﻿TACHYTHECA 
  FE0M 
  THE 
  DENBIGHSHIRE 
  GKITS. 
  105 
  

  

  formations*, 
  and 
  am 
  therefore 
  not 
  surprised 
  to 
  find 
  this 
  conjecture 
  

   realized 
  by 
  the 
  discovery 
  of 
  Dr. 
  Hicks. 
  

  

  In 
  the 
  specimen 
  sent 
  to 
  me 
  there 
  appears, 
  besides 
  the 
  fragments 
  of 
  

   Prototaxites 
  and 
  a 
  few 
  rounded 
  impressions 
  probably 
  of 
  PacJiyiheca, 
  

   a 
  fragment 
  of 
  the 
  rhizoma 
  of 
  Psilophyton 
  and 
  portions 
  of 
  epidermal 
  

   tissue. 
  The 
  state 
  of 
  preservation 
  of 
  these 
  bears 
  additional 
  testimony 
  

   to 
  the 
  woody 
  and 
  durable 
  texture 
  of 
  Prototaxites. 
  Still 
  further, 
  

   in 
  recent 
  explorations 
  in 
  the 
  Bay 
  de 
  Chaleur, 
  I 
  have 
  found 
  in 
  the 
  

   Lower 
  Devonian 
  silicified 
  trunks 
  of 
  Prototaxites 
  two 
  feet 
  and 
  a 
  half 
  

   in 
  diameter 
  ; 
  and 
  these 
  lie 
  in 
  beds 
  abounding 
  in 
  entire 
  specimens 
  

   of 
  Psilophyton, 
  some 
  of 
  them 
  apparently 
  in 
  the 
  place 
  of 
  their 
  growth, 
  

   and 
  in 
  a 
  formation 
  which 
  contains 
  only 
  land 
  plants, 
  associated 
  in 
  

   some 
  layers 
  with 
  remains 
  of 
  fishes 
  and 
  of 
  bivalve 
  Crustaceans, 
  minute 
  

   Gasteropods, 
  and 
  Spirorbis, 
  the 
  whole 
  much 
  resembling 
  the 
  coal- 
  

   formation 
  in 
  its 
  mineral 
  character 
  and 
  grouping 
  of 
  fossils. 
  The 
  idea 
  

   that 
  Prototaxites 
  may 
  have 
  affinities 
  with 
  Algse 
  has 
  been 
  sufficiently 
  

   disposed 
  of 
  in 
  my 
  communication 
  to 
  the 
  'Monthly 
  Microscopical 
  

   Journal' 
  in 
  1873 
  ; 
  and 
  the 
  characters 
  and 
  state 
  of 
  preservation 
  of 
  Dr. 
  

   Hicks's 
  specimens 
  fully 
  confirm 
  the 
  reasoning 
  in 
  that 
  paper. 
  The 
  

   large 
  specimens 
  recently 
  obtained 
  at 
  the 
  Bay 
  de 
  Chaleur 
  also 
  enable 
  

   me 
  to 
  reaffirm 
  the 
  existence 
  of 
  a 
  dense 
  coaly 
  bark 
  at 
  the 
  surface 
  of 
  

   these 
  trees. 
  Some 
  of 
  them 
  show 
  on 
  their 
  weathered 
  ends 
  evidence 
  

   of 
  remarkably 
  regular 
  exogenous 
  rings, 
  extending 
  from 
  the 
  surface 
  

   nearly 
  to 
  the 
  centre. 
  There 
  may, 
  however, 
  have 
  been 
  an 
  internal 
  

   axis 
  or 
  medulla, 
  different 
  from 
  the 
  outer 
  structure 
  ; 
  and 
  this 
  I 
  hope 
  to 
  

   be 
  able 
  to 
  ascertain 
  by 
  series 
  of 
  slices 
  from 
  the 
  centre 
  to 
  the 
  circum- 
  

   ference 
  of 
  the 
  trunk. 
  

  

  I 
  have 
  lately 
  had 
  a 
  number 
  of 
  slices 
  made 
  of 
  the 
  large 
  silicified 
  

   trunks 
  found 
  last 
  summer 
  near 
  Campbellton, 
  New 
  Brunswick. 
  They 
  

   present 
  appearances 
  of 
  a 
  very 
  peculiar 
  and 
  interesting 
  character. 
  

   In 
  the 
  better-preserved 
  specimens 
  the 
  large 
  cylindrical 
  fibres 
  are 
  filled 
  

   with 
  rows 
  of 
  rounded 
  concretions 
  of 
  silica, 
  often 
  enclosing 
  limpid 
  

   hexagonal 
  crystals. 
  In 
  many 
  cases 
  they 
  present 
  the 
  most 
  deceptive 
  

   resemblance 
  to 
  the 
  bordered 
  pores 
  of 
  coniferous 
  wood, 
  and 
  in 
  other 
  

   modes 
  of 
  occurrence 
  might 
  be 
  mistaken 
  for 
  spores 
  of 
  some 
  parasitic 
  

   fungus. 
  Under 
  polarized 
  light, 
  however, 
  they 
  are 
  seen 
  to 
  be 
  merely 
  

   crystalline 
  and 
  concretionary 
  ; 
  and 
  when 
  the 
  fibres 
  show 
  their 
  true 
  

   structure, 
  this 
  is 
  reticulated 
  or 
  spiral, 
  as 
  in 
  the 
  ordinary 
  specimens 
  

   of 
  Prototaxites. 
  In 
  many 
  parts 
  of 
  these 
  specimens, 
  however, 
  the 
  

   formation 
  of 
  granular 
  crystals 
  of 
  quartz 
  has 
  completely 
  disorganized 
  

   the 
  structure. 
  I 
  have 
  referred 
  to 
  concretionary 
  appearances 
  of 
  the 
  

   kind 
  above 
  described, 
  in 
  my 
  " 
  Report 
  on 
  the 
  Devonian 
  Plants 
  of 
  

   Canada," 
  as 
  occurring 
  in 
  the 
  Gaspe 
  specimens 
  of 
  Prototaxites 
  ; 
  but 
  

   they 
  are 
  coarser 
  and 
  less 
  beautiful 
  than 
  in 
  those 
  from 
  Campbellton. 
  

  

  It 
  is 
  possible 
  that 
  these 
  appearances 
  may 
  throw 
  some 
  light 
  on 
  the 
  

   globular 
  bodies 
  observed 
  in 
  the 
  cells 
  of 
  the 
  "Welsh 
  specimens 
  of 
  

   Prototaxites 
  and 
  PacJiyiheca, 
  though 
  I 
  cannot 
  certainly 
  affirm 
  that 
  

   the 
  latter 
  are 
  concretionary 
  and 
  not 
  structural. 
  

   * 
  Eeport 
  on 
  Devonian 
  Plants. 
  

  

  i2 
  

  

  