﻿PEOE. 
  P. 
  M. 
  DUNCAN 
  ON 
  THE 
  GENUS 
  STOLICZEAEIA. 
  73 
  

  

  is 
  of 
  carbonate 
  of 
  lime. 
  A 
  slight 
  organic 
  residue 
  is 
  left 
  after 
  treating 
  

   with 
  strong 
  hydrochloric 
  acid 
  ; 
  and 
  a 
  ferric 
  oxide 
  is 
  also 
  present. 
  

  

  Here 
  and 
  there 
  only, 
  and 
  not 
  universally, 
  interspaces 
  occur. 
  They 
  

   are 
  elongate, 
  narrow, 
  almost 
  structureless 
  parts 
  ; 
  and 
  they 
  occur 
  in 
  

   the 
  position 
  elsewhere 
  occupied 
  by 
  the 
  small 
  radial 
  tubes 
  or 
  in 
  that 
  

   of 
  the 
  interradial 
  tubes. 
  

  

  Some 
  of 
  these 
  spaces 
  are 
  filled 
  with 
  drusy-looking 
  carbonate 
  of 
  

   lime, 
  which 
  polarizes 
  well 
  ; 
  and 
  others 
  contain 
  towards 
  the 
  centre 
  of 
  

   the 
  whole 
  body 
  a 
  projection 
  which 
  resembles 
  broken-down 
  tubes. 
  

   In 
  some 
  there 
  are 
  indications 
  of 
  tubes 
  passing 
  along 
  the 
  sides 
  of 
  the 
  

   space. 
  

  

  The 
  height 
  of 
  the 
  body 
  of 
  the 
  type 
  is 
  2^ 
  inches, 
  and 
  the 
  breadth 
  

   is 
  nearly 
  3 
  inches. 
  

  

  In 
  comparing 
  this 
  form 
  with 
  Parkeria, 
  it 
  is 
  necessary 
  to 
  consider 
  

   the 
  anatomical 
  characters 
  given 
  by 
  Carpenter 
  and 
  Brady 
  of 
  the 
  in- 
  

   teresting 
  fossils 
  from 
  the 
  Cretaceous 
  rocks. 
  For 
  in 
  external 
  appear- 
  

   ance 
  (but 
  not 
  in 
  structure) 
  the 
  Syringosphseridse 
  resemble 
  the 
  genus 
  

   Parkeria. 
  The 
  spherical 
  and 
  spheroidal 
  shapes 
  are 
  common 
  to 
  both 
  

   groups; 
  and 
  so 
  are 
  the 
  granulate, 
  plain 
  and 
  mulberry-like 
  outer 
  

   configurations. 
  

  

  InParkeria 
  there 
  are 
  a 
  radial 
  series 
  of 
  large 
  and 
  often 
  solitary 
  tubes, 
  

   a 
  system 
  of 
  interspaces 
  in 
  concentric 
  series, 
  and 
  a 
  labyrinthic 
  struc- 
  

   ture 
  of 
  irregularly 
  shaped 
  chamberlets 
  communicating 
  with 
  each 
  

   other 
  and 
  cancellous 
  in 
  appearance, 
  and 
  occasionally 
  simulating 
  short 
  

   tubes. 
  

  

  The 
  interspaces 
  are 
  traversed 
  by 
  one 
  or 
  more 
  large 
  radial 
  tubes 
  ; 
  

   and 
  the 
  floor 
  of 
  each 
  interspace 
  towards 
  the 
  centre 
  of 
  the 
  body 
  is 
  

   made 
  up 
  of 
  the 
  minute 
  chamberlet 
  structure, 
  the 
  openings 
  of 
  which 
  

   communicate 
  with 
  the 
  interspace 
  beyond, 
  but 
  not 
  with 
  that 
  

   nearer 
  the 
  centre. 
  The 
  labyrinthic 
  structure 
  sometimes 
  stretches 
  

   across 
  the 
  interspaces, 
  and 
  in 
  many 
  places 
  forms 
  a 
  layer 
  around 
  the 
  

   radial 
  tubes. 
  These 
  tubes 
  open 
  at 
  their 
  sides, 
  and 
  communicate 
  

   with 
  the 
  labyrinthiform 
  chamberlets 
  of 
  the 
  lamellae 
  forming 
  the 
  floor 
  

   and 
  roof 
  of 
  the 
  interspaces, 
  and 
  are 
  much 
  larger 
  in 
  their 
  calibre 
  than 
  

   the 
  chamberlets 
  which 
  may 
  here 
  and 
  there 
  cover 
  them. 
  

  

  There 
  is 
  therefore 
  a 
  defective 
  continuity, 
  from 
  the 
  centre 
  of 
  the 
  

   body 
  to 
  the 
  circumference, 
  of 
  radial 
  tubes, 
  and 
  also 
  a 
  labyrinthic 
  

   structure 
  of 
  a 
  cellular 
  and 
  semitubular 
  character. 
  

  

  The 
  distinctnessof 
  the 
  morphology 
  of 
  the 
  two 
  genera 
  Stoliczkaria 
  

   and 
  ParJceria 
  is 
  therefore 
  evident. 
  

  

  The 
  only 
  parts 
  which 
  are 
  analogous 
  in 
  position 
  are 
  the 
  radial 
  tubes 
  

   and 
  the 
  interspaces. 
  

  

  The 
  important 
  labyrinthic 
  structure 
  is 
  wanting 
  in 
  the 
  Indian 
  

   forms. 
  

  

  AVith 
  regard 
  to 
  the 
  radial 
  tubes, 
  they 
  are 
  minute 
  and 
  numerous 
  

   and 
  in 
  systems 
  in 
  Stoliczkaria, 
  and 
  are 
  surrounded 
  by 
  interradial 
  

   tubes, 
  which 
  are 
  larger 
  and 
  which 
  are 
  greatly 
  convoluted 
  but 
  ever 
  

   tubular. 
  In 
  ParTceria 
  the 
  radial 
  tubes 
  are 
  comparatively 
  few 
  in 
  

   number, 
  one 
  exists 
  by 
  itself, 
  and 
  there 
  is 
  no 
  accompanying 
  tube- 
  

   structure 
  like 
  that 
  of 
  StoIiczJcaria. 
  The 
  labyrinthic 
  cells, 
  assuming 
  

  

  