﻿V°l« 
  53*] 
  PETALOGKAPTUS 
  AND 
  CEPHALOGBAPTUS. 
  193 
  

  

  Petalograpttts 
  palmeus 
  (Barr.). 
  

  

  1850. 
  Graptolitlius 
  palmeus, 
  Barrande, 
  'Grap. 
  de 
  Boheme,' 
  p. 
  59, 
  pi. 
  iii. 
  figs. 
  1-7. 
  

  

  1851. 
  Petalolithus 
  pahneus+parallelocostatus, 
  Suss, 
  ' 
  Ueber 
  Bohmische 
  Grapto- 
  

   lithen,' 
  pp. 
  20, 
  21, 
  pi. 
  viii. 
  figs. 
  1, 
  2, 
  4. 
  

  

  1852. 
  Diplograptus 
  palmeus, 
  Geinitz, 
  'Die 
  Graptolithen,' 
  p. 
  21, 
  pi. 
  i. 
  figs. 
  5-19. 
  

  

  1853. 
  Diplograptus 
  palmeus, 
  Kichter, 
  Zeitschr. 
  d. 
  Deutsch. 
  Geol. 
  Gesellsch. 
  vol. 
  v. 
  

   p. 
  455, 
  pi. 
  xii. 
  figs. 
  8-10. 
  

  

  1876-1880. 
  Diplograptus 
  palmeus, 
  Zittel, 
  'Traite 
  de 
  Paleont.' 
  vol. 
  i. 
  p. 
  305, 
  

   fig. 
  214, 
  d, 
  e. 
  

  

  1880-81. 
  Diplograptus 
  palmeus, 
  Lirmarsson, 
  Geol. 
  Foren. 
  Forkandl. 
  vol. 
  v. 
  p. 
  522, 
  

   pi. 
  xxiii. 
  figs. 
  26-28. 
  

  

  1887. 
  Diplograptus 
  palmeus, 
  Tornquist, 
  Geol. 
  Foren. 
  Forhandl. 
  vol. 
  ix. 
  pp. 
  478, 
  481. 
  

  

  1890. 
  Diplograptus 
  palmeus, 
  Geinitz, 
  ' 
  Graptoliten 
  des 
  k. 
  Mineralog. 
  Mus. 
  

   Dresden,' 
  p. 
  26, 
  pi. 
  A. 
  figs. 
  39, 
  41-43. 
  

  

  1893. 
  Diplograptus 
  palmeus, 
  Tornquist, 
  ' 
  Structure 
  of 
  some 
  Diprionidae,' 
  

   K. 
  Fysiogr. 
  Sallskap. 
  Handl., 
  Lund, 
  vol. 
  iv. 
  p. 
  9, 
  figs. 
  29-35. 
  

  

  This 
  species 
  has 
  been 
  very 
  generally 
  recognized, 
  but 
  the 
  details 
  

   with 
  regard 
  to 
  the 
  structure 
  of 
  its 
  proximal 
  end 
  have 
  never 
  received 
  

   proper 
  attention. 
  The 
  form 
  which 
  Tornquist 
  referred 
  to 
  this 
  species 
  

   in 
  1893 
  (op. 
  supra 
  cit.) 
  cannot, 
  I 
  think, 
  be 
  retained 
  in 
  it, 
  as 
  it 
  differs 
  

   in 
  many 
  important 
  particulars, 
  and 
  must, 
  in 
  my 
  opinion, 
  be 
  regarded 
  

   as 
  a 
  distinct 
  species. 
  

  

  I 
  can 
  find 
  no 
  evidence 
  in 
  support 
  of 
  the 
  separation 
  of 
  P. 
  parallelo- 
  

   costatus 
  from 
  the 
  true 
  P. 
  palmeus 
  (Barr.). 
  The 
  characters 
  upon 
  which 
  

   Suss 
  founded 
  this 
  species 
  have 
  been 
  shown 
  to 
  belong 
  equally 
  to 
  

   P. 
  palmeus 
  (Barr.). 
  Therefore 
  I 
  think 
  that 
  the 
  species 
  must 
  be 
  

   abolished. 
  

  

  Barrande, 
  in 
  his 
  work 
  on 
  the 
  Graptolites 
  of 
  Bohemia, 
  suggested 
  

   two 
  varieties 
  of 
  the 
  species 
  palmeus. 
  These 
  varieties 
  were 
  based 
  on 
  

   the 
  difference 
  in 
  width 
  of 
  the 
  rhabdosoma 
  in 
  different 
  individuals, 
  

   and 
  were 
  termed 
  respectively 
  (1) 
  var. 
  lata 
  and 
  (2) 
  var. 
  tenuis. 
  He 
  

   does 
  not 
  describe 
  these 
  varieties 
  in 
  detail 
  ; 
  but 
  from 
  his 
  description 
  of 
  

   Petalograptus 
  palmeus 
  we 
  must, 
  I 
  think, 
  conclude 
  that 
  he 
  meant 
  the 
  

   forms 
  that 
  exceeded 
  J 
  inch 
  (3 
  mm.) 
  to 
  be 
  termed 
  var. 
  latus, 
  and 
  

   those 
  which 
  were 
  less 
  than 
  -L 
  inch 
  (2 
  mm.) 
  to 
  be 
  called 
  var. 
  tenuis. 
  

   Hence 
  it 
  follows 
  that 
  the 
  actual 
  specific 
  name 
  Petalograptus 
  palmeus 
  

   (Barr.) 
  must 
  be 
  restricted 
  to 
  those 
  forms 
  which 
  exceed 
  yL 
  inch 
  in 
  

   width 
  and 
  which 
  do 
  not 
  exceed 
  J 
  inch. 
  Each 
  of 
  these 
  three 
  forms 
  

   has 
  a 
  slightly 
  different 
  range 
  in 
  time. 
  

  

  In 
  addition 
  to 
  the 
  three 
  forms 
  mentioned 
  above 
  there 
  exists 
  one 
  

   to 
  which 
  Kurck 
  has 
  given 
  the 
  name 
  ovato-elongatus. 
  

  

  He 
  ranked 
  it 
  as 
  a 
  distinct 
  species, 
  but, 
  for 
  reasons 
  which 
  will 
  be 
  

   given 
  later, 
  I 
  think 
  that 
  it 
  cannot 
  be 
  regarded 
  as 
  more 
  than 
  a 
  

   variety. 
  Barrande 
  recognized 
  the 
  form, 
  but 
  did 
  not 
  give 
  it 
  a 
  separate 
  

   name. 
  

  

  I 
  now 
  proceed 
  to 
  describe 
  in 
  some 
  detail 
  the 
  structure 
  of 
  the 
  

   different 
  forms 
  of 
  P. 
  palmeus 
  (Barr.). 
  

  

  Petalograpttjs 
  palmeus 
  (Barr.) 
  (restricted). 
  (PI. 
  XIV. 
  figs. 
  1-4.) 
  

  

  Structure 
  of 
  the 
  Proximal 
  End. 
  — 
  The 
  sicula 
  is 
  fairly 
  long, 
  and 
  is 
  

   broader 
  than 
  that 
  of 
  P. 
  folium 
  (His.). 
  It 
  is 
  usually 
  rather 
  less 
  than 
  

   y 
  1 
  ^ 
  inch 
  long 
  (about 
  2 
  mm.). 
  It 
  reaches 
  up 
  to 
  the 
  third 
  theca 
  of 
  each 
  

  

  