﻿art. 
  21 
  CYCLOSTOMATOUS 
  BRYOZOA 
  CANU 
  AND 
  BASSLER 
  21 
  

  

  They 
  are 
  vesiculose 
  either 
  totally 
  or 
  partially 
  (at 
  the 
  extremity). 
  

   The 
  vesicles 
  are 
  quite 
  variable 
  in 
  form 
  and 
  in 
  size. 
  When 
  large 
  

   they 
  give 
  to 
  the 
  walls 
  a 
  moniliform 
  aspect, 
  which 
  reveals 
  sometimes 
  

   annular 
  tubes. 
  When 
  they 
  are 
  very 
  small 
  the 
  tissue 
  is 
  dense 
  and 
  

   the 
  preparations 
  are 
  little 
  transparent. 
  Finally, 
  if 
  their 
  distal 
  and 
  

   proximal 
  walls 
  are 
  thin, 
  thezooecial 
  walls 
  seem 
  then 
  entirely 
  hollow. 
  

  

  The 
  vesicles 
  are 
  very 
  difficult 
  to 
  draw 
  and 
  it 
  is 
  only 
  by 
  photog- 
  

   raphy 
  that 
  they 
  can 
  be 
  figured 
  with 
  fidelity. 
  

  

  In 
  the 
  course 
  of 
  this 
  study 
  we 
  have 
  not 
  paid 
  enough 
  attention 
  to 
  

   the 
  structure 
  of 
  the 
  zooecial 
  walls 
  not 
  only 
  of 
  the 
  Ceriopores 
  but 
  also 
  

   of 
  many 
  other 
  species 
  described, 
  for 
  in 
  searching 
  for 
  the 
  general 
  laws 
  

   we 
  have 
  neglected 
  the 
  details. 
  We 
  can 
  affirm 
  that 
  very 
  close 
  study 
  

   is 
  always 
  necessary 
  because 
  we 
  are 
  convinced 
  that 
  the 
  microscopic 
  

   structure 
  of 
  the 
  zooecial 
  walls 
  is 
  the 
  best 
  specific 
  character. 
  Good 
  

   photographs 
  with 
  an 
  enlargement 
  of 
  at 
  least 
  50 
  diameters 
  are 
  also 
  

   necessary. 
  

  

  Transverse 
  sections. 
  — 
  The 
  structure 
  of 
  the 
  Ceriopores 
  does 
  not 
  differ 
  

   from 
  that 
  of 
  other 
  cyclostomata, 
  and 
  we 
  have 
  found 
  in 
  transverse 
  

   sections 
  the 
  characters 
  observed 
  and 
  described 
  hitherto. 
  We 
  have 
  

   observed 
  (1) 
  polygonal 
  zooecia 
  with 
  thin 
  adjacent 
  walls 
  occurring 
  

   more 
  often 
  in 
  the 
  central 
  part 
  of 
  the 
  zoarium; 
  (2) 
  round, 
  nonadjacent 
  

   zooecia, 
  corresponding 
  to 
  the 
  tubes 
  with 
  vesicular 
  walls 
  and 
  with 
  

   their 
  separation 
  depending 
  upon 
  the 
  thickness 
  of 
  their 
  walls; 
  (3) 
  

   polygonal 
  zooecia 
  in 
  which 
  the 
  interior 
  is 
  rounded, 
  corresponding 
  to 
  

   the 
  tubes 
  with 
  walls 
  having 
  many 
  longitudinal 
  rows 
  of 
  vesicles; 
  and 
  

   (4) 
  tubular 
  zooecia 
  which 
  correspond 
  to 
  the 
  recurved 
  parts 
  of 
  the 
  

   tubes 
  and 
  are 
  always 
  vesicular. 
  

  

  CERIOPORA 
  TENUIS, 
  new 
  species 
  

  

  Plate 
  22, 
  figs. 
  12-14 
  

  

  Description. 
  — 
  The 
  zoarium 
  is 
  very 
  thin 
  and 
  encrusts 
  shells. 
  The 
  

   orifices 
  are 
  polygonal 
  and 
  regular, 
  with 
  walls 
  little 
  thickened. 
  

  

  Measurements. 
  — 
  Diameter 
  of 
  aperatures, 
  0.10 
  mm. 
  Only 
  the 
  fig- 
  

   ured 
  specimen 
  has 
  been 
  found. 
  

  

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

   Switzerland. 
  

  

  Hohtype— 
  Cat. 
  No. 
  69862, 
  U.S.N.M. 
  

  

  CERIOPORA 
  OVOIDEA, 
  new 
  species 
  

  

  Plate 
  22, 
  figs. 
  2-5 
  

  

  Description. 
  — 
  The 
  zoarium 
  is 
  free 
  ovoid, 
  pedunculate, 
  borne 
  on 
  a 
  

   very 
  small 
  flat 
  base, 
  formed 
  sometimes 
  of 
  lamellae 
  entirely 
  covering 
  

   the 
  base. 
  The 
  apertures 
  are 
  polygonal 
  and 
  irregular. 
  The 
  zonal 
  

   lines 
  become 
  transformed 
  in 
  basal 
  lamellae. 
  

  

  