﻿G. 
  R. 
  Wieland 
  on 
  the 
  Cycadophyta. 
  397 
  

  

  If 
  anything 
  this 
  overdraws 
  the 
  reproductive 
  diver- 
  

   gence. 
  A 
  cycadeoid 
  with 
  short 
  more 
  peltate 
  micro-sporo- 
  

   phylls 
  organized 
  into 
  cones, 
  would 
  nearly 
  close 
  the 
  gap 
  

   between 
  Cycas 
  and 
  the 
  cycadeoids 
  ; 
  while 
  it 
  can 
  be 
  held 
  

   certain 
  that 
  the 
  Cycadophyte 
  types 
  presented 
  in 
  the 
  early 
  

   Mesozoic 
  many 
  vegetative 
  similarities 
  which 
  were 
  later 
  

   obscured. 
  

  

  All 
  in 
  all, 
  therefore, 
  the 
  extinct 
  group 
  of 
  cycadeoids 
  to 
  

   which 
  Cycadeoidea 
  has 
  afforded 
  the 
  structural 
  key, 
  are 
  

   half-cycacls, 
  — 
  in 
  the 
  most 
  exacting 
  sense 
  of 
  the 
  word, 
  

   Hemicycadales. 
  That 
  this 
  is 
  a 
  cosmopolitan 
  and 
  a 
  homo- 
  

   geneous 
  group 
  of 
  varied 
  stem 
  and 
  floral 
  structure 
  is 
  now 
  

   known. 
  It 
  is 
  also 
  a 
  feature 
  of 
  the 
  group 
  that 
  so 
  far 
  as 
  

   can 
  be 
  detected 
  the 
  large 
  stemmed 
  forms 
  are 
  nearest 
  the 
  

   cycads. 
  They 
  are 
  therefore 
  the 
  true 
  Pericycadeoids. 
  

  

  Of 
  these 
  Pericycadeoidace^ 
  two 
  family 
  groups 
  appear 
  

   to 
  view. 
  The 
  first 
  is 
  Bucklands 
  Cycadeoidese 
  (1828), 
  in 
  

   the 
  synonymy 
  of 
  which 
  is 
  included 
  a 
  plethoric 
  series 
  of 
  

   generic 
  names. 
  These 
  were 
  in 
  part 
  reviewed 
  by 
  Ward 
  

   (1900) 
  when 
  he 
  sought 
  to 
  establish 
  his 
  Cycadella. 
  The 
  

   material 
  has 
  afforded 
  the 
  most 
  exacting 
  and 
  complex 
  of 
  

   all 
  redintegrations 
  of 
  ancient 
  plants. 
  The 
  broader 
  out- 
  

   lines 
  of 
  the 
  second 
  family, 
  the 
  Williamsoniae 
  (Carruthers, 
  

   1870), 
  are 
  only 
  less 
  well 
  attested. 
  Doubt 
  as 
  to 
  the 
  char- 
  

   acter 
  of 
  the 
  genera 
  attributed 
  here, 
  can 
  occasion 
  no 
  great 
  

   inconvenience. 
  It 
  would, 
  for 
  instance, 
  be 
  rash 
  to 
  believe 
  

   that 
  all 
  the 
  Pterophyllums 
  can 
  belong 
  to 
  any 
  one 
  family. 
  

  

  In 
  the 
  second 
  greater 
  order 
  of 
  the 
  hemicycads, 
  so 
  far 
  

   as 
  the 
  first 
  necessities 
  of 
  a 
  preliminary 
  classification 
  are 
  

   concerned, 
  the 
  characters 
  are 
  fairly 
  enough 
  established 
  

   to 
  indicate 
  a 
  steady 
  departure 
  from 
  the 
  pericycadeoid 
  

   forms. 
  These 
  are, 
  therefore, 
  the 
  apocycadeoids 
  or 
  Apo- 
  

   cycadeoidace^e, 
  also 
  with 
  two 
  families. 
  The 
  first, 
  or 
  

   Microflora, 
  includes 
  the 
  typically 
  small-flowered 
  Wielan- 
  

   diella 
  and 
  William 
  soniella. 
  The 
  small 
  freely 
  bifurcate 
  

   stems 
  bear 
  their 
  small 
  bladed 
  leaves 
  in 
  close 
  set 
  whorls, 
  or 
  

   more 
  diffusely, 
  and 
  may 
  have 
  pertained 
  to 
  larger 
  forest 
  

   trees 
  of 
  semi-magnoliaceous 
  habitus 
  ; 
  but 
  unfortunately 
  

   the 
  stem 
  structure 
  remains 
  inferential. 
  The 
  second 
  hemi- 
  

   cycad 
  family 
  is 
  a 
  hypothetical 
  one 
  of 
  mainly 
  large-leafed 
  

   imprints, 
  numerous 
  and 
  cosmopolitan, 
  presumably 
  allied 
  

   here. 
  It 
  can 
  be 
  given 
  an 
  arbitrary 
  name, 
  the 
  Holophyt.e, 
  

   or 
  the 
  all-leaf-family, 
  with 
  both 
  fruit 
  and 
  stem 
  inferential. 
  

   The 
  genera 
  included 
  are, 
  Anomozamites, 
  Nilssonia, 
  Tacni- 
  

  

  