﻿244 
  JOURNAL 
  OF 
  the; 
  WASHINGTON 
  ACADEMY 
  OF 
  SCIENCES 
  VOL. 
  12, 
  NO. 
  10 
  

  

  is 
  evidently 
  connected 
  with 
  partial 
  replacement 
  of 
  sodium 
  bv 
  hydro- 
  

   gen, 
  total 
  alkalies 
  plus 
  total 
  water 
  amounting 
  to 
  the 
  theoretical 
  ratio 
  

   of 
  2. 
  The 
  role 
  of 
  water 
  in 
  the 
  glaucamphiboles 
  appears 
  never 
  to 
  have 
  

   been 
  studied, 
  but 
  as 
  most 
  of 
  the 
  analyses 
  show 
  on 
  the 
  average 
  2% 
  of 
  

   this 
  constituent, 
  it 
  is 
  probably 
  at 
  least 
  in 
  large 
  part 
  essential. 
  

  

  It 
  is 
  interesting 
  to 
  consider 
  the 
  mode 
  of 
  occurrence 
  of 
  the 
  material 
  : 
  

   it 
  is 
  found 
  as 
  impregnations 
  and 
  coatings 
  in 
  gneissoid 
  rocks 
  of 
  pre- 
  

   Cambrian 
  age, 
  in 
  diabase 
  of 
  Triassic 
  age, 
  and 
  in 
  sediments 
  of 
  the 
  latter 
  

   age 
  intruded 
  by 
  the 
  diabase. 
  The 
  gneisses 
  thus 
  impregnated 
  are 
  usu- 
  

   ally 
  greatly 
  shattered 
  ; 
  the 
  crocidolite 
  not 
  only 
  fills 
  the 
  resulting 
  crev- 
  

   ices, 
  but 
  also 
  replaces 
  the 
  original 
  minerals 
  of 
  the 
  gneiss. 
  Replace- 
  

   ment 
  of 
  hornblende 
  was 
  described 
  by 
  Mrs. 
  Knopf, 
  and 
  it 
  may 
  be 
  added 
  

   that 
  the 
  rocks, 
  which 
  usually 
  contain 
  considerable 
  primary 
  quartz 
  

   where 
  unaltered, 
  are 
  practically 
  free 
  from 
  this 
  mineral 
  in 
  extensively 
  

   crocidolitized 
  zones. 
  Some 
  of 
  the 
  silica 
  has 
  been 
  redeposited, 
  with 
  the 
  

   crocidolite, 
  in 
  the 
  form 
  of 
  secondary 
  quartz. 
  The 
  same 
  phenomenon 
  

   is 
  noticeable 
  in 
  the 
  replacement 
  of 
  these 
  gneisses 
  by 
  sericite'' 
  which 
  

   is 
  of 
  frequent 
  occurrence 
  in 
  the 
  region, 
  namely 
  that 
  the 
  primary 
  quartz 
  

   is 
  replaced 
  more 
  rapidly 
  than 
  the 
  feldspar. 
  This 
  points 
  to 
  the 
  depo- 
  

   sition 
  of 
  the 
  crocidolite, 
  like 
  the 
  sericite, 
  from 
  hydrothermal 
  solutions. 
  

   The 
  shattering 
  of 
  the 
  crocidolitized 
  gneisses 
  is, 
  in 
  the 
  experience 
  of 
  the 
  

   senior 
  writer, 
  almost 
  always 
  connected 
  with 
  faulting 
  of 
  late 
  Triassic 
  

   date, 
  and 
  since 
  the 
  same 
  mineral 
  occurs 
  in 
  the 
  late 
  Triassic 
  diabase 
  

   and 
  the 
  sediments 
  it 
  has 
  metamorphosed, 
  the 
  suggestion 
  is 
  here 
  made 
  

   that 
  the 
  hydrothermal 
  solutions 
  which 
  deposited 
  the 
  crocidolite 
  in 
  

   the 
  various 
  occurrences 
  came 
  alike 
  from 
  the 
  Triassic 
  diabase 
  magma. 
  

  

  PALEONTOLOGY. 
  — 
  Middle 
  Eocene 
  Foraminifera 
  of 
  the 
  genus 
  Dictyo- 
  

   conus 
  from 
  the 
  Republic 
  of 
  Haiti.''- 
  Wendell 
  P. 
  Woodring, 
  U. 
  S. 
  

   Geological 
  Survey. 
  

  

  In 
  1900, 
  Chapman 
  (1, 
  pp. 
  11-12, 
  pi. 
  2, 
  figs. 
  1-3) 
  described 
  as 
  Patel- 
  

   lina 
  egyptiensis 
  a 
  curious 
  conical 
  species 
  of 
  Foraminifera 
  that 
  was 
  col- 
  

   lected 
  in 
  northern 
  Egypt 
  between 
  Cairo 
  and 
  Suez 
  from 
  rocks 
  that 
  were 
  

   then 
  supposed 
  to 
  be 
  of 
  lower 
  Miocene 
  age. 
  The 
  generic 
  name 
  Patel- 
  

   lina 
  was 
  used 
  by 
  Chapman 
  as 
  the 
  equivalent 
  of 
  Orbitolina. 
  Blancken- 
  

   horn 
  (2, 
  pp. 
  419, 
  432-435) 
  showed 
  that 
  the 
  rocks 
  from 
  which 
  Chapman's 
  

   specimens 
  were 
  collected 
  are 
  part 
  of 
  the 
  lower 
  Mokattam 
  group 
  of 
  mid- 
  

  

  5 
  Wherry. 
  Bull. 
  Geol. 
  Soc. 
  Amer. 
  29: 
  383. 
  1918. 
  

  

  1 
  Published 
  by 
  permission 
  of 
  the 
  Engineer 
  in 
  Chief, 
  Republic 
  of 
  Haiti, 
  and 
  of 
  the 
  Direc- 
  

   tor, 
  U. 
  S. 
  Geological 
  Survey. 
  Received 
  April 
  24, 
  1922. 
  

  

  