﻿AND 
  AVES 
  OF 
  NORTH 
  AMERICA. 
  165 
  

  

  and 
  with 
  external 
  angles 
  less 
  than 
  a 
  right 
  angle. 
  It 
  marks 
  the 
  proximal 
  third 
  of 
  the 
  costal 
  hone. 
  The 
  posterior 
  is 
  

   truncate 
  behind; 
  the 
  pygal 
  is 
  considerably 
  longer 
  than 
  broad. 
  

  

  Proximal 
  halves 
  of 
  the 
  two 
  first 
  costals, 
  with 
  the 
  costal 
  crest 
  for 
  the 
  first 
  pair 
  of 
  ribs, 
  are 
  preserved. 
  The 
  suture 
  

   for 
  the 
  first 
  vertebral 
  hone 
  is 
  little 
  concave. 
  The 
  inter-vertebral 
  dermal 
  suture 
  crosses 
  it, 
  just 
  anterior 
  to 
  the 
  point 
  

   opposite 
  to 
  the 
  completed 
  capitulum 
  of 
  the 
  bone. 
  

  

  The 
  xiphisternal, 
  besides 
  being 
  much 
  thinner 
  relatively 
  than 
  that 
  of 
  Taphrosphys 
  molops, 
  is 
  of 
  different 
  form 
  ; 
  

   while 
  its 
  hyposternal 
  suture 
  forms 
  nearly 
  a 
  right 
  angle 
  with 
  the 
  common 
  suture; 
  in 
  the 
  latter 
  species, 
  an 
  acute 
  angle. 
  

   The 
  pubic 
  scar 
  in 
  P. 
  sulcatus 
  is 
  of 
  nearly 
  the 
  same 
  length, 
  but 
  much 
  narrower 
  and 
  less 
  elevated. 
  This 
  I 
  have 
  ob- 
  

   served 
  in 
  five 
  specimens. 
  The 
  posterior 
  lobe 
  of 
  the 
  sternum 
  is 
  deeply 
  emarginate. 
  The 
  pubic 
  scars 
  in 
  both 
  converge 
  

   slightly 
  anteriorly. 
  

  

  The 
  second 
  specimen, 
  above 
  mentioned, 
  furnishes 
  portions 
  of 
  marginal 
  bones 
  and 
  sternal 
  bridge. 
  The 
  latter 
  pre- 
  

   sented 
  an 
  obtuse 
  angle 
  between 
  the 
  lateral 
  and 
  inferior 
  planes. 
  It 
  also 
  possesses 
  the 
  mesosternal, 
  somewhat 
  broken. 
  

   Its 
  external 
  angle 
  is 
  considerably 
  more 
  than 
  right, 
  and 
  indicates 
  a 
  thin 
  bone 
  considerably 
  longer 
  than 
  wide, 
  and 
  more 
  

   like 
  that 
  of 
  P. 
  leslianus 
  than 
  any 
  other 
  species 
  of 
  the 
  genus. 
  

  

  Measurements 
  of 
  Spec. 
  No. 
  1. 
  

   Length 
  of 
  ante-penult 
  costal 
  bone, 
  

   Width 
  " 
  proximally, 
  

  

  " 
  " 
  distally, 
  

  

  " 
  penultimate 
  proximally, 
  

  

  " 
  posterior 
  vertebral, 
  

  

  ' 
  ' 
  posterior 
  costal 
  proximally, 
  

  

  " 
  " 
  distally, 
  

  

  Length 
  of 
  " 
  

  

  " 
  iliac 
  scar, 
  

  

  " 
  rudimental 
  costal, 
  

  

  " 
  caudal 
  marginal, 
  

  

  " 
  suture 
  between 
  posterior 
  pair 
  marginal 
  scutal, 
  

  

  Width 
  of 
  caudal 
  marginal, 
  

  

  This 
  is 
  a 
  species 
  of 
  considerable 
  size. 
  The 
  fragments 
  originally 
  described 
  by 
  Leidy 
  are 
  three 
  united 
  marginals 
  

   from 
  the 
  position 
  of 
  the 
  sternal 
  bridge. 
  They 
  show 
  that 
  these 
  elements 
  have 
  a 
  thin 
  junction 
  with 
  both 
  plastron 
  and 
  

   carapace, 
  and 
  are 
  not 
  separate 
  from 
  the 
  latter, 
  as 
  one 
  might 
  be 
  led 
  to 
  suppose. 
  

