﻿MAY 
  19, 
  1922 
  woodring: 
  dictyoconus 
  from 
  haiti 
  245 
  

  

  die 
  Eocene 
  (Lutetian) 
  age. 
  As 
  Patellina 
  egyptiensis 
  is 
  different 
  from 
  the 
  

   Recent 
  species 
  of 
  Patellina 
  and 
  the 
  Cretaceous 
  species 
  of 
  Orhitolina, 
  

   Blanckenhorn 
  proposed 
  for 
  it 
  the 
  new 
  generic 
  name 
  Dictyoconus.^ 
  

   Blanckenhorn 
  considered 
  Dictyoconus 
  a 
  guide 
  genus 
  of 
  the 
  lower 
  

   "Mokattamstufe." 
  Dictyoconus 
  egyptiensis 
  was 
  fully 
  described 
  by 
  

   Schlumberger 
  and 
  H. 
  Douville, 
  1905 
  (3, 
  pp. 
  298-304, 
  pi. 
  9). 
  

  

  During 
  a 
  geological 
  reconnaissance 
  of 
  the 
  Republic 
  of 
  Haiti 
  in 
  the 
  

   winter 
  of 
  1920-1921 
  by 
  J. 
  S. 
  Brown, 
  W. 
  S. 
  Burbank, 
  and 
  myself, 
  

   numerous 
  specimens 
  of 
  two 
  new 
  species 
  of 
  Dictyoconus 
  were 
  collected 
  

   from 
  a 
  limestone 
  that 
  crops 
  out 
  in 
  the 
  central 
  and 
  southern 
  parts 
  of 
  

   the 
  western 
  half 
  of 
  the 
  Departement 
  du 
  Nord. 
  The 
  limestone 
  was 
  

   named 
  by 
  Vaughan 
  (4, 
  pp. 
  58, 
  94) 
  the 
  Plaisance 
  limestone. 
  The 
  most 
  

   abundant 
  species 
  is 
  remarkably 
  similar 
  to 
  Dictyoconus 
  egyptiensis; 
  

   but 
  the 
  other 
  species 
  is 
  even 
  more 
  depressed 
  than 
  the 
  microscope 
  form 
  

   of 
  Dictyoconus 
  egyptiensis 
  figured 
  by 
  Schlumberger 
  and 
  H. 
  Douville, 
  

   and 
  it 
  has 
  an 
  undulate 
  base. 
  These 
  Haitian 
  species 
  will 
  be 
  described 
  

   in 
  a 
  report 
  on 
  the 
  geology 
  of 
  the 
  Republic 
  of 
  Haiti 
  now 
  being 
  prepared 
  

   for 
  publication. 
  Thin 
  sections 
  show 
  that 
  they 
  have 
  the 
  same 
  internal 
  

   structure 
  as 
  the 
  Egyptian 
  specimens. 
  

  

  The 
  structural 
  relations 
  of 
  the 
  Plaisance 
  limestone 
  indicate 
  that 
  it 
  is 
  

   of 
  middle 
  Eocene 
  (Lutetian) 
  age, 
  and 
  not 
  of 
  upper 
  Eocene 
  (Priabonian) 
  

   age, 
  as 
  was 
  supposed 
  when 
  it 
  was 
  named. 
  The 
  evidence 
  furnished 
  by 
  

   the 
  Foraminifera 
  seems 
  to 
  be 
  a 
  striking 
  confirmation 
  of 
  its 
  middle 
  

   Eocene 
  age. 
  The 
  Plaisance 
  limestone 
  is 
  the 
  first 
  formation 
  of 
  middle 
  

   Eocene 
  age 
  recognized 
  in 
  the 
  West 
  Indies 
  proper, 
  as 
  the 
  upper 
  Eocene 
  

   is 
  the 
  only 
  one 
  of 
  the 
  commonly 
  accepted 
  subdivisions 
  of 
  the 
  Eocene 
  

   heretofore 
  recognized 
  (5, 
  p. 
  607). 
  

  

  A 
  third 
  species 
  of 
  Dictyoconus 
  was 
  collected 
  at 
  many 
  localities 
  in 
  

   the 
  northern 
  part 
  of 
  the 
  Republic 
  from 
  rocks 
  that 
  are 
  clearly 
  of 
  upper 
  

   Eocene 
  (Priabonian) 
  age. 
  This 
  species 
  is 
  found 
  with 
  Orthophragmina 
  

   crassa 
  Cushman, 
  Orthophragmina 
  cubensis 
  Cushman,. 
  and 
  other 
  upper 
  

   Eocene 
  orbitoidal 
  Foraminifera, 
  and 
  it 
  seems 
  to 
  be 
  similar 
  to 
  Dictyoconus 
  

   americana 
  (Cushman), 
  which 
  was 
  described 
  from 
  the 
  upper 
  Eocene 
  

   (Priabonian) 
  St. 
  Bartholomew 
  limestone 
  of 
  the 
  island 
  of 
  St. 
  Barthol- 
  

   omew 
  (6, 
  p. 
  43, 
  text 
  fig. 
  3). 
  The 
  species 
  described 
  from 
  St. 
  Barthol- 
  

   omew 
  is 
  the 
  only 
  American 
  species 
  that 
  has 
  heretofore 
  been 
  described. 
  

   Cushman 
  (4, 
  pp. 
  105, 
  106) 
  has 
  recorded 
  the 
  same 
  or 
  a 
  similar 
  species 
  

   from 
  the 
  upper 
  Eocene 
  of 
  the 
  Dominican 
  Republic. 
  

  

  ^ 
  On 
  p. 
  419 
  where 
  the 
  genus 
  is 
  first 
  mentioned 
  by 
  Blanckenhorn 
  the 
  spelling 
  is 
  Dictyoco- 
  

   nus, 
  but 
  on 
  the 
  following 
  pages 
  the 
  less 
  desirable 
  spelling 
  Dictyoconos 
  is 
  used. 
  

  

  