﻿AND 
  AVES 
  OF 
  NORTH 
  AMERICA. 
  233 
  

  

  the 
  contracted 
  entire 
  xiphisternal 
  elements 
  pointed 
  out 
  by 
  Leidy, 
  arc 
  quite 
  like 
  those 
  of 
  A. 
  beatus, 
  to 
  which 
  it 
  is 
  

   indeed 
  very 
  nearly 
  allied. 
  

  

  The 
  narrowed 
  form 
  of 
  the 
  posterior 
  lobe 
  is 
  best 
  seen 
  in 
  the 
  specimen 
  of 
  A. 
  vyomingensis 
  described 
  by 
  Leidy, 
  and 
  

   in 
  a 
  specimen 
  of 
  A. 
  beatus, 
  noticed 
  by 
  me 
  in 
  Synopsis 
  Batr. 
  Rept. 
  N. 
  A., 
  p. 
  129. 
  I 
  there 
  state 
  that 
  it 
  is 
  emarginate, 
  

   an 
  error 
  consequent 
  on 
  a 
  certain 
  assymetry 
  of 
  the 
  specimen, 
  and 
  its 
  fractured 
  condition. 
  In 
  A. 
  agilis 
  it 
  is 
  apparently 
  

   rather 
  better 
  developed. 
  

  

  The 
  form 
  of 
  the 
  anterior 
  lobe 
  is 
  easily 
  seen 
  to 
  be 
  narrow 
  by 
  reference 
  to 
  my 
  figure 
  of 
  A. 
  pectoralis 
  (Syn. 
  Bat. 
  

   Rept., 
  N. 
  A., 
  Tab. 
  VII, 
  fig. 
  1,) 
  or 
  Leidy's 
  figure 
  of 
  A. 
  prauus, 
  Cretac. 
  Rept. 
  N. 
  Am. 
  XIX, 
  fig. 
  1. 
  In 
  the 
  nearly 
  

   perfect 
  specimen 
  of 
  A. 
  vyomingensis, 
  this 
  portion 
  is 
  broken 
  away, 
  but 
  Leidy 
  describes 
  this 
  portion 
  of 
  a 
  specimen 
  

   which 
  has 
  the 
  character 
  of 
  the 
  above 
  species. 
  

  

  The 
  species 
  differ 
  much 
  in 
  the 
  relative 
  stoutness 
  of 
  their 
  shell, 
  especially 
  of 
  the 
  plastron. 
  A. 
  pectoralis 
  is 
  the 
  

   stoutest 
  as 
  well 
  as 
  the 
  smallest; 
  A. 
  pravus 
  and 
  A. 
  agilis 
  are 
  the 
  thinnest, 
  the 
  latter 
  the 
  largest 
  of 
  the 
  genus. 
  No 
  

   portions 
  can 
  be 
  certainly 
  ascribed 
  to 
  the 
  crania 
  of 
  this 
  genus. 
  

  

  In 
  specimens 
  of 
  A. 
  agilis, 
  A. 
  pravus 
  and 
  A. 
  beatus, 
  the 
  longitudinal 
  median 
  suture 
  of 
  the 
  plastron 
  presents 
  

   much 
  irregularity 
  from 
  the 
  union 
  of 
  the 
  alternating 
  bones 
  across 
  the 
  point 
  of 
  meeting 
  of 
  four, 
  by 
  an 
  oblique 
  portion 
  

   of 
  the 
  suture. 
  

  

  Thickness 
  of 
  hyosternals 
  less 
  than 
  four 
  lines 
  in 
  the 
  transverse 
  extent 
  of 
  same; 
  intermarginals 
  short; 
  mesosterna 
  

   prolonged 
  posteriorly, 
  smooth 
  below; 
  small. 
  A. 
  pectoralis. 
  

  

  Thickness 
  of 
  hyosternals 
  one-eighth 
  transverse 
  extent 
  of 
  same; 
  above 
  with 
  sightly 
  impressed 
  dots 
  or 
  delicate 
  

   grooves, 
  closely 
  placed; 
  larger, 
  vertebral 
  bones 
  wider. 
  A. 
  beatus. 
  

  

  Sternum 
  thick; 
  vertebral 
  bones 
  narrower; 
  carapace 
  more 
  coarsely 
  longitudinally 
  impressed 
  grooved; 
  mesosternum 
  

   deeply 
  received; 
  lateral 
  intermarginals 
  elongate. 
  A. 
  vyomingensis. 
  

