﻿G. 
  E. 
  VINE 
  ON 
  THE 
  WENLOCE 
  POLYZOA. 
  55 
  

  

  jIl 
  

  

  dark 
  line 
  occupies 
  the 
  place 
  of 
  the 
  life-pulp 
  

  

  which 
  passed 
  through 
  the 
  living 
  filament. 
  The 
  first 
  indication 
  of 
  a 
  

  

  n 
  

  

  vesicle 
  is 
  a 
  bulbous 
  projection 
  of 
  this 
  vital 
  cord, 
  • 
  

  

  For 
  reasons 
  already 
  given 
  *, 
  I 
  have 
  allowed 
  my 
  descriptions 
  of 
  

   Ascodictyon 
  to 
  follow 
  the 
  descriptions 
  of 
  Stomatopora. 
  Since 
  my 
  

   former 
  paper 
  was 
  written 
  I 
  have 
  examined 
  some 
  hundreds 
  of 
  speci- 
  

   mens 
  of 
  crinoid 
  stems 
  and 
  broken 
  shells, 
  more 
  or 
  less 
  incrusted 
  with 
  

   Ascodictyon 
  and 
  Stomatopora, 
  and 
  I 
  have 
  not 
  seen 
  any 
  thing 
  that 
  

   would 
  suggest 
  a 
  different 
  opinion 
  from 
  the 
  one 
  already 
  expressed. 
  

  

  Spieopoea, 
  Lamx. 
  

  

  1821. 
  Entalopliora, 
  Lamx. 
  

  

  1821. 
  Spiropora, 
  Lamx. 
  

  

  1834. 
  Pustulipora 
  (pars), 
  Blainville. 
  

  

  The 
  desire 
  on 
  the 
  part 
  of 
  Mr. 
  Hincks 
  t 
  and 
  Prof. 
  Brauns 
  t 
  to 
  

   return 
  to 
  original 
  descriptions 
  rather 
  than 
  adopt 
  some 
  one 
  or 
  other 
  

   of 
  the 
  synonyms 
  which 
  are 
  of 
  later 
  date 
  is 
  to 
  be 
  commended. 
  It 
  

   may 
  be 
  justifiable 
  to 
  adopt 
  for 
  recent 
  species 
  the 
  genus 
  Entalopliora 
  ; 
  

   but 
  in 
  dealing 
  with 
  fossil 
  types, 
  there 
  are 
  many 
  species 
  that 
  could 
  

   not 
  be 
  conveniently 
  placed 
  under 
  that 
  name. 
  The 
  genus 
  Spiropora 
  

   has 
  been 
  very 
  appropriately 
  used 
  by 
  both 
  Jules 
  Haime 
  and 
  Prof. 
  

   Eeuss 
  in 
  their 
  works 
  on 
  the 
  Jurassic 
  and 
  Eocene 
  Bryozoa. 
  Both 
  these 
  

   authors 
  limit 
  the 
  genus 
  to 
  species 
  which 
  show 
  a 
  peculiar 
  spiral 
  arrange- 
  

   ment 
  of 
  cells, 
  independent 
  of 
  the 
  fact 
  that 
  all 
  three 
  of 
  the 
  genera 
  

   whose 
  names 
  are 
  placed 
  above 
  have 
  tubular 
  cells 
  which 
  open 
  on 
  all 
  

   sides. 
  In 
  like 
  manner 
  I 
  limit 
  the 
  genus 
  for 
  a 
  verj' 
  unique 
  palaeozoic 
  

   type 
  of 
  Polyzoa 
  which 
  had 
  a 
  very 
  wide 
  range 
  in 
  Silurian 
  times. 
  

  

  7. 
  Spieopoea 
  regulaeis, 
  sp. 
  n. 
  (Pigs. 
  4, 
  5, 
  6.) 
  

  

  Zoarium 
  erect, 
  dichotomous, 
  branches 
  rarely 
  exceeding 
  half 
  a 
  

   line 
  in 
  breadth. 
  In 
  its 
  earliest 
  stages 
  the 
  zoarium 
  is 
  attached 
  by 
  

   a 
  disk-like 
  base 
  to 
  some 
  foreign 
  object. 
  Zocecia 
  very 
  regularly 
  

   disposed, 
  spirally, 
  round 
  the 
  whole 
  stem 
  and 
  branches, 
  on 
  the 
  main 
  

   stem 
  in 
  alternate 
  rows. 
  The 
  normal 
  condition 
  is 
  for 
  the 
  zocecia 
  

   to 
  be 
  slightly 
  conical 
  and 
  covered 
  with 
  a 
  delicate 
  chalky 
  crust 
  ; 
  this, 
  

   however, 
  is 
  rarely 
  preserved. 
  When 
  worn, 
  the 
  walls 
  of 
  the 
  cells 
  are 
  

   exposed 
  ; 
  and 
  in 
  this 
  condition 
  the 
  spirals 
  are 
  better 
  shown. 
  It 
  is 
  

   then 
  seen 
  that 
  every 
  alternate 
  cell, 
  for 
  half 
  its 
  length, 
  is 
  so 
  far 
  

   separated 
  from 
  its 
  neighbour 
  as 
  to 
  allow 
  the 
  half 
  of 
  the 
  alternate 
  

   cell 
  above 
  to 
  pass 
  down 
  and 
  occupy 
  the 
  space 
  thus 
  left 
  vacant 
  ; 
  at 
  the 
  

   base 
  of 
  each 
  cell 
  a 
  small 
  secondary 
  opening 
  is 
  thus 
  exposed. 
  Aper- 
  

   ture 
  round 
  ; 
  peristome 
  slightly 
  raised 
  in 
  some 
  cases. 
  Two 
  cells 
  

   occupy 
  the 
  space 
  of 
  a 
  line 
  in 
  a 
  longitudinal 
  direction 
  ; 
  from 
  five 
  

   to 
  eight 
  cells 
  are 
  found 
  on 
  the 
  whole 
  circumference 
  of 
  the 
  stem 
  ; 
  and 
  

   they 
  vary 
  in 
  number 
  on 
  the 
  branches. 
  

  

  * 
  " 
  Silurian 
  Uniserial 
  Stomatoporae," 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  Not. 
  1881. 
  

  

  t 
  Brit. 
  Mar. 
  Polyzoa. 
  

  

  X 
  ' 
  Die 
  Bryozoen 
  des 
  mittleren 
  Jura 
  &c. 
  von 
  Metz,' 
  D. 
  Brauns, 
  1879. 
  

  

  