﻿22 
  

  

  ME. 
  A. 
  C, 
  SEWAED 
  ON 
  CTCADEOIDEA 
  GIGANTEA. 
  [FeO. 
  1 
  897, 
  

  

  Fig. 
  1. 
  — 
  Section 
  of 
  the 
  quarry 
  

   in 
  which 
  the 
  Cycadean 
  stem 
  

   ivas 
  found. 
  

  

  3. 
  On 
  Cycadeoidea 
  gigantea, 
  a 
  neiv 
  Cycadean 
  Stem 
  from 
  the 
  

   Puebeck 
  Beds 
  of 
  Portland. 
  By 
  A. 
  C. 
  Sewaed, 
  Esq., 
  M.A., 
  

   F.G.S., 
  University 
  Lecturer 
  in 
  Botany, 
  Cambridge. 
  (Read 
  

   November 
  18th, 
  1896.) 
  

  

  [Plates 
  I.-V.] 
  

  

  The 
  Isle 
  of 
  Portland 
  has 
  long 
  been 
  famous 
  for 
  the 
  silicified 
  Coni- 
  

   ferous 
  and 
  Cycadeau 
  plants 
  which 
  occur 
  in 
  the 
  surface-soils 
  of 
  

   Purbeck 
  age. 
  Buckland, 
  1 
  Carruthers, 
  2 
  and 
  others 
  have 
  described 
  

   the 
  manner 
  of 
  occurrence 
  and 
  structure 
  of 
  the 
  plant-remains 
  

   from 
  this 
  horizon, 
  and 
  the 
  fossil 
  " 
  crows' 
  nests," 
  or 
  short, 
  thick 
  

   stems 
  of 
  Cycads, 
  have 
  long 
  been 
  familiar 
  to 
  geologists. 
  The 
  plant 
  

   which 
  forms 
  the 
  subject 
  of 
  the 
  following 
  description 
  was 
  acquired 
  

   by 
  Dr. 
  "Woodward 
  in 
  1895, 
  and 
  is 
  

   now 
  one 
  of 
  the 
  most 
  remarkable 
  

   specimens 
  in 
  the 
  Fossil 
  Plant 
  Gal- 
  

   lery 
  of 
  the 
  British 
  Museum. 
  3 
  It 
  is 
  

   probably 
  the 
  largest 
  fossil 
  Cycad 
  

   hitherto 
  recorded, 
  and 
  although 
  the 
  

   internal 
  structure 
  has 
  been 
  for 
  the 
  

   most 
  part 
  very 
  imperfectly 
  pre- 
  

   served, 
  the 
  cast 
  of 
  the 
  stem 
  is 
  in 
  

   some 
  respects 
  unusually 
  complete. 
  

   The 
  specimen 
  was 
  found 
  lying 
  in 
  a 
  

   horizontal 
  position 
  in 
  a 
  bed 
  of 
  

   shaly 
  clay, 
  2 
  feet 
  thick, 
  and 
  about 
  

   17 
  feet 
  higher 
  in 
  the 
  Purbeck 
  series 
  

   than 
  the 
  Great 
  Dirt-bed, 
  from 
  which 
  

   most 
  of 
  the 
  Portland 
  plants 
  have 
  

   been 
  obtained. 
  

  

  The 
  position 
  of 
  the 
  fossil 
  is 
  shown 
  

   in 
  fig. 
  1 
  ; 
  the 
  section 
  is 
  drawn 
  from 
  

   a 
  photograph 
  of 
  the 
  rock-face 
  in 
  

   one 
  of 
  Mr. 
  Barnes's 
  quarries 
  close 
  to 
  

   St. 
  George's 
  Church 
  on 
  the 
  west 
  side 
  

   of 
  the 
  old 
  Portland 
  Wide 
  Street. 
  

  

  Seam 
  ofldaly 
  stone 
  

   9JI 
  

  

  WBSffibCycad 
  

  

  ■3£19T- 
  

  

  .//re 
  /f 
  ess/ 
  f-sr 
  

  

  ~-£- 
  

  

  .2'6'_X 
  

  

  Shifting 
  ruZlle 
  

   Top. 
  slate 
  

   Shaley 
  clay 
  

   Shinglebed 
  

   Soft 
  slaty 
  stone 
  

   Seam 
  of 
  clay 
  

  

  Hard 
  slate 
  bed 
  

  

  Bacon. 
  Tier 
  

  

  Aish 
  

   Bur 
  

   Great 
  dirt 
  led 
  

  

  Top 
  tap 
  

  

  Lower 
  did 
  led. 
  

  

  ki 
  g 
  -^ 
  PJ/ 
  Scul 
  cap 
  

  

  In 
  PI. 
  I. 
  the 
  stem 
  is 
  represented 
  

   about 
  J 
  natural 
  size 
  ; 
  it 
  measures 
  

   1 
  metre 
  18*5 
  cm. 
  in 
  height 
  (nearly 
  

   4 
  feet), 
  and 
  at 
  the 
  broadest 
  part 
  

   has 
  a 
  girth 
  of 
  1 
  m. 
  7 
  cm. 
  At 
  the 
  

   base 
  it 
  is 
  somewhat 
  narrower 
  and 
  

   thinner, 
  and 
  the. 
  surface-features 
  

  

  1 
  W. 
  Buckland, 
  ' 
  Geology 
  and 
  Mineralogy 
  considered 
  with 
  reference 
  to 
  

   Natural 
  Theology,' 
  Sixth 
  Bridgewater 
  Treatise, 
  vol. 
  i. 
  (London, 
  1836) 
  p. 
  490, 
  

   pis. 
  lx.-lxii. 
  ; 
  also 
  Trans. 
  Geol. 
  Soc. 
  ser. 
  2, 
  vol. 
  ii. 
  pt.iii. 
  (1828) 
  p. 
  395. 
  

  

  2 
  W. 
  Carruthers, 
  ' 
  On 
  Fossil 
  Cycadean 
  Stems 
  from 
  the 
  Secondary 
  Bocks 
  of 
  

   Britain,' 
  Trans. 
  Linn. 
  Soc. 
  vol. 
  xxvi. 
  (1870) 
  p. 
  675. 
  3 
  No. 
  V. 
  3454. 
  

  

  Wanteds, 
  '^o'ack 
  

   'fTbrtlahd'O'eds'X 
  

  

  [Drawn 
  hy 
  Miss 
  G. 
  M. 
  Woodward 
  

   from 
  a 
  photograph.] 
  

  

  