  

  The 
  marginals 
  near 
  the 
  bridge 
  have 
  a 
  flat 
  and 
  broad 
  inferior 
  surface, 
  and 
  are 
  produced 
  into 
  a 
  narrow 
  slightly 
  

   recurved 
  margin, 
  while 
  the 
  free 
  marginals 
  have 
  the 
  external 
  face 
  plane 
  — 
  not 
  recurved 
  — 
  and 
  the 
  internal 
  thickened 
  a 
  

   line 
  within 
  the 
  margin. 
  

  

  What 
  is 
  probably 
  a 
  nuchal 
  margin 
  (from 
  Barnesboro, 
  Professor 
  Cook's 
  Collection) 
  is 
  not 
  thickened 
  within, 
  and 
  

   has, 
  as 
  in 
  other 
  genera, 
  a 
  much 
  greater 
  transverse 
  extent 
  posteriorly 
  than 
  at 
  the 
  margin. 
  Its 
  form 
  is 
  as 
  follows 
  : 
  

   Length, 
  2 
  in., 
  81in.; 
  width, 
  2 
  in., 
  6.5 
  lin. 
  A 
  peculiarity 
  in 
  the 
  dermal 
  markings 
  is 
  

   that 
  there 
  is 
  no 
  nuchal 
  scutum, 
  but 
  a 
  suture 
  as 
  in 
  the 
  caudal 
  marginal 
  bone. 
  °' 
  

  

  Two 
  marginal 
  bones, 
  having 
  the 
  sculpture 
  characteristic 
  of 
  this 
  species, 
  appear 
  _r-"^T 
  "^ 
  -^ 
  

  

  to 
  be 
  referable 
  to 
  it 
  after 
  comparison 
  with 
  specimens 
  in 
  the 
  Museum 
  of 
  the 
  Academy. 
  J 
  \ 
  

  

  One, 
  a 
  median 
  posterior, 
  is 
  considerably 
  shorter 
  than 
  the 
  other, 
  probably 
  a 
  posterior 
  ( 
  \ 
  

  

  or 
  lateral, 
  a 
  peculiarity 
  not 
  seen 
  among 
  living 
  species. 
  The 
  latter 
  has 
  a 
  thin 
  edge, 
  V 
  

  

  is 
  thickened 
  along 
  the 
  line 
  of 
  the 
  lower 
  two-fifths 
  the 
  diameter, 
  and 
  then 
  thins 
  out 
  to 
  V^ 
  

  

  the 
  upper 
  suture, 
  which 
  is 
  only 
  1.5 
  hues 
  wide. 
  

  

  In. 
  Lin. 
  In. 
  Lin. 
  

  

  Width 
  of 
  lateral 
  plate, 
  3 
  0.5 
  Length 
  of 
  caudal, 
  2 
  7. 
  

  

  In. 
  

  

  Lin. 
  

  

  7 
  

  

  9. 
  

  

  

  20. 
  

  

  2 
  

  

  7. 
  

  

  

  15.5 
  

  

  

  14.5 
  

  

  

  13. 
  

  

  o 
  

  

  4. 
  

  

  4 
  

  

  9. 
  

  

  3 
  

  

  

  

  7. 
  

  

  2 
  

  

  10. 
  

  

  

  19. 
  

  

  2 
  

  

  7.5 
  

  

  Length 
  " 
  3 
  4.5 
  Width 
  2 
  8. 
  «- 
  - 
  / 
  

  

  These 
  plates 
  are 
  crossed 
  in 
  the 
  usual 
  manner 
  by 
  the 
  sutures 
  of 
  the 
  marginal 
  and 
  costal 
  scuta. 
  They 
  are 
  all 
  from 
  

   the 
  Birmingham 
  pits. 
  

  

  AMERI. 
  PHILO. 
  SOC. 
  — 
  VOL. 
  XIV 
  42 
  

  

  