﻿106 
  THE 
  EXTINCT 
  BATRACHIA, 
  REPTILIA 
  

  

  A 
  reasonable 
  inference 
  is 
  that 
  they 
  were 
  continuous, 
  and 
  I 
  have 
  taken 
  this 
  view. 
  (Proc. 
  Acad. 
  , 
  1 
  866, 
  p. 
  316.; 
  There 
  is 
  

   however 
  an 
  objection 
  to 
  this 
  position. 
  One 
  is 
  that 
  the 
  astragalus 
  does 
  not 
  extend 
  across 
  the 
  entire 
  end 
  of 
  the 
  tibia, 
  

   and 
  presents 
  a 
  smooth 
  surface, 
  perhaps 
  an 
  articular, 
  at 
  its 
  outer 
  extremity. 
  This 
  must 
  have 
  been 
  in 
  contact 
  with 
  a 
  

   small 
  astragalus 
  or 
  with 
  a 
  malleolar 
  extremity 
  of 
  the 
  fibula. 
  The 
  thin 
  external 
  expansion 
  of 
  the 
  tibia 
  could 
  support 
  

   but 
  little 
  weight, 
  and 
  as 
  the 
  condyloid 
  convexities 
  of 
  the 
  astragaloid 
  piece 
  are 
  nearly 
  equal, 
  there 
  would 
  seem 
  to 
  be 
  

   little 
  need 
  of 
  additional 
  condyloid 
  face. 
  Should 
  however 
  the 
  fibula 
  have 
  descended 
  to 
  this 
  point, 
  its 
  course 
  must 
  

   necessarily 
  have 
  been 
  alongside 
  the 
  ascending 
  process 
  of 
  the 
  astragalus, 
  but 
  not 
  in 
  contact 
  with 
  it. 
  There 
  is 
  no 
  trace 
  

   of 
  such 
  contact, 
  as 
  the 
  process 
  presents 
  externally 
  an 
  obliquely 
  rounded 
  surface, 
  ending 
  in 
  an 
  angular 
  margin 
  with 
  

   a 
  posterior 
  flattened 
  face. 
  

  

  Two 
  other 
  examples 
  only 
  of 
  this 
  structure 
  are 
  known 
  in 
  the 
  vertebrata, 
  one 
  of 
  which 
  I 
  find 
  mentioned 
  in 
  Cuvier 
  

   Ossemens 
  Fossiles, 
  X, 
  p. 
  204, 
  Tab. 
  249, 
  fig. 
  34-5. 
  This 
  author 
  studied 
  the 
  distal 
  extremity 
  of 
  a 
  tibia 
  with 
  applied 
  

   condyloid 
  astragalus, 
  from 
  Honfleur, 
  which 
  he 
  was 
  not 
  able 
  to 
  assign 
  to 
  any 
  known 
  species 
  or 
  genus, 
  but 
  which 
  he, 
  

   with 
  usual 
  sagacity, 
  includes 
  in 
  the 
  chapter 
  devoted 
  to 
  Megalosaurus. 
  He 
  however 
  regarded 
  the 
  face 
  of 
  the 
  tibia 
  

   receiving 
  the 
  condyloid 
  bearing 
  bone, 
  as 
  the 
  inner, 
  instead 
  of 
  the 
  anterior, 
  stating 
  that 
  the 
  tibia 
  is 
  laterally 
  instead 
  

   of 
  anteroposteriorly 
  compressed, 
  so 
  anomalous 
  is 
  this 
  structure 
  among 
  vertebrates. 
  He 
  regarded 
  the 
  bone 
  as 
  the 
  

   astragalus, 
  and 
  did 
  not 
  perceive 
  any 
  connection 
  between 
  its 
  anterior 
  ascending 
  apophysis 
  and 
  a 
  fibula, 
  partly 
  because 
  

   a 
  fibula 
  with 
  distinct 
  distal 
  articulation 
  was 
  received 
  with 
  the 
  same 
  bones. 
  

  

  Gegenbaur's 
  demonstration 
  of 
  the 
  nature 
  of 
  the 
  ankle 
  joint 
  among 
  birds 
  and 
  reptiles 
  at 
  once 
  makes 
  the 
  nature 
  

   of 
  the 
  present 
  case 
  clear.* 
  

  

  This 
  tibio-tarsal 
  bone 
  possesses 
  an 
  articular 
  facet 
  on 
  its 
  exterior 
  extremity, 
  probably 
  for 
  conjunction 
  with 
  a 
  

   calcaneum 
  which 
  supported 
  a 
  small 
  second 
  row 
  tarsal 
  and 
  perhaps 
  rudimental 
  metatarsal 
  and 
  phalange. 
  Its 
  plane 
  is 
  

   transverse 
  and 
  does 
  not 
  cover 
  the 
  whole 
  extremity, 
  the 
  anterior 
  margin 
  and 
  a 
  knob 
  on 
  the 
  anteroposterior 
  part 
  of 
  

   the 
  extremity 
  projecting 
  beyond 
  it. 
  Exterior 
  to 
  the 
  middle 
  of 
  the 
  upper 
  margin 
  of 
  this 
  piece 
  and 
  at 
  the 
  internal 
  

   base 
  of 
  the 
  ascending 
  apophysis, 
  it 
  is 
  perforate, 
  as 
  is 
  the 
  cavity 
  above 
  the 
  condyles 
  of 
  the 
  humerus 
  in 
  the 
  higher 
  apes, 
  

   and 
  may 
  have 
  received 
  a 
  similar 
  coronoid 
  process 
  of 
  a 
  scaphoides. 
  

