﻿210 
  MR. 
  E. 
  LYDEKEEE 
  OX 
  EE1IAIXS 
  OE 
  EOCENE 
  AXD 
  1IE50Z0IC 
  

  

  rior 
  nares, 
  and 
  the 
  general 
  contour 
  of 
  the 
  bones 
  of 
  the 
  palate 
  and 
  

   occiput, 
  which 
  are 
  totally 
  different 
  from 
  those 
  of 
  the 
  Chelonidae 
  ; 
  

   similarly, 
  in 
  the 
  upper 
  surface 
  of 
  the 
  skull 
  the 
  peculiar 
  upward 
  

   direction 
  of 
  the 
  nares. 
  and 
  the 
  thin 
  bar 
  separating 
  them 
  from 
  the 
  

   large 
  orbits, 
  both 
  of 
  which 
  are 
  characteristic 
  features 
  of 
  Dermato- 
  

   clielys. 
  A 
  second 
  skull 
  in 
  the 
  Museum 
  exhibits, 
  moreover, 
  the 
  

   absence 
  of 
  descending 
  parietal 
  plates 
  which 
  distinguish 
  the 
  skulls 
  of 
  

   this 
  group 
  from 
  those 
  of 
  all 
  ether 
  Chelonians. 
  Further 
  evidence 
  is 
  

   afforded 
  by 
  a 
  humerus 
  attached 
  to 
  the 
  block 
  in 
  which 
  this 
  skull 
  is 
  

   imbedded, 
  which 
  is 
  of 
  the 
  same 
  general 
  type 
  as 
  that 
  of 
  the 
  under- 
  

   mentioned 
  extinct 
  genus. 
  

  

  The 
  skull 
  is 
  much 
  flatter 
  and 
  wider 
  than 
  that 
  of 
  the 
  existing 
  

   genus, 
  and 
  in 
  this 
  respect 
  it 
  agrees 
  with, 
  the 
  description 
  given 
  by 
  

   M. 
  Dollo* 
  of 
  the 
  Miocene 
  and 
  Upper 
  and 
  Middle 
  Eocene 
  genus 
  Pse- 
  

   phophorus, 
  an 
  extinct 
  representative 
  of 
  the 
  Dermatochelydidae. 
  For 
  

   the 
  present, 
  therefore, 
  until 
  I 
  have 
  investigated 
  into 
  the 
  structure 
  of 
  

   the 
  carapace, 
  I 
  propose 
  to 
  refer 
  the 
  Lower 
  Eocene 
  form 
  to 
  the 
  latter 
  

   genus. 
  

  

  [Xote, 
  February 
  1889. 
  — 
  Since 
  the 
  above 
  was 
  written, 
  I 
  have 
  

   made, 
  in 
  company 
  with 
  M. 
  L. 
  Dollo 
  and 
  Mr. 
  Boulenger 
  +, 
  a 
  careful 
  

   examination 
  of 
  the 
  mass 
  of 
  rock 
  i 
  described 
  by 
  Sir 
  E. 
  Owen 
  in 
  the 
  

   memoir 
  cited, 
  which 
  contains 
  the 
  bones 
  of 
  the 
  pectoral 
  girdle 
  and 
  

   portions 
  of 
  the 
  ribs 
  and 
  carapace 
  of 
  this 
  form. 
  The 
  remains 
  con- 
  

   tained 
  in 
  this 
  mass 
  of 
  rock 
  are 
  stated 
  by 
  Sir 
  E. 
  Owen 
  to 
  have 
  been 
  

   associated 
  with 
  the 
  figured 
  cranium: 
  but 
  although 
  this 
  is 
  not 
  the 
  

   case, 
  there 
  is 
  no 
  doubt 
  that 
  these 
  bones 
  belong 
  to 
  the 
  same 
  form, 
  

   since 
  there 
  is 
  associated 
  with 
  them 
  the 
  distal 
  portion 
  of 
  a 
  humerus 
  § 
  

   corresponding 
  exactly 
  with 
  the 
  entire 
  humerus 
  attached 
  to 
  the 
  un- 
  

   figured 
  cranium. 
  It 
  was 
  on 
  the 
  evidence 
  of 
  this 
  specimen 
  that 
  Sir 
  

   B. 
  Owen 
  relied 
  in 
  referring 
  the 
  species 
  to 
  Chelone 
  rather 
  than 
  to 
  

   the 
  Dermatochelyidte. 
  

  

  The 
  six 
  or 
  seven 
  large 
  and 
  transversely 
  elongated 
  bony 
  plates 
  lying 
  

   on 
  the 
  dorsal 
  surface 
  of 
  the 
  ribs 
  of 
  this 
  specimen 
  were 
  described 
  by 
  

   Sir 
  E. 
  Owen 
  as 
  neural 
  bones. 
  In 
  addition, 
  however, 
  to 
  their 
  wide 
  

   difference 
  in 
  form 
  from 
  the 
  neurals 
  of 
  any 
  known 
  Testudinata 
  (The- 
  

   cophora) 
  it 
  can 
  at 
  once 
  be 
  shown 
  that 
  this 
  interpretation 
  is 
  incor- 
  

   rect, 
  since 
  three 
  of 
  them 
  overlie 
  two 
  ribs. 
  Again, 
  at 
  that 
  extremity 
  

   of 
  the 
  specimen 
  where 
  they 
  overlie 
  the 
  ribs 
  they 
  can 
  distinctly 
  be 
  

   seen 
  to 
  form 
  a 
  separate 
  layer 
  : 
  while 
  at 
  the 
  other 
  extremity 
  of 
  the 
  

   slab 
  they 
  are 
  not 
  underlain 
  by 
  ribs 
  at 
  all. 
  This 
  clearly 
  shows 
  that 
  

   these 
  plates 
  are 
  merely 
  dermal 
  ossifications, 
  which 
  from 
  their 
  posi- 
  

   tion 
  evidently 
  formed 
  a 
  median 
  dorsal 
  series. 
  The 
  total 
  absence 
  of 
  

   polygonal 
  tesserae 
  like 
  those 
  of 
  PsejoliopJiorus 
  in 
  this 
  slab, 
  and 
  also 
  in 
  

  

  * 
  Bull. 
  Mus. 
  E. 
  Hist. 
  Nat 
  Belgr. 
  vol. 
  v. 
  p. 
  59 
  et 
  seq. 
  (1883) 
  ; 
  also 
  Ann. 
  Soc. 
  

   Sci. 
  Brux. 
  1887. 
  p. 
  139 
  et 
  seq. 
  

  

  t 
  I 
  am 
  greatly 
  indebted 
  to 
  these 
  gentlemen 
  in 
  regard 
  to 
  the 
  determination 
  of 
  

   the 
  real 
  nature 
  of 
  the 
  carapace 
  in 
  this 
  specimen. 
  

  

  t 
  B.M. 
  3fo. 
  440S9. 
  

  

  | 
  B.M. 
  No. 
  41090. 
  

  

  