﻿250 
  G. 
  R. 
  Wieland 
  — 
  Huge 
  Cretaceous 
  Turtles. 
  

  

  With 
  increasing 
  knowledge 
  of 
  Protostega 
  and 
  its 
  allies, 
  that 
  

   most 
  interesting 
  of 
  questions 
  pertaining 
  to 
  the 
  Testudinata, 
  

   the 
  origin 
  of 
  Dermochelys, 
  remains 
  quite 
  as 
  enigmatic 
  as 
  

   ever. 
  Hence 
  only 
  the 
  following 
  tentative 
  classification 
  can 
  

   now 
  be 
  presented, 
  the 
  writer 
  hoping 
  to 
  again 
  attack 
  the 
  

   general 
  subject 
  at 
  a 
  future 
  time. 
  

  

  Family— 
  Pjrotostegedje 
  Cope. 
  

   Genera 
  — 
  Protostega 
  and 
  Archelon. 
  

  

  j 
  Doubtfully 
  belonging 
  to 
  the 
  Protostegidw, 
  Protosphargis 
  Vero- 
  

   nensis 
  Capellini 
  (3, 
  4), 
  and 
  still 
  more 
  doubtfully 
  Pseudosphargis 
  

   ingens 
  von 
  Konen 
  and 
  Dames 
  (8).} 
  

  

  Synopsis 
  of 
  Characters 
  of 
  the 
  Protostegidce. 
  

  

  Marine 
  turtles 
  with 
  carapace 
  of 
  medium 
  curvature. 
  Neu- 
  

   ralia 
  and 
  pleuralia 
  thin 
  and 
  investing 
  the 
  ribs 
  but 
  slightly. 
  

   Marginalia 
  usually 
  spiniferous 
  on 
  interior 
  borders. 
  Plastral 
  

   elements 
  of 
  medium 
  development 
  with 
  numerous 
  digitations. 
  

   Normal 
  epiplastron 
  unknown, 
  the 
  three 
  anterior 
  plastral 
  ele- 
  

   ments 
  probably 
  uniting 
  into 
  an 
  entepi- 
  or 
  paraplastron. 
  Body 
  

   enveloped 
  in 
  a 
  leathery 
  hide? 
  Skull 
  intermediate 
  between 
  

   that 
  of 
  the 
  Dermochelyidw 
  and 
  the 
  Cheloniidce. 
  

  

  Genus 
  Protostega 
  Cope. 
  — 
  Squamoso-jugal 
  union 
  probable. 
  

   Quadrato-jugal 
  triangular. 
  Mandibular 
  rami 
  coossiiied. 
  Radial 
  

   process 
  of 
  humerus 
  strong. 
  Carpals 
  and 
  tarsals 
  unknown. 
  

   Complete 
  outline 
  of 
  obturator 
  foramen 
  unknown. 
  — 
  Only 
  

   species 
  P. 
  gigas 
  from 
  the 
  Niobrara 
  Cretaceous 
  of 
  Kansas. 
  

  

  Genus 
  Archelon 
  Wieland. 
  — 
  Quadrato-jugal 
  strongly 
  united 
  

   with 
  the 
  postfrontai, 
  and 
  of 
  crescentic 
  outline. 
  Mandibular 
  

   symphysis 
  remaining 
  distinct. 
  Radial 
  process 
  of 
  humerus 
  

   weak, 
  ectepicondyle 
  strong. 
  Carpals 
  and 
  tarsals 
  undescribed. 
  

   Obturator 
  foramen 
  small 
  elliptical 
  and 
  enclosed. 
  — 
  Type 
  of 
  the 
  

   genus, 
  A. 
  ischyros 
  Wieland. 
  Second 
  species, 
  A. 
  Marshii 
  

   Wieland. 
  Humerus 
  straight 
  and 
  robust. 
  Plastron 
  unusually 
  

   heavy. 
  Both 
  species 
  from 
  the 
  Upper 
  Fort 
  Pierre 
  Cretaceous 
  

   of 
  South 
  Dakota. 
  

  

  References 
  to 
  Literature. 
  

  

  1. 
  Baur, 
  G. 
  — 
  Die 
  Systematische 
  Stellung 
  von 
  Dermochelys 
  

   Blainville. 
  Biologische 
  Centralblatt, 
  Band 
  ix, 
  Nos. 
  

   5 
  and 
  6, 
  with 
  Nachtragliche 
  Bemerkung 
  in 
  No. 
  20 
  

   and 
  21, 
  p. 
  617-620. 
  Erlangen, 
  1889. 
  

  

  Ueber 
  die 
  Morphologie 
  des 
  Unterkiefers 
  der 
  Rep- 
  

   tilien. 
  Anatomischer 
  Anzeiger, 
  Band 
  xi, 
  No. 
  13. 
  

   (Nachtrag, 
  Band 
  xi, 
  p. 
  569). 
  Leipsic, 
  1895. 
  

  

  