﻿G. 
  R. 
  Wieland 
  — 
  On 
  Liassic 
  Floras. 
  277 
  

  

  Such 
  is 
  the 
  academical 
  result 
  ; 
  for 
  we 
  hold 
  that 
  no 
  part 
  of 
  

   the 
  plant 
  beds 
  can 
  be 
  Rh'atic. 
  As 
  already 
  quoted, 
  Zeiller 
  has 
  

   shown 
  that 
  a 
  typical 
  Rhatic 
  flora 
  (that 
  of 
  Tonkin) 
  which 
  

   actually 
  contains 
  some 
  elements 
  found 
  to 
  persist 
  in 
  Oaxaca, 
  is 
  

   half 
  made 
  up 
  of 
  ferns 
  of 
  the 
  older 
  type, 
  one 
  tenth 
  of 
  the 
  plants 
  

   being 
  conifers 
  and 
  only 
  one-third 
  cycads.. 
  While 
  on 
  the 
  other 
  

   hand, 
  there 
  is 
  much 
  more 
  of 
  agreement 
  in 
  the 
  Liassic 
  propor- 
  

   tions 
  for 
  these 
  forms 
  as 
  already 
  displayed 
  in 
  Tables 
  IV- 
  V. 
  

  

  Moreover, 
  we 
  encounter 
  difficulties 
  as 
  soon 
  as 
  an 
  attempt 
  is 
  

   made 
  to 
  draw 
  close 
  parallels 
  with 
  presumably 
  post-Liassic 
  

   florae. 
  That 
  from 
  Oroville, 
  California, 
  appears 
  much 
  more 
  

   recent 
  in 
  type. 
  So 
  does 
  that 
  of 
  Graham 
  Land. 
  

  

  (d) 
  Source 
  of 
  the 
  Mixteea 
  Alta 
  Flora. 
  

  

  Are 
  these 
  Oaxacan 
  plants 
  northern 
  or 
  southern 
  in 
  origin 
  ? 
  

   Or, 
  are 
  they 
  essentially 
  equatorial, 
  and 
  such 
  a 
  distinctive 
  part 
  

   of 
  the 
  more 
  strictly 
  cosmopolitan 
  vegetation 
  of 
  the 
  Jura 
  that 
  

   no 
  source 
  or 
  original 
  home 
  of 
  the 
  major 
  elements 
  can 
  be 
  dis- 
  

   cerned 
  ? 
  

  

  It 
  is 
  unfortunate 
  that 
  sections 
  through 
  the 
  plant 
  beds 
  of 
  the 
  

   Argentine 
  or 
  other 
  South 
  American 
  mainland 
  localities 
  yield- 
  

   ing 
  Jurassic 
  plants 
  have 
  not 
  been 
  made 
  by 
  qualified 
  plant 
  col- 
  

   lectors 
  ; 
  whilst 
  all 
  we 
  so 
  far 
  have 
  from 
  Antarctica 
  is 
  the 
  

   recently 
  published 
  work 
  of 
  Halle 
  on 
  the 
  Mesozoic 
  flora 
  of 
  

   Graham 
  Land. 
  A 
  brief 
  note 
  of 
  Nathorst 
  in 
  the 
  Compte 
  

   Rendu 
  (p. 
  1449, 
  June 
  6th, 
  1904) 
  first 
  made 
  it 
  known 
  that 
  a 
  

   varied 
  vegetation 
  resembling 
  that 
  of 
  the 
  Jabalpur-Kach 
  beds 
  

   of 
  India, 
  and, 
  therefore, 
  affiliated 
  with 
  the 
  Northern 
  florae 
  of 
  

   early 
  to 
  decidedly 
  mid 
  -Jurassic 
  facies, 
  once 
  flourished 
  in 
  

   Antarctica. 
  And 
  a 
  little 
  later 
  the 
  study 
  of 
  this 
  notable 
  

   material 
  was 
  taken 
  up 
  by 
  Halle. 
  

  

  Typical 
  Graham 
  Land 
  plants 
  are 
  Cladophleois, 
  Todites, 
  

   Coniopteris, 
  Sphenopterids, 
  Otozamites 
  Hislopi, 
  Pseitdoctenis^ 
  

   a 
  Pterophylhtm 
  Morrissianum 
  equivalent, 
  and 
  a 
  notable 
  

   group 
  of 
  conifers 
  including 
  Araucarites 
  cutchensis, 
  Pagio- 
  

   'phylhim, 
  Brachyphyllum, 
  and 
  Elatocladus 
  Jabalpurensis 
  

   f=PalissyaJ, 
  with 
  various 
  other 
  less 
  important 
  species. 
  

  

  Evidently 
  many 
  of 
  the 
  most 
  conspicuous 
  plants 
  of 
  early 
  

   Jurassic 
  and 
  later 
  time 
  were 
  nearly 
  as 
  distinctly 
  cosmopolitan 
  

   as 
  the 
  Paleozoic 
  types, 
  a 
  fact 
  which 
  must 
  make 
  the 
  unravelling 
  

   of 
  the 
  course 
  of 
  plant 
  origin 
  and 
  migration 
  in 
  the 
  mid-M 
  esozoic 
  

   or' 
  " 
  proangiosperm 
  " 
  age 
  an 
  exceedingly 
  complicated 
  if 
  not 
  

   virtually 
  impossible 
  task. 
  But, 
  needless 
  to 
  say, 
  the 
  difficulty 
  

   here 
  confronted 
  must 
  incite 
  paleobotanists 
  to 
  put 
  forth 
  every 
  

   effort 
  before 
  finally 
  accepting 
  negative 
  results. 
  

  

  Meanwhile, 
  such 
  evidence 
  as 
  we 
  do 
  possess 
  at 
  least 
  makes 
  

   possible 
  various 
  interesting 
  inferences. 
  As 
  already 
  noted, 
  

  

  