﻿72 
  PKOF. 
  P. 
  M. 
  DUNCAN 
  ON 
  THE 
  GENUS 
  STOLICZKARIA. 
  

  

  separate, 
  circular 
  or 
  stellate 
  structures 
  surrounded 
  by 
  a 
  dense 
  tabu- 
  

   lation, 
  which 
  may 
  be 
  convoluted 
  here 
  and 
  there. 
  

  

  The 
  circular 
  structures 
  are 
  continuations 
  of 
  the 
  granulations 
  ; 
  or 
  

   rather 
  the 
  granulations 
  are 
  the 
  ends 
  of 
  the 
  circular 
  systems. 
  In 
  the 
  

   section 
  the 
  central 
  space 
  of 
  each 
  system 
  is 
  occupied 
  by 
  from 
  four 
  to 
  

   six 
  or 
  seven 
  small 
  tube-openings 
  and 
  by 
  clear 
  calcite. 
  These 
  small 
  

   tubes, 
  the 
  terminal 
  openings 
  of 
  which 
  are 
  seen 
  on 
  the 
  tops 
  of 
  the 
  

   granulations, 
  are 
  about 
  y^, 
  inch 
  in 
  diameter. 
  They 
  are 
  connected 
  

   together 
  by 
  a 
  few 
  small 
  tubules 
  which 
  stretch 
  across 
  the 
  space 
  now 
  

   filled 
  with 
  calcite 
  ; 
  and 
  they 
  also 
  give 
  forth 
  tubes 
  which 
  open 
  into 
  

   geniculate 
  or 
  elongated 
  processes 
  of 
  the 
  larger 
  tubes 
  of 
  the 
  inter- 
  

   radial 
  series 
  environing 
  them. 
  The 
  surrounding, 
  large, 
  inter 
  radial 
  

   tribulation 
  is 
  very 
  distinct 
  ; 
  and 
  the 
  circular 
  openings 
  produced 
  by 
  

   sections 
  of 
  the 
  tubes 
  are 
  from 
  y4- 
  - 
  to 
  y^- 
  inch 
  across. 
  Outside 
  of 
  

   the 
  circular 
  ring 
  of 
  the 
  system 
  is 
  a 
  mass 
  of 
  these 
  tube-openings 
  and 
  

   tube-bendings 
  ; 
  and 
  the 
  tubes 
  communicate 
  with 
  larger 
  long 
  and 
  

   short 
  tubes 
  and 
  with 
  those 
  forming 
  the 
  circular 
  ring. 
  The 
  sections 
  

   of 
  some 
  of 
  the 
  tubes 
  of 
  this 
  circular 
  ring 
  present 
  a 
  flask-shaped 
  

   outline, 
  the 
  projection 
  being 
  inwards, 
  and 
  it 
  ends 
  in 
  a 
  tube 
  which 
  

   joins 
  a 
  small 
  inner 
  tube 
  of 
  the 
  radial 
  series. 
  (Plate 
  II. 
  fig. 
  2.) 
  

  

  lladial 
  sections 
  present 
  a 
  totally 
  different 
  appearance. 
  Made 
  close 
  

   to 
  the 
  surface 
  and 
  implicating 
  rows 
  of 
  the 
  projections, 
  the 
  small 
  

   tabulation, 
  distant 
  and 
  surrounded 
  by 
  calcite, 
  is 
  noticed 
  to 
  run 
  up 
  

   in 
  a 
  radial 
  direction 
  through 
  the 
  body 
  into 
  the 
  middle 
  of 
  the 
  

   projections. 
  This 
  radial 
  system 
  of 
  tubes 
  is 
  very 
  distinct 
  ; 
  and 
  on 
  

   either 
  side 
  are 
  the 
  much 
  larger 
  tubes, 
  either 
  straight 
  in 
  their 
  

   course 
  or 
  greatly 
  convoluted, 
  close, 
  inosculating 
  and 
  bifurcating 
  fre- 
  

   quently. 
  These 
  tubes 
  form 
  the 
  wide 
  interradial 
  systems, 
  and 
  reach 
  

   the 
  surface, 
  some 
  on 
  the 
  flanks 
  of 
  the 
  projections, 
  and 
  others 
  on 
  the 
  

   intermediate 
  surface. 
  (Plate 
  II. 
  figs. 
  3, 
  4, 
  5.) 
  

  

  The 
  radial 
  direction 
  of 
  each 
  individual 
  interradial 
  tube 
  is 
  most 
  

   distinct 
  near 
  the 
  surface. 
  

  

  Eadial 
  sections 
  made 
  nearly 
  halfway 
  through 
  the 
  fossil 
  show 
  

   this 
  same 
  repetition 
  of 
  radial 
  and 
  interradial 
  parts. 
  The 
  general 
  

   appearance 
  is 
  of 
  numbers 
  of 
  radii 
  of 
  minute 
  tubes 
  surrounded 
  by 
  

   wider 
  radii 
  of 
  large 
  and 
  contorted 
  tubes, 
  the 
  radii, 
  of 
  course, 
  con- 
  

   verging 
  to 
  the 
  centre. 
  

  

  It 
  is 
  evident 
  that 
  the 
  tubes 
  of 
  all 
  kinds 
  increase 
  in 
  number 
  from 
  

   the 
  centre 
  to 
  the 
  circumference 
  of 
  the 
  body 
  by 
  frequently 
  repeated 
  

   bifurcation 
  ; 
  and 
  hence 
  the 
  number 
  of 
  systems 
  increases. 
  

  

  The 
  tubes 
  are 
  bent, 
  often 
  at 
  right 
  angles, 
  and 
  sometimes 
  seem 
  to 
  

   terminate 
  in 
  blind 
  ends 
  ; 
  but 
  there 
  is 
  always 
  a 
  connexion 
  close 
  by 
  

   with 
  a 
  neighbouring 
  tube. 
  The 
  radial 
  and 
  interradial 
  tubes 
  are 
  well 
  

   separated 
  throughout 
  ; 
  but 
  occasionally 
  a 
  large 
  tube 
  transgresses 
  on 
  

   the 
  central 
  space, 
  and 
  some 
  small 
  radial 
  tubes 
  are 
  double 
  their 
  

   normal 
  size. 
  (Plate 
  II. 
  figs. 
  4, 
  5.) 
  

  

  The 
  continuity 
  of 
  the 
  tubes 
  from 
  the 
  centre 
  to 
  the 
  circumference 
  

   is 
  undoubted. 
  Clear 
  or 
  slightly 
  coloured 
  calcite 
  is 
  seen 
  between 
  the 
  

   tubes 
  ; 
  but 
  it 
  is 
  structureless, 
  and 
  no 
  ccenenchyma 
  appears 
  to 
  have 
  

   existed. 
  The 
  structure 
  of 
  the 
  tube-wall 
  is 
  very 
  minutely 
  granular, 
  and 
  

  

  