﻿54 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL. 
  MUSEUM 
  vol.67 
  

  

  PLETHOPORELLA 
  RAMULOSA 
  D'Orbigny, 
  1847 
  

  

  1847. 
  Monticulipora 
  ramulosa 
  D'Orbigny, 
  Prodrome 
  de 
  Paleontologie 
  Strati- 
  

  

  graphique, 
  p. 
  279, 
  no. 
  1345. 
  

   1854. 
  Plcthopora 
  ramulosa 
  D'Orbigny, 
  Paleontologie 
  frangaise, 
  Terrain 
  Cretace, 
  

  

  p. 
  1045, 
  pi. 
  799, 
  figs. 
  1-3. 
  

  

  Structure. 
  — 
  D'Orbigny 
  was 
  deceived 
  by 
  the 
  tuberosities 
  which 
  

   ornament 
  the 
  zoarial 
  surface 
  and 
  classed 
  this 
  species 
  in 
  PletJiopora 
  

   incorrectly. 
  The 
  section 
  which 
  he 
  illustrated, 
  however, 
  indicates 
  

   not 
  a 
  single 
  bunch 
  of 
  tubes. 
  We 
  have 
  prepared 
  several 
  excellent 
  

   longitudinal 
  sections, 
  one 
  of 
  which 
  made 
  from 
  a 
  normal 
  zoarium 
  

   showed 
  on 
  one 
  side 
  two 
  subcolonies, 
  while 
  on 
  the 
  other 
  side 
  the 
  tubes 
  

   continued 
  to 
  grow 
  regularly. 
  The 
  enveloping 
  lamella 
  partially 
  sur- 
  

   rounded 
  the 
  primitive 
  colony 
  and 
  had 
  its 
  origin 
  in 
  a 
  normal 
  tube. 
  

   All 
  the 
  species 
  with 
  peripheral 
  gemmation 
  pass 
  easily 
  from 
  the 
  free 
  

   form 
  to 
  the 
  incrusting 
  form 
  and 
  conversely. 
  Another 
  longitudinal 
  

   section 
  shows 
  that 
  the 
  tubes 
  of 
  the 
  tuberosities 
  are 
  simply 
  somewhat 
  

   wider 
  than 
  the 
  tubes 
  of 
  the 
  intermediate 
  spaces. 
  The 
  moniliform 
  

   structure 
  and 
  the 
  gemmation 
  are 
  identical 
  in 
  the 
  two 
  cases. 
  The 
  

   walls 
  are 
  formed 
  of 
  large 
  vesicles. 
  

  

  In 
  transverse 
  sections 
  the 
  central 
  tubes 
  are 
  equal 
  in 
  size 
  and 
  

   polygonal. 
  The 
  smaller 
  ones, 
  which 
  appear 
  sporadically, 
  are 
  indic- 
  

   ative 
  of 
  the 
  peripheral 
  gemmation. 
  The 
  lozenge-shaped 
  ones 
  of 
  the 
  

   periphery 
  represent 
  the 
  superior 
  and 
  recurved 
  part 
  of 
  the 
  tubes. 
  

  

  In 
  tangential 
  sections 
  the 
  tubes 
  are 
  subcircular 
  and 
  buried 
  in 
  a 
  

   thick 
  vesicular 
  coenenchyma. 
  They 
  are 
  smaller 
  in 
  the 
  intertuberose 
  

   zones, 
  in 
  conformity 
  with 
  the 
  longitudinal 
  section. 
  The 
  small 
  tubes 
  

   which 
  appear 
  sporadically 
  are 
  young 
  tubes; 
  they 
  reveal 
  the 
  peripheral 
  

   gemmation. 
  

  

  This 
  structure 
  is 
  exactly 
  that 
  of 
  ramose 
  Ceriopora, 
  and 
  it 
  is 
  in 
  this 
  

   genus 
  that 
  we 
  would 
  have 
  classed 
  this 
  species 
  had 
  we 
  not 
  had 
  the 
  

   chance 
  to 
  discover 
  the 
  ovicell. 
  The 
  latter 
  is 
  analogous 
  to 
  that 
  of 
  

   other 
  Cytisidae 
  and 
  is 
  simply 
  more 
  elliptical. 
  

  

  Occurrence.— 
  Cretaceous 
  (Campanian) 
  : 
  Montmoreau, 
  Brossac, 
  

   Draullard, 
  St. 
  Aulais, 
  Echebrune 
  and 
  Daviat 
  (Charente), 
  France. 
  

   Cretaceous 
  (Maastrichtian) 
  : 
  Royan 
  (Charente 
  inferieure), 
  Manie 
  

   Roux 
  and 
  St. 
  Lheurine 
  (Dordogne), 
  France. 
  

  

  Plesiotypes. 
  — 
  Canu 
  collection 
  and 
  Cat. 
  No. 
  68980, 
  U.S.N. 
  M. 
  

  

  Genus 
  CHARTECYTIS, 
  new 
  genus 
  

  

  Greek: 
  Chartes, 
  sheet, 
  in 
  allusion 
  to 
  the 
  form 
  of 
  the 
  branches. 
  

  

  The 
  ovicell 
  is 
  elliptical, 
  transverse, 
  placed 
  in 
  the 
  vicinity 
  of 
  the 
  

   bifurcations. 
  The 
  tubes 
  are 
  cylindrical, 
  with 
  greatly 
  thickened 
  

   walls, 
  with 
  regular 
  peripheral 
  gemmation. 
  The 
  orifice 
  is 
  lozenge- 
  

   shaped, 
  much 
  elongated, 
  without 
  peristome. 
  

  

  