﻿AND 
  AVES 
  OF 
  NORTH 
  AMERICA. 
  105 
  

  

  condyles. 
  Posterior 
  condyles 
  separated 
  by 
  a 
  deep 
  notch, 
  inner 
  larger 
  than 
  outer 
  (outer 
  larger, 
  Megalosaurus 
  buck- 
  

   landii). 
  Shaft 
  much 
  compressed 
  from 
  before 
  backwards, 
  and 
  distal 
  articulation 
  at 
  right 
  angles 
  to 
  proximal, 
  concave 
  

   on 
  its 
  interior 
  half. 
  On 
  the 
  exterior 
  face 
  a 
  strong 
  crest 
  extends 
  along 
  the 
  proximal 
  fourth 
  of 
  the 
  length, 
  not 
  reaching 
  

   the 
  head, 
  which 
  is 
  the 
  point 
  of 
  contact 
  of 
  the 
  slender 
  fibula, 
  and 
  is 
  similar 
  to 
  the 
  same 
  in 
  birds. 
  

  

  In. 
  

   Length 
  of 
  tibia, 
  30. 
  75 
  

  

  Circumference 
  proximal 
  head, 
  15. 
  

  

  Anteroposterior 
  diameter 
  do. 
  7. 
  5 
  

  

  Posterior 
  transverse 
  do. 
  do. 
  5.5 
  

  

  Transverse 
  length 
  distal 
  condyle, 
  7. 
  

  

  Longitudinal 
  inner 
  breadth, 
  2.5 
  

  

  Circumference 
  of 
  shaft 
  at 
  middle, 
  10.5 
  

  

  These 
  long 
  bones 
  are 
  hollow, 
  with 
  thick 
  walls 
  of 
  dense 
  bone; 
  diameter 
  of 
  medullary 
  cavity 
  at 
  middle 
  of 
  tibia 
  

   1.5 
  inch. 
  

  

  Left 
  Fibula. 
  — 
  Twenty-four 
  inches 
  preserved, 
  proximally 
  concave 
  and 
  dilated; 
  condyle 
  curved, 
  narrow 
  acuminate 
  

   oval, 
  in 
  profile 
  concave, 
  then 
  rounded 
  descending; 
  length 
  6 
  in., 
  median 
  breadth 
  1.75 
  in. 
  Just 
  below 
  the 
  condyle 
  on 
  

   the 
  inside 
  is 
  a 
  deep 
  concavity 
  with 
  abrupt 
  superior 
  and 
  lateral 
  walls. 
  Shaft 
  less 
  flattened 
  below, 
  but 
  slender, 
  reaching 
  

   a 
  width 
  of 
  1^ 
  in. 
  The 
  fragment 
  which 
  occupied 
  the 
  most 
  distal 
  position 
  which 
  is 
  preserved, 
  is 
  rather 
  less 
  flattened, 
  

   but 
  quite 
  convex 
  on 
  the 
  outer 
  face. 
  It 
  is 
  not 
  very 
  unlike 
  in 
  general 
  form 
  the 
  fibula 
  of 
  the 
  ostrich, 
  and 
  like 
  it 
  is 
  

   continued 
  to 
  the 
  tarsus, 
  closely 
  applied 
  to 
  the 
  tibia. 
  Its 
  proximal 
  half 
  lies 
  on 
  a 
  ridge 
  of 
  the 
  tibia 
  in 
  Laelaps, 
  but 
  

   when 
  the 
  distal 
  end 
  of 
  the 
  latter 
  expands, 
  the 
  fibula 
  continues 
  directly 
  across 
  the 
  expansion, 
  appressed 
  to 
  the 
  anterior 
  

   face, 
  in 
  a 
  shallow 
  groove. 
  

  

  I 
  have 
  given 
  the 
  fibula 
  a 
  relation 
  the 
  reverse 
  of 
  that 
  assigned 
  to 
  Hadrosaurus 
  and 
  Iguanodon 
  by 
  Leidy 
  and 
  Owen 
  

   respectively, 
  that 
  is, 
  I 
  consider 
  their 
  inferior 
  extremity 
  the 
  superior, 
  and 
  vice 
  versa. 
  This 
  relation 
  is 
  coincident 
  with 
  

   their 
  bird-like 
  affinities, 
  which 
  require 
  a 
  restriction 
  of 
  the 
  fibula 
  distally, 
  not 
  proximally. 
  It 
  also 
  furnishes 
  the 
  

   requisite 
  extent 
  of 
  articular 
  surface 
  for 
  the 
  condyles 
  of 
  the 
  femur 
  in 
  Laelaps 
  and 
  Hadrosaurus, 
  as 
  well 
  as 
  in 
  Scelido- 
  

   saurus, 
  according 
  to 
  Owen's 
  plate. 
  The 
  head 
  of 
  the 
  tibia, 
  alone, 
  is 
  too 
  narrow 
  for 
  the 
  femur 
  in 
  the 
  two 
  genera 
  first 
  

   mentioned. 
  This 
  structure 
  accords 
  also 
  with 
  Compsognathus, 
  where 
  the 
  fibula 
  is 
  reduced 
  distally. 
  

