﻿PEff-Y-GLOG 
  SLATE-QUARRY, 
  NORTH 
  WALES. 
  99 
  

  

  rous 
  measures 
  ; 
  but 
  whether 
  they 
  represent 
  a 
  new 
  generic 
  type 
  or 
  

   an 
  early 
  form 
  of 
  Lepidodendron, 
  cannot 
  be 
  determined." 
  

  

  From 
  the 
  specimens 
  which 
  have 
  been 
  already 
  obtained, 
  it 
  is 
  evi- 
  

   dent 
  that 
  the 
  trees 
  attained 
  to 
  a 
  considerable 
  size, 
  many 
  of 
  the 
  frag- 
  

   ments 
  being 
  from 
  4 
  to 
  5 
  inches 
  wide 
  as 
  now 
  compressed 
  on 
  the 
  slabs. 
  

   In 
  the 
  quarry, 
  before 
  the 
  larger 
  blocks 
  were 
  broken 
  up, 
  I 
  traced 
  some 
  

   branches 
  to 
  some 
  feet 
  in 
  length. 
  All, 
  as 
  far 
  as 
  could 
  be 
  made 
  out, 
  

   were 
  fragments 
  of 
  the 
  trees 
  only, 
  as 
  if 
  they 
  had 
  floated 
  from 
  some 
  

   neighbouring 
  land 
  into 
  their 
  present 
  position. 
  

  

  Though 
  the 
  majority 
  of 
  the 
  specimens 
  do 
  not 
  appear 
  to 
  retain 
  in- 
  

   dications 
  of 
  leaf-markings, 
  some 
  are 
  wrinkled 
  in 
  a 
  manner 
  which, 
  I 
  

   think, 
  proves 
  that 
  the 
  plant 
  was 
  freely 
  covered 
  with 
  leaves 
  spirally 
  

   arranged 
  around 
  the 
  stem, 
  as 
  in 
  Lepiclodendron. 
  In 
  some 
  of 
  the 
  

   decorticated 
  fragments 
  (see 
  fig. 
  1, 
  PI. 
  III.) 
  these 
  markings 
  are 
  

   still 
  more 
  definite. 
  Perhaps 
  the 
  most 
  interesting 
  are 
  some 
  frag- 
  

   ments, 
  apparently 
  of 
  roots, 
  having 
  a 
  close 
  affinity 
  with 
  Stigmariu 
  

   (see 
  figs. 
  3, 
  3 
  a, 
  PI. 
  III.). 
  If 
  these 
  can 
  be 
  proved 
  to 
  belong 
  to 
  

   similar 
  plants 
  to 
  the 
  above-described 
  stems 
  and 
  branches, 
  we 
  have 
  

   here 
  an 
  interesting 
  early 
  type 
  of 
  plants 
  combining 
  the 
  characters 
  of 
  

   Sigillaria 
  and 
  Lepidodendron 
  in 
  a 
  more 
  marked 
  degree 
  than 
  any 
  

   which 
  appear 
  hitherto 
  to 
  have 
  been 
  found. 
  This 
  would 
  tend 
  also 
  to 
  

   confirm 
  the 
  view, 
  held 
  for 
  some 
  time 
  by 
  Mr. 
  Carruthers 
  and 
  others, 
  

   that 
  Sigillaria 
  was 
  allied 
  to 
  the 
  Lycopodiacese. 
  These 
  specimens 
  

   were 
  found 
  near 
  the 
  base 
  of 
  the 
  quarry, 
  in 
  a 
  bed 
  which 
  con- 
  

   tained 
  also 
  some 
  anthracitic 
  fragments 
  of 
  stems 
  ; 
  and 
  it 
  seemed 
  to 
  

   me 
  that 
  the 
  evidence 
  generally 
  tended 
  to 
  show 
  that 
  both 
  were 
  frag- 
  

   ments 
  of 
  different 
  portions 
  of 
  the 
  same 
  or 
  of 
  similar 
  kinds 
  of 
  plants. 
  

   In 
  these 
  specimens 
  a 
  very 
  thin 
  film 
  of 
  carbonaceous 
  matter 
  only 
  re- 
  

   mains, 
  as 
  in 
  the 
  case 
  of 
  the 
  younger 
  branches. 
  Over 
  this 
  surface 
  

   are 
  scattered, 
  apparently 
  with 
  no 
  definite 
  order, 
  numerous 
  circular 
  

   slightly 
  raised 
  scars. 
  In 
  their 
  centre 
  there 
  is 
  frequently 
  to 
  be 
  seen 
  

   a 
  small 
  raised 
  point, 
  probably 
  the 
  spot 
  through 
  which 
  the 
  vascular 
  

   bundle 
  passed 
  (PI. 
  III. 
  fig. 
  3 
  a). 
  Though 
  the 
  scars 
  seem 
  to 
  be 
  scat- 
  

   tered 
  about 
  irregularly, 
  yet 
  they 
  appear 
  more 
  or 
  less 
  in 
  groups 
  ; 
  and 
  

   possibly 
  a 
  somewhat 
  regular 
  arrangement 
  could 
  be 
  observed 
  but 
  for 
  

   the 
  distortion 
  produced 
  by 
  the 
  cleavage. 
  They 
  number 
  in 
  some 
  

   places 
  as 
  many 
  as 
  twenty 
  or 
  more 
  to 
  the 
  square 
  inch 
  ; 
  and 
  their 
  

   average 
  size 
  may 
  be 
  said 
  to 
  be 
  about 
  -^ 
  of 
  an 
  inch 
  in 
  diameter. 
  

   Between 
  the 
  scars 
  the 
  surface 
  is 
  more 
  or 
  less 
  wrinkled 
  ; 
  and 
  on 
  this 
  

   surface 
  are 
  seen 
  scattered 
  about 
  numerous 
  slender 
  tapering 
  frag- 
  

   ments, 
  probably 
  portions 
  of 
  rootlets 
  (see 
  fig. 
  3, 
  PI. 
  III.). 
  

  

  I 
  have 
  not 
  been 
  able 
  to 
  find 
  descriptions 
  of 
  any 
  plants 
  hitherto 
  

   found 
  to 
  which 
  this 
  plant 
  with 
  the 
  very 
  marked 
  combined 
  charac- 
  

   ters 
  above 
  given 
  could 
  be 
  very 
  closely 
  associated. 
  The 
  genera 
  

   which 
  approach 
  nearest 
  to 
  it 
  are 
  Cydostigma, 
  Arthrostigma, 
  and 
  

   Psilophyton 
  ; 
  but 
  to 
  neither 
  of 
  these 
  does 
  it 
  seem 
  to 
  be 
  very 
  inti- 
  

   mately 
  allied. 
  I 
  am 
  therefore 
  tempted, 
  considering 
  the 
  numerous 
  

   specimens 
  which 
  have 
  already 
  been 
  found, 
  and 
  the 
  apparent 
  abund- 
  

   ance 
  of 
  these 
  plants 
  in 
  the 
  early 
  Silurian 
  rocks 
  of 
  North 
  Wales, 
  to 
  

  

  