﻿XVIII 
  LIST 
  OF 
  ILLUSTRATIONS 
  

  

  Facing 
  page 
  

  

  36. 
  Diplocava 
  incondita, 
  new 
  species. 
  A. 
  Longitudinal 
  section, 
  X 
  16, 
  

  

  through 
  a 
  specimen 
  with 
  two 
  joined 
  branches. 
  B. 
  Longitudinal 
  

   section, 
  X 
  16, 
  through 
  the 
  extremity 
  of 
  a 
  branch 
  in 
  which 
  the 
  tubes 
  

   have 
  facettes. 
  The 
  walls 
  are 
  hollow 
  and 
  moniliform. 
  Lower 
  Cre- 
  

   taceous 
  (Valangian) 
  : 
  Sainte-Croix, 
  Switzerland 
  72 
  

  

  37. 
  Diplocava 
  inordinata, 
  new 
  species. 
  Longitudinal 
  section, 
  X 
  16, 
  ex- 
  

  

  hibiting 
  the 
  variations 
  in 
  diameter 
  of 
  the 
  tubes 
  at 
  their 
  extremity. 
  

   Lower 
  Cretaceous 
  (Valangian): 
  Sainte-Croix, 
  Switzerland 
  73 
  

  

  38. 
  Diplocava 
  globulosa, 
  new 
  species. 
  A. 
  Meridian 
  section, 
  X 
  16, 
  show- 
  

  

  ing 
  the 
  many 
  enveloping 
  lamellae. 
  B. 
  Tangential 
  thin 
  section, 
  X 
  

   16. 
  Dimorphism 
  occurs. 
  Lower 
  Cretaceous 
  (Valangian) 
  : 
  Sainte- 
  

   Croix, 
  Switzerland 
  74 
  

  

  39. 
  Genus 
  Leiosoecia 
  Canu 
  and 
  Bassler, 
  1920. 
  A-B. 
  Leiosoecia 
  proxima, 
  

  

  new 
  species. 
  A. 
  Longitudinal 
  section, 
  X 
  16, 
  through 
  a 
  specimen 
  

   with 
  an 
  extra 
  lamellar 
  layer. 
  B. 
  Transverse 
  section, 
  X 
  16, 
  of 
  the 
  

   same 
  specimen. 
  Lower 
  Cretaceous 
  (Valangian) 
  : 
  Sainte-Croix, 
  

   Switzerland. 
  C. 
  Leiosoecia 
  aequiporosa, 
  new 
  species. 
  Transverse 
  

   thin 
  section, 
  X 
  16. 
  Lower 
  Cretaceous. 
  D. 
  Leiosoecia 
  grandi- 
  

   pora, 
  new 
  species. 
  Longitudinal 
  thin 
  section, 
  X 
  16, 
  showing 
  the 
  

   rarity 
  of 
  mesopores. 
  Lower 
  Cretaceous 
  (Valangian) 
  : 
  Sainte-Croix, 
  

   Switzerland 
  76 
  

  

  40. 
  Leiosoecia 
  constanti 
  D'Orbigny, 
  1850. 
  A. 
  Longitudinal 
  section, 
  X 
  16, 
  

  

  showing 
  the 
  zonal 
  lines 
  and 
  the 
  undulated 
  tubes 
  with 
  their 
  dia- 
  

   phragms. 
  B. 
  Portion 
  of 
  a 
  transverse 
  section, 
  X 
  16, 
  illustrating 
  

   the 
  polygonal 
  form 
  of 
  the 
  tubes. 
  Lower 
  Cretaceous 
  (Valangian) 
  : 
  

   Sainte-Croix, 
  Switzerland 
  78 
  

  

  41. 
  Clausa 
  zonifera, 
  new 
  species. 
  A. 
  Longitudinal 
  section, 
  X 
  16. 
  The 
  

  

  dactylethrae 
  are 
  produced 
  by 
  dichotomous 
  branching 
  of 
  the 
  walls 
  

