﻿CHELOOTA 
  AND 
  A 
  TOOTH 
  OF 
  (?) 
  ORNITHOPSIS. 
  241 
  

  

  the 
  matrix 
  containing 
  the 
  unfigured 
  skull 
  and 
  associated 
  bones, 
  leads 
  

   to 
  the 
  conclusion 
  (as 
  suggested 
  to 
  me 
  by 
  M. 
  Dollo) 
  that 
  the 
  cara- 
  

   pace 
  of 
  this 
  form 
  consisted 
  only 
  of 
  the 
  median 
  row 
  of 
  ossifications, 
  

   together 
  with 
  a 
  series 
  of 
  marginals. 
  M 
  . 
  Dollo 
  also 
  states 
  that, 
  al- 
  

   though 
  the 
  cranium 
  is 
  very 
  like 
  that 
  of 
  Psephophorus, 
  yet 
  there 
  are 
  

   certain 
  differences, 
  and 
  more 
  especially 
  the 
  apparent 
  absence 
  in 
  the 
  

   premaxillae 
  of 
  the 
  descending 
  process 
  found 
  in 
  that 
  genus 
  and 
  Der- 
  

   matochelys. 
  

  

  Under 
  these 
  circumstances, 
  I 
  am 
  disposed 
  to 
  regard 
  Chelone 
  gigas 
  

   as 
  indicating 
  a 
  new 
  genus 
  of 
  Dermatochelyidse, 
  for 
  which 
  I 
  pro- 
  

   pose 
  the 
  name 
  Eosphargis, 
  and 
  which 
  may 
  be 
  briefly 
  defined 
  as 
  

   follows 
  : 
  — 
  Skull 
  and 
  humerus 
  of 
  the 
  general 
  type 
  of 
  Psephophorus 
  ; 
  

   carapace 
  consisting 
  of 
  a 
  median 
  dorsal 
  row 
  of 
  large 
  carinated 
  plates, 
  

   of 
  which 
  the 
  width 
  largely 
  exceeds 
  the 
  length, 
  and 
  probably 
  also 
  of 
  

   a 
  series 
  of 
  large 
  marginals.] 
  

  

  6. 
  Dacochelys 
  (n. 
  gen.) 
  from 
  the 
  London 
  Clay. 
  

  

  Among 
  the 
  numerous 
  remains 
  of 
  Chelonians 
  from 
  the 
  London 
  Clay 
  

   in 
  the 
  British 
  Museum 
  is 
  the 
  imperfect 
  anterior 
  extremity 
  of 
  the 
  man- 
  

   dible 
  of 
  a 
  large 
  form 
  (No. 
  39257), 
  hitherto 
  placed 
  with 
  the 
  Chelonidse, 
  

   but 
  which 
  has 
  evidently 
  nothing 
  to 
  do 
  with 
  that 
  group. 
  The 
  whole 
  of 
  

   the 
  symphysis 
  is 
  nearly 
  entire, 
  and 
  affords 
  very 
  distinctive 
  characters. 
  

   The 
  outer 
  alveolar 
  ridge 
  is, 
  indeed, 
  somewhat 
  broken, 
  but 
  sufficient 
  

   remains 
  to 
  show 
  that 
  it 
  was 
  elevated 
  mesially 
  into 
  a 
  sharp 
  point, 
  

  

  Fig. 
  6. 
  — 
  Restoration 
  of 
  the 
  Anterior 
  Extremity 
  of 
  the 
  Mandible 
  of 
  

   Dacochelys 
  Delabechei, 
  viewed 
  from 
  in 
  front 
  and 
  from 
  the 
  right 
  

   from 
  the 
  London 
  Clay. 
  (§ 
  nat. 
  size.) 
  

  

  while 
  laterally 
  it 
  had 
  a 
  number 
  of 
  tooth-like 
  processes 
  similar 
  to 
  

   those 
  in 
  the 
  Batagurs 
  and 
  in 
  Testudo 
  elephantina. 
  This 
  character 
  

   at 
  once 
  distinguishes 
  the 
  specimen 
  from 
  all 
  members 
  of 
  the 
  Chelonidae, 
  

   in 
  which 
  the 
  alveolar 
  borders 
  of 
  the 
  jaws 
  are 
  invariably 
  smooth. 
  

   Within 
  this 
  alveolar 
  ridge 
  is 
  a 
  deep 
  groove, 
  succeeded 
  inwardly 
  by 
  a 
  

   second 
  ridge, 
  which 
  appears 
  to 
  have 
  been 
  likewise 
  serrated, 
  and 
  is 
  

   higher 
  than 
  the 
  outer 
  one. 
  In 
  the 
  middle 
  line 
  the 
  inner 
  ridge 
  is 
  

   developed 
  into 
  a 
  huge 
  triangular 
  process, 
  projecting 
  far 
  above 
  the 
  

  

  t2 
  

  

  