﻿76 
  

  

  PROCEEDINGS 
  OF 
  THE 
  NATIONAL, 
  MUSEUM 
  

  

  In 
  transverse 
  section 
  the 
  tubes 
  are 
  polygonal, 
  with 
  adjacent 
  walls. 
  

   The 
  thickening 
  of 
  the 
  walls 
  of 
  the 
  mesopores 
  forms 
  a 
  thick 
  parietal 
  

   zone. 
  

  

  In 
  tangential 
  section 
  the 
  mesopores 
  are 
  smaller 
  than 
  the 
  tubes 
  

   because 
  their 
  orifice 
  is 
  infundibuliform; 
  they 
  are 
  separated 
  by 
  a 
  

   thick, 
  lamellose 
  tissue. 
  

  

  

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  Affinities. 
  — 
  This 
  species 
  differs 
  from 
  Leiosoecia 
  grandipora, 
  in 
  which 
  

   the 
  mesopores 
  have 
  the 
  same 
  dimension, 
  in 
  the 
  smaller 
  zoarium, 
  in 
  

   the 
  smaller 
  aperture 
  (not 
  0.12 
  mm.), 
  and 
  in 
  the 
  less 
  regular 
  ovicell. 
  

  

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

   land 
  (rare). 
  

  

  Cotype.—C&t. 
  No. 
  69930, 
  U.S.N.M. 
  

  

  