﻿G. 
  R. 
  Wieland 
  on 
  the 
  Cycadophyta. 
  405 
  

  

  recent, 
  long 
  continental 
  emergences 
  are 
  required. 
  Here, 
  

   Archaic, 
  Ancient, 
  Transition, 
  and 
  Recent, 
  may 
  serve 
  to 
  

   indicate 
  the 
  four 
  great 
  land 
  plant 
  worlds 
  of 
  the 
  past, 
  fol- 
  

   lowing 
  the 
  Eopaleozoic 
  aquatics. 
  

  

  The 
  view 
  here 
  emphasized 
  is 
  not 
  new, 
  but 
  goes 
  back 
  to 
  

   Saporta 
  (1881), 
  and 
  has 
  been 
  only 
  recently 
  again 
  brought 
  

   forward 
  by 
  Clements 
  in 
  his 
  Plant 
  Succession 
  (p. 
  288). 
  

   It 
  will 
  be 
  observed 
  however 
  that 
  the 
  terms 
  suggested 
  are 
  

   used 
  in 
  the 
  physical 
  as 
  well 
  as 
  phytologic 
  sense, 
  and 
  that 
  

   both 
  the 
  divisions 
  and 
  events 
  are 
  set 
  back 
  much 
  further 
  

   in 
  time. 
  This 
  is 
  held 
  absolutely 
  justifiable 
  from 
  both 
  the 
  

   plant 
  and 
  diastrophic 
  records. 
  

  

  In 
  lieu 
  of 
  a 
  resume, 
  let 
  the 
  fact 
  be 
  emphasized 
  that 
  the 
  

   various 
  "paleobotanic 
  trees' 
  ' 
  and 
  gymnosperm 
  classi- 
  

   fications 
  still 
  include 
  features 
  irreconcilably 
  divergent. 
  

   One 
  of 
  the 
  most 
  suggestive 
  "trees" 
  is 
  that 
  of 
  Lignier 
  

   (1903), 
  written 
  out 
  as 
  follows: 
  

  

  I. 
  LYCOPODINALES 
  (Lycopodinea). 
  

   II. 
  PROTOPTERIDEANS 
  (Filicinales, 
  Filices) 
  

  

  , 
  R 
  jCYCADALES 
  (Cycadacese) 
  M 
  v 
  .. 
  \ 
  

  

  TTT 
  ) 
  a 
  \ 
  SALISBURIALES 
  (Salisburiacece 
  \ 
  %' 
  ^ 
  c 
  ? 
  mlev8 
  ) 
  

   11L 
  - 
  1 
  A 
  j 
  BENNETTITALES 
  ( 
  Z 
  ' 
  laxmeas 
  ^ 
  

  

  l 
  ^ 
  ICORDAITALES 
  (Gnetales, 
  Angiosperms) 
  

  

  Now 
  Lignier 
  's 
  "tree," 
  viewed 
  in 
  the 
  light 
  of 
  his 
  later 
  

   critical 
  studies 
  of 
  the 
  Gnetaleans, 
  gives 
  a 
  degree 
  of 
  

   expression 
  to 
  that 
  extreme 
  homoplasy 
  which 
  becomes 
  

   with 
  every 
  succeeding 
  year 
  of 
  investigation, 
  more 
  and 
  

   more 
  evident, 
  especially 
  in 
  the 
  four 
  great 
  gymnosperm 
  

   lines. 
  But 
  it 
  has 
  the 
  lack 
  inherent 
  to 
  all 
  such 
  schemes. 
  

   They 
  always 
  somewhere 
  detach 
  or 
  separate 
  important 
  

   groups, 
  here 
  the 
  cycads 
  and 
  cycadeoids. 
  Plotted 
  on 
  a 
  

   cylinder 
  (better 
  a 
  hemisphere), 
  this 
  difficulty 
  is 
  partly 
  

   met. 
  

  

  It 
  is 
  worth 
  while 
  to 
  give 
  and 
  to 
  examine 
  diagram 
  3, 
  the 
  

   sectors 
  being 
  movable 
  (and 
  also 
  to 
  be 
  taken 
  in 
  the 
  spher- 
  

   ical 
  sense). 
  This 
  diagram, 
  while 
  showing 
  the 
  Cycado- 
  

   phyte-Coniferophyte 
  division, 
  is 
  not 
  given 
  as 
  a 
  formal 
  

   classification, 
  but 
  as 
  a 
  first 
  step 
  in 
  reaching 
  one. 
  It 
  is 
  

   believed 
  to 
  be 
  a 
  better 
  form 
  than 
  any 
  other 
  for 
  bringing 
  

   out 
  certain 
  inconsistencies 
  in 
  the 
  classification 
  — 
  taken 
  

   from 
  the 
  paleobotanic 
  viewpoint. 
  Ampliation 
  is 
  much 
  

   simplified; 
  at 
  the 
  center 
  are 
  the 
  early 
  Lvcopods 
  and 
  

   "seed-bearing 
  quasi-f 
  erns. 
  " 
  Dicotyledony 
  is 
  not 
  brack- 
  

   eted 
  ; 
  most 
  spermatophytes 
  have 
  been 
  dicotyledonous 
  far 
  

  

  