﻿Dr. 
  G. 
  Baur 
  on 
  " 
  Aulacochelys, 
  Lydekker, 
  &c. 
  275 
  

  

  of 
  which 
  (three 
  to 
  ten) 
  are 
  connected 
  with 
  the 
  ends 
  of 
  the 
  ribs. 
  

   We 
  find 
  the 
  same 
  in 
  Anosteira 
  and 
  Pseudotrionyx. 
  In 
  all 
  the 
  

   Staurqtypidae 
  and 
  Cinosternidse 
  one 
  or 
  more 
  of 
  the 
  posterior 
  

   neurals 
  are 
  absent, 
  and 
  in 
  all 
  only 
  one 
  postneural 
  is 
  developed. 
  

   In 
  Anosteira 
  and 
  Pseudotrionyx 
  there 
  are 
  only 
  seven 
  neurals 
  

   and 
  one 
  postneural. 
  

  

  The 
  form 
  >f 
  the 
  xiphiplastron 
  in 
  Anosteira 
  is 
  like 
  that 
  of 
  

   the 
  Cinosternidas 
  (especially 
  Monochelys) 
  ; 
  but 
  whether 
  the 
  

   endoplastron 
  vths 
  present 
  or 
  not 
  is 
  still 
  a 
  question. 
  The 
  

   Staurotypidae 
  have 
  this 
  element; 
  in 
  the 
  Cinosternidas 
  it 
  is 
  

   missing. 
  Prof. 
  Cope 
  * 
  observes 
  that 
  in 
  Staurotypus 
  the 
  endo- 
  

   plastron 
  (mesoplastron, 
  Cope) 
  is 
  missing. 
  

  

  But 
  after 
  examination 
  of 
  Prof. 
  Cope's 
  originals 
  I 
  find 
  that 
  

   there 
  is 
  a 
  well-developed 
  endoplastron, 
  as 
  mentioned 
  by 
  

   Giinther 
  and 
  Boulenger. 
  Le 
  Conte 
  f 
  has 
  stated 
  that 
  a 
  rudi- 
  

   ment 
  of 
  the 
  endoplastron 
  is 
  present 
  in 
  the 
  young 
  Cinoster- 
  

   nidaa. 
  I 
  find 
  in 
  specimens 
  of 
  Monochelys 
  odorata 
  and 
  Cino- 
  

   sternum 
  pennsylvanicum 
  (length 
  of 
  plastron 
  15 
  millim.), 
  

   which 
  I 
  owe 
  to 
  the 
  kindness 
  of 
  Prof. 
  A. 
  Agassiz, 
  no 
  trace 
  of 
  

   an 
  endoplastron. 
  The 
  epiplastra 
  are 
  separated 
  from 
  the 
  

   hyoplastra 
  in 
  the 
  median 
  line, 
  the 
  xiphiplastra 
  from 
  the 
  

   hypoplasia, 
  forming 
  two 
  considerable 
  fontanelles. 
  

  

  Hyo- 
  and 
  hypoplastic 
  are 
  suturally 
  united, 
  without 
  any 
  

   fontanelle 
  in 
  the 
  middle. 
  

  

  The 
  plastron 
  of 
  the 
  Cinosternidae 
  and 
  probably 
  the 
  Stauro- 
  

   typidse 
  develops 
  in 
  a 
  way 
  totally 
  different 
  from 
  the 
  other 
  

   Testudinata, 
  so 
  far 
  as 
  I 
  am 
  aware. 
  We 
  always 
  find 
  in 
  them 
  

   a 
  median 
  fontanelle 
  in 
  the 
  young 
  animal. 
  Until 
  it 
  is 
  ascer- 
  

   tained 
  whether 
  Anosteira 
  and 
  Pseudotrionyx 
  have 
  an 
  endo- 
  

   plastron 
  or 
  not, 
  it 
  is 
  impossible 
  to 
  determine 
  the 
  correct 
  

   systematic 
  position. 
  Undoubtedly 
  these 
  forms 
  are 
  very 
  near 
  

   to 
  the 
  families 
  mentioned. 
  

  

  It 
  is 
  probable 
  that 
  the 
  nuchal 
  had 
  well- 
  developed 
  lateral 
  

   processes 
  ; 
  I 
  find 
  a 
  gioove 
  for 
  such 
  a 
  process 
  on 
  the 
  second 
  

   peripheral, 
  but 
  none 
  on 
  the 
  first. 
  I 
  have 
  not 
  seen, 
  however, 
  

   a 
  complete 
  nuchal. 
  In 
  Pseudotrionyx 
  there 
  is 
  no 
  trace 
  of 
  a 
  

   protuberance 
  on 
  the 
  eighth 
  pleural 
  (fig. 
  of 
  Dollo). 
  This 
  is 
  

   present 
  in 
  the 
  Cinosternidee, 
  where 
  the 
  ilium 
  is 
  connected; 
  I 
  

   do 
  not 
  know 
  how 
  the 
  Staurotypidse 
  are 
  in 
  this 
  regard, 
  having 
  

   no 
  skeleton 
  before 
  me 
  now. 
  Until 
  the 
  endoplastron-question 
  

  

  * 
  Cope, 
  E. 
  D., 
  " 
  Catalogue 
  of 
  Batrachians 
  and 
  Reptiles 
  of 
  Central 
  

   America 
  and 
  Mexico," 
  Bull. 
  Un. 
  Stat. 
  Nat. 
  Mus. 
  no. 
  82, 
  Washington, 
  

   1887, 
  p. 
  23. 
  

  

  t 
  Le 
  Conte, 
  John, 
  " 
  Description 
  of 
  four 
  new 
  Species 
  of 
  Kinosfernon," 
  

   Proc. 
  Acad. 
  Nat. 
  Sci. 
  Philad. 
  vol. 
  vii. 
  1854-55 
  : 
  Philadelphia, 
  185(3, 
  

   p. 
  18(3. 
  

  

  