﻿24 
  J. 
  W. 
  HULKE 
  ON 
  THE 
  ASTRAGALUS 
  OF 
  IGTJANODOX. 
  

  

  5. 
  Note 
  on 
  an 
  Astragalus 
  of 
  IguanodoJst 
  Mantelli. 
  By 
  J. 
  W. 
  

   Hulke, 
  Esq., 
  F.R.S., 
  F.G.S. 
  . 
  (Read 
  November 
  5, 
  1873.) 
  

  

  I 
  am 
  indebted 
  to 
  the 
  courtesy 
  of 
  one 
  of 
  our 
  Fellows, 
  E.P.~Wilkins,Esq., 
  

   of 
  Newport, 
  Isle 
  of 
  Wight, 
  for 
  the 
  opportunity 
  of 
  exhibiting 
  this 
  re- 
  

   markable 
  astragalus 
  of 
  Mantell's 
  Iguanodon, 
  a 
  bone 
  not 
  contained 
  in 
  the 
  

   rich 
  series 
  of 
  remains 
  of 
  this 
  Dinosaur 
  preserved 
  in 
  the 
  British 
  Museum 
  , 
  

   and, 
  so 
  far 
  as 
  I 
  can 
  ascertain, 
  hitherto 
  unknown. 
  Mr. 
  Wilkins 
  ac- 
  

   quired 
  it 
  several 
  years 
  ago 
  with 
  other 
  reptilian 
  fossils 
  obtained 
  from 
  

   the 
  cliffs 
  in 
  Brixton 
  Bay 
  ; 
  and 
  last 
  September, 
  when 
  I 
  paid 
  a 
  hasty 
  

   visit 
  to 
  his 
  collection, 
  he 
  showed 
  it 
  to 
  me 
  as 
  a 
  bone 
  which 
  had 
  much 
  

   puzzled 
  him, 
  and 
  which 
  he 
  had 
  been 
  unable 
  to 
  determine. 
  On 
  learn- 
  

   ing 
  its 
  extreme 
  interest, 
  he 
  anticipated 
  my 
  wish 
  for 
  a 
  sketch 
  of 
  it 
  by 
  

   suggesting 
  that 
  I 
  might 
  take 
  it 
  with 
  me 
  to 
  London 
  and 
  bring 
  it 
  under 
  

   the 
  notice 
  of 
  the 
  Geological 
  Society. 
  

  

  It 
  has 
  a 
  depressed 
  oblong 
  figure, 
  measuring 
  in 
  its 
  long 
  axis 
  between 
  

   the 
  extreme 
  limits 
  9| 
  inches, 
  and 
  in 
  its 
  short 
  axis 
  5| 
  inches. 
  The 
  

   under 
  surface 
  has 
  the 
  regular 
  pulley-shape 
  characteristic 
  of 
  a 
  movable 
  

   hinge-joint 
  (fig. 
  1). 
  A 
  well-marked 
  median 
  constriction 
  separates 
  the 
  

   lateral 
  portions, 
  the 
  inner 
  of 
  which 
  is 
  rather 
  more 
  swollen 
  .than 
  the 
  

   outer. 
  The 
  upper 
  surface 
  (fig. 
  2) 
  has 
  an 
  irregular 
  unsymmetrical 
  

   shape, 
  adapted 
  to 
  that 
  of 
  the 
  distal 
  end 
  of 
  the 
  tibia 
  of 
  Mantell's 
  

   Iguanodon. 
  The 
  applied 
  surfaces 
  of 
  astragalus 
  and 
  tibia 
  must 
  have 
  

   so 
  interlocked 
  as 
  to 
  have 
  prevented 
  all 
  motion 
  between 
  them. 
  A 
  

   strong 
  ridge 
  passing 
  between 
  the 
  anterior 
  and 
  posterior 
  margins 
  divides 
  

   the 
  upper 
  surface 
  into 
  a 
  larger 
  antero-internal 
  and 
  a 
  lesser 
  postero- 
  

   external 
  moiety. 
  The 
  former 
  of 
  these 
  is 
  a 
  wide 
  trough 
  strongly 
  con- 
  

   cave 
  from 
  back 
  to 
  front. 
  The 
  outer 
  moiety 
  slants 
  steeply 
  down 
  from 
  

   the 
  dividing 
  ridge, 
  and 
  it 
  descends 
  much 
  lower 
  than 
  the 
  general 
  level 
  of 
  

   the 
  inner 
  half 
  of 
  the 
  same 
  surface, 
  than 
  which 
  it 
  is 
  also 
  much 
  narrower. 
  

   The 
  inner 
  half 
  looks 
  upwards, 
  backwards, 
  and 
  inwards 
  ; 
  and 
  the 
  outer 
  

   half 
  looks 
  upwards, 
  forwards, 
  and 
  outwards. 
  The 
  downward 
  slope 
  of 
  

   the 
  outer 
  moiety 
  of 
  this 
  surface 
  renders 
  the 
  outer 
  border 
  of 
  the 
  bone 
  

   very 
  thin 
  ; 
  it 
  is 
  indented 
  at 
  its 
  middle 
  by 
  a 
  notch 
  ; 
  and 
  in 
  its 
  pre- 
  

   sent 
  condition 
  it 
  does 
  not 
  show 
  any 
  mark 
  of 
  an 
  articulation 
  with 
  an 
  

   os 
  calcis. 
  The 
  inner 
  border 
  of 
  the 
  bone 
  is 
  so 
  stout 
  that 
  it 
  might 
  be 
  

   properly 
  termed 
  a 
  surface; 
  it 
  has 
  a 
  vertical 
  depth 
  of 
  about 
  2| 
  

   inches. 
  The 
  posterior 
  border, 
  less 
  stout, 
  rises 
  quickly 
  from 
  its 
  outer 
  

   end, 
  where 
  it 
  includes 
  a 
  right 
  angle 
  with 
  the 
  outer 
  border 
  to 
  the 
  

   ridge 
  which 
  divides 
  the 
  upper 
  surface; 
  and 
  from 
  here 
  it 
  curves 
  

   gently 
  downwards, 
  rising 
  again 
  at 
  its 
  inner 
  end 
  (fig. 
  3). 
  The 
  anterior 
  

   border, 
  thinner 
  than 
  the 
  posterior, 
  rises 
  from 
  both 
  ends 
  in 
  the 
  form 
  of 
  

   a 
  blunt 
  lip, 
  which 
  belongs 
  more 
  to 
  the 
  inner 
  than 
  to 
  the 
  outer 
  moiety 
  

   of 
  the 
  bone 
  (fig. 
  4), 
  and 
  was 
  received 
  into 
  the 
  entering 
  angle 
  and 
  

   groove 
  present 
  in 
  the 
  anterior 
  surface 
  of 
  the 
  distal 
  end 
  of 
  the 
  tibia. 
  

   The 
  base 
  of 
  this 
  lip 
  in 
  the 
  present 
  specimen 
  has 
  been 
  fractured 
  and 
  

   pressed 
  backwards 
  so 
  as 
  to 
  make 
  the 
  outer 
  edge 
  of 
  the 
  lip 
  now 
  appear 
  

  

  