﻿A 
  MONOGEAPH 
  OF 
  THE 
  VICTORIAN 
  SPONGES. 
  63 
  

  

  of 
  the 
  colony 
  is 
  irregular 
  and 
  somewhat 
  variable 
  and 
  will 
  be 
  best 
  understood 
  by 
  

   reference 
  to 
  Figures 
  1, 
  2, 
  Plate 
  II., 
  representing 
  two 
  slight 
  varieties 
  in 
  one 
  of 
  which 
  

   the 
  oval 
  pseudopores 
  are 
  conspicuously 
  larger 
  than 
  in 
  the 
  other. 
  On 
  the 
  upper 
  

   surface 
  of 
  the 
  colony 
  are 
  numerous 
  conical 
  projections, 
  each 
  having 
  a 
  small 
  osculum 
  

   at 
  its 
  summit. 
  The 
  greatest 
  diameter 
  of 
  a 
  colony 
  is 
  usually 
  only 
  about 
  6 
  or 
  7 
  mm. 
  

   The 
  colour 
  in 
  spirit 
  is 
  nearly 
  white. 
  

  

  The 
  canal 
  system 
  belongs 
  to 
  type 
  E. 
  and 
  is 
  fully 
  described 
  on 
  pp. 
  32, 
  33 
  

   and 
  illustrated 
  in 
  Figures 
  1, 
  2, 
  Plate 
  VIII. 
  

  

  (b.) 
  Arrangemeitt 
  of 
  tjie 
  Skeleton. 
  — 
  The 
  skeleton 
  consists 
  of 
  triradiate 
  spicules 
  

   only, 
  arranged 
  as 
  usual 
  in 
  the 
  thickness 
  of 
  the 
  mesoderm, 
  the 
  dermal 
  spicules 
  being 
  

   larger 
  than 
  the 
  deep 
  ones. 
  

  

  (c.) 
  The 
  Spicules 
  (PI. 
  XI., 
  Fig. 
  2). 
  — 
  DennaL 
  Piegular; 
  rays 
  stout, 
  conical, 
  

   gradually 
  and 
  sharply 
  pointed, 
  measuring 
  about 
  0"16 
  by 
  0.021 
  mm. 
  Deep. 
  

   Similar 
  to 
  the 
  dermal 
  spicules 
  but 
  with 
  the 
  rays 
  shorter 
  and 
  scarcely 
  half 
  as 
  stout. 
  

  

  {(l.) 
  Affinities.- 
  — 
  Were 
  it 
  not 
  for 
  the 
  peculiar 
  ingrowth 
  of 
  the 
  mesoderm 
  into 
  the 
  

   gastral 
  cavities 
  this 
  species 
  would 
  present 
  no 
  peculiarity 
  and 
  would 
  come 
  near 
  to 
  

   Leiicosolenia 
  piilcherrinia 
  ; 
  as 
  it 
  is 
  it 
  forms 
  a 
  very 
  interesting 
  connecting 
  link 
  between 
  

   the 
  species 
  with 
  simple 
  gastral 
  cavities 
  {Indivisa) 
  and 
  sucli 
  forms 
  as 
  Leiicosolenia 
  

   wilsoni. 
  

  

  {e.) 
  Locality.— 
  ^ea,Y 
  Port 
  Phillip 
  Heads. 
  (Coll, 
  J. 
  B. 
  Wilson.) 
  

  

  12. 
  Leiicosolenia 
  zui/som, 
  n. 
  sp. 
  

  

  (PL 
  II., 
  Figs 
  3, 
  3a, 
  4; 
  PL 
  VII. 
  ; 
  PL 
  XL, 
  Fig. 
  3.) 
  

  

  {a.) 
  General 
  Appearance 
  and 
  Canal 
  System. 
  — 
  -The 
  sponge 
  forms 
  a 
  low-growing, 
  

   much 
  flattened, 
  spreading 
  mass 
  (PL 
  II., 
  Figs. 
  3, 
  4), 
  sometimes 
  growing 
  out 
  into 
  

   rounded 
  lobes 
  (as 
  at 
  ;r 
  in 
  Figure 
  4). 
  From 
  the 
  lower 
  surface 
  arise 
  a 
  few 
  short, 
  

   root-like 
  processes 
  whicli 
  serve 
  to 
  attach 
  the 
  sponge 
  to 
  the 
  substratum. 
  On 
  the 
  

   up})er 
  surface, 
  at 
  irregular 
  intervals, 
  occur 
  small 
  conical 
  papillae, 
  each 
  with 
  a 
  minute 
  

   osculum 
  at 
  its 
  apex. 
  On 
  the 
  U})per 
  surface 
  the 
  pseudopores 
  are 
  mostly 
  elongated, 
  

   narrow 
  and 
  slit-like, 
  on 
  the 
  lower 
  surface 
  they 
  are 
  more 
  rounded. 
  The 
  greatest 
  

   horizontal 
  diameter 
  of 
  the 
  single 
  adult 
  specimen 
  in 
  the 
  collection 
  was 
  about 
  35 
  mm. 
  

   and 
  its 
  thickness 
  very 
  variable. 
  In 
  spirit 
  the 
  specimen 
  has 
  a 
  characteristic 
  dead 
  

   wliite, 
  solid 
  appearance, 
  du(> 
  to 
  the 
  partial 
  filling 
  up 
  of 
  the 
  Ascon-tub(>s. 
  

  

  The 
  canal 
  system 
  (PL 
  VII., 
  Figs. 
  1, 
  2, 
  3) 
  belongs 
  to 
  type 
  1'' 
  and 
  is 
  fully 
  

  

  