﻿PACHYTHECA 
  FKOM 
  THE 
  DENBIGHSHIRE 
  GRITS. 
  107 
  

  

  totaxites, 
  the 
  presumption 
  becomes 
  strong 
  that 
  the 
  connexion 
  is 
  not 
  

   accidental. 
  Under 
  these 
  circumstances, 
  and 
  considering 
  the 
  Taxine 
  

   affinities 
  of 
  JEiheotesta, 
  it 
  would 
  seem 
  that 
  Pachytheca 
  may 
  be 
  

   accepted 
  as 
  affording 
  some 
  corroboration 
  of 
  the 
  gymnospermous 
  

   nature 
  of 
  Prototcuvites*. 
  

  

  Dr. 
  Hicks 
  has 
  also 
  sent 
  a 
  specimen 
  of 
  the 
  so-called 
  " 
  micro- 
  

   spores 
  " 
  found 
  with 
  Pachytheca. 
  They 
  occur 
  in 
  this 
  specimen 
  in 
  a 
  

   little 
  semicircular 
  patch 
  or 
  group, 
  and 
  are 
  represented 
  by 
  mere 
  im- 
  

   pressions 
  without 
  any 
  trace 
  of 
  organic 
  matter. 
  The 
  lobed 
  or 
  fur- 
  

   rowed 
  appearance 
  which 
  they 
  present 
  gives 
  to 
  some 
  of 
  them 
  the 
  

   aspect 
  of 
  tetraspores 
  enclosed 
  in 
  mother-cells, 
  like 
  the 
  " 
  Triplospo- 
  

   rites 
  " 
  of 
  Brown, 
  in 
  which 
  case 
  they 
  might, 
  as 
  suggested 
  by 
  Mr. 
  

   Carruthers, 
  be 
  Lycopodiaceous 
  ; 
  but 
  these 
  furrows 
  are 
  so 
  irregular 
  

   that 
  they 
  may 
  be 
  accidental 
  wrinkles. 
  The 
  occurrence 
  of 
  these 
  

   objects 
  in 
  patches 
  or 
  groups 
  suggests 
  affinities 
  with 
  the 
  Parka 
  

   decipiensf 
  of 
  Fleming, 
  a 
  Devonian 
  fossil 
  at 
  one 
  time 
  believed 
  

   to 
  be 
  vegetable, 
  but 
  more 
  recently 
  referred 
  to 
  ova 
  of 
  Crustaceans. 
  

   Similar 
  groups 
  of 
  small 
  rounded 
  bodies 
  occur 
  in 
  the 
  Devonian 
  of 
  

   Gaspe 
  ; 
  but 
  I 
  have 
  not 
  been 
  able 
  to 
  decide 
  as 
  to 
  their 
  nature. 
  

  

  Discussion. 
  

  

  The 
  President 
  referred 
  to 
  the 
  wide 
  interest 
  which 
  the 
  discoveries 
  

   of 
  Dr. 
  Hicks 
  had 
  evidently 
  excited. 
  

  

  Mr. 
  Carruthers 
  referred 
  to 
  a 
  specimen 
  sent 
  to 
  him 
  by 
  Dr. 
  

   Dawson, 
  which 
  had 
  its 
  structure 
  beautifully 
  exhibited 
  externally 
  

   from 
  weathering, 
  and 
  which 
  he 
  hoped 
  to 
  study 
  by 
  means 
  of 
  

   sections. 
  He 
  thought 
  that 
  Dr. 
  Dawson's 
  ideas 
  were 
  the 
  result 
  

   of 
  having 
  examined 
  the 
  specimens 
  by 
  imperfect 
  means. 
  He 
  

   insisted 
  that 
  the 
  minute 
  structure 
  of 
  these 
  plants 
  was 
  quite 
  dif- 
  

   ferent 
  from 
  that 
  of 
  Conifers. 
  The 
  stems 
  are 
  made 
  up 
  of 
  inter- 
  

   lacing 
  tubes 
  ; 
  the 
  smaller, 
  which 
  crossed 
  the 
  larger 
  obliquely, 
  were 
  

   not 
  spiral 
  fibres 
  inside 
  wood-cells 
  as 
  supposed 
  by 
  Dr. 
  Dawson. 
  

   He 
  thought 
  no 
  one 
  acquainted 
  with 
  the 
  minute 
  structures 
  of 
  Coni- 
  

   ferous 
  wood 
  and 
  of 
  Algae 
  could 
  be 
  led 
  to 
  accept 
  the 
  views 
  of 
  Dr. 
  

   Dawson. 
  The 
  pseudo- 
  exogenous 
  structure 
  is 
  found 
  in 
  some 
  living 
  

   Algse, 
  as 
  in 
  Laminaria. 
  "With 
  respect 
  to 
  Pachytheca 
  he 
  had 
  always 
  

   experienced 
  great 
  difficulty 
  at 
  arriving 
  at 
  any 
  conclusion. 
  He 
  

  

  * 
  It 
  occurs 
  to 
  me 
  to 
  add 
  here 
  that 
  the 
  beds 
  in 
  which 
  Prototaxites 
  is 
  met 
  with, 
  in 
  

   Gaspe 
  and 
  near 
  Campbellton, 
  contain 
  no 
  marine 
  remains, 
  but 
  only 
  land-plants; 
  

   and 
  though 
  it 
  would 
  appear 
  that 
  in 
  the 
  Corwen 
  beds 
  the 
  plants 
  are 
  associated 
  

   with 
  marine 
  remains, 
  yet 
  the 
  nature 
  of 
  the 
  specimens 
  sent 
  to 
  me 
  is 
  evidently 
  

   of 
  littoral 
  rather 
  than 
  deep-sea 
  character, 
  and 
  here 
  also 
  they 
  are 
  associated 
  

   with 
  land 
  vegetation. 
  These 
  modes 
  of 
  occurrence, 
  as 
  I 
  have 
  elsewhere 
  pointed 
  

   out, 
  are 
  not 
  in 
  harmony 
  with 
  the 
  supposition 
  that 
  in 
  these 
  plants 
  we 
  have 
  to 
  

   deal 
  with 
  great 
  oceanic 
  Algas. 
  Nor 
  does 
  this 
  supposition 
  accord 
  with 
  the 
  fact 
  

   that 
  the 
  wood 
  of 
  Prototaxites 
  retains 
  its 
  form 
  and 
  is 
  silicified 
  in 
  beds 
  in 
  which 
  

   herbaceous 
  land-plants 
  are 
  perfectly 
  flattened. 
  

  

  t 
  Lyell, 
  'Student's 
  Elements/ 
  p. 
  444; 
  Nicholson, 
  ' 
  Paleontology,' 
  vol. 
  i. 
  

   p. 
  382 
  (Dr. 
  Hicks 
  has, 
  1 
  see, 
  made 
  the 
  same 
  suggestions 
  in 
  his 
  " 
  Additional 
  

   Notes," 
  Quart. 
  Journ, 
  Geol. 
  Soc, 
  Feb. 
  1882). 
  

  

  