﻿G. 
  R. 
  Wieland 
  — 
  On 
  Liassic 
  Floras. 
  251 
  

  

  Art. 
  XXVI. 
  — 
  The 
  Liassic 
  Flora 
  of 
  the 
  Mixteoa 
  Alta 
  of 
  

   Mexico, 
  — 
  Its 
  Composition, 
  Age, 
  and 
  Source 
  y* 
  by 
  G. 
  R. 
  

   Wieland. 
  

  

  During 
  the 
  year 
  1909 
  the 
  writer 
  enjoyed 
  the 
  permission 
  of 
  

   the 
  Carnegie 
  Institution 
  of 
  Washington 
  to 
  make, 
  in 
  conjunction 
  

   with 
  the 
  Instituto 
  Geologico 
  of 
  Mexico, 
  a 
  long 
  projected 
  recon- 
  

   naissance 
  in 
  search 
  of 
  fossil 
  cycads 
  in 
  southern 
  Mexico. 
  But 
  

   inasmuch 
  as 
  the 
  publication 
  by 
  the 
  Instituto 
  Geologico 
  of 
  the 
  

   results 
  later 
  brought 
  together 
  in 
  the 
  form 
  of 
  a 
  considerable 
  

   memoir 
  in 
  quarto 
  illustrated 
  by 
  text 
  figures 
  and 
  fifty 
  excellent 
  

   plates, 
  under 
  the 
  title 
  La 
  Flora 
  Lidsica 
  de 
  la 
  Mixteca 
  Alta, 
  

   (Boletin 
  No. 
  31), 
  promises 
  to 
  proceed 
  slowly, 
  a 
  supplementary 
  

   abstract 
  in 
  English 
  indicating 
  the 
  scope 
  of 
  the 
  field 
  and 
  labora- 
  

   tory 
  work 
  accomplished 
  has 
  the 
  sanction 
  of 
  Director 
  Yillerello 
  

   and 
  seems 
  doubly 
  desirable. 
  The 
  more 
  is 
  this 
  the 
  case 
  because 
  

   the 
  southern 
  Mexican 
  plant 
  beds 
  prove 
  to 
  begin 
  with 
  the 
  lower 
  

   Lias 
  and 
  thus 
  represent 
  the 
  first 
  typical 
  Liassic 
  series 
  to 
  be 
  

   described 
  from 
  North 
  America. 
  Not 
  only 
  so, 
  but 
  the 
  Wil- 
  

   liamsonian 
  cycads 
  yielded 
  in 
  unsurpassed 
  abundance 
  through- 
  

   out 
  the 
  great 
  thicknesses 
  of 
  strata 
  measured 
  must 
  be 
  ranked 
  

   geographically 
  as 
  one 
  of 
  the 
  most 
  interesting 
  Mesozoic 
  cycad 
  

   floras 
  of 
  the 
  globe. 
  That 
  results 
  of 
  first 
  importance 
  were 
  

   obtained 
  has 
  already 
  been 
  pointed 
  out 
  in 
  a 
  brief 
  paper 
  in 
  the 
  

   Botanical 
  Gazette 
  for 
  December, 
  1909 
  ; 
  although 
  in 
  that 
  con- 
  

   tribution 
  the 
  facts 
  considered 
  were 
  mainly 
  biologic. 
  

  

  Since 
  not 
  only 
  the 
  paleobotany 
  of 
  the 
  great 
  plant 
  beds 
  of 
  

   Oaxaca 
  but 
  all 
  present 
  views 
  of 
  their 
  age 
  and 
  structure 
  must 
  

   undergo 
  extensions 
  and 
  revisions 
  involving 
  many 
  years 
  of 
  

   work, 
  the 
  use 
  of 
  a 
  somewhat 
  general 
  regional 
  name 
  in 
  the 
  title 
  

   of 
  the 
  present 
  purely 
  initial 
  study 
  has 
  seemed 
  most 
  appropriate. 
  

   That 
  chosen 
  is 
  -a 
  semi-geographic, 
  semi-ethnologic 
  one 
  first 
  

   called 
  to 
  my 
  attention 
  by 
  Sr. 
  Gonzales 
  of 
  the 
  Instituto 
  Geo- 
  

   logico. 
  The 
  " 
  Mixteca 
  Alta 
  " 
  or 
  upper 
  country 
  of 
  the 
  Mixtecas 
  

   is 
  only 
  a 
  more 
  or 
  less 
  indefinite 
  portion 
  of 
  the 
  plateau 
  and 
  

   mountain 
  region 
  of 
  Oaxaca 
  and 
  adjoining 
  states 
  occupied 
  by 
  

   the 
  original 
  Mixtecan 
  tribes. 
  The 
  name 
  is 
  used 
  for 
  the 
  

   " 
  Tierra 
  templada 
  y 
  fria 
  " 
  in 
  contradistinction 
  to 
  the 
  " 
  Mixteca 
  

   baja 
  " 
  or 
  lower 
  country 
  of 
  the 
  " 
  Tierra 
  caliente 
  " 
  over 
  which 
  

   these 
  tribes 
  extended. 
  Conveniently 
  speaking, 
  then, 
  the 
  Mix- 
  

   teca 
  Alta 
  is 
  a 
  portion 
  of 
  the 
  southern 
  border 
  region 
  of 
  the 
  Cor- 
  

  

  * 
  The 
  present 
  article 
  is 
  properly 
  a 
  continuation 
  of 
  the 
  series 
  of 
  prelimin- 
  

   ary 
  Studies 
  of 
  American 
  Fossil 
  Cycads 
  brought 
  out 
  in 
  this 
  Journal 
  under 
  the 
  

   auspices 
  of 
  the 
  Carnegie 
  Institution 
  of 
  Washington. 
  These 
  studies 
  now 
  

   include 
  : 
  Parts 
  I-III 
  which 
  appeared 
  serially 
  in 
  March-May 
  1899, 
  — 
  Part 
  IV, 
  

   June 
  1901,— 
  Part 
  V, 
  August 
  1911, 
  -Part 
  VI, 
  February 
  1912; 
  together 
  with 
  

   additional 
  papers 
  on 
  the 
  Proembryo 
  of 
  the 
  Bennettiteae, 
  December 
  1904, 
  — 
  

   Historic 
  Fossil 
  Cycads, 
  February 
  1908, 
  and 
  the 
  contribution 
  on 
  the 
  William- 
  

   sonian 
  Tribe 
  of 
  December 
  1911. 
  

  

  Am. 
  Jour. 
  Sci. 
  — 
  Fourth 
  Series, 
  Vol. 
  XXXVI, 
  No. 
  213. 
  — 
  September, 
  1913. 
  

  

  17 
  

  

  