  

  Plastron 
  quite 
  thin; 
  mesosternal 
  deeply 
  received 
  in 
  the 
  hyosternals. 
  A. 
  pravus. 
  

  

  Plastron 
  quite 
  thin; 
  mesosternal 
  occupying 
  an 
  open 
  concavity 
  of 
  the 
  hyosternals; 
  surface 
  everywhere 
  delicately 
  

   impressed 
  punctate 
  and 
  grooved; 
  intermarginal 
  scuta 
  very 
  long 
  .and 
  narrow. 
  A. 
  agilis. 
  

  

  Adocus 
  pectoralis, 
  Cope. 
  

  

  Pleurostemum 
  pectorale, 
  Cope, 
  Proc. 
  Ac. 
  Nat. 
  Sci. 
  Phila., 
  1868, 
  236; 
  Trans. 
  Amer 
  Philos. 
  Soc. 
  XIV, 
  1869, 
  130, 
  Tab. 
  

  

  VII. 
  fig. 
  1. 
  

  

  Indicated 
  by 
  a 
  pair 
  of 
  perfect 
  hyosternal 
  bones 
  from 
  the 
  upper 
  Cretaceous 
  marl 
  bed, 
  near 
  Medford, 
  Burlington 
  

   Co., 
  N. 
  J. 
  

  

  Adocus 
  beatus, 
  Leidy. 
  

  

  Ernys 
  beatus, 
  Leidy. 
  Cretaceous 
  Reptiles. 
  N. 
  Amer. 
  p. 
  107, 
  Tab. 
  XVIII, 
  fig. 
  1-3. 
  Adocus 
  beatus, 
  Cope, 
  Proc. 
  A. 
  

  

  N. 
  S., 
  Phila., 
  1868, 
  235. 
  Geological 
  Survey, 
  N. 
  Jersey, 
  App. 
  C, 
  p. 
  174. 
  

  

  Not 
  uncommon. 
  It 
  is 
  considerably 
  less 
  stout 
  than 
  the 
  preceding. 
  The 
  edges 
  of 
  the 
  posterior 
  lobe 
  of 
  the 
  plastron 
  

   are 
  thinned 
  out 
  by 
  a 
  submarginal 
  groove. 
  As 
  in 
  other 
  Emydoids 
  there 
  is 
  a 
  marked 
  concavity 
  for 
  each 
  pubic 
  bone. 
  

   The 
  suture 
  between 
  the 
  hyo- 
  and 
  hypostemal 
  bones 
  is 
  less 
  interlocking 
  than 
  in 
  A. 
  agilis, 
  and 
  less 
  fine 
  than 
  in 
  A. 
  pec- 
  

   toralis. 
  I 
  have 
  suggested 
  that 
  it 
  may 
  have 
  possessed 
  a 
  slight 
  mobility 
  in 
  life. 
  Its 
  face 
  is 
  longitudinally 
  grooved 
  in 
  

   the 
  hyposternal, 
  and 
  a 
  corresponding 
  convexity 
  of 
  the 
  face 
  of 
  the 
  hyosternal 
  fits 
  it. 
  In 
  a 
  specimen 
  from 
  Medford, 
  

   N. 
  J., 
  the 
  posterior 
  lobe 
  is 
  5 
  in. 
  9 
  lin. 
  long, 
  and 
  5 
  in. 
  8 
  lin. 
  wide 
  at 
  the 
  marginal 
  notches. 
  Hyosternal 
  of 
  nearly 
  equal 
  

   thickness, 
  medially 
  7 
  lines. 
  

  

  Adocus 
  vyomingensis, 
  Leidy. 
  

  

  Ernys 
  vyomingensis, 
  Leidy, 
  Proc. 
  Ac. 
  Nat. 
  Sci. 
  Phila., 
  1869, 
  p. 
  66. 
  Baptemys 
  vyomingensis, 
  Leidy, 
  loc. 
  cit. 
  1870, 
  

  

  January. 
  

  

  Best 
  known 
  from 
  an 
  almost 
  complete 
  specimen 
  consolidated 
  by 
  the 
  contained 
  mass 
  of 
  mineral. 
  There 
  are 
  three 
  

   intermarginal 
  bones, 
  of 
  which 
  the 
  middle 
  one 
  is 
  more 
  elongate 
  than 
  the 
  others. 
  There 
  is 
  a 
  weak 
  carina 
  on 
  some 
  of 
  the 
  

   AMERI. 
  PHILO. 
  SOC. 
  — 
  VOL. 
  XIV. 
  — 
  59. 
  

  

  