﻿186 
  MISS 
  G. 
  L. 
  ELLES 
  ON 
  THE 
  SUBGENERA 
  [May 
  1 
  897, 
  

  

  14. 
  The 
  Subgenera 
  Petalograptus 
  and 
  Cephalograptus. 
  By 
  

   Miss 
  G. 
  L. 
  Elles. 
  (Communicated 
  by 
  J. 
  E. 
  Marr, 
  Esq., 
  M.A., 
  

   E.R.S., 
  E.G.S. 
  Eead 
  February 
  3rd, 
  1897.) 
  

  

  [Plates 
  XIII. 
  & 
  XIV.] 
  

  

  Contents. 
  

  

  Page 
  

  

  I. 
  Introduction 
  186 
  

  

  II. 
  Definition 
  of 
  the 
  Subgenera 
  188 
  

  

  III. 
  Description 
  of 
  the 
  Species 
  188 
  

  

  IV. 
  General 
  Conclusions 
  209 
  

  

  I. 
  Introduction. 
  

  

  Much 
  confusion 
  has 
  arisen 
  in 
  our 
  own 
  country 
  and 
  on 
  the 
  Continent 
  

   with 
  regard 
  to 
  the 
  use 
  of 
  the 
  names 
  Petalograptus 
  and 
  Cephalo- 
  

   graptus 
  for 
  certain 
  subgenera 
  of 
  Graptolites. 
  Both 
  names 
  have 
  

   sometimes 
  been 
  employed 
  for 
  the 
  very 
  same 
  species. 
  Such 
  an 
  error 
  

   can 
  only 
  have 
  arisen 
  through 
  ignorance 
  of 
  the 
  detailed 
  structure 
  of 
  

   the 
  type-forms. 
  Thus, 
  for 
  example, 
  in 
  1873 
  Lap 
  worth 
  1 
  gave 
  Petalo- 
  

   graptus 
  folium 
  (His.) 
  as 
  the 
  type 
  of 
  the 
  subgenus 
  Petalograptus. 
  

   In 
  1882 
  Tullberg, 
  in 
  his 
  paper 
  on 
  the 
  ' 
  Graptolites 
  described 
  by 
  

   Hisinger,' 
  called 
  it 
  Cephalograptus 
  folium, 
  and 
  classed 
  it 
  with 
  

   Cephalograptus 
  cometa 
  (Gein.). 
  ISTo 
  wonder, 
  then, 
  that 
  Geinitz, 
  

   writing 
  later, 
  2 
  adopted 
  the 
  safer 
  plan 
  of 
  ignoring 
  both 
  subgenera, 
  and 
  

   referred 
  the 
  species 
  to 
  the 
  more 
  embracing 
  genus 
  Diplograptus. 
  

   The 
  object 
  of 
  this 
  paper 
  is 
  to 
  bring 
  out 
  the 
  following 
  facts 
  : 
  — 
  

  

  (1) 
  That 
  both 
  Petalograptus 
  and 
  Cephalograptus 
  should 
  be 
  re- 
  

   garded 
  as 
  subgenera 
  of 
  the 
  genus 
  Diplograptus. 
  

  

  (2) 
  That 
  these 
  subgenera 
  are 
  perfectly 
  distinct, 
  and 
  can 
  readily 
  

   be 
  distinguished 
  one 
  from 
  the 
  other. 
  

  

  (3) 
  That 
  certain 
  species 
  should 
  be 
  referred 
  to 
  one 
  or 
  other 
  sub- 
  

   genus. 
  

  

  (4) 
  The 
  detailed 
  structure 
  of 
  the 
  various 
  species, 
  showing 
  the 
  

   relationship 
  existing 
  between 
  them. 
  

  

  I 
  have 
  endeavoured 
  to 
  make 
  my 
  work 
  on 
  these 
  subgenera 
  as 
  

   complete 
  as 
  possible 
  by 
  examining 
  specimens 
  from 
  many 
  British 
  

   and 
  foreign 
  localities. 
  Many 
  of 
  the 
  British 
  specimens 
  were 
  collected 
  

   by 
  myself 
  in 
  the 
  field, 
  while 
  others 
  are 
  to 
  be 
  found 
  in 
  the 
  collections 
  

   of 
  the 
  Woodwardian 
  Museum 
  at 
  Cambridge, 
  and 
  in 
  the 
  British 
  

   Museum 
  (Natural 
  History). 
  During 
  a 
  recent 
  visit 
  to 
  Sweden 
  I 
  was 
  

   enabled, 
  through 
  the 
  great 
  kindness 
  of 
  Dr. 
  Tornquist, 
  of 
  Lund, 
  

   to 
  study 
  his 
  magnificent 
  collection 
  of 
  graptolites. 
  This 
  collection 
  

   not 
  only 
  contains 
  specimens 
  from 
  almost 
  every 
  locality 
  in 
  Sweden 
  

   where 
  graptolites 
  are 
  to 
  be 
  found, 
  but 
  is 
  also 
  rich 
  in 
  typical 
  

   forms 
  from 
  many 
  other 
  European 
  areas 
  (Bohemia, 
  Thuringia, 
  etc.). 
  

   From 
  some 
  Swedish 
  localities 
  I 
  obtained 
  specimens 
  for 
  myself, 
  and 
  

  

  1 
  Geol. 
  Mag. 
  pt. 
  ii. 
  p. 
  555. 
  

  

  2 
  ' 
  Graptoliten 
  des 
  k. 
  Mineralog. 
  Mus. 
  Dresden,' 
  1890. 
  

  

  