﻿212 
  G. 
  P. 
  Wieland 
  — 
  Huge 
  Cretaceous 
  Turtles. 
  

  

  element 
  are 
  very 
  distinct. 
  It 
  has 
  an 
  especially 
  broad 
  posterior 
  

   development. 
  Anteriorly 
  it 
  is 
  greatly 
  strengthened 
  by 
  the 
  

   heavy 
  post-orbital 
  border, 
  which 
  runs 
  up 
  internally 
  as 
  a 
  sharp 
  

   but 
  heavy 
  buttressing 
  ridge 
  full 
  2*5 
  cm 
  high 
  in 
  its 
  middle 
  part, 
  

   and 
  not 
  disappearing 
  wholly 
  until 
  the 
  parietal 
  is 
  reached. 
  No 
  

   such 
  ridge 
  is 
  present 
  in 
  Per?nochelys, 
  though 
  a 
  similar 
  one 
  of 
  

   much 
  less 
  development 
  is 
  seen 
  in 
  Thalassochelys. 
  The 
  bound- 
  

   aries 
  are 
  approximately 
  those 
  of 
  the 
  latter 
  form, 
  union 
  with 
  

   the 
  quadrato-jugal 
  being 
  very 
  distinct. 
  

  

  The 
  Parietals. 
  — 
  These 
  were 
  deeply 
  escalloped 
  posteriorly, 
  

   nearly 
  as 
  much 
  as 
  in 
  the 
  Chelydridw. 
  As 
  they 
  had 
  been 
  sub- 
  

   jected 
  to 
  crushing 
  their 
  outlines 
  were 
  not 
  so 
  distinct 
  as 
  in 
  the 
  

   case 
  of 
  the 
  other 
  external 
  elements 
  of 
  the 
  skull. 
  Most 
  unfortu- 
  

   nately 
  the 
  vexed 
  question 
  as 
  to 
  descending 
  processes 
  of 
  the 
  

   parietals 
  and 
  parieto-pterygoidal 
  union 
  can 
  not 
  be 
  definitely 
  

   settled 
  from 
  the 
  present 
  specimen. 
  There 
  certainly 
  was 
  some, 
  

   if 
  not 
  a 
  strong 
  development 
  of 
  these 
  processes. 
  

  

  Both 
  Baur 
  and 
  Case 
  (1 
  and 
  5) 
  have 
  stated 
  that 
  there 
  were 
  

   strongly 
  developed 
  descending 
  parietal 
  processes 
  uniting 
  with 
  

   the 
  pterygoids 
  in 
  Protostega. 
  

  

  Whether 
  or 
  not 
  the 
  absence 
  of 
  these 
  processes 
  in 
  Dermo- 
  

   chelys 
  is 
  as 
  important 
  anatomically 
  as 
  convenient 
  in 
  classifica- 
  

   tion, 
  it 
  is 
  to 
  be 
  hoped 
  that 
  future 
  material 
  will 
  determine 
  what 
  

   the 
  exact 
  condition 
  was 
  in 
  these 
  Dakota 
  descendants 
  of 
  Pro- 
  

   tostega. 
  

  

  The 
  Quadrates. 
  — 
  These 
  are 
  both 
  present 
  in 
  fair 
  condition 
  

   and 
  but 
  slightly 
  crushed 
  out 
  of 
  their 
  natural 
  articulations. 
  

   They 
  are 
  short 
  and 
  unusually 
  massive, 
  particularly 
  the 
  posterior 
  

   border 
  as 
  it 
  extends 
  from 
  the 
  stapedial 
  notch 
  to 
  the 
  squamosal. 
  

   A 
  portion 
  of 
  the 
  right 
  stapes 
  was 
  still 
  to 
  be 
  seen 
  in 
  the 
  stape- 
  

   dial 
  notch. 
  As 
  implied 
  by 
  the 
  differences 
  between 
  the 
  quad- 
  

   rato-jugal 
  and 
  squamosal 
  of 
  Archelon 
  and 
  Protostega 
  as 
  pointed 
  

   out 
  above, 
  the 
  aspect 
  of 
  the 
  quadrate 
  and 
  its 
  boundaries 
  as 
  seen 
  

   in 
  the 
  present 
  fossil 
  must 
  vary 
  sharply 
  from 
  that 
  of 
  Protostega. 
  

   The 
  quadrates 
  of 
  the 
  latter 
  are 
  illustrated 
  by 
  Case 
  (5), 
  w 
  T 
  hile 
  

   those 
  of 
  Archelon 
  are 
  seen 
  as 
  thrust 
  slightly 
  back 
  in 
  Plate 
  II. 
  

  

  The 
  Vomer. 
  — 
  The 
  vomer 
  is 
  present 
  in 
  place 
  and 
  is 
  remark- 
  

   ably 
  developed. 
  It 
  is 
  illustrated 
  in 
  fig. 
  2. 
  As 
  in 
  Protostega 
  

   (5) 
  the 
  anterior 
  relations 
  are 
  distinctly 
  Dermochelan, 
  the 
  vomer 
  

   and 
  palatines 
  not 
  roofing 
  the 
  posterior 
  nares. 
  But 
  with 
  these 
  

   boundaries 
  resemblance 
  to 
  this 
  form 
  ceases. 
  Conforming 
  

   to 
  the 
  great 
  development 
  of 
  its 
  anterior 
  bounding 
  elements, 
  

   the 
  vomer 
  is 
  unusually 
  massive. 
  It 
  takes 
  part 
  in 
  the 
  palatal 
  

   surface 
  as 
  a 
  prominent 
  conical 
  projection 
  in 
  front 
  of 
  the 
  

   posterior 
  nares 
  2 
  cm 
  high. 
  Taken 
  in 
  conjunction 
  with 
  the 
  descend- 
  

   ing 
  premaxillary 
  beak, 
  this 
  is 
  quite 
  the 
  reverse 
  relation 
  to 
  

   that 
  seen 
  in 
  Colpochelys 
  Kempii 
  Garman, 
  which 
  has 
  a 
  flat 
  

  

  