﻿G. 
  R. 
  Wieland 
  — 
  Huge 
  Cretaceous 
  Turtles. 
  243 
  

  

  tinctly 
  shown 
  

   only 
  doubtful 
  

   exact 
  size 
  of 
  

   sphenoid 
  and 
  

  

  ~pm 
  

  

  palate 
  and 
  no 
  decurvature 
  of 
  the 
  preraaxillaries, 
  but 
  an 
  upturned 
  

   lower 
  jaw 
  with 
  a 
  prominent 
  cone 
  at 
  the 
  inner 
  vertex 
  of 
  the 
  

   ramial 
  angle. 
  

  

  The 
  superior 
  surface 
  of 
  the 
  vomer 
  forms 
  a 
  distinct 
  saddle 
  con- 
  

   tracting 
  as 
  it 
  rises 
  from 
  beneath 
  the 
  overlap 
  of 
  the 
  premaxil- 
  

   laries 
  and 
  passes 
  back 
  to 
  support 
  the 
  inner 
  buttresses 
  of 
  the 
  

   prefrontals, 
  between 
  which 
  it 
  appears 
  to 
  end. 
  Whether 
  this 
  

   was 
  the 
  natural 
  condition 
  could 
  not 
  be 
  precisely 
  determined. 
  

   There 
  is 
  a 
  bare 
  possibility 
  that 
  the 
  vomer 
  did 
  not 
  pass 
  back 
  to 
  

   form 
  the 
  usual 
  vomero-palatal 
  union. 
  But 
  whether 
  this 
  was 
  

   the 
  case, 
  or 
  whether 
  the 
  palatals 
  sent 
  a 
  median 
  branch 
  far 
  for- 
  

   ward 
  must 
  for 
  the 
  present 
  remain 
  undetermined. 
  The 
  poste- 
  

   rior 
  nares 
  however 
  were 
  not 
  bridged 
  by 
  a 
  nether 
  vomero-palatal 
  

   union, 
  the 
  condition 
  being, 
  owing 
  to 
  the 
  deep 
  gap 
  between 
  the 
  

   palatals 
  and 
  the 
  prominence 
  of 
  the 
  vomer, 
  intermediate 
  between 
  

   Dermochelys 
  and 
  Eretmochelys. 
  Yomero-premaxillar 
  union 
  is 
  

   stronger 
  than 
  in 
  either 
  the 
  latter 
  genus 
  or 
  Argillochelys. 
  

  

  Main 
  Features 
  of 
  the 
  Pala- 
  3 
  

  

  tal 
  Aspect. 
  — 
  These 
  are 
  dis- 
  

   in 
  tig. 
  3. 
  The 
  

   points 
  are 
  the 
  

   the 
  small 
  basi- 
  

   the 
  boundaries 
  

   in 
  the 
  vomero-palatal 
  region 
  

   just 
  mentioned. 
  Anteriorly 
  

   the 
  relations 
  are 
  partly 
  Dermo- 
  

   chelan; 
  posteriorly 
  they 
  are 
  

   Thalassochelan, 
  with 
  the 
  ex- 
  

   ception 
  of 
  the 
  basal 
  processes 
  

   of 
  the 
  basioccipital, 
  which 
  are 
  

   heavy 
  and 
  project 
  downwards 
  

   and 
  outwards 
  as 
  in 
  Dermo- 
  

   chelys. 
  They 
  are 
  however 
  

   much 
  longer 
  an 
  tero 
  posteriorly 
  

   than 
  in 
  this 
  form. 
  

  

  There 
  is 
  a 
  continual 
  reminder 
  

  

  that 
  we 
  have 
  here 
  to 
  deal 
  with 
  

  

  a 
  remarkable 
  blending 
  of 
  the 
  

  

  i*elations 
  seen 
  in 
  the 
  two 
  genera 
  

  

  jnst 
  mentioned, 
  with 
  certain 
  

  

  ■, 
  -, 
  -^ 
  . 
  ,, 
  Figure 
  3. 
  Archelon 
  ischyros 
  Wieland 
  

  

  unusual 
  characters. 
  Especially 
  palatal 
  view 
  x 
  about 
  

  

  the 
  great 
  development 
  of 
  the 
  maxillary; 
  v, 
  vomer; 
  pn 
  

  

  jngal 
  nearly 
  cutting 
  out 
  the 
  

   quadrato-jugal 
  in 
  the 
  basal 
  

   view 
  will 
  be 
  noted. 
  Also 
  the 
  

   girder-like 
  palatals 
  are 
  quite 
  

   a 
  prominent 
  

  

  unique, 
  forming 
  

  

  iV- 
  P 
  m 
  < 
  P 
  re 
  " 
  

  

  posterior 
  narial 
  

   opening; 
  m, 
  maxillary; 
  vp, 
  the 
  uncertain 
  

   vomero-palatal 
  region; 
  pi, 
  palatals 
  form- 
  

   ing 
  a 
  girder-like 
  structure; 
  j\ 
  jugal; 
  pi, 
  

   pterygoid; 
  bs, 
  basisphenoid; 
  qj, 
  quad- 
  

   rato-jugal 
  ; 
  q, 
  quadrate 
  ; 
  s, 
  squamosal 
  ; 
  oc, 
  

   occipital 
  condyle. 
  

  

  