﻿566 
  MR. 
  E. 
  A. 
  WALFORD 
  ON 
  SOME 
  BRYOZOA 
  EROM 
  THE 
  

  

  of 
  demarcation 
  between 
  the 
  two 
  genera. 
  The 
  series 
  to 
  be 
  subsequently 
  

   dealt 
  with 
  furnish 
  a 
  good 
  illustration 
  of 
  the 
  wide 
  variation 
  in 
  mode 
  

   of 
  growth 
  of 
  one 
  zocecial 
  type, 
  and 
  it 
  has 
  only 
  been 
  by 
  the 
  collection 
  

   of 
  a 
  large 
  number 
  of 
  examples 
  that 
  the 
  connecting-links 
  have 
  been 
  

   found. 
  Forms 
  of 
  considerable 
  difference 
  in 
  size 
  of 
  cell 
  and 
  aperture 
  

   are 
  seen 
  to 
  go 
  through 
  similar 
  phases 
  of 
  zoarial 
  growth, 
  so 
  that 
  one 
  

   cannot 
  do 
  otherwise 
  than 
  recognize 
  their 
  close 
  relationship. 
  Just 
  as 
  

   Prof. 
  Smitthas 
  shown 
  Tubulipora 
  incrassata, 
  d'Orb., 
  to 
  pass 
  through 
  

   the 
  stages 
  of 
  Stomatopora 
  and 
  Proboscina 
  to 
  that 
  of 
  Tubulipora, 
  so 
  I 
  

   shall 
  endeavour 
  to 
  demonstrate 
  the 
  stages 
  of 
  growth 
  of 
  one 
  type 
  

   from 
  Stowatojjora 
  to 
  Proboscina, 
  and 
  thence 
  to 
  Tubulipora 
  or 
  

   Diastopora. 
  Hincks 
  has 
  also 
  pointed 
  out 
  how 
  shadowy 
  are 
  the 
  

   distinctions 
  between 
  these 
  genera. 
  At 
  present, 
  however, 
  no 
  more 
  

   satisfactory 
  method 
  of 
  classification 
  seems 
  to 
  be 
  practicable 
  than 
  

   the 
  one 
  now 
  in 
  use 
  ; 
  hence 
  the 
  forms 
  will 
  be 
  placed 
  under 
  the 
  

   old 
  family 
  names, 
  but 
  with 
  a 
  uniform 
  specific 
  name. 
  

  

  The 
  group 
  for 
  illustration 
  is 
  figured 
  on 
  PL 
  XVII. 
  figs. 
  1, 
  2, 
  3, 
  7, 
  8, 
  

   and 
  PI. 
  XVIII. 
  figs. 
  10, 
  11, 
  12. 
  Its 
  earliest 
  stage 
  is 
  that 
  of 
  a, 
  Stoma- 
  

   topora 
  with 
  uniserial 
  zocecia 
  and 
  widely 
  dilated 
  margin 
  (PI. 
  XYIL 
  

   fig. 
  1), 
  merging 
  into 
  an 
  irregular 
  bi- 
  or 
  triserial 
  growth 
  (PI. 
  XVII. 
  

   figs. 
  2, 
  3). 
  The 
  anastomosing 
  of 
  the 
  branches 
  is 
  frequently 
  so 
  

   dense 
  as 
  to 
  produce 
  a 
  Diastopora-like 
  colony 
  (PI. 
  XYIL 
  fig. 
  8), 
  

   and 
  all 
  intermediate 
  phases 
  of 
  growth 
  are 
  met 
  with. 
  Such 
  

   colonies 
  are 
  frequently 
  recognizable 
  by 
  the 
  trailing 
  lines 
  of 
  the 
  

   branches 
  (PL 
  XVII. 
  fig. 
  7), 
  but 
  forms 
  occur 
  (PL 
  XVII. 
  fig. 
  8) 
  which 
  

   are 
  not 
  distinguishable 
  from 
  Blastopores 
  of 
  the 
  ordinary 
  discoid 
  

   growth. 
  When 
  the 
  zocecia 
  are 
  thus 
  massed 
  there 
  is 
  a 
  tendency 
  to 
  the 
  

   production 
  of 
  erect 
  branches, 
  as 
  shown 
  in 
  the 
  capitulum 
  on 
  the 
  colony 
  

   (PL 
  XVII. 
  fig. 
  7), 
  and 
  though 
  it 
  is 
  not 
  at 
  present 
  clear, 
  there 
  is 
  

   reason 
  to 
  suppose 
  that 
  the 
  form 
  subsequently 
  described 
  as 
  Entalopliora 
  

   magnipora 
  (PL 
  XIX. 
  figs. 
  11, 
  12) 
  may 
  be 
  the 
  erect 
  stage. 
  The 
  inter- 
  

   weaving 
  of 
  the 
  Stomatoporoid 
  branches 
  gives 
  rise 
  to 
  another 
  phase 
  

   of 
  growth 
  (PL 
  XVIII. 
  figs. 
  10, 
  11, 
  12), 
  Tubuliporoid, 
  and 
  it 
  will 
  be 
  

   seen 
  that 
  the 
  ventricose 
  forms 
  approach 
  T. 
  ventricosa, 
  Busk. 
  Con- 
  

   siderable 
  variability 
  is 
  also 
  met 
  with 
  in 
  the 
  shape 
  of 
  the 
  zocecia 
  : 
  some 
  

   are 
  cylindrical 
  throughout, 
  whilst 
  others 
  have 
  the 
  exsert 
  parts 
  conical, 
  

   or, 
  again, 
  they 
  may 
  be 
  leathern-bottle-shaped 
  (utriform). 
  The 
  

   dimensions 
  of 
  the 
  zocecia 
  in 
  width 
  vary 
  from 
  0*3 
  millim. 
  to 
  0*5 
  millim., 
  

   the 
  apertures 
  from 
  0-13 
  millim. 
  to 
  0-2 
  millim. 
  

  

  1. 
  Proboscina 
  spatiosa, 
  sp. 
  nov. 
  (PL 
  XVII. 
  figs. 
  1-3.) 
  

  

  Zocecial 
  length 
  1*16 
  to 
  0'5 
  millim., 
  width 
  0*5 
  to 
  0*7; 
  aperture 
  

   0-13 
  to 
  0-2. 
  

  

  Zoarium 
  adnate, 
  ramose, 
  varying 
  from 
  a 
  uniserial 
  to 
  an 
  irregular 
  

   bi-, 
  tri-, 
  or 
  multiserial 
  arrangement 
  of 
  zocecia, 
  the 
  branches 
  fre- 
  

   quently 
  anastomosing. 
  Zocecia 
  ranging 
  from 
  nearly 
  immersed 
  to 
  

   p 
  artially 
  free, 
  of 
  variable 
  shape, 
  cylindrical 
  or 
  somewhat 
  compressed, 
  

   the 
  free 
  part 
  conical 
  or 
  of 
  uniform 
  diameter, 
  though 
  more 
  rarely 
  the 
  

   whole 
  cell 
  is 
  leathern-bottle-shaped. 
  The 
  zocecia 
  have, 
  especially 
  in 
  

   the 
  uniserial 
  stage, 
  widely 
  dilated 
  bases. 
  ■ 
  Aperture 
  orbicular 
  or 
  

  

  