﻿142 
  THE 
  EXTINCT 
  BATRACHIA, 
  HEPTILIA 
  

  

  The 
  humerus 
  is 
  curved 
  like 
  the 
  femur. 
  but 
  is 
  flatter 
  and 
  broader 
  as 
  compared 
  with 
  the 
  other 
  dimensions. 
  The 
  

   shank 
  is 
  flattened, 
  and 
  the 
  condyles 
  relatively 
  less 
  dilated 
  transversely 
  than 
  those 
  of 
  the 
  femur. 
  Inside 
  the 
  inner 
  

   distal 
  margin 
  is 
  a 
  deep 
  open 
  groove, 
  for 
  the 
  passage 
  of 
  the 
  humeral 
  artery. 
  The 
  coracoid 
  has 
  a 
  constricted 
  shaft 
  ; 
  

   its 
  clavicular 
  articular 
  face 
  is 
  short, 
  and 
  the 
  suture 
  smooth. 
  In 
  Trionyx, 
  the 
  latter 
  is 
  longer 
  ar.d 
  interlocking. 
  

  

  In. 
  

   Estimated 
  length 
  carapace, 
  2G 
  

  

  Estimated 
  width 
  " 
  24 
  

  

  The 
  following 
  characters 
  are 
  observed 
  in 
  the 
  Harrisonville 
  specimen 
  : 
  

  

  The 
  species 
  differs 
  from 
  the 
  Osteopyges 
  in 
  its 
  relatively 
  wider 
  posterior 
  marginal 
  plate, 
  with 
  very 
  indistinct 
  

   dermal 
  sutures 
  ; 
  though 
  the 
  surface 
  is 
  fully 
  preserved 
  and 
  the 
  vascular 
  grooves 
  distinct, 
  these 
  are 
  very 
  faint. 
  The 
  

   costal 
  pit 
  is 
  less 
  flattened, 
  and 
  the 
  inner 
  margins 
  of 
  the 
  plate 
  are 
  equal, 
  the 
  upper 
  being 
  less 
  prolonged. 
  .The 
  ante- 
  

   rior 
  marginal 
  differs 
  from 
  the 
  same 
  in 
  0. 
  emarginatus, 
  in 
  lacking 
  an 
  open 
  groove 
  within 
  the 
  lower 
  margin. 
  The 
  form 
  

   of 
  the 
  femur 
  has 
  been 
  noticed 
  in 
  the 
  remarks 
  on 
  the 
  genus. 
  It 
  is 
  considerably 
  curved, 
  and 
  with 
  a 
  slender 
  shaft. 
  

   The 
  inner 
  condyle 
  is 
  the 
  larger, 
  and 
  within 
  it 
  is 
  a 
  compressed 
  longitudinal 
  ridge. 
  Surface 
  striate 
  with 
  small 
  ridges. 
  

  

  Edge 
  of 
  the 
  posterior 
  marginal 
  bone 
  slightly 
  recurved. 
  

  

  Length 
  eighth 
  marginal, 
  

  

  Width 
  " 
  •' 
  

  

  Depth 
  " 
  " 
  at 
  rib 
  pit, 
  

  

  " 
  last 
  anter. 
  marginal 
  with 
  rib 
  at 
  margin, 
  

   "Width 
  condyles 
  femur, 
  

   Diameter 
  shaft 
  near 
  middle, 
  

   Length 
  phalange, 
  

  

  The 
  Euclastes 
  platyops, 
  Oopc 
  r 
  is 
  only 
  known~from 
  a 
  cranium 
  found 
  in 
  the 
  same 
  limestone. 
  The 
  present 
  species 
  

   bears 
  some 
  nearer 
  relation 
  to 
  that 
  in 
  dimensions 
  than 
  any 
  known. 
  

  

  A 
  very 
  large 
  specimen 
  of 
  this 
  species 
  was 
  presented 
  to 
  the 
  author 
  by 
  John 
  Miers, 
  who 
  procured 
  it 
  from 
  his 
  pit 
  near 
  

   Hornerstown, 
  from 
  the 
  upper 
  cretaceous 
  green 
  sand. 
  Its 
  dimensions 
  exceed 
  those 
  of 
  any 
  of 
  the 
  other 
  Chelydrinae. 
  

   yet 
  they 
  present 
  the 
  incomplete 
  ^extension 
  of 
  the 
  union 
  of 
  the 
  marginal 
  and 
  carapacial 
  bones 
  characteristic 
  of 
  the 
  

   genus. 
  

  

  Length 
  of 
  ninth 
  marginal 
  

  

  Width, 
  

  

  Depth 
  (medially 
  within), 
  

  

  Length 
  tenth 
  marginal, 
  

  

  Width, 
  

  

  These 
  marginals 
  are 
  opened 
  by 
  1. 
  1, 
  c. 
  marginatc 
  at 
  the 
  end 
  of 
  the 
  inter-marginal 
  Ecutal 
  sutures. 
  The 
  measure- 
  

   ments 
  of 
  the 
  proximal 
  extremity 
  of 
  the 
  humerus 
  give 
  further 
  indication 
  of 
  its 
  proportions. 
  

  

  In. 
  I. 
  in. 
  

  

  Length 
  of 
  the 
  condyle 
  and 
  deltoid 
  ridge, 
  ~ 
  9 
  

  

  " 
  " 
  " 
  alone, 
  1 
  4.5 
  

  

  " 
  " 
  postero-interior 
  crest, 
  1 
  

  

  In. 
  

  

  Lin. 
  

  

  3 
  

  

  7.5 
  

  

  3 
  

  

  1.5 
  

  

  

  11.5 
  

  

  

  9.5 
  

  

  1 
  

  

  97 
  

  

  

  8.5 
  

  

  1 
  

  

  1 
  

  

  In. 
  

  

  Lin 
  

  

  4 
  

  

  4 
  

  

  o 
  

   O 
  

  

  6 
  

  

  1 
  

  

  2 
  

  

  4 
  

  

  1 
  

  

  4 
  

  

  1 
  

  

  