﻿CHELONIAN 
  REMAINS 
  FROM 
  THE 
  WEALDEN 
  AND 
  PUREECK. 
  

  

  511 
  

  

  32. 
  On 
  certain 
  Chelonian 
  Remains 
  from 
  the 
  Wealden 
  and 
  Ptjrbecx. 
  

   By 
  R. 
  Lydekker, 
  Esq., 
  F.G.S., 
  F.Z.S., 
  &c. 
  (Read 
  June 
  5, 
  1889.) 
  

  

  a. 
  Plastron 
  from 
  tlie 
  Wealden. 
  

  

  Certain 
  fragments 
  of 
  the 
  plastron 
  of 
  a 
  Chelonian 
  collected 
  by 
  the 
  

   late 
  Dr. 
  Mantell 
  from 
  the 
  Wealden 
  of 
  Sussex, 
  and 
  now 
  preserved 
  

   in 
  the 
  British 
  Museum, 
  are 
  of 
  some 
  interest 
  as 
  affording 
  evidence 
  of 
  

   the 
  presence 
  of 
  an 
  additional 
  series 
  of 
  epidermal 
  shields 
  unknown 
  in 
  

   any 
  previously 
  described 
  form, 
  and 
  probably 
  indicating 
  an 
  extremely 
  

   archaic 
  type 
  of 
  structure. 
  

  

  Kg. 
  1, 
  

  

  -Left 
  hypo- 
  and 
  xiphiplastral 
  of 
  a 
  Chelonian 
  ; 
  from 
  the 
  

   Wealden 
  of 
  Caclcfield. 
  (J 
  nat. 
  size.) 
  

  

  ab., 
  abdominal 
  shield 
  ; 
  fern., 
  femoral 
  do. 
  ; 
  an., 
  anal 
  do. 
  ; 
  i.ab., 
  interabdominal 
  

   do. 
  ; 
  i.fem., 
  interfemoral 
  do. 
  

  

  The 
  first 
  specimen 
  that 
  may 
  be 
  noticed 
  is 
  the 
  imperfect 
  left 
  

   xiphiplastral, 
  to 
  which 
  is 
  suturally 
  united 
  a 
  portion 
  of 
  the 
  hypo- 
  

   plastral, 
  this 
  bone 
  (No. 
  3506) 
  being 
  represented 
  in 
  fig. 
  1. 
  It 
  

   appears 
  probable 
  that 
  the 
  proximal 
  portion 
  of 
  the 
  bone 
  is 
  broken 
  

   away, 
  and 
  that 
  the 
  hypoplastral 
  element 
  was 
  originally 
  extended 
  

   upwards 
  to 
  form 
  the 
  inguinal 
  portion 
  of 
  the 
  bridge 
  for 
  connexion 
  

   with 
  the 
  carapace. 
  The 
  peculiar 
  features 
  connected 
  with 
  this 
  speci- 
  

   men 
  are, 
  however, 
  the 
  sulci 
  left 
  by 
  the 
  epidermal 
  shields. 
  It 
  will 
  

   be 
  seen 
  from 
  the 
  figure 
  that 
  on 
  the 
  outer 
  border 
  there 
  are 
  two 
  

   narrow 
  shields 
  (an., 
  fern.) 
  which 
  from 
  their 
  relation 
  to 
  the 
  xiphi- 
  

   plastral 
  suture 
  I 
  take 
  to 
  represent 
  the 
  anal 
  and 
  femoral 
  shields 
  of 
  

  

  