﻿52 
  

  

  PROCEEDINGS 
  OF 
  THE 
  NATIONAL. 
  MUSEUM 
  

  

  The 
  base 
  of 
  the 
  small 
  zoarium 
  is 
  pointed, 
  but 
  in 
  the 
  large 
  zoaria 
  

   it 
  is 
  somewhat 
  wider; 
  they 
  are 
  flabelliform, 
  and 
  it 
  is 
  difficult 
  to 
  

   understand 
  how 
  they 
  were 
  able 
  to 
  maintain 
  equilibrium 
  on 
  their 
  

   support. 
  

  

  In 
  longitudinal 
  section 
  the 
  tubes 
  are 
  long, 
  cylindrical, 
  with 
  intra- 
  

   zoarial 
  gemmation; 
  the 
  walls 
  are 
  vesicular 
  but 
  with 
  very 
  small 
  

   elements. 
  The 
  zoarial 
  walls 
  are 
  thickened. 
  

  

  Occurrence. 
  — 
  Lower 
  Cretaceous 
  (Valangian) 
  : 
  Sainte-Croix 
  (Vaud), 
  

   Switzerland. 
  

  

  Plesiotype 
  — 
  Cat. 
  No. 
  69902, 
  U.S.N.M. 
  

  

  Family 
  CYTISIDAE 
  D'Orbigny, 
  1854 
  

  

  Genus 
  CYRTOPORA 
  Hagenow, 
  1851 
  

  

  CYRTOPORA 
  CAMPICHEANA 
  D'Orbigny, 
  1853 
  

  

  1853. 
  Cyrtopora 
  campicheana 
  D'Orbigny, 
  Pal6ontologie 
  francaise, 
  Terrain 
  Cre- 
  

   tac6, 
  vol. 
  5, 
  p. 
  673, 
  pi. 
  761, 
  figs. 
  14, 
  15. 
  

  

  Fig. 
  25.— 
  Genus 
  Plethopora 
  Hagenow, 
  1851. 
  A, 
  B. 
  Plethopora 
  malmi 
  Hennig, 
  1894. 
  A. 
  Zoarium, 
  X 
  2. 
  G. 
  

   B. 
  Longitudinal 
  section 
  magnified, 
  showing 
  zooecia! 
  tubes 
  (z) 
  and 
  the 
  nematopores 
  (/) 
  (A, 
  B, 
  after 
  Hen- 
  

   nig, 
  1894). 
  Upper 
  Cretaceous 
  of 
  Sweden. 
  C, 
  D. 
  Plethopora 
  aptensis, 
  new 
  species. 
  C. 
  Longitudinal 
  sec- 
  

   tion, 
  X 
  16, 
  showing 
  the 
  nematopores 
  with 
  thickened 
  walls 
  and 
  the 
  large 
  axial 
  tubes. 
  D. 
  Transverse 
  

   section, 
  X 
  16, 
  exhibiting 
  the 
  base 
  of 
  the 
  saliant 
  fascicles 
  with 
  open 
  tubes 
  and 
  the 
  thin 
  zone 
  of 
  nemato- 
  

   pores. 
  Lower 
  Cretaceous 
  (Aptian): 
  Faringdon, 
  England 
  

  

  Our 
  transverse 
  section 
  confirms 
  that 
  of 
  Gregory, 
  1909. 
  The 
  tubes 
  

   are 
  very 
  large, 
  polygonal, 
  with 
  thin 
  adjacent 
  walls. 
  

  

  Occurrence. 
  — 
  Lower 
  Cretaceous 
  (Valangian): 
  Sainte-Croix 
  (Vaud), 
  

   Switzerland. 
  

  

  Plesiotype.— 
  Cat. 
  No. 
  69950, 
  U.S.N.M. 
  

  

  Genus 
  PLETHOPORA 
  Hagenow, 
  1851 
  

  

  1851. 
  Plethopora 
  Hagenow, 
  Die 
  Bryozoen 
  der 
  Maastrichter 
  Kreidebildung, 
  

   p. 
  45. 
  

  

  The 
  tubes 
  are 
  cylindrical; 
  they 
  are 
  grouped 
  in 
  salient, 
  orbicular 
  

   bundles 
  opening 
  in 
  all 
  directions. 
  The 
  nematopores 
  are 
  arranged 
  

   entirely 
  around 
  the 
  zoarium. 
  

  

  