﻿SPONGIIDA. 
  405 
  

  

  has 
  a 
  slightly 
  but 
  regularly 
  uneven 
  surface, 
  the 
  tissue 
  covering 
  it 
  

   being, 
  however, 
  almost 
  smooth. 
  Vents 
  with 
  thin 
  everted 
  margins 
  

   about 
  -5 
  millim. 
  high, 
  abundant, 
  irregularly 
  uniserial, 
  1 
  to 
  3 
  millim. 
  

   in 
  diameter 
  on 
  one 
  (presumably 
  the 
  upper) 
  side 
  of 
  the 
  stem 
  and 
  

   branches, 
  less 
  abundant 
  and 
  generally 
  smaller 
  on 
  the 
  opposite 
  side. 
  

   Branching 
  dichotomous, 
  at 
  angles 
  of 
  50° 
  to 
  60° 
  ; 
  the 
  branches 
  rather 
  

   flexuous 
  ; 
  branches 
  and 
  stem 
  8 
  to 
  18 
  millim. 
  in 
  diameter. 
  Texture 
  

   in 
  spirit 
  firm, 
  but 
  flexible, 
  tough 
  ; 
  colour 
  dark 
  dull 
  grey. 
  Main 
  

   skeleton 
  composed 
  of 
  tough, 
  flexible 
  primary 
  fibres 
  of 
  closely 
  packed 
  

   spicules, 
  about 
  6- 
  to 
  i2-serial, 
  running 
  approximately 
  at 
  right 
  

   angles 
  to 
  surface 
  (no 
  horny 
  uuiting-matter 
  visible), 
  the 
  fibres 
  

   nearly 
  approximated 
  to 
  each 
  other 
  ; 
  and 
  of 
  irregular 
  and 
  often 
  loose 
  

   crossing 
  secondary 
  tracts 
  of 
  spicules 
  2 
  to 
  -i 
  spicules 
  broad, 
  not 
  strictly 
  

   at 
  right 
  angles 
  to 
  primaries. 
  Dermal 
  skeleton 
  a 
  closely-set 
  coat 
  of 
  

   subparallel 
  spiculo-fibres 
  about 
  8 
  spicules 
  broad. 
  Barcode 
  dark 
  

   brownish, 
  granular. 
  Spicules 
  accrate, 
  slightly 
  but 
  sharply 
  bent, 
  

   tapering 
  slightly 
  from 
  middle, 
  and 
  rather 
  suddenly 
  from 
  within 
  

   about 
  two 
  diameters 
  of 
  ends, 
  to 
  moderately 
  sharp 
  points 
  ; 
  size 
  -2 
  by 
  

   •0128 
  milhm. 
  

  

  Hah. 
  Port 
  Darwin, 
  7-12 
  fms. 
  ; 
  bottom 
  mud 
  and 
  sand. 
  

  

  Distribution. 
  East-Indian 
  seas 
  {Esper)'! 
  

  

  The 
  only 
  specimen 
  measures 
  150 
  millim. 
  (6 
  inches) 
  in 
  extreme 
  

   length. 
  The 
  species 
  is 
  at 
  any 
  rate 
  distinct 
  from 
  Spongia 
  arhoresceyis 
  

   of 
  Lamarck, 
  who 
  gives 
  S. 
  lobata, 
  Esper, 
  as 
  a 
  sj'nouym 
  of 
  his 
  species. 
  

   It 
  stands 
  on 
  the 
  borderland 
  between 
  Pacini 
  chalina 
  and 
  the 
  branched 
  

   and 
  large-vented 
  Renieridoe. 
  I 
  assign 
  it 
  to 
  the 
  former, 
  as 
  its 
  fibres 
  

   are 
  evidently 
  formed 
  in 
  part 
  by 
  a 
  flexible 
  horny 
  material. 
  It 
  differs 
  

   from 
  the 
  described 
  specimens 
  of 
  S.'lohata 
  in 
  having 
  approximately 
  

   cylindrical 
  branches 
  and 
  bearrng 
  some 
  vents 
  on 
  both 
  sides. 
  

  

  36. 
  Pachyclialina 
  macrodactyla. 
  (Plate 
  XL. 
  figs. 
  B, 
  B'; 
  

   Plate 
  XLI. 
  fig. 
  o.) 
  

  

  Spongia 
  macrodactyla, 
  Lamarck^ 
  Ann. 
  Mus. 
  Hist. 
  Nat. 
  xx. 
  p. 
  457. 
  

  

  Guided 
  only 
  by 
  the 
  short 
  and 
  superficial 
  description 
  given 
  by 
  

   Lamarck, 
  and 
  by 
  the 
  locality 
  (" 
  probably 
  Indian 
  Ocean 
  ") 
  assigned 
  

   by 
  him, 
  I 
  refer 
  to 
  his 
  species 
  some 
  dry 
  fragments 
  of 
  an 
  exquisite 
  

   Pachychalina, 
  possibly 
  originally 
  belonging 
  to 
  one 
  specimen. 
  It 
  

   Las 
  some 
  external 
  resemblance 
  to 
  Spongia 
  asparagus, 
  Lamarck, 
  of 
  

   which 
  I 
  have 
  seen 
  a 
  specimen 
  ; 
  but 
  the 
  branches 
  in 
  the 
  latter 
  are 
  

   cylindrical, 
  the 
  vents 
  open 
  on 
  the 
  level 
  of 
  the 
  general 
  surface, 
  

   and 
  the 
  fibre-structure 
  is 
  that 
  of 
  Chalina 
  rather 
  than 
  PachgcJudina. 
  

   I 
  will 
  proceed 
  to 
  supplement 
  the 
  original 
  incomplete 
  descrijjtion 
  by 
  

   a 
  fuller 
  one. 
  

  

  The 
  stem 
  and 
  branches 
  are 
  flattened 
  out, 
  somewhat 
  knife-like, 
  in 
  

   most 
  places, 
  the 
  edges 
  being 
  sometimes 
  quite 
  sharp 
  ; 
  the 
  lateral 
  

   diameter 
  is 
  here 
  about 
  twice 
  the 
  antero-posterior 
  one 
  (viz. 
  about 
  13 
  

   millim. 
  at 
  largest 
  part 
  of 
  stem, 
  millim. 
  just 
  below 
  apex 
  of 
  branches) 
  ; 
  

   the 
  stem 
  near 
  the 
  base 
  appears 
  to 
  be 
  normally 
  cylindrical, 
  about 
  6 
  

   millim. 
  in 
  diameter. 
  Branches 
  (in 
  present 
  specimens) 
  given 
  off" 
  pin- 
  

  

  