one 
  individual, 
  it 
  has 
  its 
  own 
  characteristic 
  size 
  and 
  shape, 
  its 
  own 
  

   exhalant 
  openings 
  (oscula* 
  or 
  pseudoscula) 
  and 
  its 
  own 
  inhalant 
  pores 
  {pseudopores) 
  

   and 
  external 
  skin 
  (pseiidodenn). 
  

  

  We 
  must 
  now 
  describe 
  in 
  detail 
  the 
  principal 
  modifications 
  which 
  the 
  sponge 
  

   colony, 
  and 
  as 
  a 
  direct 
  consequence 
  the 
  canal 
  system 
  of 
  the 
  colony, 
  present 
  amongst 
  

   the 
  Victorian 
  Calcarea 
  Homocoela. 
  

  

  According 
  to 
  the 
  modifications 
  in 
  the 
  form 
  of 
  the 
  colony 
  and 
  of 
  the 
  canal 
  system 
  

   I 
  propose 
  to 
  divide 
  the 
  genus 
  Leucosolenia, 
  which 
  with 
  Polejaeff 
  and 
  Vosmaer 
  I 
  

   regard 
  as 
  the 
  sole 
  genus 
  of 
  Homocoela, 
  into 
  three 
  sections, 
  Simplicia, 
  Reticulata, 
  and 
  

   Radiata. 
  We 
  will 
  deal 
  with 
  these 
  divisions 
  in 
  order, 
  beginning 
  with 
  the 
  least 
  

   complex. 
  

  

  Section 
  I. 
  simplicia. 
  

  

  The 
  Simplicia 
  include 
  such 
  simple 
  Olynthus 
  types 
  as 
  never 
  form 
  colonies, 
  and 
  also 
  

   those 
  colonial 
  forms 
  in 
  which 
  the 
  whole 
  colony 
  consists 
  of 
  individuals 
  (Ascon-persons) 
  

   which 
  may 
  branch, 
  but 
  which 
  never 
  form 
  complex 
  anastomoses 
  nor 
  give 
  off 
  radial 
  

   tubes, 
  so 
  that 
  the 
  individuality 
  of 
  the 
  different 
  members 
  of 
  the 
  colony 
  is 
  always 
  

   recognisable. 
  

  

  As 
  already 
  stated, 
  no 
  species 
  which 
  permanently 
  retain 
  the 
  simple 
  Olynthus 
  

   form 
  have 
  been 
  met 
  with 
  amongst 
  the 
  Victorian 
  Sponges, 
  The 
  simplest 
  form 
  which 
  

   we 
  have 
  appears 
  to 
  be 
  Leucosolenia 
  lucasi. 
  

  

  This 
  sponge 
  is 
  very 
  minute, 
  the 
  individuals 
  (Ascon-persons) 
  of 
  which 
  the 
  colony 
  

   is 
  composed 
  measuring 
  only 
  about 
  2 
  or 
  3 
  mm. 
  in 
  length 
  and 
  0*7 
  mm. 
  in 
  diameter. 
  

   The 
  colony 
  increases 
  by 
  budding, 
  the 
  buds 
  appearing 
  on 
  the 
  parent 
  tube 
  first 
  as 
  blind 
  

   outgrowths, 
  which 
  subsequently 
  develop 
  each 
  an 
  osculum 
  at 
  its 
  free 
  end. 
  Hence 
  the 
  

   whole 
  colony 
  forms 
  a 
  loose, 
  branching 
  mass 
  of 
  indefinite 
  size 
  and 
  shape, 
  attached 
  to 
  

   some 
  foreign 
  object. 
  A 
  portion 
  of 
  such 
  a 
  colony 
  is 
  represented 
  on 
  Plate 
  I., 
  

   Figure 
  1. 
  

  

  Each 
  individual 
  tube 
  resembles 
  an 
  Olynthus 
  except 
  that 
  instead 
  of 
  being 
  closed 
  

   at 
  its 
  lower 
  extremity 
  it 
  remains 
  in 
  open 
  communication 
  with 
  its 
  neighbours. 
  The 
  

   minute 
  structure 
  of 
  a 
  single 
  individual 
  is 
  shown 
  on 
  Plate 
  IV., 
  Figure 
  1. 
  It 
  consists 
  

   of 
  a 
  thin-walled, 
  sub-cylindrical 
  or 
  sometimes 
  nearly 
  conical 
  tube 
  with 
  a 
  wide 
  osculum 
  

  

  * 
  The 
  osculum 
  of 
  a 
  compound 
  aponge 
  is 
  not 
  strictly 
  homologous 
  with 
  the 
  osculum 
  of 
  an 
  Olynthus, 
  but 
  corresponds 
  

   to 
  a 
  number 
  of 
  Olynthus 
  oscula 
  run 
  together. 
  

  

  