﻿274 
  Dr. 
  G. 
  Baur 
  on 
  " 
  Aulacochelys," 
  Lydekker, 
  &c. 
  

  

  steroidal. 
  I 
  now 
  give 
  a 
  more 
  detailed 
  account 
  of 
  my 
  reasons. 
  

   When 
  Prof. 
  Leidy 
  * 
  gave 
  the 
  first 
  notice 
  of 
  this 
  interesting 
  

   fossil 
  he 
  said 
  : 
  — 
  " 
  None 
  of 
  the 
  plates 
  exhibit 
  scute 
  impres- 
  

   sions, 
  generally 
  so 
  evident 
  in 
  the 
  Emydes." 
  But 
  in 
  his 
  full 
  

   description 
  he 
  states 
  f 
  : 
  — 
  " 
  A 
  few 
  of 
  the 
  plates 
  exhibit 
  obscure 
  

   lines, 
  but 
  I 
  am 
  uncertain 
  as 
  to 
  whether 
  they 
  accord 
  with 
  the 
  

   areas 
  of 
  the 
  scutes." 
  

  

  Prof. 
  Leidy 
  does 
  not 
  give 
  to 
  Anosteira 
  a 
  definite 
  position 
  in 
  

   the 
  system. 
  Prof. 
  Cope 
  % 
  places 
  the 
  form 
  among 
  the 
  Chely- 
  

   dridae, 
  and 
  observes 
  : 
  — 
  " 
  This 
  genus 
  must 
  be 
  regarded 
  as 
  an 
  

   interesting 
  intermediate 
  type 
  connecting 
  Pleistomenus 
  and 
  

   Chelydra 
  or 
  Dermatemys. 
  In 
  skin 
  and 
  sculpture 
  it 
  is 
  iden- 
  

   tical 
  with 
  the 
  first, 
  in 
  carapace 
  and 
  plastron 
  most 
  like 
  

   Chelydra'' 
  1 
  (p. 
  127). 
  This 
  view 
  is 
  adopted 
  by 
  Dollo 
  §, 
  who 
  

   places 
  Anosteira 
  together 
  with 
  his 
  Pseudotrionyx 
  among 
  the 
  

   Chelydridse. 
  

  

  Lydekker, 
  in 
  some 
  notes 
  on 
  this 
  paper, 
  held 
  the 
  opinion 
  that 
  

   Pseudotrionyx 
  might 
  perhaps 
  be 
  referred 
  to 
  the 
  Trionychidse 
  

   (Geol. 
  Mag. 
  1886, 
  p. 
  521) 
  ; 
  but 
  this 
  view 
  was 
  abandoned 
  in 
  

   1887, 
  when 
  Boulenger 
  and 
  Lydekker|| 
  declared 
  that 
  it 
  may 
  pro- 
  

   bably 
  be 
  regarded 
  as 
  belonging 
  to 
  a 
  distinct 
  family 
  from 
  the 
  

   absence 
  of 
  epidermal 
  shields. 
  This 
  family 
  was 
  called 
  the 
  

   Pseudotrionychidas 
  by 
  Boulenger 
  ^j, 
  containing 
  Pseudotrionyx 
  

   and 
  Anosteira^ 
  and 
  placed 
  near 
  the 
  Cinosternida3. 
  

  

  The 
  absence 
  of 
  dermal 
  scutes 
  seems 
  to 
  be 
  generally 
  ad- 
  

   mitted. 
  But 
  in 
  fact 
  they 
  are 
  not 
  entirely 
  missing. 
  The 
  

   marks 
  observed 
  by 
  Leidy 
  are 
  really 
  marks 
  produced 
  by 
  the 
  

   impression 
  of 
  scutes. 
  They 
  are 
  well 
  shown 
  at 
  the 
  posterior 
  

   peripheralia 
  (marginals), 
  and 
  especially 
  on 
  the 
  pygal, 
  in 
  a 
  

   specimen 
  of 
  Anosteira 
  ornata, 
  Leidy, 
  in 
  the 
  Yale 
  College 
  

   Museum. 
  I 
  could 
  not 
  find 
  any 
  marks 
  on 
  the 
  plastron 
  ; 
  but 
  

   it 
  seems 
  probable 
  that 
  scutes 
  existed 
  all 
  over 
  the 
  shell. 
  The 
  

   impressions 
  on 
  the 
  plastron 
  of 
  the 
  Cinosternidas, 
  particularly 
  

   in 
  Monochelys 
  odorata, 
  are 
  already 
  insignificant. 
  

  

  I 
  have 
  shown 
  (Osteol. 
  Notizen 
  iiber 
  Ileptilien, 
  Fortsetzung 
  

   vi.) 
  that 
  the 
  Staurotypidas 
  and 
  Cinosternidee 
  are 
  the 
  only 
  

   known 
  living 
  Testudinata 
  which 
  have 
  ten 
  peripheralia, 
  eight 
  

  

  * 
  Proc. 
  Ac. 
  Nat. 
  Sci. 
  Philad. 
  1871, 
  pp. 
  102, 
  103. 
  

  

  t 
  Leidy, 
  Joseph, 
  ' 
  Contributions 
  to 
  the 
  Extinct 
  Vertebrate 
  Fauna 
  of 
  

   the 
  Western 
  Territories,' 
  Washington, 
  1873, 
  p. 
  17o. 
  

  

  X 
  Cope, 
  E. 
  D., 
  'The 
  Vertebrata 
  of 
  the 
  Tertiary, 
  &c.,' 
  p. 
  112. 
  

  

  § 
  Dollo, 
  L., 
  " 
  Premiere 
  note 
  sur 
  les 
  Cheloniens 
  du 
  Bruxellien 
  (Eocene 
  

   Moven) 
  de 
  la 
  Belgique," 
  Bull. 
  JMus. 
  Roy. 
  Hist. 
  Nat. 
  Belg. 
  tome 
  iv. 
  1«86, 
  

   p. 
  96, 
  

  

  || 
  Lydekker, 
  R., 
  and 
  G. 
  A. 
  Boulenger, 
  " 
  Notes 
  on 
  Chelonia 
  from 
  the 
  

   Purbeck, 
  Wealden, 
  and 
  London 
  Clay," 
  Geol. 
  Mag. 
  June 
  1887, 
  p. 
  274. 
  

  

  % 
  ' 
  Encyclopaedia 
  Brhannica,' 
  9th 
  ed. 
  vol. 
  xxiii. 
  1888, 
  p. 
  457. 
  

  

  