﻿G. 
  R. 
  Wieland 
  — 
  Huge 
  Cretaceous 
  Turtles. 
  245 
  

  

  being 
  distinct. 
  The 
  presplenial 
  region 
  has 
  rather 
  the 
  appear- 
  

   ance 
  of 
  being 
  a 
  long 
  anterior 
  projection 
  of 
  the 
  splenial 
  (Baur's 
  

   angular). 
  On 
  the 
  contrary, 
  the 
  angular 
  is 
  a 
  little 
  broader 
  and 
  

   extends 
  farther 
  forward 
  than 
  in 
  Protostega. 
  Again, 
  the 
  nar- 
  

   row 
  but 
  nevertheless 
  robust 
  aspect 
  of 
  the 
  anterior 
  or 
  sym- 
  

   physial 
  portion 
  of 
  the 
  dentary 
  in 
  Archelon 
  is 
  notable. 
  Rela- 
  

   tively 
  to 
  length 
  the 
  symphysial 
  depth 
  is 
  great, 
  and 
  the 
  weight 
  

   of 
  this 
  portion 
  of 
  the 
  jaw 
  suggests 
  a 
  hammer-like 
  action 
  

   against 
  the 
  palatal 
  cone. 
  This 
  would 
  have 
  been 
  very 
  effective 
  

   in 
  the 
  crushing 
  for 
  food 
  of 
  large 
  mollusca 
  and 
  Crustacea, 
  if 
  

   perchance 
  the 
  Archelones 
  were 
  in 
  any 
  wise 
  similar 
  in 
  feeding 
  

   habits 
  to 
  existing 
  carnivorous 
  sea 
  turtles. 
  

  

  Another 
  well 
  marked 
  character 
  is 
  the 
  persistent 
  symphysial 
  

   suture. 
  While 
  in 
  half 
  grown 
  forms 
  of 
  Protostega 
  this 
  suture 
  

   is 
  wholly 
  obliterated, 
  in 
  the 
  present 
  specimen, 
  which 
  may 
  have 
  

   been 
  from 
  adult 
  to 
  three-fifths 
  grown, 
  the 
  rami 
  readily 
  sepa- 
  

   rated 
  on 
  this 
  line. 
  So 
  pronounced 
  a 
  suture 
  is 
  rare. 
  

  

  The 
  ramial 
  angle, 
  which 
  is 
  50° 
  in 
  Thalassochelys 
  and 
  Dermo- 
  

   chelys, 
  and 
  40° 
  in 
  Protostega, 
  may 
  not 
  have 
  been 
  more 
  than 
  

   25° 
  in 
  Archelon. 
  The 
  latter 
  is 
  a 
  very 
  narrow 
  form, 
  and 
  the 
  

   vertex 
  of 
  the 
  rami 
  forms 
  a 
  nearly 
  sharp 
  instead 
  of 
  rounded 
  

   angle. 
  

  

  It 
  is 
  scarcely 
  necessary 
  to 
  compare 
  further. 
  There 
  is 
  cer- 
  

   tainly 
  more 
  resemblance 
  in 
  the 
  mandibulum 
  to 
  Thalassochelys 
  

   than 
  Dermochelys, 
  but 
  withal 
  intermediate 
  characters 
  as 
  in 
  

   other 
  parts 
  of 
  the 
  skull. 
  

  

  General 
  appearance 
  of 
  the 
  skull. 
  — 
  The 
  skull 
  of 
  A. 
  ischyros 
  

   is 
  long 
  in 
  proportion 
  both 
  to 
  the 
  body 
  and 
  to 
  its 
  width, 
  but 
  

   nevertheless 
  massive. 
  There 
  is 
  in 
  the 
  deeply 
  notched 
  parietals, 
  

   the 
  decurved 
  beak, 
  and 
  the 
  depressed 
  vicious-looking 
  fore- 
  

   head, 
  a 
  distinct 
  reminder 
  of 
  the 
  features 
  in 
  such 
  carnivorous 
  

   land 
  turtles 
  as 
  the 
  Chelydridce. 
  Every 
  relation 
  bespeaks 
  a 
  

   ferocious 
  form. 
  So 
  far 
  as 
  may 
  be 
  inferred 
  from 
  physiognomy 
  

   it 
  is 
  easy 
  to 
  conceive 
  this 
  turtle 
  with 
  his 
  powerful 
  pinching 
  

   and 
  clasping 
  beak, 
  as 
  preying 
  not 
  only 
  on 
  crustaceans, 
  but 
  

   even 
  upon 
  the 
  larger 
  fishes 
  and 
  reptiles 
  of 
  the 
  Cretaceous 
  seas. 
  

  

  The 
  turtle 
  to 
  which 
  this 
  skull 
  belonged 
  was 
  not 
  more 
  than 
  

   ten 
  feet 
  in 
  length, 
  but 
  had 
  a 
  remarkably 
  broad 
  and 
  robust 
  

   form. 
  The 
  flippers 
  were 
  short, 
  broad, 
  and 
  of 
  great 
  power. 
  

  

  Measurements 
  of 
  the 
  Cranium 
  of 
  Archelon 
  ischyros 
  Wieland. 
  

   (From 
  a 
  cotype 
  approximately 
  three-fifths 
  the 
  size 
  of 
  the 
  type.) 
  

  

  M. 
  

  

  Greatest 
  length 
  . 
  -72 
  

  

  Width 
  taken 
  across 
  the 
  maxillo-premaxillar 
  suture.. 
  "138 
  

   Width 
  across 
  middle 
  of 
  vomer 
  . 
  -145 
  

  

  