﻿OF 
  THE 
  WENLOCK 
  SHALES. 
  383 
  

  

  the 
  matrix 
  seen 
  in 
  nibbed 
  specimens 
  is 
  the 
  contents 
  of 
  the 
  rounded 
  

   hollow 
  annular 
  layers 
  of 
  growth 
  of 
  the 
  tube. 
  A 
  very 
  close 
  corre- 
  

   spondence 
  therefore 
  exists 
  between 
  this 
  ancient 
  type 
  of 
  Tubicolar 
  

   Annelid 
  and 
  a 
  similar 
  one 
  dredged 
  from 
  the 
  .Bay 
  of 
  Naples 
  (50 
  

   fathoms), 
  picked 
  out 
  from 
  material 
  sent 
  to 
  me 
  by 
  Mr. 
  A. 
  W. 
  Waters, 
  

   F.G.S. 
  The 
  recent 
  species 
  is 
  not 
  much 
  longer 
  than 
  0. 
  Nicholsoni, 
  

   but 
  it 
  reveals 
  the 
  structure 
  of 
  the 
  annular 
  layers 
  very 
  satisfactorily 
  ; 
  

   and 
  one 
  of 
  my 
  specimens 
  is 
  attached 
  by 
  its 
  proximal 
  end 
  to 
  a 
  frag- 
  

   ment 
  of 
  shell, 
  but 
  the 
  point 
  of 
  attachment 
  is 
  covered 
  by 
  a 
  small 
  

   colony 
  of 
  Cellepora 
  ; 
  the 
  rest 
  of 
  the 
  tube 
  is 
  free. 
  

  

  Genus 
  Oetonia, 
  Nicholson. 
  

  

  Ortonia, 
  Nicholson, 
  Geol. 
  Mag. 
  1872. 
  Type 
  0. 
  conica, 
  Nich., 
  

   Silurian. 
  

  

  Ortonia, 
  Nicholson, 
  Geol. 
  Mag. 
  1873. 
  Sp. 
  0. 
  minor, 
  Nich., 
  

   Silurian. 
  

  

  Ortonia, 
  Nicholson, 
  Geol. 
  Mag. 
  1874. 
  Sp. 
  0. 
  intermedia, 
  Nich., 
  

   Devonian. 
  

  

  This 
  genus 
  was 
  originally 
  founded 
  by 
  Prof. 
  Nicholson 
  for 
  the 
  

   first 
  of 
  the 
  three 
  species 
  named 
  above. 
  Ortonia 
  conica 
  is 
  of 
  a 
  cellu- 
  

   lar 
  character 
  along 
  the 
  plane 
  opposite 
  to 
  the 
  plane 
  of 
  attachment. 
  

   The 
  other 
  species 
  are 
  somewhat 
  different 
  from 
  the 
  original 
  0. 
  conica 
  ; 
  

   and 
  upon 
  the 
  publication 
  of 
  the 
  characters 
  and 
  figures 
  of 
  0. 
  minor 
  

   Mr. 
  John 
  Young, 
  of 
  Glasgow, 
  published 
  in 
  the 
  ' 
  Geological 
  Magazine,' 
  

   1874, 
  his 
  description 
  of 
  Ortonia 
  carhonaria 
  * 
  of 
  the 
  Carboniferous 
  

   formation 
  of 
  Scotland 
  as 
  nearly 
  identical 
  with 
  0. 
  minor. 
  I 
  can 
  now 
  

   add 
  to 
  our 
  British 
  Silurian 
  fauna 
  at 
  least 
  two 
  types 
  of 
  this 
  genus 
  

   from 
  the 
  Wenlock 
  Shales. 
  

  

  4. 
  Oetonia 
  conica, 
  Nicholson. 
  

  

  Ortonia 
  conica, 
  Nicholson 
  (type), 
  Geol. 
  Mag. 
  1872. 
  

  

  Var. 
  pseudo-pttnctata, 
  n. 
  var. 
  (Plate 
  XV. 
  fig. 
  3.) 
  

  

  Tube 
  solitary, 
  slightly 
  flexuous, 
  adherent 
  to 
  stems 
  of 
  Crinoids 
  ; 
  

   average 
  length 
  about 
  two 
  lines. 
  Along 
  the 
  plane 
  opposite 
  to 
  the 
  

   attached 
  side 
  are 
  apparently 
  minute 
  punctures, 
  corresponding 
  to 
  

   the 
  punctured 
  surface 
  of 
  the 
  type 
  species. 
  Walls 
  of 
  tube 
  compara- 
  

   tively 
  thick 
  ; 
  mouth 
  or 
  orifice 
  small. 
  Attached 
  by 
  lateral 
  annula- 
  

   tions. 
  In 
  one 
  specimen, 
  two 
  lines 
  in 
  length, 
  there 
  are 
  sixteen 
  rings, 
  

   most 
  of 
  which 
  are 
  prolonged 
  laterally. 
  

  

  Loc. 
  Buildwas 
  beds, 
  22 
  and 
  38. 
  

  

  This 
  variety 
  is 
  better 
  preserved 
  in 
  no. 
  22 
  than 
  in 
  no. 
  38. 
  It 
  is 
  

   very 
  rare, 
  however, 
  in 
  the 
  first-named 
  washing, 
  but 
  rather 
  more 
  

   abundant 
  in 
  the 
  last. 
  It 
  has, 
  as 
  will 
  be 
  seen 
  by 
  the 
  description, 
  

   many 
  of 
  the 
  characters 
  of 
  the 
  species 
  ; 
  the 
  most 
  marked 
  differences 
  

   are 
  the 
  size 
  and 
  the 
  punctations 
  of 
  the 
  surface. 
  

  

  * 
  I 
  have 
  a 
  fine 
  series 
  of 
  this 
  type 
  in 
  my 
  cabinet, 
  which 
  has 
  been 
  a 
  very 
  great 
  

   help 
  to 
  me 
  in 
  the 
  study 
  of 
  the 
  Silurian 
  species. 
  

  

  