﻿86 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL. 
  MUSEUM 
  vol.67 
  

  

  We 
  have 
  sectioned 
  a 
  specimen 
  containing 
  on 
  one 
  side 
  an 
  exterior 
  

   accessory 
  intrazoarial 
  lamella. 
  It 
  is 
  a 
  curious 
  phenomenon 
  which 
  

   we 
  have 
  observed 
  for 
  the 
  first 
  time. 
  

  

  On 
  the 
  broad 
  sides 
  the 
  peristomes 
  are 
  arranged 
  irregularly 
  on 
  the 
  

   median 
  axis 
  and 
  in 
  laterally 
  transverse 
  lines, 
  an 
  arrangement 
  close 
  

   to 
  that 
  observed 
  in 
  Hornera. 
  

  

  Occurrence. 
  — 
  Lower 
  Cretaceous 
  (Aptian) 
  : 
  Grandpre 
  (Ardennes), 
  

   France; 
  Faringd 
  on, 
  England 
  (common). 
  

  

  Plesioty 
  pes. 
  —Cat. 
  No. 
  69941, 
  U.S.N.M. 
  

  

  LATEROCAVEA 
  INTERMEDIA, 
  new 
  species 
  

  

  Plate 
  13, 
  figs. 
  9-17 
  

  

  Description. 
  — 
  The 
  zoarium 
  is 
  small, 
  cylindrical, 
  dichotomously 
  

   branched. 
  On 
  the 
  principal 
  branches 
  the 
  orifices 
  are 
  arranged 
  lat- 
  

   erally, 
  although 
  the 
  entire 
  anterior 
  surf 
  ace 
  is 
  occupied 
  bymesopores. 
  

   On 
  the 
  terminal 
  branches 
  the 
  orifices 
  are 
  disposed 
  entirely 
  around 
  

   the 
  colony. 
  In 
  the 
  cellular 
  parts 
  the 
  orifices 
  are 
  arranged 
  in 
  irregu- 
  

   lar 
  transverse 
  lines; 
  the 
  peristomes 
  are 
  almost 
  always 
  adjacent 
  and 
  

   separated 
  longitudinally 
  by 
  groups 
  of 
  four 
  mesopores. 
  The 
  ovi- 
  

   cell 
  is 
  globular, 
  elliptical, 
  large, 
  and 
  always 
  placed 
  on 
  a 
  side 
  with 
  

   mesopores. 
  

  

  Measurements. 
  — 
  Diameter 
  of 
  orifice, 
  0.08 
  mm.; 
  zooecial 
  width, 
  

   0.14 
  mm.; 
  distance 
  of 
  orifices, 
  0.25 
  mm.; 
  diameter 
  of 
  branches, 
  

   1 
  mm. 
  

  

  Affinities. 
  — 
  The 
  arrangement 
  of 
  the 
  orifices 
  is 
  absolutely 
  contrary 
  

   to 
  that 
  in 
  Laterocavea 
  dutempleana 
  D'Orbigny, 
  1853, 
  because 
  they 
  

   are 
  lateral 
  and 
  not 
  on 
  the 
  plane 
  of 
  dichotomisation. 
  Furthermore, 
  

   the 
  small 
  branches, 
  bearing 
  orifices 
  entirety 
  around 
  the 
  colony, 
  offer 
  

   the 
  aspect 
  of 
  Petalopora 
  Lonsdale, 
  1850. 
  Complete 
  zoaria 
  present, 
  

   therefore, 
  all 
  the 
  characters 
  intermediate, 
  between 
  the 
  two 
  genera 
  

   Laterocavea 
  and 
  Petalopora. 
  This 
  species 
  differs 
  again 
  from 
  Latero- 
  

   cavea 
  dutempleana 
  D'Orbigny, 
  1853, 
  in 
  its 
  rounded 
  instead 
  of 
  com- 
  

   pressed 
  and 
  much 
  smaller 
  branches. 
  

  

  Occurrence. 
  — 
  Lower 
  Cretaceous 
  (Aptian): 
  Faringdon, 
  England. 
  

  

  Cotypes.— 
  Cat. 
  No. 
  69942, 
  U.S.N.M. 
  

  

  Genus 
  SIPHODICTYUM 
  Lonsdale, 
  1849 
  

  

  1849. 
  Siphodictyum 
  Lonsdale, 
  Notes 
  on 
  Fossil 
  Zoophytes, 
  Quarterly 
  Journal 
  

   Geological 
  Society 
  London, 
  vol. 
  5. 
  p. 
  94. 
  

  

  The 
  ovicell 
  is 
  an 
  elliptical, 
  very 
  convex 
  sack, 
  perforated 
  by 
  a 
  

   certain 
  number 
  of 
  tubes 
  (type 
  of 
  Ascosoecia) 
  . 
  The 
  tubes 
  are 
  short, 
  

   with 
  peristome, 
  with 
  triparietal 
  gemmation 
  around 
  a 
  central 
  axis. 
  

   The 
  zoarial 
  epithoca 
  is 
  very 
  thick 
  and 
  perforated 
  all 
  around 
  the 
  col- 
  

   ony 
  by 
  small 
  numerous 
  vacuoles, 
  issuing 
  from 
  aborted 
  tubes 
  and 
  

   arranged 
  at 
  the 
  bottom 
  of 
  the 
  sulci. 
  

  

  