  

  As 
  compared 
  with 
  the 
  species 
  examined 
  by 
  Cuvier, 
  this 
  astragalus 
  has 
  a 
  less 
  elevated 
  form; 
  in 
  Cuvier's 
  specimen 
  

   the 
  ascending 
  apophysis 
  was 
  flatter, 
  broader, 
  and 
  directed 
  toward 
  the 
  calcaneal 
  facet 
  instead 
  of 
  from 
  it; 
  it 
  lacked 
  

   the 
  submedian 
  perforation. 
  Its 
  tibial 
  face 
  appears 
  to 
  have 
  been 
  rounded, 
  not 
  angulate. 
  The 
  tibia 
  presented 
  an 
  

   ascending 
  ridge, 
  to 
  the 
  face 
  of 
  which 
  the 
  ascending 
  apophysis 
  was 
  applied; 
  in 
  the 
  Laelaps 
  aquilunguis 
  there 
  is 
  

   no 
  ridge, 
  the 
  apophyses 
  reposing 
  in 
  a 
  slight 
  concavity. 
  This 
  apophysis, 
  like 
  the 
  slender 
  portion 
  of 
  the 
  fibula, 
  is 
  

   composed 
  of 
  dense 
  bone. 
  

  

  Cuvier 
  describes 
  at 
  the 
  same 
  time 
  a 
  bone, 
  of 
  which 
  he 
  says 
  "il 
  ne 
  serait 
  pas 
  impossible 
  que 
  l'os 
  (fig. 
  39 
  j 
  fut 
  la 
  

   tete 
  superieur 
  du 
  pei'one 
  du 
  pied 
  que 
  je 
  viens 
  de 
  decrire." 
  This 
  piece 
  has 
  a 
  shaft 
  compressed 
  at 
  right 
  angles 
  to 
  the 
  

   direction 
  of 
  its 
  head, 
  a 
  form 
  so 
  unlike 
  the 
  fibulae 
  of 
  known 
  Dinosauria, 
  including 
  Megalosaurus 
  and 
  Laelaps, 
  as 
  to 
  

   render 
  such 
  a 
  relation 
  to 
  the 
  before-mentioned 
  tibia, 
  very 
  doubtful. 
  It 
  is 
  probably 
  a 
  metatarsus.. 
  

  

  The 
  second 
  example 
  of 
  the 
  clasping 
  astragalus 
  with 
  anteriorly 
  directed 
  condyle 
  is 
  the 
  Poecilopleurum 
  of 
  Des- 
  

   longcbamps. 
  Here 
  the 
  angle 
  between 
  tibia 
  and 
  metatarsus 
  lias 
  been 
  even 
  greater 
  than 
  in 
  Laelaps. 
  The 
  ascending 
  

   anterior 
  ala 
  is 
  broader 
  than 
  in 
  Laelaps, 
  and 
  appears 
  to 
  be 
  complete 
  and 
  not 
  continuous 
  above 
  with 
  the 
  fibula. 
  

   That 
  it 
  is 
  in 
  contact 
  with 
  the 
  fibula 
  he 
  states 
  thus: 
  "its 
  internal 
  face 
  is 
  applied 
  to 
  the 
  tibia, 
  while 
  its 
  external 
  was 
  

   without 
  doubt 
  covered 
  in 
  part 
  by 
  the 
  inferior 
  extremity 
  of 
  the 
  fibula." 
  This, 
  with 
  identity 
  of 
  form 
  between 
  the 
  

   extremities 
  of 
  the 
  fibula, 
  and 
  of 
  the 
  ascending 
  process 
  of 
  the 
  astragalus, 
  in 
  Laelaps, 
  renders 
  it 
  probable 
  that 
  the 
  rela- 
  

   tion 
  is 
  similar 
  in 
  the 
  latter. 
  I 
  may 
  add 
  that 
  I 
  suspect 
  that 
  Deslongchamps 
  like 
  others 
  has 
  reversed 
  the 
  relations 
  of 
  

   the 
  extremities 
  of 
  the 
  fibula. 
  If 
  both 
  the 
  extremities 
  figured 
  by 
  this 
  author 
  belong 
  to 
  it, 
  it 
  is 
  much 
  less 
  attenuated 
  

   than 
  in 
  Laelaps. 
  

  

  The 
  tibiae 
  figure 
  by 
  Cuvier 
  and 
  Deslongchamps 
  appear 
  to 
  belong 
  to 
  different 
  species. 
  They 
  differ 
  in 
  many 
  

   respects 
  as 
  figured. 
  The 
  former 
  has 
  a 
  more 
  contracted 
  shaft 
  than 
  the 
  other 
  ; 
  its 
  extremity 
  is 
  less 
  oblique 
  ; 
  the 
  infe- 
  

   rior 
  plate 
  of 
  the 
  astragalus 
  thicker 
  and 
  less 
  produced 
  ; 
  the 
  anterior 
  plate 
  in 
  every 
  way 
  smaller. 
  The 
  species 
  should 
  

   be 
  called 
  Poecilopleiu-um 
  gallicum. 
  (Laelaps 
  gallicus 
  m. 
  Pro. 
  Ac. 
  N. 
  Sci., 
  Phil., 
  1867, 
  235.) 
  

  

  * 
  See 
  Gegenbaur, 
  Carpus 
  and 
  Tarsus; 
  tarsus 
  of 
  Chick 
  ninth 
  day, 
  Tab. 
  

  

  