﻿art. 
  21 
  CYCLOSTOMATOUS 
  BRYOZOA 
  CANU 
  AND 
  BASSLER 
  77 
  

  

  LEIOSOECIA 
  GRANDIPORA, 
  new 
  species 
  

  

  Plate 
  16, 
  figs. 
  1-4 
  

  

  Description. 
  — 
  The 
  zoarium 
  is 
  free, 
  cylindrical, 
  bifurcated. 
  The 
  ori- 
  

   fices 
  are 
  polygonal; 
  the 
  peristomes 
  are 
  thin, 
  nonsalient. 
  The 
  meso- 
  

   pores 
  are 
  large, 
  polygonal, 
  few 
  in 
  number, 
  irregularly 
  placed. 
  The 
  

   ovicell 
  is 
  large, 
  orbicular, 
  convex, 
  smooth. 
  

  

  Measurements. 
  — 
  Diameter 
  of 
  aperture, 
  0.12 
  mm. 
  ; 
  diameter 
  of 
  meso- 
  

   pores, 
  0.10 
  mm.; 
  diameter 
  of 
  zoarium, 
  4 
  mm. 
  

  

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

   very 
  thick 
  walls, 
  recurved 
  at 
  their 
  extremity, 
  with 
  axial 
  gemmation. 
  

   The 
  mesopores 
  have 
  a 
  variable 
  length; 
  they 
  appear 
  at 
  all 
  heights 
  and 
  

   their 
  distinction 
  from 
  the 
  tubes 
  is 
  very 
  difficult; 
  they 
  appear 
  little 
  

   numerous. 
  

  

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

   as 
  large 
  at 
  the 
  center 
  as 
  at 
  the 
  periphery. 
  The 
  terminal 
  thickening 
  

   of 
  the 
  tubes 
  and 
  of 
  the 
  mesopores 
  forms 
  a 
  thick 
  parietal 
  zone. 
  

  

  Affinities. 
  — 
  The 
  species 
  differs 
  from 
  Leiosoecia 
  aequiporosa 
  in 
  its 
  

   apertural 
  diameter 
  of 
  0.12 
  mm. 
  and 
  in 
  its 
  larger 
  zoaria. 
  

  

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

   land 
  (rare). 
  

  

  Cotypes.— 
  Cat. 
  No. 
  69932, 
  U.S.N.M. 
  

  

  LEIOSOECIA 
  CONSTANTI 
  D'Orbigny, 
  1850 
  

  

  Plate 
  17, 
  figs. 
  1-5 
  

  

  1850. 
  Ceriopora 
  constanti 
  D'Orbigny, 
  Prodrome 
  de 
  Pal^ontologie, 
  vol. 
  2, 
  p. 
  143. 
  

   1854. 
  Heteropora 
  constanti 
  D'Orbigny, 
  Paleontologie 
  frangaise, 
  Terrain 
  Cr6tac6, 
  

   vol. 
  5, 
  p. 
  1071, 
  pi. 
  799, 
  figs. 
  6, 
  7. 
  

  

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

   stome, 
  0.14 
  mm.; 
  diameter 
  of 
  mesopores, 
  0.06 
  mm.; 
  diameter 
  of 
  

   terminal 
  branches, 
  3 
  mm.; 
  diameter 
  of 
  large 
  branches, 
  7 
  mm. 
  

  

  Structure. 
  — 
  We 
  have 
  found 
  very 
  typical 
  specimens 
  corresponding 
  

   to 
  D'Orbigny's 
  figures. 
  They 
  have, 
  indeed, 
  polygonal 
  orifices 
  sur- 
  

   rounded 
  by 
  small 
  mesopores. 
  Moreover, 
  the 
  zoarial 
  surface 
  presents 
  

   undulations 
  and 
  in 
  places 
  circular 
  areas 
  of 
  mesopores. 
  

  

  Other 
  specimens, 
  less 
  typical 
  in 
  appearance, 
  have 
  the 
  same 
  aper- 
  

   tural 
  diameter, 
  the 
  same 
  orbicular 
  area 
  of 
  mesopores, 
  the 
  same 
  char- 
  

   acters 
  in 
  longitudinal 
  section, 
  but 
  the 
  zoaria 
  lack 
  the 
  undulations, 
  

   and 
  the 
  mesopores 
  (0.07, 
  0.08 
  mm.) 
  are 
  a 
  little 
  larger. 
  

  

  It 
  is 
  difficult 
  to 
  recognize 
  two 
  species 
  in 
  these 
  specimens. 
  The 
  

   first 
  lot 
  seems 
  to 
  us 
  to 
  be 
  the 
  terminal 
  branches, 
  the 
  second, 
  more- 
  

   over, 
  larger, 
  are 
  the 
  large 
  adult 
  branches. 
  On 
  the 
  other 
  hand, 
  on 
  

   the 
  same 
  specimen 
  it 
  is 
  easy 
  to 
  observe 
  the 
  variations 
  in 
  the 
  size 
  of 
  

   the 
  mesopores. 
  

  

  In 
  longitudinal 
  sections 
  the 
  tubes 
  are 
  cylindrical, 
  with 
  rather 
  reg- 
  

   ular 
  peripheral 
  gemmation. 
  The 
  mesopores 
  are 
  rather 
  long 
  and 
  

  

  