﻿AND 
  AVES 
  OF 
  NORTH 
  AMERICA. 
  121 
  

  

  This 
  gentleman 
  observing 
  that 
  the 
  gradual 
  advance 
  of 
  the 
  tide, 
  owing 
  to 
  the 
  slow 
  depres- 
  

   sion 
  of 
  the 
  coast 
  line, 
  was 
  undermining 
  a 
  long 
  bank 
  of 
  the 
  cretaceous 
  clay, 
  carefully 
  

   examined 
  the 
  debris, 
  from 
  time 
  to 
  time, 
  and 
  made 
  the 
  discovery 
  of 
  the 
  fragment 
  men- 
  

   tioned. 
  No 
  other 
  portions 
  rewarded 
  his 
  search, 
  and 
  as 
  the 
  bank 
  has 
  been 
  gradually 
  

   carried 
  aAvay 
  since, 
  there 
  is 
  little 
  probability 
  of 
  the 
  remainder 
  being 
  found. 
  

  

  The 
  specimen 
  consists 
  of 
  the 
  extremity 
  of 
  the 
  tibia 
  with 
  anchylosed 
  astragalus, 
  with 
  

   part 
  of 
  the 
  shaft 
  and 
  distal 
  portion 
  of 
  the 
  fibula 
  adherent. 
  From 
  this 
  the 
  character 
  of 
  

   the 
  genus 
  may 
  be 
  derived, 
  as 
  follows 
  : 
  

  

  Astragalus 
  confluent 
  with 
  calcaneum, 
  both 
  together 
  anchylosed 
  to 
  the 
  tibia 
  : 
  articular 
  

   face 
  directed 
  downwards 
  and 
  a 
  little 
  forwards. 
  Fibula 
  slender, 
  articulating 
  with 
  the 
  first 
  

   tarsal 
  bone. 
  Medullary 
  cavity 
  of 
  tibia 
  small, 
  occupied 
  by 
  a 
  coarse 
  cancellous 
  tissue. 
  

  

  This 
  genus 
  confirms 
  remarkably 
  the 
  propositions 
  suggested 
  by 
  the 
  remains 
  of 
  Laelaps, 
  

   as 
  to 
  the 
  probable 
  continuity 
  of 
  the 
  tarsal 
  and 
  tibial 
  elements 
  in 
  certain 
  of 
  this 
  order, 
  and 
  

   the 
  relation 
  of 
  the 
  fibula 
  to 
  the 
  same. 
  It 
  proves 
  that 
  the 
  latter 
  bone 
  has 
  been 
  reversed 
  in 
  

   the 
  descriptions 
  of 
  Iguanodon 
  and 
  Hadrosaurus. 
  

  

  The 
  suture 
  connecting 
  tibia 
  and 
  astragalus 
  is 
  distinct, 
  so 
  that 
  I 
  suspect 
  that 
  the 
  latter 
  

   is 
  distinct 
  from 
  the 
  former 
  during 
  a 
  part 
  at 
  least 
  of 
  the 
  early 
  life 
  of 
  the 
  animal. 
  Thus 
  

   there 
  is 
  the 
  usual 
  "parallelism" 
  between 
  the 
  adult 
  Orthopocl 
  and 
  young 
  Symphypod. 
  

   There 
  is 
  an 
  obliquity 
  of 
  the 
  ^articular 
  extremity 
  to 
  the 
  axis 
  of 
  the 
  tibia, 
  indicating 
  a 
  

   prominence 
  of 
  the 
  external 
  tuberosity. 
  

  

  The 
  fibula 
  is 
  subtrilateral, 
  the 
  posterior 
  face 
  being 
  obtusely 
  angular 
  and 
  fitting 
  a 
  slight 
  

   groove, 
  as 
  in 
  Hadrosaurus. 
  The 
  extremity 
  presents 
  an 
  obtuse 
  condyle 
  inwards 
  and 
  down- 
  

   wards, 
  which 
  is 
  applied 
  to 
  a 
  corresponding 
  concavity 
  of 
  the 
  superior 
  projecting 
  face 
  of 
  the 
  

   astragalo-calcaneum. 
  The 
  external 
  angle 
  is 
  slightly 
  prominent 
  and 
  angular. 
  

  

  The 
  affinities 
  of 
  this 
  genus 
  are 
  perhaps 
  in 
  some 
  degree 
  to 
  Hadrosaurus 
  ; 
  certainly 
  

   nearer 
  to 
  it 
  than 
  to 
  Laelaps. 
  The 
  inferior 
  presentation 
  of 
  the 
  ankle 
  joint 
  indicates 
  short 
  

   metatarsals, 
  so 
  that 
  the 
  form 
  was 
  probably 
  heavy 
  footed. 
  

  

  ORNITHOTARSUS 
  IMMANIS, 
  Cope. 
  

   Proceed. 
  Amer. 
  Philos. 
  Sci., 
  1869, 
  p. 
  117. 
  

  

  The 
  accompanying 
  cuts 
  will 
  give 
  a 
  good 
  idea 
  of 
  the 
  proportions 
  of 
  this 
  fragment. 
  The 
  extremity 
  of 
  the 
  tibia 
  

   exhibits 
  the 
  anterior 
  longitudinal 
  concavity 
  common 
  to 
  all 
  the 
  types 
  of 
  the 
  order, 
  and 
  which 
  as 
  in 
  them, 
  is 
  occupied 
  

   by 
  the 
  ascending 
  apophysis 
  of 
  the 
  astragalus. 
  The 
  astragalo-calcaneum 
  is 
  a 
  thin 
  bone, 
  and 
  does 
  not 
  cover 
  the 
  

   extremity 
  of 
  the 
  tibia 
  internally 
  and 
  posteriorly. 
  It 
  thins 
  out 
  posteriorly 
  and 
  leaves 
  a 
  strong 
  groove 
  to 
  mark 
  the 
  

   suture, 
  apparently 
  for 
  ligamentous 
  insertion. 
  The 
  transverse 
  plane 
  of 
  the 
  articular 
  face 
  is 
  nearly 
  even 
  ; 
  and 
  it 
  is 
  

   little 
  contracted 
  medially, 
  much 
  less 
  than 
  in 
  Laelaps 
  aquilunguis. 
  

  

  As 
  compared 
  with 
  Hadrosaurus 
  foulkii, 
  which 
  it 
  most 
  resembles, 
  the 
  extremity 
  of 
  the 
  tibia 
  presents 
  many 
  

   differences. 
  First, 
  the 
  external 
  face 
  is 
  much 
  narrower, 
  and 
  more 
  transverse, 
  forming 
  thus 
  a 
  less 
  open 
  angle 
  with 
  the 
  

   posterior 
  face. 
  Second 
  ; 
  the 
  anterior 
  concavity 
  is 
  less 
  profound, 
  giving 
  the 
  outline 
  a 
  more 
  transverse 
  direction. 
  

   AMERI. 
  PHILOSO. 
  SOC 
  VOL. 
  XIV. 
  31 
  

  

  