﻿210 
  

  

  miss 
  g. 
  l. 
  elles 
  on 
  the 
  subgeneka. 
  

  

  Suggested 
  Phylogeny. 
  

   Orthograptus 
  truncatus 
  (Lapw.). 
  

  

  [May 
  1897, 
  

  

  Petalograptus 
  palmeus 
  (Barr.). 
  

  

  [(Kurck). 
  

   P.p. 
  var. 
  ovato-elongatus 
  

  

  P. 
  palmeus, 
  var. 
  tenuis. 
  

  

  [(Barr.). 
  

   -P. 
  palmeus 
  var. 
  latus 
  

  

  P. 
  ovatus 
  (Barr.). 
  

  

  P. 
  minor, 
  sp. 
  nov. 
  

   P. 
  folium 
  (His.). 
  

   C. 
  petalum, 
  sp. 
  nov. 
  

  

  C. 
  cometa 
  (Gein.). 
  

  

  In 
  conclusion 
  I 
  offer 
  my 
  grateful 
  thanks 
  to 
  Prof 
  .'T. 
  McK. 
  Hughes, 
  

   F.R.S., 
  for 
  much 
  kind 
  encouragement 
  ; 
  to 
  Prof. 
  Lapworth, 
  F.R.S., 
  

   and 
  Mr. 
  J. 
  E. 
  Marr, 
  F.R.S., 
  for 
  kind 
  help 
  and 
  advice, 
  and 
  for 
  the 
  

   loan 
  of 
  specimens 
  ; 
  and 
  to 
  Prof. 
  Otto 
  Torell, 
  Director 
  of 
  the 
  Swedish 
  

   Geological 
  Survey, 
  Dr. 
  G. 
  Holm, 
  and 
  Dr. 
  Tornquist 
  for 
  facilitating 
  

   my 
  work 
  in 
  every 
  way 
  during 
  my 
  stay 
  in 
  Sweden*. 
  

  

  EXPLANATION 
  OF 
  PLATES 
  XIII. 
  & 
  XIV. 
  

  

  All 
  the 
  figures 
  are 
  X 
  2. 
  Those 
  marked 
  * 
  are 
  in 
  the 
  

   British 
  Museum 
  (Nat. 
  History). 
  

  

  Plate 
  XIII. 
  

  

  Figs. 
  1-5. 
  Petalograptus 
  folium 
  (His.). 
  

  

  Fig. 
  1. 
  Eeverse 
  aspect 
  of 
  mature 
  specimen, 
  showing 
  the 
  base 
  of 
  the 
  sicula 
  on 
  

   the 
  left. 
  Belcraig. 
  

  

  2. 
  Obverse 
  aspect, 
  in 
  relief, 
  of 
  mature 
  specimen, 
  showing 
  the 
  position 
  

  

  of 
  the 
  sicula 
  and 
  the 
  character 
  of 
  the 
  proximal 
  end. 
  Thecal 
  striae 
  

   well 
  seen. 
  Kallholn. 
  

  

  3. 
  The 
  same, 
  in 
  relief. 
  Kallholn. 
  

  

  4. 
  Eeverse 
  aspect 
  of 
  the 
  proximal 
  end, 
  showing 
  the 
  base 
  of 
  the 
  sicula 
  

  

  with 
  the 
  apertural 
  spine. 
  Kallholn. 
  

  

  *5. 
  Obverse 
  aspect 
  of 
  a 
  young 
  specimen. 
  

  

  Duffkinnell 
  Burn, 
  near 
  Wamphray. 
  

  

  Figs. 
  6-9. 
  Cephalograptus 
  petalum, 
  sp. 
  nov. 
  

  

  Fig. 
  *6. 
  Obverse 
  aspect 
  of 
  foliate 
  form, 
  showing 
  the 
  position 
  of 
  the 
  sicula 
  and 
  

  

  the 
  course 
  of 
  the 
  virgula. 
  Duffkinnell 
  Burn. 
  

  

  *7. 
  Beverse 
  aspect 
  of 
  a 
  young 
  specimen 
  incomplete 
  at 
  the 
  proximal 
  end, 
  

  

  showing 
  only 
  the 
  apex 
  of 
  the 
  sicula. 
  Duffkinnell 
  Burn. 
  

  

  *8. 
  Beverse 
  aspect, 
  showing 
  the 
  splitting 
  of 
  the 
  virgula 
  outside 
  the 
  

  

  rhabdosoma. 
  Frenchland 
  Burn. 
  

  

  9. 
  Eeverse 
  aspect 
  of 
  a 
  very 
  long 
  specimen. 
  Dobb's 
  Linn. 
  

  

  