﻿80 
  Mr. 
  A. 
  Dendy 
  on 
  Sponges 
  from 
  

  

  a 
  greyish-yellow 
  colour. 
  They 
  exhibit 
  a 
  more 
  strongly 
  

   marked 
  tendency 
  to 
  form 
  digitate 
  processes 
  than 
  do 
  the 
  

   specimens 
  in 
  the 
  second 
  collection. 
  

  

  Pachychalina 
  deticatula, 
  n. 
  sp. 
  

  

  Sponge 
  erect, 
  sessile, 
  bushily 
  lamellar, 
  with 
  a 
  slight 
  ten- 
  

   dency 
  to 
  throw 
  off 
  digitate 
  processes. 
  Very 
  delicate 
  in 
  

   appearance. 
  Surface 
  smooth, 
  covered 
  by 
  a 
  very 
  delicate 
  

   dermal 
  membrane. 
  Texture 
  open, 
  resilient. 
  Colour 
  in 
  the 
  

   dry 
  state 
  light 
  yellow. 
  Oscula 
  situated 
  chiefly 
  on 
  the 
  mar- 
  

   gins 
  of 
  the 
  lamella;. 
  The 
  single 
  specimen 
  in 
  the 
  collection 
  

   is 
  180 
  millim. 
  high 
  and 
  220 
  millim. 
  in 
  greatest 
  breadth. 
  

   The 
  lamella; 
  measure 
  up 
  to 
  21 
  millim. 
  in 
  thickness 
  at 
  the 
  

   margin, 
  but 
  usually 
  much 
  less. 
  The 
  oscula 
  average 
  about 
  

   3 
  millim. 
  in 
  diameter. 
  

  

  The 
  dermal 
  skeleton 
  is 
  a 
  close-meshed 
  irregular 
  reticulation 
  

   of 
  slender 
  horny 
  fibre 
  containing 
  very 
  slender 
  spicules 
  arranged 
  

   sometimes 
  uniserially 
  and 
  sometimes 
  multiserially. 
  The 
  

   main 
  skeleton 
  is 
  a 
  wide-meshed 
  reticulation 
  of 
  very 
  stout 
  

   primary 
  and 
  secondary 
  fibres. 
  Both 
  primary 
  and 
  secondary 
  

   fibres 
  are 
  composed 
  of 
  a 
  very 
  great 
  number 
  of 
  slender 
  spicules 
  

   packed 
  close 
  together 
  all 
  through 
  the 
  fibre 
  and 
  united 
  by 
  

   spongin. 
  Both 
  primary 
  and 
  secondary 
  fibres 
  average 
  about 
  

   0*126 
  millim. 
  in 
  diameter. 
  The 
  wide 
  interspaces 
  between 
  

   them 
  are 
  partially 
  occupied 
  by 
  an 
  irregular 
  network 
  of 
  very 
  

   much 
  slenderer 
  polyspiculous 
  fibres* 
  about 
  0*0175 
  millim. 
  in 
  

   diameter, 
  branching 
  and 
  anastomosing 
  freely 
  with 
  each 
  other 
  

   and 
  with 
  the 
  primaries 
  and 
  secondaries. 
  Numerous 
  spicules 
  

   occur 
  scattered 
  outside 
  the 
  fibres. 
  

  

  The 
  spicules 
  are 
  very 
  slender 
  slightly 
  curved 
  oxea, 
  

   measuring 
  about 
  0'098 
  by 
  00035 
  millim. 
  

  

  Pachychalina 
  sjjinilamella, 
  n. 
  sp. 
  

  

  Sponge 
  consisting 
  of 
  erect, 
  flattened, 
  frondose 
  or 
  digitate 
  

   thick 
  lamella;. 
  Both 
  surfaces 
  of 
  the 
  lamella; 
  are 
  covered 
  

   with 
  numerous 
  short 
  stout 
  spines. 
  The 
  largest 
  specimen 
  is 
  

   attached 
  to 
  a 
  mass 
  of 
  nullipore 
  ; 
  it 
  is 
  160 
  millim. 
  high 
  and 
  

   185 
  millim. 
  broad, 
  while 
  the 
  thickness 
  of 
  the 
  lamella; 
  is 
  about 
  

   Yd 
  millim. 
  (Another 
  specimen 
  consists 
  of 
  a 
  short 
  stalk 
  about 
  

   47 
  millim. 
  high 
  and 
  20 
  millim. 
  in 
  diameter, 
  dividing 
  into 
  

   two 
  upright 
  flattened 
  branches, 
  one 
  of 
  which 
  is 
  hollow, 
  

   penetrated 
  by 
  a 
  wide, 
  vertical, 
  oscular 
  tube 
  ; 
  total 
  height 
  of 
  

  

  * 
  For 
  the 
  sake 
  of 
  convenience 
  these 
  n'bres 
  nmv 
  be 
  termed 
  " 
  tertiary.'" 
  

  

  