﻿the 
  Gulf 
  of 
  Manaar. 
  79 
  

  

  very 
  dense 
  and 
  irregular 
  and 
  contains 
  a 
  large 
  amount 
  of 
  

   spongin. 
  

  

  The 
  spicules 
  (fig. 
  9) 
  are 
  slightly 
  curved 
  oxea, 
  tapering 
  

   gradually 
  to 
  a 
  sharp 
  point 
  at 
  each 
  end. 
  Average 
  size 
  of 
  

   full-grown 
  spicule 
  about 
  0*175 
  by 
  0*007 
  milliin. 
  

  

  This 
  species 
  resembles 
  most 
  nearly 
  Bowerbank's 
  Isodictya 
  

   dichotoma* 
  } 
  but 
  the 
  growth 
  is 
  much 
  more 
  robust, 
  the 
  texture 
  

   harder, 
  the 
  skeleton 
  less 
  regularly 
  arranged, 
  and 
  the 
  spicules 
  

   longer 
  than 
  in 
  that 
  species, 
  so 
  that, 
  taking 
  into 
  consideration 
  

   the 
  great 
  difference 
  in 
  locality, 
  I 
  have 
  thought 
  it 
  desirable 
  to 
  

   keep 
  them 
  separate. 
  

  

  Pachychalina 
  multiformis, 
  Lendenfeld, 
  sp., 
  

   var. 
  manaarensis, 
  nov. 
  

  

  1887. 
  Ceraochalina 
  multiformis, 
  Lendenfeld, 
  ZoologiscLe 
  Jalirbiieher, 
  

   Bd. 
  ii. 
  p. 
  783. 
  

  

  This 
  variety 
  is 
  represented 
  in 
  the 
  collection 
  by 
  fifteen 
  dry 
  

   specimens 
  and 
  two 
  pieces 
  in 
  spirit. 
  The 
  sponge 
  consists 
  of 
  

   erect, 
  sessile, 
  flattened 
  lamellae, 
  with 
  irregularly 
  undulating 
  

   and 
  frequently 
  proliferating 
  surface. 
  The 
  colour 
  of 
  the 
  living 
  

   sponge 
  was 
  in 
  one 
  case 
  pale 
  violet 
  and 
  in 
  another 
  light 
  pink 
  ; 
  

   when 
  dry 
  it 
  is 
  greyish 
  yellow, 
  orange, 
  or 
  pale 
  violet, 
  and 
  in 
  

   spirit 
  greyish 
  yellow. 
  The 
  largest 
  specimen 
  is 
  250 
  millim. 
  

   wide 
  and 
  175 
  millim. 
  high 
  and 
  the 
  thickness 
  of 
  the 
  lamellae 
  

   is 
  about 
  5 
  millim. 
  The 
  texture 
  of 
  the 
  dry 
  specimens 
  is 
  

   tough 
  and 
  rather 
  hard. 
  The 
  oscula 
  are 
  numerous 
  and 
  con- 
  

   fined 
  almost 
  entirely 
  to 
  one 
  surface 
  of 
  the 
  lamellee 
  ; 
  they 
  are 
  

   about 
  1 
  millim. 
  in 
  diameter 
  and 
  they 
  have 
  slightly 
  raised 
  

   margins. 
  

  

  The 
  dermal 
  skeleton 
  is 
  a 
  close 
  network 
  of 
  relatively 
  stout 
  

   horny 
  fibres, 
  containing 
  spicules 
  for 
  the 
  most 
  part 
  uniserially 
  

   arranged. 
  

  

  The 
  main 
  skeleton 
  is 
  a 
  fairly 
  regular 
  rectangular 
  network 
  

   of 
  stout 
  horny 
  fibres 
  containing 
  a 
  great 
  deal 
  of 
  spongin. 
  The 
  

   spicules 
  are 
  numerous 
  in 
  the 
  primary 
  fibres 
  and 
  few 
  in 
  the 
  

   secondaries 
  ; 
  they 
  also 
  occur 
  outside 
  the 
  fibres. 
  

  

  The 
  spicules 
  are 
  short 
  slender 
  oxea, 
  straight 
  or 
  very 
  slightly 
  

   curved 
  ; 
  the 
  average 
  size 
  of 
  a 
  full-grown 
  example 
  is 
  about 
  

   0077 
  by 
  0-0036 
  millim. 
  

  

  The 
  external 
  form 
  of 
  this 
  variety 
  is 
  characteristic 
  and 
  fairly 
  

   constant. 
  Six 
  dry 
  specimens 
  of 
  it 
  also 
  occur 
  in 
  Mr. 
  Thurs- 
  

   ton's 
  first 
  collection, 
  but 
  are 
  not 
  mentioned 
  in 
  my 
  Report 
  ; 
  

   three 
  of 
  these 
  are 
  of 
  a 
  violet 
  colour, 
  and 
  the 
  other 
  three 
  are 
  of 
  

  

  * 
  Mon. 
  Brit, 
  Spong. 
  vol. 
  ii. 
  p. 
  300, 
  vol. 
  iii. 
  pi. 
  liii. 
  figs. 
  12-14. 
  

  

  