﻿56 
  

  

  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  

  

  Measurements. 
  — 
  Diameter 
  of 
  orifice, 
  0.08 
  mm.; 
  diameter 
  of 
  

   branches, 
  2.5 
  mm.; 
  length 
  of 
  orifice, 
  016-0.20 
  mm. 
  

  

  Structure. 
  — 
  In 
  transverse 
  section 
  the 
  tubes 
  are 
  cylindrical, 
  with 
  

   greatly 
  thickened 
  walls; 
  the 
  central 
  tube 
  is 
  perhaps 
  a 
  little 
  larger. 
  

   In 
  longitudinal 
  section 
  the 
  tubes 
  are 
  very 
  long, 
  with 
  peripheral 
  gem- 
  

   mation, 
  very 
  regular, 
  with 
  thickened 
  walls. 
  

  

  This 
  structure 
  is 
  quite 
  simple. 
  In 
  general 
  these 
  forms 
  of 
  the 
  

   tubes 
  are 
  oriented 
  on 
  one 
  zoarial 
  side; 
  here 
  the 
  colony 
  has 
  two 
  

   cellular 
  sides, 
  a 
  rare 
  occurrence. 
  

  

  Occurrence. 
  — 
  Lower 
  Cretaceous. 
  Valangian 
  at 
  

   Sainte-Croix, 
  Switzerland; 
  Hauterivian 
  at 
  Censeau 
  

   (Doubs) 
  ; 
  Neocomian 
  at 
  St. 
  Claude 
  and 
  Cinquetral 
  

   (Doubs), 
  France. 
  

  

  Cotypes.—Cfit. 
  No. 
  69904, 
  U.S.N.M. 
  

  

  Genus 
  RETENOA 
  Gregory, 
  1909 
  

  

  1909. 
  Retenoa 
  Gregory, 
  Catalogue 
  of 
  Cretaceous 
  Bryozoa 
  

   in 
  the 
  British 
  Museum, 
  vol. 
  2, 
  p. 
  28. 
  

  

  Cytisidae, 
  with 
  an 
  erect 
  frondose 
  zoarium, 
  com- 
  

   posed 
  of 
  a 
  network 
  of 
  dichotomous, 
  anastomosing 
  

   branches. 
  The 
  apertures 
  all 
  open 
  on 
  one 
  face 
  of 
  

   the 
  zoarium. 
  The 
  tubes 
  are 
  cylindrical, 
  with 
  loz- 
  

   enge-shaped 
  orifices, 
  with 
  intrazoarial 
  gemmation. 
  

   Genotype. 
  — 
  Retenoa 
  (Frondipora) 
  campicheana 
  

   D'Orbigny, 
  1853. 
  

  

  This 
  genus 
  is 
  little 
  different 
  from 
  Homoeosolen 
  

  

  Lonsdale, 
  1850. 
  It 
  differs 
  exteriorily 
  in 
  the 
  absence 
  

  

  fig. 
  2&.-jRetenoa 
  cam- 
  °f 
  pinnules, 
  and 
  especially 
  in 
  its 
  reticulate 
  zoarium, 
  

  

  pkheana 
  D'Orbigny, 
  which 
  is 
  a 
  character 
  of 
  little 
  importance. 
  However, 
  

  

  section, 
  x 
  1 
  16? 
  showing 
  *he 
  gemmation 
  is 
  intrazoarial 
  and 
  not 
  dorsal, 
  which 
  

  

  the 
  cylindrical 
  tubes 
  is 
  a 
  genuine 
  difference. 
  Gregory 
  erroneously 
  in 
  1909 
  

  

  and 
  the 
  intrazoarial 
  , 
  . 
  n 
  , 
  ,-, 
  • 
  ,-, 
  £ 
  -i 
  rpr. 
  „ 
  • 
  1 
  ■* 
  : 
  

  

  gemmation. 
  Lower 
  classified 
  this 
  genus 
  in 
  the 
  family 
  Iheonoidae; 
  it 
  is 
  

   cretaceous 
  (Vaian- 
  one 
  f 
  the 
  typical 
  Cytisidae 
  on 
  account 
  of 
  the 
  nature 
  

  

  gian): 
  Sainte-Croix, 
  ... 
  . 
  -,, 
  

  

  Switzerland 
  of 
  its 
  OVICell. 
  

  

  RETENOA 
  CAMPICHEANA 
  D'Orbigny, 
  1853 
  

  

  Plate 
  7, 
  figs. 
  5-7 
  

  

  1853. 
  Frondipora 
  campicheana 
  D'Orbigny, 
  Paleontologie 
  francaise, 
  Terrain 
  

  

  Cretace, 
  vol. 
  5, 
  p. 
  678, 
  pi. 
  783, 
  figs. 
  12-16. 
  

   1909. 
  Retenoa 
  campicheana 
  Gregory, 
  Catalogue 
  of 
  the 
  Cretaceous 
  Bryozoa 
  in 
  the 
  

  

  British 
  Museum, 
  vol. 
  2, 
  p. 
  28. 
  (Geologic 
  distribution.) 
  

  

  Structure. 
  — 
  We 
  have 
  had 
  the 
  good 
  fortune 
  to 
  discover 
  numerous 
  

   ovicelled 
  specimens. 
  The 
  ovicell 
  is 
  an 
  elliptical 
  capsule, 
  limited, 
  

   convex, 
  smooth, 
  placed 
  laterally 
  on 
  the 
  dorsal, 
  usually 
  beneath 
  the 
  

   bifurcations. 
  

  

  