﻿498 
  Mr. 
  J. 
  W. 
  Gregory 
  on 
  Zeuglopleurus. 
  

  

  tion 
  the 
  anus 
  can 
  be 
  seen 
  above 
  the 
  unpaired 
  basal, 
  whereas 
  

   in 
  Z. 
  costulatus 
  it 
  is 
  then 
  hidden. 
  

  

  3. 
  Zeuglopleurus 
  (?) 
  cannabis 
  (Des.), 
  185S. 
  

  

  18-58. 
  Glyphocyphus 
  cannabis, 
  Decor, 
  Syn. 
  p. 
  4-50. 
  

  

  1864. 
  Glyphocyphus 
  cannabis, 
  Cott., 
  Pal. 
  Franc. 
  Terr. 
  Cre"t. 
  t. 
  vii. 
  

   p. 
  545.' 
  

  

  1865. 
  Glyphocyphus 
  cannabis, 
  Cott., 
  fitudea 
  sur 
  les 
  kchinides 
  fossiles 
  

   du 
  dtSpartement 
  de 
  l'Yonne, 
  feuille 
  16, 
  pp. 
  232, 
  233 
  (footnote). 
  

  

  This 
  species, 
  briefly 
  described 
  by 
  Desor 
  in 
  the 
  appendix 
  to 
  

   his 
  ' 
  Synopsis,' 
  has 
  never 
  since 
  been 
  met 
  with. 
  Cotteau 
  

   retains 
  it 
  on 
  Desor's 
  authority 
  in 
  the 
  * 
  Paleontologie 
  Fran- 
  

   chise,' 
  but 
  merely 
  quotes 
  the 
  founder's 
  description 
  ; 
  and 
  he 
  

   again 
  refers 
  to 
  it 
  in 
  the 
  l 
  Ech. 
  Fossiles 
  de 
  l'Yonne.' 
  The 
  

   specific 
  diagnosis 
  is 
  that 
  " 
  the 
  tubercles 
  are 
  less 
  conjugate 
  ; 
  

   the 
  apical 
  system 
  is 
  also 
  less 
  annular." 
  The 
  latter 
  character 
  

   renders 
  it 
  probable 
  that 
  the 
  apical 
  system 
  was 
  as 
  in 
  Zeuglo- 
  

   pleurus 
  ; 
  but 
  if 
  so, 
  the 
  former 
  will 
  readily 
  distinguish 
  it 
  from 
  

   Z. 
  costulatus. 
  

  

  The 
  Affinities 
  and 
  Differences 
  of 
  the 
  Genus 
  Zeuglopleurus. 
  

   — 
  The 
  two 
  nearest 
  allies 
  of 
  Zeuglopleurus 
  are 
  its 
  contempo- 
  

   raries 
  Glyphocyphus 
  and 
  Echinocyphus. 
  The 
  main 
  features 
  

   that 
  ally 
  it 
  to 
  the 
  former 
  are 
  the 
  deep 
  grooves 
  under 
  the 
  

   tubercles, 
  and 
  the 
  resemblance 
  of 
  the 
  epistroma, 
  the 
  general 
  

   facies 
  of 
  which 
  is 
  the 
  same, 
  though 
  differing 
  in 
  details. 
  It 
  is, 
  

   however, 
  clearly 
  distinguished 
  from 
  this 
  genus 
  by 
  the 
  imper- 
  

   forate 
  nature 
  of 
  the 
  mamelons 
  and 
  by 
  the 
  fact 
  that 
  only 
  two 
  of 
  

   the 
  radials 
  enter 
  the 
  anal 
  ring 
  (fig. 
  6). 
  To 
  Echinocyphus 
  it 
  is 
  

   probably 
  nearer, 
  though 
  its 
  general 
  appearance 
  is 
  more 
  dis- 
  

   similar 
  ; 
  it 
  agrees 
  in 
  the 
  non-perforation 
  of 
  the 
  tubercles 
  ; 
  from 
  

   it, 
  however, 
  it 
  is 
  distinguished 
  by 
  the 
  absence 
  of 
  the 
  hori- 
  

   zontal 
  regular 
  sutural 
  furrows, 
  which 
  are 
  replaced 
  by 
  fossettes, 
  

   by 
  a 
  much 
  greater 
  development 
  of 
  epistroma, 
  and 
  by 
  the 
  struc- 
  

   ture 
  of 
  the 
  apical 
  disk 
  (tig. 
  7), 
  which 
  is 
  oval 
  in 
  Zeuglopleurus 
  

   and 
  subpentagonal 
  in 
  Echinocyphus 
  ; 
  in 
  the 
  latter, 
  moreover, 
  

   the 
  postero-lateral 
  as 
  well 
  as 
  the 
  antero-lateral 
  basals 
  unite 
  

   across 
  the 
  middle 
  of 
  the 
  apical 
  disk, 
  and 
  there 
  form 
  a 
  basal 
  

   mass 
  that 
  pushes 
  the 
  periproct 
  far 
  posteriorly. 
  Another 
  

   genus 
  to 
  which 
  Zeuglopleurus 
  is 
  allied 
  is 
  Dictyopleurus, 
  Dune. 
  

   & 
  Slad. 
  *, 
  from 
  the 
  Eocene 
  of 
  Sind, 
  in 
  which 
  the 
  apical 
  

  

  * 
  Duncan 
  and 
  Sladen, 
  ' 
  Palreontologia 
  Indica,' 
  ser. 
  xiv. 
  vol. 
  i. 
  pt. 
  3, 
  

   fasc. 
  ii. 
  : 
  " 
  The 
  Fossil 
  Ecbihoidea 
  from 
  the 
  Ranikot 
  Series 
  of 
  Nummu- 
  

   litic 
  Strata 
  in 
  W. 
  Sind 
  ' 
  (London, 
  1882), 
  p. 
  38, 
  pi. 
  ix. 
  fig. 
  2. 
  

  

  