﻿the 
  GulfofManaar. 
  77 
  

  

  a 
  condition 
  intermediate 
  between 
  collenchymatous 
  (gelatinous) 
  

   and 
  sarcenchymatous 
  (granular). 
  The 
  flagellated 
  chambers 
  

   are 
  more 
  or 
  less 
  spherical 
  and 
  about 
  O02 
  millim. 
  in 
  diameter 
  ; 
  

   their 
  mode 
  of 
  opening 
  I 
  have 
  not 
  been 
  able 
  to 
  determine 
  

   precisely. 
  

  

  MONAXONIDA. 
  

  

  Petrosia 
  testudinaria, 
  Lamarck, 
  sp. 
  (PI. 
  I 
  IT. 
  figs. 
  1, 
  2, 
  3.) 
  

  

  1815. 
  Alcyonium 
  testudinarium, 
  Lamarck, 
  Me'uioire3 
  du 
  Museum 
  

  

  d'Histoire 
  naturelle, 
  tome 
  i. 
  p. 
  167. 
  

   1882. 
  Reniera 
  crater 
  if 
  or 
  mis, 
  Carter, 
  Ann. 
  & 
  Mag. 
  Nat. 
  Hist. 
  ser. 
  5, 
  

  

  vol. 
  x. 
  p. 
  115. 
  

   1884. 
  Reniera 
  testudinaria, 
  Ridley, 
  Zool. 
  Coll. 
  H.M.S. 
  'Alert' 
  (Brit. 
  

  

  Mus.), 
  p. 
  409. 
  

   1887. 
  Reniera 
  crater 
  if 
  or 
  mis, 
  Carter, 
  Journ. 
  Linn. 
  Soc, 
  Zool. 
  vol. 
  xxi. 
  

  

  p. 
  71. 
  

  

  This 
  species 
  is 
  represented 
  in 
  the 
  collection 
  by 
  a 
  single 
  

   very 
  fine 
  cup-shaped 
  specimen 
  (PI. 
  III. 
  fig. 
  1). 
  It 
  measures 
  40 
  

   centim. 
  in 
  height 
  and 
  127 
  centim. 
  in 
  maximum 
  circumference; 
  

   the 
  longer 
  diameter 
  of 
  the 
  aperture 
  of 
  the 
  cup 
  is 
  38 
  centim., 
  

   the 
  shorter 
  diameter 
  17 
  centim., 
  and 
  the 
  depth 
  of 
  the 
  cup 
  

   18 
  centim. 
  ; 
  the 
  diameter 
  of 
  the 
  base 
  of 
  the 
  sponge 
  is 
  30 
  

   centim. 
  

  

  The 
  outer 
  surface 
  of 
  the 
  sponge 
  is 
  beset 
  with 
  very 
  promi- 
  

   nent 
  parallel 
  ridges 
  running 
  vertically 
  upwards 
  ; 
  these 
  ridges 
  

   are 
  much 
  better 
  defined 
  and 
  more 
  regular 
  and 
  continuous 
  than 
  

   in 
  any 
  other 
  specimen 
  in 
  the 
  British-Museum 
  collection 
  j 
  

   their 
  average 
  height 
  is 
  4 
  or 
  5 
  centim. 
  and 
  the 
  average 
  dis- 
  

   tance 
  between 
  them 
  is 
  5 
  centim. 
  

  

  The 
  colour 
  of 
  the 
  sponge 
  in 
  the 
  living 
  state 
  is 
  pink, 
  in 
  the 
  

   dry 
  state 
  light 
  brownish 
  yellow. 
  The 
  texture 
  of 
  the 
  dry 
  

   specimen 
  is 
  fragile 
  and 
  crumbling. 
  

  

  The 
  sponge 
  is 
  lipostomous 
  ; 
  wide 
  canals 
  are 
  seen 
  running 
  

   outwards 
  at 
  right 
  angles 
  to 
  the 
  general 
  surface 
  of 
  the 
  sponge 
  

   and 
  terminating 
  underneath 
  networks 
  on 
  the 
  margins 
  of 
  the 
  

   ridges. 
  

  

  There 
  are 
  similar 
  covered 
  oscula 
  on 
  the 
  inside 
  of 
  the 
  cup. 
  

   It 
  thus 
  appears 
  that 
  the 
  oscula 
  occur 
  on 
  the 
  inside 
  of 
  the 
  

   cup 
  and 
  on 
  the 
  ridges, 
  but 
  are 
  hidden 
  by 
  a 
  spicular 
  network 
  

   similar 
  to 
  that 
  which 
  covers 
  the 
  general 
  surface 
  of 
  the 
  sponge, 
  

   only 
  coarser. 
  

  

  The 
  skeleton 
  is 
  a 
  close 
  irregular 
  network 
  of 
  stout 
  fibres 
  com- 
  

   posed 
  of 
  a 
  great 
  number 
  of 
  spicules 
  loosely 
  and 
  irregularly 
  

   bound 
  together. 
  

  

  The 
  spicules 
  are 
  slightly 
  curved, 
  ranging 
  in 
  form 
  from 
  

  

  