﻿68 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL. 
  MUSEUM 
  vol.67 
  

  

  Measurements. 
  — 
  Diameter 
  of 
  interior 
  orifice, 
  0.16 
  by 
  0.20 
  mm.; 
  

  

  diameter 
  of 
  exterior 
  orifice, 
  0.22 
  mm. 
  ; 
  diameter 
  of 
  branches, 
  2.5 
  mm. 
  

  

  Structure. 
  — 
  The 
  basal 
  parts 
  of 
  the 
  zoarium 
  have 
  the 
  Semicava 
  

  

  growth 
  of 
  D'Orbigny, 
  but 
  the 
  branches 
  which 
  they 
  emit 
  are 
  solid 
  

  

  and 
  their 
  sections 
  are 
  identical 
  with 
  those 
  of 
  

  

  Ceriocava. 
  

  

  It 
  is 
  difficult 
  to 
  predict 
  the 
  direction 
  of 
  the 
  

   tubes 
  in 
  an 
  incrusting 
  colony 
  in 
  order 
  to 
  section 
  

   it 
  correctly. 
  

  

  In 
  tangential 
  section 
  it 
  may 
  be 
  noted 
  that 
  

  

  Fig. 
  U— 
  Ceriocava 
  junctata, 
  the 
  tubes 
  are 
  polygonal, 
  adjacent, 
  but 
  their 
  in- 
  

   new 
  species. 
  Transverse 
  terior 
  is 
  calcified 
  and 
  thus 
  forms 
  a 
  rounded 
  

  

  section, 
  X 
  16, 
  through 
  a 
  . 
  . 
  , 
  

  

  solid 
  cylindrical 
  branch, 
  interior 
  tube. 
  

  

  Lower 
  Cretaceous 
  (Vaian- 
  Occurrence. 
  — 
  Lower 
  Cretaceous 
  (Valangian): 
  

  

  gian): 
  Sainte-Croix, 
  Swit- 
  _ 
  . 
  „ 
  . 
  __ 
  , 
  Q 
  . 
  ° 
  

  

  zeriand 
  bamte-(Jroix 
  (Vaud), 
  Switzerland 
  (rare). 
  

  

  Coty 
  pes. 
  —Cat. 
  No. 
  69921, 
  U.S.N.M. 
  

  

  CERIOCAVA 
  MULTILAMELLOSA, 
  new 
  species 
  

  

  Plate 
  9, 
  figs. 
  1-10 
  

  

  Description. 
  — 
  The 
  zoarium 
  is 
  free, 
  cylindrical, 
  dichotomous, 
  formed 
  

   of 
  many 
  enveloping 
  lamellae; 
  the 
  outermost 
  lamellae 
  are 
  incomplete 
  

   and 
  show 
  at 
  their 
  extremity 
  a 
  short 
  zone 
  of 
  growth. 
  The 
  facettes 
  

   are 
  hexagonal, 
  arranged 
  in 
  transverse 
  rows, 
  perforated 
  at 
  the 
  center 
  

   by 
  the 
  aperture. 
  The 
  aperture 
  is 
  orbicular 
  and 
  surrounded 
  by 
  a 
  

   thin 
  and 
  somewhat 
  salient 
  peristome. 
  The 
  orifices 
  of 
  the 
  tubes 
  

   without 
  facettes 
  are 
  irregularly 
  polygonal. 
  

  

  Measurements. 
  — 
  Diameter 
  of 
  apertures, 
  0.08 
  mm.; 
  diameter 
  of 
  

   peristomes, 
  0.10 
  mm.; 
  diameter 
  of 
  facettes, 
  0.16 
  mm.; 
  diameter 
  of 
  

   larger 
  branches, 
  2.5 
  mm. 
  

  

  Structure. 
  — 
  The 
  extremity 
  of 
  the 
  branches 
  is 
  conical, 
  as 
  in 
  all 
  

   colonies 
  in 
  which 
  the 
  tubes 
  are 
  expanded. 
  This 
  conical 
  part 
  is 
  con- 
  

   sidered 
  as 
  the 
  zone 
  of 
  growth 
  and 
  the 
  orifices 
  here 
  do 
  not 
  bear 
  

   facettes 
  (fig. 
  3). 
  

  

  The 
  exterior 
  lamellae 
  grow 
  around 
  the 
  interior 
  trunk 
  and 
  appear 
  

   around 
  it 
  as 
  a 
  rather 
  thick 
  but 
  short 
  zone 
  of 
  growth 
  (fig. 
  2) 
  ; 
  these 
  

   lamellae 
  bear 
  facettes 
  like 
  the 
  central 
  trunk. 
  

  

  The 
  facettes 
  are 
  often 
  well 
  distributed 
  over 
  all 
  the 
  colony 
  (figs. 
  

   2, 
  3), 
  but 
  frequently 
  they 
  appear 
  only 
  in 
  zones 
  (fig. 
  5). 
  We 
  can 
  not 
  

   affirm 
  that 
  their 
  existence 
  is 
  normal, 
  for 
  entire 
  branches 
  are 
  deprived 
  

   of 
  them 
  and 
  seem 
  even 
  never 
  to 
  have 
  had 
  them 
  (fig. 
  9). 
  The 
  appear- 
  

   ance 
  of 
  facettes 
  in 
  the 
  genus 
  Ceriocava 
  still 
  remains 
  a 
  mystery. 
  Per- 
  

   haps 
  they 
  are 
  very 
  fragile, 
  as 
  in 
  Meliceritites, 
  and 
  disappear 
  easily 
  by 
  

   slight 
  abrasion. 
  

  

  