﻿16 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL, 
  MUSEUM 
  vol.67 
  

  

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

   mesopores, 
  0.06 
  mm.; 
  diameter 
  of 
  zoarium, 
  2.5 
  by 
  1.5 
  cm. 
  

  

  Structure. 
  — 
  The 
  zoarial 
  base 
  is 
  an 
  epitheca 
  concentrically 
  wrinkled 
  

   flat, 
  or 
  concave. 
  Some 
  zoaria 
  completely 
  surround 
  small 
  shells. 
  

  

  Exteriorly 
  there 
  are 
  no 
  subcolonies 
  visible, 
  as 
  in 
  D'Orbigny's 
  fig- 
  

   ure, 
  so 
  that 
  our 
  determination 
  of 
  the 
  species, 
  made 
  according 
  to 
  zoa- 
  

   rial 
  analogies, 
  is 
  doubtful. 
  We 
  know, 
  however, 
  that 
  this 
  character 
  

   disappears 
  easily 
  upon 
  the 
  least 
  superficial 
  alteration. 
  

  

  In 
  meridian 
  section 
  the 
  tubes 
  are 
  cylindrical 
  and 
  the 
  mesopores 
  of 
  

   variable 
  length. 
  The 
  tubes 
  are 
  annular 
  and 
  their 
  walls 
  vesicular. 
  

   The 
  small 
  parietal 
  vesicles 
  correspond 
  to 
  the 
  successive 
  annuli 
  of 
  the 
  

   tubes. 
  The 
  subcolonies 
  are 
  clearly 
  outlined 
  by 
  their 
  initial 
  tubes. 
  

  

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

   Switzerland 
  (rare). 
  

  

  Plesiotypes.—C&t. 
  No. 
  69856, 
  U.S.N.M. 
  

  

  MULTICRESCIS 
  LAMELLOSA. 
  new 
  species 
  

  

  Plate 
  21, 
  figs. 
  7-9 
  

  

  Description. 
  — 
  The 
  zoarium 
  is 
  free, 
  large, 
  lamellose, 
  orbicular, 
  formed 
  

   of 
  many 
  thin 
  superposed 
  lamellae. 
  The 
  inferior 
  face 
  is 
  wrinkled 
  

   concentrically. 
  The 
  apertures 
  are 
  polygonal, 
  arranged 
  in 
  irregular 
  

   quincunx. 
  The 
  mesopores 
  are 
  smaller, 
  polygonal, 
  irregularly 
  placed. 
  

  

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

   pores, 
  0.08 
  mm.; 
  zoarial 
  diameter, 
  2.5 
  cm. 
  

  

  Structure. 
  — 
  The 
  specimen 
  figured 
  is 
  the 
  largest 
  fragment 
  observed 
  ; 
  

   it 
  belonged 
  certainly 
  to 
  a 
  large 
  orbicular 
  colony. 
  

  

  In 
  meridian 
  section 
  the 
  tubes 
  are 
  cylindrical, 
  short, 
  recurved 
  at 
  

   their 
  extremity. 
  The 
  mesopores 
  are 
  rather 
  short. 
  The 
  walls 
  are 
  

   entire. 
  

  

  Affinities. 
  — 
  In 
  zoarial 
  aspect 
  this 
  species 
  much 
  resembles 
  that 
  

   which 
  we 
  have 
  called 
  Multicrescis 
  landrioti 
  Miehelin, 
  1841, 
  but 
  differs 
  

   in 
  its 
  greater 
  micrometric 
  dimensions 
  and 
  in 
  sections 
  by 
  the 
  nonan- 
  

   nulated 
  tubes. 
  

  

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

   Switzerland 
  (rare). 
  

  

  Cotypes. 
  — 
  Cat. 
  No. 
  69857, 
  U.S.N.M., 
  and 
  Museum 
  Comparative 
  

   Zoology. 
  

  

  MULTICRESCIS 
  MAMMILLOSA, 
  new 
  species 
  

  

  Plate 
  21, 
  figs. 
  5, 
  6 
  

  

  Description. 
  — 
  -The 
  zoarium 
  encrusts 
  shells 
  and 
  is 
  formed 
  of 
  many 
  

   thin 
  superposed 
  lamellae. 
  The 
  orifices 
  are 
  polygonal 
  or 
  suborbicular, 
  

   arranged 
  in 
  quincunx. 
  The 
  mesopores 
  are 
  few 
  in 
  number, 
  polygonal, 
  

   smaller 
  than 
  the 
  orifices, 
  irregularly 
  placed. 
  The 
  zoarial 
  surface 
  is 
  

   mammillose. 
  

  

  Measurements. 
  — 
  Diameter 
  of 
  apertures, 
  0.10 
  mm.; 
  diameter 
  of 
  

   mesopores, 
  0.06 
  mm. 
  

  

  