﻿Geology 
  and 
  Mineralogy. 
  473 
  

  

  been 
  distributed, 
  has 
  been 
  thoroughly 
  worked 
  over 
  and 
  improved 
  

   in 
  minor 
  details, 
  as 
  well 
  as 
  largely 
  added 
  to 
  where 
  the 
  develop- 
  

   ment 
  of 
  the 
  science 
  has 
  called 
  for 
  this. 
  The 
  amount 
  of 
  new 
  mat- 
  

   ter 
  added 
  will 
  be 
  appreciated 
  from 
  the 
  statement 
  that 
  the 
  work 
  

   has 
  been 
  increased 
  one-fifth 
  in 
  size 
  since 
  it 
  was 
  first 
  issued. 
  

  

  II. 
  Geology 
  and 
  Mlnekalogy. 
  

  

  1. 
  Discovery 
  of 
  a 
  dicotyledonous 
  Flora 
  hi 
  the 
  Cheyenne 
  sand- 
  

   stone. 
  — 
  In 
  a 
  letter 
  to 
  the 
  editors 
  of 
  the 
  Journal, 
  Mr. 
  Robert 
  T. 
  

   Hill 
  of 
  the 
  United 
  States 
  Geological 
  Survey, 
  reports 
  " 
  the 
  dis- 
  

   covery 
  of 
  a 
  typical 
  dicotyledonous 
  flora 
  in 
  the 
  Cheyenne 
  sand- 
  

   stone 
  at 
  the 
  base 
  of 
  the 
  beds 
  belonging 
  to 
  the 
  Comanche 
  Series 
  

   in 
  Comanche 
  and 
  Barber 
  counties 
  of 
  Southern 
  Kansas. 
  This 
  

   sandstone 
  has 
  hitherto 
  been 
  referred 
  to 
  the 
  Trinity 
  Division 
  of 
  

   Texas 
  by 
  Prof. 
  F. 
  W. 
  Cragin, 
  but 
  the 
  flora 
  as 
  determined 
  by 
  

   Prof. 
  F. 
  H. 
  Knowlton 
  of 
  the 
  U. 
  S. 
  Geological 
  Survey 
  consists 
  

   entirely 
  of 
  species 
  hitherto 
  supposed 
  to 
  be 
  peculiar 
  to 
  the 
  Dakota 
  

   Group, 
  while 
  the 
  flora 
  of 
  the 
  Trinity 
  Division 
  of 
  Texas 
  as 
  has 
  

   been 
  reported 
  by 
  Prof. 
  Fontaine 
  is 
  all 
  of 
  the 
  non-dicotyledonous 
  

   Potomac 
  type. 
  The 
  Cheyenne 
  sandstones 
  are 
  separated 
  from 
  the 
  

   true 
  Dakota 
  sands 
  of 
  Kansas 
  by 
  nearly 
  200 
  feet 
  of 
  shale, 
  contain- 
  

   ing 
  a 
  molluscan 
  fauna 
  composed 
  of 
  fifteen 
  species 
  characteristic 
  

   of 
  the 
  Washita 
  Division 
  of 
  the 
  Comanche 
  Series 
  in 
  Texas, 
  and 
  

   about 
  twenty 
  littoral 
  species 
  peculiar 
  to 
  the 
  locality, 
  thus 
  extend- 
  

   ing 
  the 
  hitherto 
  known 
  downward 
  range 
  of 
  the 
  Dakota 
  flora 
  

   from 
  the 
  Dakota 
  position 
  to 
  the 
  base 
  of 
  the 
  Washita." 
  The 
  

   details 
  aud 
  results 
  of 
  Mr. 
  Hill's 
  observations 
  will 
  be 
  published 
  in 
  

   an 
  early 
  number 
  of 
  the 
  Journal. 
  

  

  2. 
  On 
  the 
  Geological 
  Aspects 
  of 
  Variation. 
  — 
  An 
  interesting 
  and 
  

   suggestive 
  paper 
  on 
  the 
  relation 
  of 
  varietal 
  modification 
  of 
  form 
  

   to 
  the 
  geological 
  range 
  of 
  a 
  fossil 
  species 
  is 
  contributed 
  by 
  M. 
  

   Gosselet 
  in 
  his 
  memoir 
  on 
  the 
  variation 
  of 
  Spirifer 
  verneuili* 
  

   M. 
  Gosselet 
  has 
  accumulated 
  large 
  collections 
  of 
  this 
  common 
  

   species 
  of 
  the 
  Upper 
  Devonian 
  formations 
  of 
  northern 
  Europe, 
  

   has 
  made 
  exact 
  and 
  minute 
  study 
  of 
  the 
  various 
  elements 
  of 
  their 
  

   morphological 
  characters, 
  has 
  classified 
  them 
  into 
  groups 
  on 
  the 
  

   basis 
  of 
  their 
  differences 
  and 
  has 
  given 
  a 
  beautiful 
  series 
  of 
  illus- 
  

   trations 
  of 
  the 
  varieties 
  and 
  of 
  the 
  most 
  closely 
  allied 
  species. 
  

  

  From 
  his 
  studies 
  he 
  draws 
  the 
  following 
  important 
  generaliza- 
  

   tions, 
  viz 
  : 
  (Translated 
  from 
  the 
  French). 
  

  

  "From 
  the 
  comparison 
  of 
  diverse 
  forms 
  of 
  Spirifer 
  verneuili, 
  

   either 
  among 
  themselves, 
  or 
  with 
  allied 
  species, 
  the 
  conclusion 
  is 
  

   reached 
  that 
  this 
  Spirifer 
  is 
  a 
  very 
  polymorphic 
  species, 
  of 
  which 
  

   all 
  the 
  elements 
  vary, 
  except 
  the 
  -character 
  of 
  the 
  plications, 
  

   which 
  remain 
  always 
  simple 
  upon 
  the 
  sides 
  while 
  they 
  multiply 
  

   by 
  bifurcation 
  or 
  by 
  intercalation 
  on 
  the 
  fold 
  and 
  on 
  the 
  sinus. 
  

  

  There 
  are 
  insensible 
  passages 
  between 
  all 
  the 
  varieties. 
  The 
  

  

  * 
  Etude 
  sur 
  les 
  variations 
  du 
  Spirifer 
  verneuili 
  par 
  J. 
  Gosselet. 
  Mem. 
  Soc. 
  

   Geol. 
  du 
  Nord, 
  [France] 
  Tome 
  iv, 
  I, 
  pp. 
  1-61, 
  Plates 
  I- 
  VII. 
  1894. 
  

  

  