﻿38 
  3MR. 
  A 
  C. 
  SEWARD 
  ON 
  CYCADEOIDEA 
  GIGAN1EA. 
  [Feb. 
  1 
  897, 
  

  

  Plate 
  III. 
  

  

  Fig. 
  1. 
  Transverse 
  section 
  through 
  the 
  periderm 
  of 
  a 
  petiole 
  of 
  Cycadeoidea 
  

   gigantea. 
  (X 
  52.) 
  ?*:=: 
  ramenta 
  ; 
  c^cuticle; 
  e= 
  epidermis 
  ; 
  

   c&=cork; 
  £>A/=phellogen 
  ; 
  phd 
  — 
  phelloderm 
  ; 
  g 
  = 
  ground-tissue. 
  

  

  2. 
  Transverse 
  section 
  of 
  the 
  periderm 
  of 
  Macrozamia 
  Benisoni. 
  Lettering 
  

  

  as 
  in 
  fig. 
  1. 
  (X 
  52.) 
  s=sclerenchymatous 
  cells. 
  

  

  3. 
  Cells 
  of 
  the 
  cork-cambium 
  (phellogen) 
  of 
  fig. 
  1 
  more 
  highly 
  magnified. 
  

  

  (X 
  230.) 
  

   Figs. 
  4 
  & 
  8. 
  Kainenta 
  of 
  Cycadeoidea 
  gigantea 
  in 
  transverse 
  section. 
  ( 
  X 
  52.) 
  

   Fig. 
  5. 
  Single 
  ramental 
  layer 
  of 
  Cyathea 
  excelsa. 
  ( 
  X 
  52.) 
  

  

  6. 
  Epidermal 
  hair 
  of 
  Bioon 
  edule. 
  (X 
  230.) 
  

  

  7. 
  Eamentum 
  of 
  Bennettites 
  Gibsonianus, 
  Carr. 
  ( 
  X 
  52.) 
  

  

  Plate 
  IV. 
  

  

  Fig. 
  9. 
  Yascular 
  bundle 
  of 
  a 
  petiole 
  of 
  Cycadeoidea 
  gigantea. 
  ( 
  X 
  320.) 
  s= 
  

   solerenchyma 
  (?) 
  ; 
  ^A 
  = 
  crushed 
  phloem; 
  c=camjpium; 
  <?/=centri- 
  

   fugal 
  wood 
  ; 
  m 
  = 
  medullary 
  rays. 
  

   10. 
  Vascular 
  bundle 
  of 
  Bennettites 
  Gibsonianus. 
  jM?:=protoxylem 
  ; 
  cp= 
  

   centripetal 
  xylem. 
  Other 
  lettering 
  as 
  in 
  fig. 
  1. 
  ( 
  X 
  320.) 
  

  

  Figs. 
  11, 
  12, 
  & 
  13. 
  Cells 
  of 
  the 
  parenchymatous 
  ground-tissue 
  of 
  the 
  petiole 
  a 
  

   shown 
  in 
  fig. 
  14. 
  w=nucleus 
  (?). 
  Fig. 
  12 
  ( 
  X 
  230). 
  Figs. 
  11 
  & 
  13 
  

   (X 
  355). 
  Reduced 
  one-half 
  from 
  the 
  original 
  drawing. 
  

  

  Plate 
  V. 
  

  

  Fig. 
  14. 
  Longitudinal 
  section 
  showing 
  portions 
  of 
  the 
  petioles 
  and 
  an 
  inter- 
  

   vening 
  mass 
  of 
  ramenta. 
  (x 
  17.) 
  «=upper 
  petiole, 
  with 
  

   parenchyma 
  and 
  secretory 
  cells 
  of 
  the 
  fundamental 
  tissue, 
  p 
  — 
  

   periderm, 
  including 
  phelloderm 
  and 
  cork 
  ; 
  adjunction 
  of 
  ramenta 
  

   with 
  the 
  epidermis; 
  r= 
  ramenta. 
  

   15. 
  Stoma, 
  with 
  guard-cells 
  and 
  pore 
  ; 
  also 
  a 
  few 
  epidermal 
  cells 
  showing 
  

   the 
  form 
  of 
  the 
  walls. 
  </<£= 
  guard-cells 
  ; 
  s=subsidiary 
  cells. 
  

  

  Figs. 
  16-18. 
  Semi-diagrammatic 
  sketches 
  slightly 
  enlarged 
  (fig. 
  16 
  — 
  section 
  

   1-6x2 
  cm., 
  fig. 
  17— 
  2-lxl 
  -3 
  cm., 
  fig. 
  18— 
  2"3xF8 
  cm.), 
  showing 
  

   portions 
  of 
  petioles, 
  ramental 
  tissue, 
  and 
  bud, 
  b. 
  

  

  Fig. 
  19. 
  Section 
  of 
  the 
  bud 
  as 
  shown 
  at 
  b 
  in 
  fig. 
  17. 
  (X 
  24.) 
  ax=axis 
  of 
  

   bud, 
  surrounded 
  by 
  leaves 
  and 
  ramenta. 
  Reduced 
  one-third 
  from 
  

   the 
  original 
  drawing. 
  

  

  Discussion. 
  

  

  Dr. 
  D. 
  H. 
  Scott 
  thought 
  that 
  this 
  paper 
  was 
  of 
  the 
  greatest 
  

   interest. 
  Nothing 
  was 
  more 
  remarkable 
  in 
  paleobotany 
  than 
  the 
  

   prevalence 
  during 
  the 
  Mesozoic 
  period 
  of 
  plants 
  which 
  exactly- 
  

   resembled 
  existing 
  Cycadeae 
  in 
  habit 
  and 
  external 
  characters, 
  but 
  

   which, 
  in 
  the 
  best 
  known 
  cases, 
  differed 
  absolutely 
  from 
  them 
  as 
  

   regarded 
  their 
  fructification. 
  This 
  was 
  the 
  case 
  notably 
  with 
  

   Bennettites, 
  investigated 
  by 
  Carruthers, 
  Solms-Laubach, 
  and 
  Lignier, 
  

   which 
  bore 
  reproductive 
  organs 
  totally 
  unlike 
  those 
  of 
  Cycadeae 
  or 
  

   any 
  other 
  known 
  gymnosperms, 
  and 
  approaching 
  in 
  some 
  respects 
  

   those 
  of 
  angiosperms. 
  The 
  existence 
  of 
  the 
  Bennettiteae 
  and 
  certain 
  

   other 
  fossil 
  groups 
  showed 
  that 
  our 
  recent 
  Cycads 
  form 
  only 
  a 
  small 
  

   surviving 
  family, 
  representing 
  what 
  was 
  once 
  an 
  extensive 
  and 
  varied 
  

   class 
  of 
  plants. 
  

  

  It 
  was 
  an 
  interesting 
  question, 
  to 
  which 
  group 
  of 
  Cy 
  cad-like 
  plants 
  

   the 
  fine 
  specimen 
  described 
  by 
  the 
  Author 
  belonged. 
  The 
  ramenta 
  

  

  