  

  Tarsus 
  and 
  Metatarsus. 
  — 
  The 
  distal 
  extremity 
  of 
  the 
  tibia 
  is 
  transverse, 
  and 
  much 
  compressed, 
  and 
  does 
  not 
  ex- 
  

   hibit 
  any 
  of 
  the 
  usual 
  appearances 
  of 
  an 
  articular 
  surface, 
  neither 
  the 
  reptilian 
  condyle, 
  nor 
  a 
  cotyloid 
  cavity 
  sufficient 
  

   for 
  an 
  astragalus 
  of 
  the 
  size 
  necessary 
  for 
  an 
  animal 
  of 
  such 
  bulk. 
  A 
  bone, 
  presenting 
  a 
  broad 
  hour 
  glass 
  faced 
  

   articular 
  surface 
  was 
  discovered 
  with 
  the 
  other 
  remains, 
  and 
  had 
  puzzled 
  the 
  anatomists 
  who 
  had 
  seen 
  it. 
  This 
  

   piece 
  exhibits 
  along 
  its 
  whole 
  posterior 
  aspect 
  two 
  faces, 
  which 
  form 
  a 
  reentrant 
  angle 
  for 
  a 
  fixed 
  articulation: 
  this 
  

   is 
  found 
  to 
  have 
  been 
  applied 
  to 
  the 
  extremity 
  of 
  the 
  tibia 
  exactly, 
  and 
  to 
  have 
  been 
  fixed 
  by 
  strong 
  articular 
  liga- 
  

   ments. 
  The 
  medially 
  constricted 
  condyle 
  presenting 
  forwards 
  and 
  a 
  little 
  downwards 
  exhibits 
  an 
  unusual 
  modification 
  

   of 
  the 
  vertebrate 
  astragalus. 
  

  

  The 
  fibula 
  presents 
  a 
  long 
  and 
  narrow 
  articular 
  surface 
  at 
  the 
  knee, 
  and 
  fitting 
  the 
  tibia 
  by 
  the 
  concavity 
  of 
  its 
  

   inner 
  face, 
  becomes 
  greatly 
  attenuated 
  at 
  its 
  distal 
  third, 
  where 
  it 
  is, 
  in 
  consequence 
  of 
  an 
  obliquity 
  of 
  its 
  direction 
  

   applied 
  to 
  the 
  anterior 
  face 
  of 
  the 
  former 
  bone. 
  It 
  may 
  then 
  be 
  supposed 
  to 
  extend 
  to 
  the 
  outer 
  margin 
  of 
  the 
  

   astragalus, 
  and 
  terminate 
  at 
  the 
  small 
  calcaneum 
  which 
  embraced 
  the 
  outer 
  anterior 
  extremity 
  of 
  the 
  tibia, 
  like 
  an 
  

   epiphysis. 
  In 
  applying 
  the 
  astragalus, 
  we 
  see 
  that 
  a 
  process 
  projects 
  from 
  its 
  superior 
  margin, 
  which 
  when 
  applied 
  

   to 
  the 
  face 
  of 
  the 
  tibia 
  occupies 
  with 
  its 
  flat 
  inner 
  face 
  a 
  shallow 
  longitudinal 
  concavity 
  of 
  that 
  bone. 
  This 
  concavity 
  

   continues 
  across 
  the 
  external 
  expansion 
  of 
  the 
  same, 
  and 
  is 
  continuous 
  with 
  its 
  outer 
  margin 
  in 
  direct 
  line 
  with 
  the 
  posi- 
  

   tion 
  of 
  the 
  fibula. 
  The 
  continually 
  increasing 
  slenderness 
  of 
  the 
  tibia 
  as 
  represented 
  by 
  a 
  large 
  fragment 
  of 
  its 
  distal 
  

   portion, 
  renders 
  it 
  extremely 
  improbable 
  that 
  it 
  spanned 
  the 
  concave 
  outline 
  of 
  the 
  tibia, 
  to 
  be 
  in 
  contact 
  as 
  in 
  reptiles, 
  

   with 
  the 
  distal 
  extremity 
  of 
  the 
  tibia, 
  in 
  the 
  usual 
  position 
  of 
  the 
  malleolus, 
  especially 
  as 
  there 
  is 
  no 
  face 
  for 
  contact 
  

   on 
  the 
  latter. 
  Continued 
  from 
  its 
  point 
  of 
  obvious 
  contact 
  with 
  the 
  external 
  margin 
  of 
  the 
  tibia, 
  it 
  falls 
  nearly 
  into 
  the 
  

   shallow 
  groove 
  mentioned 
  and 
  into 
  the 
  line 
  of 
  the 
  ascending 
  portion 
  of 
  the 
  astragalus. 
  The 
  latter 
  is 
  broken 
  off 
  at 
  the 
  

   extremity, 
  but 
  presents 
  a 
  form 
  not 
  very 
  different 
  from 
  the 
  broken 
  slender 
  end 
  of 
  the 
  fibula, 
  and 
  is 
  of 
  about 
  the 
  same 
  size. 
  

   AMERI. 
  PHILOSO. 
  SOC. 
  — 
  VOL. 
  XIV. 
  27 
  

  

  