﻿THE 
  

  

  AMERICAN 
  JOURNAL 
  OF 
  SCIENCE 
  

  

  [FOURTH 
  SERIES.!* 
  jy*> 
  

  

  % 
  

  

  Aet. 
  XXVI. 
  — 
  Classification 
  of 
  the 
  Cycadophyta* 
  

  

  R. 
  WlELAND. 
  

  

  Extension 
  of 
  the 
  knowledge 
  of 
  cycads, 
  cycad-like 
  

   plants, 
  and 
  their 
  remoter 
  relatives, 
  has 
  now 
  gone 
  on 
  for 
  

   just 
  90 
  years. 
  When 
  Buckland 
  in 
  1828 
  came 
  to 
  give 
  

   closer 
  attention 
  to 
  the 
  " 
  crow's 
  nests" 
  of 
  the 
  Isle 
  of 
  

   Portland, 
  he 
  happily 
  emphasized 
  the 
  cycad-like 
  character 
  

   of 
  these 
  petrified 
  stems 
  in 
  the 
  generic 
  name 
  Cycadeoidea; 
  

   while 
  the 
  great 
  contemporary 
  botanist 
  Robert 
  Brown 
  

   suggested 
  the 
  family 
  name 
  Cycadeoidese. 
  Brown 
  evi- 
  

   dently 
  regarded 
  the 
  abundant 
  ramentum, 
  and 
  free 
  lateral 
  

   budding, 
  as 
  the 
  main 
  characters 
  indicating 
  the 
  new 
  family. 
  

   He 
  doubtless 
  recognized 
  that 
  the 
  fructification 
  must 
  vary 
  ; 
  

   but 
  as 
  Buckland 
  very 
  soon 
  sought 
  to 
  give 
  even 
  more 
  

   emphasis 
  to 
  a 
  cycad 
  relationship 
  by 
  inadmissibly 
  using 
  

   Cycadites 
  for 
  Cycadeoidea, 
  it 
  is 
  evident 
  that 
  only 
  the 
  

   simpler 
  outer 
  characters 
  were 
  the 
  ones 
  held 
  mainly 
  in 
  

   mind. 
  

  

  The 
  first 
  evidence 
  to 
  deeply 
  affect 
  the 
  classification 
  was 
  

   forty 
  years 
  in 
  appearing. 
  In 
  1870 
  came 
  the 
  two 
  notable 
  

   papers 
  of 
  Williamson 
  and 
  Carruthers. 
  Williamson 
  asso- 
  

   ciated 
  the 
  Zamites 
  fronds, 
  "pyriform 
  axes," 
  and 
  the 
  

   4 
  ' 
  collars" 
  or 
  " 
  disks" 
  of 
  the 
  Yorkshire 
  coast; 
  while 
  

   Carruthers 
  described 
  the 
  Isle 
  of 
  Wight 
  trunk 
  Cycadeo- 
  

   idea 
  (Bennettites) 
  gibsoniana 
  with 
  its 
  unique 
  ovulate 
  

  

  * 
  To 
  give 
  all 
  of 
  the 
  references 
  bearing 
  on 
  this 
  classification 
  would 
  require 
  

   undue 
  space. 
  The 
  reader 
  should 
  refer 
  to 
  the 
  chronologic 
  list 
  of 
  literature 
  

   on 
  the 
  Williamsonian 
  Tribe, 
  this 
  Journal, 
  vol. 
  32, 
  p. 
  465, 
  Dec, 
  1911. 
  See 
  

   also 
  the 
  bibliography 
  in 
  my 
  American 
  Fossil 
  Cycads, 
  Carnegie 
  Institution 
  

   of 
  Washington 
  Publication 
  34, 
  vol. 
  II, 
  1916. 
  The 
  dates 
  here 
  freely 
  given 
  

   will 
  facilitate 
  such 
  reference 
  in 
  most 
  instances. 
  The 
  two 
  volumes 
  on 
  the 
  

   American 
  Fossil 
  Cycads 
  now 
  constitute 
  an 
  extensive 
  catalogue 
  to 
  which 
  there 
  

   is 
  constant 
  occasion 
  to 
  refer. 
  Accordingly 
  it 
  is 
  wished 
  to 
  use 
  an 
  abbrevi- 
  

   ated 
  reference 
  form, 
  thus, 
  Am. 
  Fos. 
  Cy., 
  Vol. 
  I, 
  Vol. 
  II. 
  

  

  Am. 
  Jour. 
  Sci.— 
  Fourth 
  Series, 
  Vol. 
  XL 
  VII, 
  No. 
  282.— 
  June, 
  1919. 
  

  

  27 
  

  

  