﻿54 
  0. 
  K. 
  VTNE 
  ON 
  THE 
  WENLOCK 
  POLYZOA. 
  

  

  only 
  a 
  mere 
  point 
  or 
  a 
  " 
  central 
  circular 
  depression 
  " 
  *. 
  Vesicles 
  

   fusiform, 
  or 
  tongue-like 
  ; 
  their 
  bases 
  connected 
  with 
  the 
  central 
  

   axis 
  by 
  hollow 
  filamentous 
  cords. 
  The 
  vesicles 
  are 
  rarely 
  simple, 
  

   as 
  shown 
  in 
  A. 
  radians, 
  Nich. 
  and 
  Eth., 
  but 
  are 
  in 
  most 
  cases 
  

   jointed 
  ; 
  and 
  these 
  bifurcate 
  at 
  intervals, 
  and 
  ultimately 
  pass 
  out- 
  

   wards 
  into 
  fine 
  cord-like 
  filaments, 
  which 
  may 
  or 
  may 
  not 
  connect 
  

   other 
  stellate 
  groups. 
  In 
  the 
  free 
  surfaces 
  of 
  some 
  of 
  the 
  vesicles 
  

   " 
  the 
  excessively 
  minute, 
  closely 
  approximated 
  pores 
  " 
  referred 
  to 
  

   by 
  Nicholson 
  in 
  his 
  description 
  of 
  his 
  type, 
  may 
  be 
  detected, 
  

   although 
  sometimes 
  with 
  difficulty, 
  in 
  the 
  Silurian 
  species 
  also. 
  

   Some 
  specimens 
  measured 
  across 
  the 
  centre 
  either 
  way 
  are 
  from 
  

   one 
  and 
  a 
  half 
  to 
  two 
  lines 
  ; 
  and 
  the 
  number 
  of 
  vesicles 
  to 
  each 
  

   rosette 
  varies 
  from 
  four 
  to 
  twelve. 
  

  

  Obs. 
  At 
  first 
  I 
  was 
  incliued 
  to 
  regard 
  this 
  species 
  as 
  a 
  variety 
  of 
  

   A. 
  radians, 
  Nich. 
  and 
  Eth. 
  In 
  working 
  out 
  the 
  details, 
  I 
  found 
  

   that 
  I 
  was 
  obliged 
  to 
  adopt 
  a 
  new 
  specific 
  name. 
  A. 
  radians 
  of 
  the 
  

   above 
  authors 
  is 
  a 
  typical 
  Scottish 
  Carboniferous 
  fossil 
  ; 
  and 
  although 
  

   some 
  of 
  the 
  specimens 
  from 
  different 
  localities 
  vary 
  in 
  facial 
  outline, 
  

   still 
  the 
  differences 
  between 
  the 
  Carboniferous 
  and 
  the 
  Silurian 
  spe- 
  

   cies 
  are 
  too 
  decided 
  in 
  character 
  to 
  be 
  lightly 
  passed 
  over. 
  The 
  

   rosettes 
  of 
  the 
  Carboniferous 
  forms 
  are 
  very 
  regularly 
  formed 
  round 
  a 
  

   central 
  axis 
  ; 
  the 
  rosettes 
  of 
  the 
  Silurian 
  species 
  are 
  very 
  irregularly 
  

   placed 
  ; 
  and 
  the 
  earlier 
  form 
  is 
  also 
  much 
  larger 
  than 
  the 
  species 
  

   described 
  by 
  Nicholson. 
  

  

  Localities. 
  Buildwas 
  beds, 
  36 
  and 
  38 
  of 
  the 
  collection 
  generally, 
  

   rarely 
  in 
  the 
  other 
  washings 
  from 
  these 
  beds. 
  Above 
  the 
  Buildwas 
  

   beds 
  I 
  have 
  found 
  but 
  few 
  minute 
  fragments 
  ; 
  in 
  all 
  probability 
  these 
  

   are 
  stray 
  specimens 
  from 
  either 
  36-38 
  or 
  40. 
  I 
  have 
  not 
  been 
  

   able 
  to 
  detect 
  in 
  these 
  washings 
  the 
  least 
  fragment 
  of 
  Ascodictyon 
  

   fusiforme, 
  Nich. 
  and 
  Eth. 
  The 
  anomalous 
  character 
  of 
  this 
  type 
  

   leads 
  me 
  to 
  suspect 
  that 
  the 
  species, 
  whatever 
  it 
  may 
  be, 
  is 
  not 
  an 
  

   Ascodictyon, 
  the 
  true 
  types 
  of 
  which 
  may 
  be 
  accepted, 
  extreme 
  

   though 
  they 
  be 
  in 
  individual 
  character, 
  as 
  A. 
  stellatum, 
  Nich. 
  and 
  

   Eth., 
  A. 
  radians, 
  Nich. 
  and 
  Eth., 
  and 
  the 
  new 
  type 
  described 
  

   above, 
  A. 
  radiciforme, 
  Vine. 
  We 
  have 
  these 
  typical 
  species 
  from 
  

   the 
  Silurian 
  Wenlock 
  Shales, 
  Shropshire, 
  the 
  Middle 
  Devonian 
  of 
  

   Ontario, 
  and 
  the 
  Carboniferous 
  Limestone 
  series 
  of 
  Scotland. 
  

  

  6. 
  Ascodictyon 
  filifokme. 
  

  

  I 
  cannot 
  help 
  putting 
  upon 
  record 
  this 
  name; 
  but 
  I 
  have 
  no 
  

   desire 
  to 
  establish 
  it 
  as 
  a 
  species. 
  On 
  several 
  fragments 
  of 
  shell, 
  on 
  

   stems 
  of 
  Encrinite, 
  and 
  in 
  some 
  rare 
  instances 
  on 
  other 
  organisms, 
  

   I 
  find 
  filamentous 
  threads 
  bisecting 
  other 
  threads, 
  the 
  points 
  of 
  

   bisection 
  in 
  some 
  cases 
  swelling 
  out. 
  There 
  is 
  in 
  this 
  a 
  biological 
  

   peculiarity 
  to 
  which 
  it 
  may 
  be 
  well 
  to 
  direct 
  attention 
  ; 
  and 
  I 
  cannot 
  

   do 
  this 
  better 
  than 
  by 
  giving 
  a 
  name 
  to 
  this 
  peculiarity, 
  so 
  as 
  to 
  

   individualize 
  the 
  type. 
  Otherwise 
  these 
  filamentous 
  cords 
  belong 
  

   to 
  the 
  species 
  of 
  Ascodictyon 
  described. 
  They 
  are 
  hollow; 
  but 
  a 
  

  

  * 
  Nich. 
  and 
  Eth. 
  Ann. 
  & 
  Mag. 
  Nat. 
  Hist. 
  1877, 
  vol. 
  xix. 
  p. 
  465. 
  

  

  