﻿AND 
  AYES 
  OF 
  NORTH 
  AMERICA 
  

  

  83 
  

  

  APPENDIX 
  TO 
  THE 
  CROCODILIA. 
  

  

  PEROSUCHTTS, 
  Cope. 
  

   Proc. 
  Acad. 
  N. 
  Sci., 
  PMla., 
  18G8, 
  p. 
  203. 
  

  

  Characters. 
  — 
  Toes 
  5 
  — 
  4, 
  with 
  claws 
  two- 
  three. 
  No 
  osseous 
  nasal 
  septum 
  or 
  bony 
  eyelid. 
  Belly 
  protected 
  by 
  

   series 
  of 
  osseous 
  plates, 
  as 
  well 
  as 
  the 
  back. 
  

  

  All 
  the 
  genera 
  of 
  Crocodiles 
  hitherto 
  known 
  as 
  living, 
  are 
  characterized 
  by 
  the 
  possession 
  of 
  three 
  claws 
  on 
  

   the 
  fore-foot. 
  The 
  present 
  therefore 
  offers 
  a 
  remarkable 
  exception. 
  The 
  free 
  fingers 
  and 
  half 
  webbed 
  toes, 
  and 
  the 
  

   bony 
  abdominal 
  buckler, 
  together 
  with 
  the 
  cartilaginous 
  nasal 
  septum, 
  are 
  points 
  of 
  strong 
  resemblance 
  to 
  Jacare 
  

   (Gray 
  including 
  Caeman 
  Gray) 
  but 
  it 
  differs 
  from 
  these 
  creatures 
  in 
  the 
  lack 
  of 
  bony 
  orbit. 
  In 
  specific 
  characters 
  it 
  

   differs 
  from 
  those 
  of 
  this 
  genus 
  which 
  it 
  most 
  resembles 
  — 
  as 
  J. 
  nigra, 
  in 
  the 
  absence 
  of 
  a 
  transverse 
  bony 
  ridge 
  

   between 
  the 
  orbits. 
  Another 
  feature 
  of 
  importance 
  is 
  the 
  relation 
  of 
  the 
  canine 
  teeth 
  of 
  the 
  lower 
  jaw 
  to 
  the 
  upper. 
  

   On 
  one 
  side 
  this 
  tooth 
  is 
  received 
  into 
  a 
  notch 
  as 
  in 
  Crocodiles, 
  on 
  the 
  others, 
  it 
  enters 
  a 
  pit 
  of 
  the 
  maxillary 
  bone, 
  

   within 
  the 
  border 
  of 
  the 
  same 
  as 
  in 
  Alligators 
  ! 
  This 
  remarkable 
  combination 
  may 
  be 
  abnormal 
  even 
  in 
  this 
  species, 
  

   but 
  this 
  cannot 
  be 
  now 
  ascertained, 
  as 
  it 
  rests 
  at 
  the 
  present 
  time 
  on 
  a 
  single 
  specimen 
  only. 
  As 
  its 
  affinities 
  are 
  

   rather 
  more 
  Alligatorial, 
  I 
  am 
  disposed 
  to 
  anticipate 
  that 
  the 
  dental 
  arrangement 
  of 
  the 
  latter 
  animals 
  will 
  be 
  most 
  

   common. 
  

  

  Fig. 
  21. 
  

  

  Fiff. 
  23. 
  

  

  Fif. 
  22. 
  

  

  Fig. 
  24. 
  

  

  PEROSUCHTJS 
  FUSCUS, 
  Cope. 
  

  

  Char, 
  specificus. 
  — 
  Nuchal 
  plates 
  in 
  a 
  cross 
  row 
  of 
  six 
  ; 
  cervicals 
  in 
  four 
  cross-rows, 
  all 
  of 
  four 
  plates 
  except 
  the 
  

   last 
  of 
  two. 
  Dorsal 
  plates 
  in 
  six 
  — 
  in 
  a 
  few 
  eight 
  in 
  each 
  transverse 
  row. 
  No 
  posterior 
  crest 
  on 
  arm 
  or 
  leg. 
  Tail 
  

   short 
  with 
  remarkably 
  low 
  crest. 
  Muzzle 
  broad 
  flat, 
  without 
  any 
  ridges 
  ; 
  its 
  width 
  at 
  the 
  eighth 
  tooth 
  entering 
  1.4 
  

   in 
  length 
  from 
  end 
  muzzle 
  to 
  anterior 
  margin 
  of 
  orbit. 
  

  

  Description. 
  — 
  The 
  specimen 
  in 
  the 
  Museum 
  of 
  the 
  Academy 
  is 
  young, 
  measuring 
  only 
  2 
  feet 
  5 
  inches 
  in 
  length. 
  

   Of 
  this 
  the 
  skull 
  measures 
  to 
  the 
  margin 
  of 
  the 
  supra-occipital 
  2 
  in. 
  10.5 
  lilies 
  ; 
  and 
  the 
  tail 
  to 
  the 
  vent 
  13 
  in. 
  7 
  lin. 
  

   From 
  groin 
  to 
  heel 
  3 
  in. 
  2.5 
  lin., 
  and 
  the 
  hind 
  foot 
  3 
  in. 
  7.5 
  lin. 
  The 
  muzzle 
  is 
  a 
  broad 
  ovate, 
  the 
  sides 
  rather 
  more 
  

   convergent 
  anteriorly 
  than 
  in 
  the 
  Alligator 
  mississippitnsis. 
  There 
  is 
  a 
  thickening 
  in 
  front 
  of 
  each 
  orbit, 
  and 
  

  

  