﻿46 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL, 
  MUSEUM 
  you 
  er 
  

  

  salient 
  thread, 
  a 
  phenomenon 
  produced 
  in 
  many 
  other 
  species 
  with 
  

   tubes 
  much 
  longer. 
  Finally, 
  there 
  is 
  never 
  an 
  operculum, 
  and 
  the 
  

   ovicell 
  is 
  very 
  different 
  from 
  that 
  in 
  the 
  Eleidae. 
  The 
  separating 
  

   threads 
  outline 
  the 
  peristome 
  entirely, 
  a 
  characteristic 
  which 
  deceived 
  

   D'Orbigny. 
  

  

  Structure. 
  — 
  In 
  longitudinal 
  section 
  the 
  tubes 
  are 
  short, 
  cylindrical, 
  

   somewhat 
  expanded 
  nevertheless 
  in 
  the 
  vicinity 
  of 
  the 
  pseudofacettes 
  ; 
  

   gemmation 
  is 
  triparietal 
  on 
  a 
  basal 
  lamella. 
  

  

  The 
  transverse 
  section 
  does 
  not 
  show 
  a 
  large 
  number 
  of 
  tubes; 
  they 
  

   are 
  polygonal, 
  with 
  thin 
  and 
  adjacent 
  walls; 
  the 
  smallest 
  are 
  in 
  the 
  

   vicinity 
  of 
  the 
  median 
  lamella. 
  

  

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

   (Valangian); 
  Morteau 
  (Doubs), 
  France 
  (D'Orbigny) 
  (Neocomian). 
  

  

  Plesioty 
  pes. 
  —Cat. 
  No. 
  69894, 
  U.S.N.M. 
  

  

  NEMATIFERA 
  ACUTA 
  D'Orbigny, 
  1853 
  

  

  Plate 
  4, 
  fig. 
  12 
  

  

  1853. 
  Bidiastopora 
  acuta 
  D'Orbigny, 
  Paleontologie 
  francaise, 
  Terrain 
  Crdtace, 
  

   vol. 
  5, 
  p. 
  799, 
  pi. 
  784, 
  figs. 
  3-5. 
  

  

  Measurements. 
  — 
  Diameter 
  of 
  orifice, 
  0.08-0.10 
  mm.; 
  diameter 
  of 
  

   peristome, 
  0.12 
  mm.; 
  diameter 
  of 
  zooecium, 
  0.20 
  mm. 
  

  

  This 
  species 
  is 
  well 
  characterized 
  by 
  its 
  very 
  thin 
  and 
  sharp 
  zoa- 
  

   rial 
  margins. 
  The 
  separating 
  threads 
  turn 
  around 
  the 
  peristome, 
  

   which 
  is 
  thin; 
  the 
  pseudofacettes 
  are 
  flat. 
  

  

  We 
  have 
  not 
  had 
  the 
  chance 
  to 
  discover 
  the 
  ovicell, 
  and 
  we 
  have 
  

   classified 
  the 
  species 
  according 
  to 
  its 
  exterior 
  analogies 
  and 
  the 
  trans- 
  

   verse 
  section 
  which 
  is 
  always 
  easily 
  observed. 
  

  

  According 
  to 
  Pergens, 
  18S9, 
  Bidiastopora 
  campicheana 
  D'Orbigny, 
  

   1853, 
  is 
  a 
  synonym, 
  but 
  we 
  do 
  not 
  believe 
  this 
  is 
  true; 
  moreover 
  

   D'Orbigny's 
  figure 
  indicates 
  an 
  altered 
  specimen. 
  

  

  Marsson, 
  1887, 
  believed 
  he 
  had 
  found 
  this 
  species 
  in 
  the 
  Cam- 
  

   panian 
  of 
  Rugen. 
  We 
  have 
  not 
  rediscovered 
  it 
  ourselves. 
  

  

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

   Switzerland. 
  

  

  Plesioty 
  pe.— 
  Oat. 
  No. 
  69895, 
  U.S.N.M. 
  

  

  NEMATIFERA 
  INCRUSTANS, 
  new 
  species 
  

  

  Plate 
  4, 
  figs. 
  5-7 
  

  

  Description. 
  — 
  The 
  zoarium 
  encrusts 
  shells, 
  with 
  many 
  irregularly 
  

   arranged 
  lamellae; 
  it 
  emits 
  free, 
  thick 
  expansions 
  irregular 
  around 
  a 
  

   median 
  lamella. 
  The 
  tubes 
  are 
  distinct, 
  separated 
  by 
  a 
  salient 
  thread, 
  

   flat, 
  short 
  (pseudofacettes). 
  The 
  peristomes 
  are 
  orbicular, 
  salient, 
  

  

  