﻿ON 
  REMAINS 
  OF 
  CHELONIA 
  AND 
  A 
  TOOTH 
  OF 
  (?) 
  OEKITHOPSIS. 
  227 
  

  

  14. 
  On 
  Eemains 
  of 
  Eocene 
  and 
  Mesozoic 
  Chelonia 
  and 
  a 
  Tooth 
  

   of 
  (?) 
  Oknithopsis. 
  By 
  E. 
  Lydekkek, 
  Esq., 
  B.A., 
  F.Gr.S. 
  (Eead 
  

   January 
  23, 
  1889.) 
  

  

  [Plate 
  VIII.] 
  

  

  Introductory 
  . 
  

  

  The 
  greater 
  portion 
  of 
  the 
  present 
  communication 
  is 
  devoted 
  to 
  the 
  

   consideration 
  of 
  Chelonia, 
  and 
  more 
  especially 
  to 
  specimens 
  from 
  the 
  

   Cambridge 
  Greensand, 
  most 
  of 
  which 
  were 
  collected 
  nearly 
  twenty 
  

   years 
  ago 
  by 
  my 
  college 
  friend 
  Mr. 
  T. 
  Jesson, 
  P.G.S., 
  of 
  Northampton. 
  

   It 
  includes, 
  however, 
  the 
  description 
  of 
  an 
  interesting 
  Chelonian 
  from 
  

   the 
  Wealden, 
  kindly 
  lent 
  to 
  me 
  by 
  the 
  Eev. 
  P. 
  B. 
  Brodie 
  ; 
  and 
  also 
  

   makes 
  certain 
  redeterminations 
  as 
  to 
  the 
  affinities 
  and 
  serial 
  position 
  

   of 
  some 
  of 
  the 
  marine 
  Chelonians 
  of 
  the 
  London 
  Clay. 
  The 
  tooth 
  

   from 
  the 
  Wealden 
  referred 
  to 
  Omithopsis 
  leads 
  to 
  the 
  consideration 
  

   of 
  the 
  affinities 
  of 
  some 
  allied 
  specimens 
  from 
  the 
  Portlandian 
  of 
  

   Prance. 
  

  

  1. 
  The 
  Genus 
  Ehinochelys, 
  of 
  the 
  Cambridge 
  Greensand. 
  

  

  The 
  name 
  Ehinochelys 
  was 
  applied 
  in 
  1869 
  by 
  Prof. 
  H. 
  G. 
  Seeley* 
  

   to 
  the 
  Chelonian 
  cranium 
  from 
  the 
  Cambridge 
  Greensand 
  figured 
  by 
  

   Sir 
  E. 
  Owen 
  in 
  his 
  ' 
  Cretaceous 
  Eeptilia 
  ' 
  (Mon. 
  Pal. 
  Soc), 
  pt. 
  i. 
  

   pi. 
  vii.A, 
  figs. 
  1-3 
  (1851), 
  under 
  the 
  name 
  of 
  Chelone 
  pidcJiriceps, 
  of 
  

   which 
  species 
  it 
  is 
  the 
  type. 
  The 
  distinctive 
  features 
  of 
  this 
  cranium, 
  

   as 
  shown 
  by 
  the 
  figure, 
  are 
  that 
  the 
  pterygoids, 
  which 
  are 
  in 
  contact 
  

   throughout 
  their 
  length, 
  are 
  comparatively 
  narrow 
  and 
  emarginate, 
  

   and 
  that 
  the 
  palatines 
  unite 
  in 
  the 
  median 
  line. 
  There 
  are, 
  more- 
  

   over, 
  distinct 
  nasals, 
  the 
  prefrontals 
  being 
  separated 
  from 
  one 
  another 
  

   by 
  the 
  nasals 
  and 
  frontals. 
  Again, 
  the 
  temporal 
  fossae 
  are 
  completely 
  

   roofed 
  over, 
  after 
  a 
  manner 
  now 
  obtaining 
  only 
  in 
  the 
  Chelonidae 
  — 
  

   that 
  is 
  to 
  say, 
  there 
  is 
  both 
  an 
  inferior 
  and 
  a 
  superior 
  temporal 
  

   arcade 
  ; 
  the 
  postfrontal 
  articulates 
  by 
  a 
  long 
  suture 
  with 
  the 
  parietal 
  ; 
  

   and 
  it 
  seems, 
  judging 
  from 
  other 
  specimens, 
  that 
  the 
  squamosal 
  

   may 
  have 
  joined 
  the 
  parietal 
  to 
  form 
  a 
  parieto-squamosal 
  or 
  post- 
  

   temporal 
  bar. 
  The 
  whole 
  of 
  the 
  tympanic 
  area 
  is 
  not 
  shown, 
  but 
  it 
  

   appears 
  that 
  the 
  tympanic 
  ring 
  was 
  very 
  largely 
  ossified, 
  although 
  

   perhaps 
  open 
  inferiorly, 
  and 
  that, 
  as 
  in 
  the 
  Chelonidge, 
  the 
  quadrato- 
  

   jugal 
  entered 
  into 
  the 
  formation 
  of 
  this 
  ring. 
  Other 
  specimens 
  seem 
  

   to 
  show 
  that 
  the 
  auditory 
  labyrinth 
  was 
  completely 
  open 
  posteriorly, 
  

   after 
  the 
  Pleurodiran 
  manner. 
  Further, 
  there 
  is 
  no 
  flooring 
  of 
  the 
  

   narial 
  passage, 
  and 
  the 
  oral 
  surface 
  of 
  the 
  palate 
  has 
  a 
  prominent 
  

   ridge 
  on 
  either 
  side. 
  

  

  In 
  establishing 
  the 
  genus 
  Rhinochelys, 
  Prof. 
  Seeley 
  pointed 
  out 
  that 
  

   it 
  could 
  not 
  belong 
  to 
  the 
  Chelonidae, 
  observing 
  that 
  "it 
  is 
  Emydian 
  

   in 
  its 
  affinities, 
  and 
  well 
  characterized 
  by 
  having 
  the 
  nasal 
  and 
  pre- 
  

  

  * 
  ' 
  Index 
  to 
  Aves 
  &c. 
  in 
  Cambridge 
  Museum,' 
  p. 
  25. 
  

  

  