﻿SPONOIIDA. 
  

  

  Of 
  the 
  two 
  species 
  assigned 
  by 
  Mr. 
  Carter 
  (I. 
  c.) 
  to 
  the 
  genus, 
  

   S. 
  simplex, 
  recorded 
  from 
  Freemantle, 
  Australia, 
  and 
  Hayti, 
  is 
  the 
  

   most 
  closely 
  allied 
  to 
  the 
  present, 
  but 
  differs 
  from 
  it 
  in 
  the 
  pos- 
  

   session 
  of 
  the 
  bacillar 
  tuberculate 
  flesh-spicule. 
  Mr. 
  Carter, 
  how- 
  

   ever, 
  described 
  in 
  the 
  same 
  paper 
  as 
  that 
  in 
  which 
  he 
  founded 
  

   SteUeUinopsis 
  (torn. 
  cit. 
  p. 
  344), 
  a 
  species 
  which 
  even 
  more 
  nearly 
  

   approaches 
  the 
  present 
  : 
  this 
  is 
  AmorpJiina 
  stellifera 
  from 
  South 
  

   Australia, 
  which 
  differs 
  from 
  the 
  present 
  form 
  only 
  in 
  its 
  amor- 
  

   phous, 
  non-pedicellate 
  growth 
  and 
  the 
  proportions 
  of 
  its 
  spicules, 
  

   which 
  I 
  now 
  give, 
  reduced 
  to 
  metric 
  measurements 
  : 
  — 
  

  

  1. 
  Acerate, 
  -7 
  by 
  '017 
  millim. 
  

  

  2. 
  Stellate 
  (stated 
  to 
  have 
  no 
  central 
  inflation 
  ; 
  that 
  in 
  S. 
  carteri 
  

   is 
  hardly 
  worth 
  the 
  name), 
  -017 
  millira. 
  in 
  diameter. 
  

  

  Thus 
  the 
  acerate 
  is 
  one 
  fourth 
  and 
  the 
  stellate 
  two 
  thirds 
  smaller 
  

   than 
  in 
  our 
  species, 
  and 
  hence 
  the 
  two 
  species 
  are, 
  in 
  my 
  view, 
  suffi- 
  

   ciently 
  distinct. 
  Amorphina 
  stdlifera 
  should, 
  however, 
  stand 
  as 
  

   SteUeUinopsis 
  stellifera. 
  

  

  TETHYOPSIS. 
  

  

  Steivart, 
  Quart. 
  Journ. 
  3Iicr. 
  Sci. 
  n. 
  s. 
  x. 
  (1870) 
  p. 
  281 
  (nee 
  Zittel, 
  

   Abh. 
  buyer. 
  Ak. 
  xiii., 
  ii. 
  (1879) 
  p. 
  9). 
  

  

  To 
  this 
  remarkable 
  genus 
  I 
  propose 
  to 
  assign 
  a 
  species 
  which 
  

   has, 
  as 
  described 
  recent 
  allies, 
  the 
  species 
  T. 
  columnifera, 
  from 
  the 
  Phi- 
  

   lippine 
  Islands, 
  on 
  which 
  the 
  genus 
  was 
  based, 
  and 
  Tribrachion 
  (um) 
  

   schmidti, 
  from 
  the 
  Gulf 
  of 
  Mexico. 
  Like 
  the 
  latter, 
  the 
  present 
  

   form 
  exhibits 
  a 
  singular 
  divergence 
  from 
  the 
  more 
  normal 
  Tetrac- 
  

   tinellid 
  types, 
  in 
  that 
  its 
  chief 
  spicule 
  has 
  lost 
  one 
  of 
  its 
  arms, 
  and 
  

   is 
  only 
  triactiuellid. 
  The 
  genus 
  appears 
  to 
  be 
  allied 
  to 
  JStelletta, 
  

   the 
  peculiar 
  development 
  of 
  its 
  large 
  tetractinellid 
  spicule 
  being 
  

   apparently 
  caused 
  by 
  the 
  erect 
  growth 
  aiid 
  non-corticate 
  character 
  

   of 
  the 
  sponge. 
  

  

  105. 
  Tethyopsis 
  dissimilis. 
  

   (Plate 
  XL. 
  fig. 
  H 
  ; 
  Plate 
  XLIII. 
  figs. 
  l~l"""".) 
  

  

  Sponge 
  elongated, 
  slender, 
  cylindrical 
  or 
  suboblong, 
  tapering 
  

   to 
  the 
  free 
  extremity, 
  which 
  is 
  pointed 
  ; 
  attached 
  by 
  a 
  narrow 
  base 
  

   which 
  throws 
  out 
  a 
  thin 
  horizontal 
  expansion 
  outside 
  the 
  sponge 
  

   itself. 
  Flexible 
  ; 
  surface 
  formed 
  by 
  a 
  thin 
  and 
  delicate 
  dermal 
  mem- 
  

   brane 
  of 
  a 
  dark 
  grey 
  colour 
  in 
  spirit. 
  Yent 
  ? 
  Pores 
  •04--08 
  in 
  

   diameter, 
  crowded 
  in 
  the 
  interfascicular 
  spaces 
  of 
  the 
  dermis. 
  

   Skeleton 
  formed 
  by 
  a 
  number 
  of 
  narrow 
  Ijands 
  of 
  aggregated 
  spicule- 
  

   shafts 
  (spicule 
  Xo. 
  1) 
  running 
  longitudinally 
  down 
  the 
  interior 
  of 
  the 
  

   sponge; 
  the 
  bands 
  are 
  united 
  laterally 
  (see 
  fig. 
  V") 
  by 
  means 
  of 
  the 
  

   arms 
  of 
  the 
  triradiate 
  spicule, 
  are 
  clothed 
  with 
  the 
  soft 
  tissues, 
  

   and 
  serve 
  to 
  break 
  up 
  the 
  space 
  within 
  the 
  sponge 
  into 
  8 
  or 
  9 
  

   elongated 
  cavities 
  running 
  from 
  the 
  base 
  towards 
  the 
  apex 
  of 
  the 
  

   sponge, 
  viz. 
  (1) 
  anterior, 
  (2) 
  posterior, 
  (i3 
  and 
  4) 
  lateral, 
  (5 
  and 
  6) 
  

   antero-lateral, 
  (7 
  and 
  8) 
  postero-lateral, 
  and 
  in 
  one 
  case 
  (9) 
  axial 
  (see 
  

   figs. 
  I 
  and 
  I'). 
  Subdermal 
  skeleton 
  formed 
  by 
  similar 
  longitudinal 
  

  

  