   (peripheral 
  gemmation). 
  B. 
  Transverse 
  section, 
  X 
  16. 
  The 
  dis- 
  

   persion 
  of 
  the 
  small 
  tubes 
  among 
  the 
  large 
  ones 
  show 
  that 
  gemma- 
  

   tion 
  occurs 
  at 
  all 
  distances 
  from 
  the 
  central 
  axis 
  by 
  regular 
  periph- 
  

   eral 
  dichotomous 
  branching. 
  Lower 
  Cretaceous 
  (Aptian) 
  : 
  Faring- 
  

   don, 
  England 
  80 
  

  

  42. 
  Tretocycloecia 
  densa, 
  new 
  species. 
  A, 
  B. 
  Longitudinal 
  sections, 
  X 
  16. 
  

  

  The 
  mesopores 
  are 
  almost 
  closed 
  by 
  thick 
  tissue. 
  Lower 
  Cretaceous 
  

   (Aptian): 
  Faringdon, 
  England 
  83 
  

  

  43. 
  Laierocavea 
  dutempleana 
  D'Orbigny, 
  1853. 
  A. 
  Meridian 
  section, 
  X 
  16, 
  

  

  through 
  a 
  growing 
  branch, 
  showing 
  the 
  lozenge-shaped 
  areas. 
  B. 
  

   Longitudinal 
  section, 
  X 
  16, 
  with 
  an 
  accessory 
  exterior 
  lamella 
  at 
  

   the 
  left. 
  C. 
  Meridian 
  section, 
  X 
  16, 
  showing 
  mesopores 
  only 
  in 
  

   the 
  lateral 
  faces. 
  D. 
  Transverse 
  section, 
  X 
  16, 
  through 
  a 
  normal 
  

   branch. 
  E. 
  Longitudinal 
  section, 
  X 
  16, 
  illustrating 
  the 
  cylindrical 
  

   tubes 
  with 
  triparietal 
  gemmation 
  around 
  a 
  central 
  tube. 
  Lower 
  

   Cretaceous 
  (Aptian) 
  : 
  Faringdon, 
  England 
  84 
  

  

  44. 
  Genus 
  Siphodiclyum 
  Lonsdale, 
  1849. 
  A-E. 
  Siphodictyum 
  irregidare, 
  

  

  new 
  species. 
  A. 
  Transverse 
  section, 
  X 
  16, 
  showing 
  the 
  polygonal 
  

   tubes. 
  B. 
  Another 
  transverse 
  section, 
  X 
  16, 
  exhibiting 
  the 
  central 
  

   axis. 
  C. 
  Tangential 
  section, 
  X 
  16, 
  illustrating 
  the 
  arrangement 
  of 
  

   the 
  vacuoles 
  around 
  the 
  orifices. 
  D. 
  Longitudinal 
  section, 
  X 
  16. 
  

   The 
  vacuoles 
  perforate 
  the 
  epitheca 
  all 
  around 
  the 
  zoarium. 
  E. 
  

   Longitudinal 
  section, 
  X 
  16, 
  showing 
  the 
  cylindrical 
  tubes 
  and 
  the 
  

   vacuoles 
  perforating 
  the 
  epitheca. 
  Lower 
  Cretaceous 
  (Aptian) 
  : 
  

   Faringdon, 
  England. 
  F-H. 
  Siphodictyum 
  gracile 
  Lonsdale, 
  1849. 
  

   F. 
  Transverse 
  section, 
  X 
  16. 
  G. 
  Meridian 
  section, 
  X 
  16. 
  H. 
  

   Longitudinal 
  section, 
  X 
  16, 
  with 
  the 
  vacuoles 
  perforating 
  the 
  thick 
  

   epitheca. 
  Lower 
  Cretaceous 
  (Aptian) 
  : 
  Faringdon, 
  England 
  88 
  

  

  