﻿1875.] 
  Fossil 
  Plants 
  of 
  the 
  Coal-measures. 
  453 
  

  

  a 
  canal, 
  of 
  varied 
  sizes 
  and 
  shapes, 
  which 
  appears 
  to 
  have 
  been 
  ori- 
  

   ginally 
  a 
  gum-canal, 
  subsequently 
  enlarged 
  irregularly 
  by 
  the 
  shrinking 
  

   of 
  the 
  neighbouring 
  tissues. 
  In 
  the 
  larger 
  and 
  more 
  matured 
  petioles 
  

   these 
  vascular 
  bundles 
  are 
  very 
  conspicuous, 
  both 
  in 
  transverse 
  and 
  longi- 
  

   tudinal 
  sections 
  ; 
  but 
  in 
  the 
  small, 
  young, 
  and 
  terminal 
  subdivisions 
  of 
  

   the 
  rachides 
  the 
  vessels 
  are 
  so 
  small 
  as 
  to 
  be 
  almost 
  undistinguishable 
  from 
  

   the 
  surrounding 
  parenchyma, 
  while 
  the 
  gum-canals 
  of 
  such 
  examples 
  

   are, 
  on 
  the 
  other 
  hand, 
  conspicuously 
  large. 
  Transverse 
  sections 
  of 
  

   the 
  most 
  perfect 
  examples 
  of 
  these 
  young 
  rachides 
  exhibit, 
  on 
  their 
  

   upper 
  surface, 
  a 
  rounded 
  central 
  ridge, 
  flanked 
  on 
  either 
  side 
  by 
  a 
  longi- 
  

   tudinal 
  groove, 
  which 
  arrangements 
  are 
  so 
  conspicuous 
  in 
  the 
  corre- 
  

   sponding 
  portions 
  of 
  the 
  petioles 
  of 
  the 
  Marattiaceae 
  and 
  of 
  other 
  ferns. 
  

   The 
  ultimate 
  leaflet-petioles 
  were 
  given 
  off 
  at 
  right 
  angles 
  to 
  the 
  central 
  

   rachis 
  from 
  which 
  they 
  sprang, 
  corresponding 
  in 
  this 
  respect 
  with 
  one 
  

   of 
  the 
  types 
  described 
  by 
  M. 
  Renault. 
  The 
  author 
  has 
  not 
  yet 
  found 
  in 
  

   Lancashire 
  any 
  of 
  the 
  large 
  specimens 
  that 
  have 
  been 
  met 
  with 
  on 
  the 
  

   continent 
  at 
  Autun 
  and 
  in 
  the 
  localities 
  whence 
  M. 
  Cotta 
  obtained 
  his 
  

   examples. 
  He 
  has 
  found 
  a 
  few 
  and 
  yet 
  smaller 
  fragments 
  among 
  the 
  

   sections 
  from 
  Burntisland. 
  The 
  recognition 
  of 
  the 
  Marattiaceous 
  cha- 
  

   racter 
  of 
  these 
  plants 
  excludes 
  the 
  Palmacece 
  for 
  the 
  present 
  from 
  all 
  

   claim 
  to 
  share 
  in 
  the 
  glories 
  of 
  the 
  carboniferous 
  vegetation. 
  

  

  The 
  second 
  plant 
  described 
  by 
  the 
  author 
  consists 
  of 
  clusters 
  of 
  

   roots 
  with 
  a 
  portion 
  of 
  the 
  outermost 
  parenchymatous 
  layer 
  of 
  the 
  stem 
  

   of 
  a 
  tree 
  fern, 
  corresponding 
  to 
  those 
  of 
  the 
  Psaronites 
  long 
  known 
  

   to 
  characterize 
  the 
  upper 
  carboniferous 
  deposits 
  of 
  Autun 
  and 
  other 
  

   localities. 
  The 
  roots 
  of 
  the 
  Oldham 
  specimen, 
  to 
  which 
  the 
  author 
  has 
  

   assigned 
  the 
  name 
  of 
  Psaronites 
  Renaultii, 
  consist 
  of 
  a 
  well-defined 
  

   cylinder 
  of 
  sclerenchymatous 
  prosenchyma, 
  within 
  which 
  has 
  been 
  a 
  

   mass 
  of 
  more 
  delicate 
  parenchyma, 
  in 
  the 
  centre 
  of 
  which 
  was 
  the 
  usual 
  

   vascular 
  bundle. 
  But 
  what 
  characterizes 
  the 
  specimens, 
  distinguishing 
  

   them 
  from 
  the 
  numerous 
  species 
  described 
  by 
  Corda, 
  is 
  the 
  existence 
  of 
  

   vast 
  numbers 
  of 
  cylindrical 
  hairs, 
  each 
  composed 
  of 
  a 
  linear 
  row 
  of 
  elon- 
  

   gated 
  cylindrical 
  cells 
  : 
  these 
  have 
  obviously 
  been 
  the 
  absorbent 
  root- 
  

   hairs 
  of 
  the 
  living 
  plant, 
  which 
  may 
  possibly 
  have 
  been 
  some 
  species 
  of 
  

   Stemmatopteris 
  ; 
  but 
  of 
  this 
  there 
  is 
  as 
  yet 
  no 
  evidence. 
  

  

  The 
  author 
  then 
  describes 
  a 
  small 
  but 
  very 
  remarkable 
  stem, 
  to 
  which 
  

   he 
  assigns 
  the 
  name 
  of 
  Kaloxylon 
  Hookeri. 
  This 
  is 
  a 
  slender 
  stem, 
  rarely 
  

   more 
  than 
  from 
  one 
  seventh 
  to 
  one 
  tenth 
  of 
  an 
  inch 
  in 
  diameter. 
  In 
  its 
  

   young 
  state 
  it 
  consists 
  of 
  a 
  central 
  vascular 
  axis 
  which 
  has 
  an 
  hexagonal 
  

   section, 
  and 
  which 
  is 
  composed 
  of 
  numerous 
  vessels 
  of 
  various 
  sizes, 
  each 
  

   of 
  which 
  exhibits 
  the 
  reticulate 
  form 
  of 
  the 
  scalariform 
  or 
  barred 
  type, 
  

   and 
  which 
  is 
  so 
  common 
  amongst 
  the 
  plants 
  of 
  the 
  Coal-measures. 
  No 
  

   true 
  barred 
  or 
  spiral 
  vessels 
  have 
  yet 
  been 
  seen 
  in 
  the 
  Kaloxylon. 
  In 
  the 
  

   young 
  twigs 
  this 
  vascular 
  axis 
  is 
  surrounded 
  by 
  a 
  mass 
  of 
  large-celled 
  

   cortical 
  parenchyma, 
  which, 
  in 
  turn, 
  is 
  encased 
  by 
  an 
  epidermal 
  struc- 
  

  

  