﻿A 
  MONOGRAPH 
  OF 
  THE 
  VICTORIAN 
  SPONGES. 
  37 
  

  

  Certainly 
  if 
  the 
  sponge 
  is 
  to 
  continue 
  to 
  exist 
  there 
  must 
  be 
  some 
  exhalant 
  opening 
  ; 
  

   moreover, 
  if 
  there 
  be 
  no 
  osculum, 
  why 
  should 
  there 
  be 
  a 
  " 
  cloacal 
  cavity," 
  as 
  Mr. 
  

   Carter 
  calls 
  it 
  ? 
  I 
  can 
  understand 
  the 
  sponge 
  having 
  been 
  perhaps 
  damaged, 
  and 
  its 
  

   groAvth 
  consequently 
  disturbed, 
  and 
  the 
  osculum 
  perhaps 
  concealed 
  by 
  overgrowth 
  of 
  

   the 
  neighbouring 
  parts, 
  but 
  I 
  cannot 
  believe 
  that 
  there 
  exists 
  a 
  sponge 
  with 
  no 
  

   exhalant 
  opening 
  (vide 
  infra). 
  

  

  Abnormalities 
  in 
  the 
  form 
  of 
  the 
  sponge 
  may 
  certainly 
  occur, 
  for 
  in- 
  one 
  of 
  my 
  

   specimens 
  a 
  kind 
  of 
  secondary 
  osculum, 
  if 
  one 
  may 
  use 
  the 
  term, 
  has 
  been 
  

   established 
  near 
  the 
  base 
  of 
  the 
  sponge, 
  the 
  radial 
  tubes 
  being 
  absent 
  over 
  a 
  small 
  

   area 
  and 
  the 
  thin 
  wall 
  of 
  the 
  central 
  A 
  scon-tube 
  perforated 
  by 
  a 
  relatively 
  large 
  

   opening. 
  Whether 
  this 
  is 
  the 
  result 
  of 
  injury 
  or 
  .not 
  it 
  is 
  impossible 
  to 
  say, 
  but 
  it 
  

   seems 
  not 
  unlikely. 
  

  

  D. 
  — 
  The 
  Canal 
  System 
  of 
  the 
  Calcarea 
  Homoc(ela 
  in 
  General. 
  

  

  After 
  what 
  has 
  been 
  said 
  in 
  the 
  previous 
  section 
  there 
  remains 
  but 
  little 
  to 
  add 
  

   concerning 
  the 
  canal 
  system 
  of 
  the 
  Homoccela. 
  The 
  Victorian 
  species 
  of 
  Leucosolcnia 
  

   so 
  completely 
  represent 
  the 
  genus 
  that 
  a 
  knowledge 
  of 
  their 
  anatomy 
  is 
  nearly 
  all 
  that 
  

   is 
  required 
  to 
  understand 
  the 
  anatomy 
  of 
  the 
  Homocoela 
  in 
  general. 
  The 
  different 
  

   forms 
  of 
  canal 
  system 
  enumerated 
  and 
  described 
  above 
  include 
  with 
  a 
  few 
  doubtful 
  

   exceptions 
  all 
  the 
  known 
  types, 
  and 
  even 
  add 
  to 
  those 
  already 
  described. 
  The 
  most 
  

   important 
  exceptions 
  to 
  this 
  statement 
  are 
  what 
  are 
  known 
  as 
  the 
  lipostomous 
  

   forms, 
  i.e., 
  forms 
  without 
  any 
  osculum, 
  including 
  Hcuckel's 
  " 
  artificial 
  genera," 
  

   Clistolyiithiis 
  and 
  Anloplegma, 
  the 
  former 
  being 
  a 
  simple 
  Olyntlius 
  with 
  no 
  osculum, 
  

   and 
  the 
  latter 
  a 
  reticulate 
  colony 
  with 
  no 
  osculum. 
  According 
  to 
  Hieckel 
  the 
  

   osculum 
  may 
  be 
  entirely 
  wanting, 
  and 
  then 
  part 
  of 
  the 
  prosopyles 
  (Tiibi 
  porales, 
  

   Hccckel) 
  serve 
  for 
  the 
  admission 
  of 
  water 
  and 
  })art 
  for 
  its 
  expulsion 
  from 
  the 
  gastral 
  

   cavity. 
  It 
  is 
  a 
  signilicant 
  fact 
  that 
  amongst 
  the 
  numerous 
  forms 
  of 
  Homoccela 
  which 
  

   I 
  have 
  had 
  the 
  opportunity 
  of 
  examining, 
  I 
  have 
  never 
  met 
  with 
  an 
  example 
  of 
  what 
  

   can 
  be 
  considered 
  as 
  true 
  lipostoiny. 
  Certainly, 
  as 
  1 
  liavo 
  pointed 
  out 
  previously 
  (in 
  

   the 
  case 
  of 
  I.ciicosoloiia 
  litcasi 
  and 
  L. 
  stoloiiifcr) 
  the 
  young 
  Ascon-persons, 
  formed 
  as 
  

   buds 
  from 
  the 
  i)arent 
  tube, 
  at 
  Urst 
  end 
  blindly 
  and 
  acquire 
  an 
  osculum 
  only 
  when 
  

   they 
  reach 
  a 
  certain 
  age; 
  but 
  this 
  is 
  only 
  an 
  immatiii'c 
  condition, 
  and 
  it 
  seems 
  to 
  me 
  

   not 
  impossible 
  that 
  Jiieckel's 
  Clistolyitthits 
  may 
  siui[)ly 
  be 
  an 
  immature 
  form 
  in 
  which 
  

   the 
  osculum 
  is 
  not 
  yet 
  devolo})ed. 
  As 
  to 
  the 
  AitlopU'i^ind 
  form, 
  I 
  cannot 
  hel)) 
  regarding 
  

   this 
  as 
  simply 
  a 
  reticulate 
  colony 
  in 
  which 
  the 
  oscula, 
  opt'iiing 
  t'ithcr 
  into 
  a- 
  

   l)seudogaster 
  or 
  directly 
  on 
  the 
  surface 
  of 
  the 
  colony, 
  have 
  been 
  overlooked 
  owing 
  to 
  

   their 
  small 
  size. 
  In 
  those 
  forms 
  provided 
  with 
  a 
  pseudogaster 
  which 
  1 
  ha\e 
  

   examined 
  (e.g., 
  Leiicosoleiiia 
  veii/ritosd) 
  T 
  have 
  always 
  been 
  able 
  to 
  Imd 
  ilirect 
  

  

  