﻿80 
  A 
  MONOGRAPH 
  OF 
  THE 
  VICTORIAN 
  SPONGES. 
  

  

  Figure 
  3. 
  — 
  Leiicosolen'm 
  diibia. 
  

  

  a. 
  Triradiates. 
  

  

  a: 
  Strongly 
  sagittal 
  triradiate 
  (abnormal). 
  

  

  b. 
  Qiiadriradiate; 
  facial 
  view, 
  the 
  apical 
  ray 
  represented 
  as 
  seen 
  

  

  in 
  optical 
  section 
  at 
  its 
  base. 
  

  

  c. 
  Oxeotes. 
  

  

  Figure 
  4. 
  — 
  Leucosolenia 
  cavata. 
  

  

  a. 
  Triradiates. 
  

  

  b. 
  Quadriradiate 
  ; 
  facial 
  view, 
  the 
  apical 
  ray 
  represented 
  as 
  seen 
  

  

  in 
  optical 
  section 
  at 
  its 
  base. 
  

  

  c. 
  Oxeotes. 
  

  

  Figure 
  5. 
  — 
  Leucosolenia 
  stipitata. 
  

  

  Triradiates 
  from 
  the 
  body 
  of 
  the 
  sponge. 
  

  

  Note. 
  — 
  The 
  figures 
  are 
  all 
  drawn 
  to 
  the 
  same 
  scale, 
  with 
  Zeiss's 
  camera 
  hicida, 
  and 
  

   multiplied 
  by 
  about 
  260 
  diameters. 
  After 
  the 
  drawings 
  were 
  completed 
  it 
  w^as 
  

   found 
  that 
  the 
  camera 
  employed 
  caused 
  a 
  certain 
  amount 
  of 
  distortion; 
  this, 
  

   however, 
  only 
  affects 
  the 
  largest 
  spicules 
  to 
  any 
  perceptible 
  degree, 
  causing 
  

   some 
  of 
  the 
  rays 
  to 
  be 
  unduly 
  elongated. 
  As 
  full 
  descriptions 
  and 
  measure- 
  

   ments 
  of 
  the 
  spicules 
  are 
  given 
  in 
  the 
  text 
  it 
  is 
  hoped 
  that 
  the 
  error 
  thus 
  

   introduced 
  will 
  not 
  cause 
  any 
  serious 
  inconvenience. 
  

  

  PLATE 
  X. 
  

  

  Spicules. 
  

   Figure 
  1.— 
  Leucosolenia 
  pelliculata 
  (Specimen 
  A). 
  

  

  a. 
  Triradiates. 
  

  

  a.' 
  Sagittal 
  oscular 
  triradiate, 
  

  

  b. 
  Quadriradiates; 
  facial 
  view, 
  the 
  apical 
  ray 
  represented 
  as 
  

  

  seen 
  in 
  optical 
  section 
  at 
  its 
  base. 
  

   b: 
  Quadriradiate; 
  side 
  view, 
  showing 
  the 
  full 
  length 
  of 
  the 
  

  

  apical 
  ray 
  (a. 
  v.), 
  the 
  facial 
  rays 
  being 
  broken 
  off 
  short. 
  

   b." 
  Sagittal 
  oscular 
  quadriradiate; 
  facial 
  view, 
  the 
  apical 
  ray 
  

  

  represented 
  as 
  seen 
  in 
  optical 
  section 
  at 
  its 
  base. 
  

  

  Figure 
  2. 
  — 
  Leucosolenia 
  pelliculata. 
  (Specimen 
  D.) 
  

   Lettering 
  as 
  in 
  Figure 
  1. 
  

  

  