﻿SPONGTIDA. 
  419 
  

  

  DESMACIDINID^ 
  (Schmidt, 
  1870). 
  

  

  If 
  all 
  those 
  sponges 
  which 
  contain 
  hooked 
  or 
  bow-like 
  flesh- 
  

   spicules 
  were, 
  in 
  accordance 
  with 
  Vosmaer's 
  views, 
  as 
  expressed 
  

   in 
  his 
  vei'y 
  useful 
  llevision 
  (Notes 
  lioy. 
  Mus, 
  Netherl. 
  ii. 
  p, 
  99), 
  

   included 
  in 
  this 
  family, 
  it 
  would 
  not 
  only 
  be 
  the 
  largest, 
  in 
  all 
  pro- 
  

   bability, 
  of 
  the 
  families 
  of 
  Siliceous 
  S])onges, 
  but 
  it 
  would 
  leave 
  

   some 
  of 
  the 
  remaining 
  ones 
  mere 
  skeletons. 
  Judged 
  by 
  the 
  facts 
  

   DOW 
  known, 
  the 
  boundary 
  region 
  between 
  the 
  Desmacidinidae 
  and 
  

   Chalinida? 
  is 
  now 
  narrow, 
  but 
  not 
  in 
  reality 
  so 
  narrow 
  as 
  it 
  would 
  

   be 
  if 
  the 
  above 
  definition 
  is 
  insisted 
  on. 
  Whatever 
  may 
  be 
  the 
  

   affinities 
  of 
  Homoeodicti/a, 
  with 
  its 
  anchorate 
  flesh- 
  spicules 
  (referred 
  

   by 
  Mr. 
  Carter 
  to 
  the 
  Chalinidae), 
  those 
  of 
  Toxoclialhia, 
  mihi 
  (see 
  

   Chalinidfe, 
  supra), 
  are 
  undoubtedly 
  with 
  that 
  group 
  ; 
  yet 
  it 
  has 
  

   a 
  bow-like 
  flesh-spicule 
  in 
  conjunction 
  with 
  a 
  Chalinid 
  acerate 
  

   skeleton-spicule, 
  horny 
  fibre, 
  and 
  digitate 
  habit. 
  Until 
  the 
  homo- 
  

   logies 
  of 
  the 
  fiesh-spicules 
  are 
  better 
  understood 
  than 
  they 
  are 
  at 
  

   present, 
  I 
  believe 
  that 
  cases 
  such 
  as 
  those 
  just 
  mentioned 
  will 
  

   have 
  to 
  be 
  considered 
  separately 
  on 
  their 
  individual 
  merits 
  as 
  they 
  

   arise, 
  having 
  special 
  regard 
  to 
  the 
  direction 
  in 
  which 
  the 
  greater 
  

   assemblage 
  of 
  affinities 
  point. 
  It 
  seems 
  probable 
  that 
  this 
  family 
  

   will 
  only 
  prove 
  a 
  fresh 
  illustration 
  of 
  the 
  maxim 
  " 
  Natura 
  non 
  

   facit 
  saltum." 
  Besides 
  To.vochalina 
  I 
  here 
  exclude 
  from 
  the 
  family 
  

   those 
  genera 
  (e. 
  g. 
  C'lathria, 
  Acarnns, 
  Ecliinonema) 
  in 
  which 
  any 
  

   of 
  the 
  spicules 
  project 
  laterally 
  from 
  the 
  fibre 
  ; 
  such 
  forms 
  as 
  these 
  

   seem 
  to 
  pass 
  by 
  gradations 
  {Echinodictyum, 
  Raspailia) 
  almost 
  into 
  

   AxineUa 
  and 
  PhaccUla, 
  by 
  losing, 
  in 
  the 
  first 
  case, 
  the 
  fiesh- 
  

   spicules, 
  and 
  in 
  the 
  second 
  {Axinclla 
  &c.) 
  the 
  spined 
  echinating 
  

   cylindricals. 
  RMzocludina, 
  on 
  the 
  other 
  hand, 
  seems 
  linked 
  to 
  the 
  

   family 
  by 
  its 
  occasionally 
  horny 
  fibres, 
  and 
  by 
  its 
  ally 
  Oceanapia 
  

   with 
  its 
  bihamate 
  flesh-spicule 
  ; 
  and 
  I 
  have 
  ranged 
  it 
  (although 
  only 
  

   provisionally) 
  here 
  as 
  a 
  degraded 
  Desmacidine. 
  It 
  probably 
  owes 
  

   its 
  peculiar 
  form 
  to 
  its 
  mud-loving 
  habits. 
  Two 
  new 
  generic 
  types, 
  

   Gelliodes 
  and 
  lotrochnfa, 
  are 
  described 
  below. 
  

  

  RHIZOCHALINA. 
  

  

  Schmidt, 
  Atl. 
  Geb. 
  p. 
  3o. 
  

  

  Phloeodictyon, 
  Carter, 
  Ann. 
  8f 
  Mag. 
  Nat. 
  Hist. 
  1882, 
  x. 
  p. 
  122. 
  

  

  This 
  form 
  is 
  so 
  aberrant 
  in 
  its 
  coarser 
  anatomy 
  that 
  I 
  think 
  there 
  

   can 
  be 
  little 
  doubt 
  that 
  Carter 
  has 
  done 
  right 
  {I. 
  c.) 
  in 
  making 
  it 
  the 
  type 
  

   of 
  a 
  distinct 
  group, 
  although 
  we 
  have 
  as 
  yet 
  no 
  satisfactory 
  information 
  

   about 
  the 
  arrangement 
  and 
  structure 
  of 
  the 
  soft 
  parts. 
  Although 
  I 
  

   can 
  see 
  no 
  sufficient 
  reason 
  why 
  the 
  name 
  Oceanapia, 
  Norman, 
  should 
  

   give 
  way 
  to 
  the 
  above 
  names 
  for 
  such 
  species 
  as 
  Desmacidon 
  jeffrcysi, 
  

   Bowerbank, 
  whose 
  spicnlation 
  includes 
  a 
  bihamate, 
  yet 
  it 
  seems 
  

   not 
  undesirable 
  to 
  retain 
  the 
  older 
  of 
  the 
  two 
  for 
  those 
  which 
  have 
  

   simply 
  an 
  acerate 
  spicule. 
  With 
  regard 
  to 
  the 
  question 
  of 
  svste- 
  

  

  2e2 
  

  

  