﻿550 
  Mr. 
  J\. 
  W. 
  Ilooley 
  on 
  the 
  

  

  diagonally 
  from 
  tlie 
  preaxial 
  distal 
  border. 
  This 
  is 
  not 
  

   exliibited 
  in 
  the 
  Cambridge 
  examples. 
  The 
  specimen 
  no. 
  2 
  

   is 
  not 
  as 
  compressed 
  as 
  nos, 
  1 
  and 
  3, 
  or 
  as 
  Omit 
  hodesmus 
  

   latidens, 
  and 
  the 
  dorsal 
  surface 
  is 
  more 
  concave 
  distally. 
  

  

  The. 
  Ulna. 
  

   Proximal 
  end. 
  

  

  The 
  six 
  specimens 
  on 
  tablet 
  J. 
  a. 
  9 
  are 
  the 
  proximal 
  ends 
  

   of 
  ulnie. 
  Nos. 
  1, 
  2, 
  4, 
  and 
  5 
  are 
  tigui'ed 
  in 
  ' 
  Ornithosauria,' 
  

   plate 
  iii. 
  figs. 
  4, 
  5, 
  6, 
  7, 
  8, 
  9. 
  J. 
  a. 
  9, 
  1, 
  belonging 
  to 
  the 
  

   left 
  ulna, 
  differs 
  from 
  Ornithodesmus 
  latidens 
  in 
  the 
  absence 
  

   of 
  the 
  longitudinal 
  ridge 
  on 
  the 
  ventral 
  surface 
  of 
  the 
  shaft, 
  

   in 
  lieu 
  of 
  which 
  there 
  is 
  a 
  raised 
  and 
  roughened 
  surface, 
  

   prtaxial 
  to 
  the 
  radius 
  instead 
  of 
  postaxial, 
  for 
  the 
  attachment 
  

   of 
  the 
  biceps 
  tendon. 
  This 
  feature 
  is 
  also 
  seen 
  in 
  nos. 
  2 
  

   and 
  4. 
  The 
  dorsal 
  surface 
  is 
  strongly 
  convex, 
  and 
  the 
  

   ventral 
  slightly, 
  and 
  free 
  from 
  any 
  pit 
  or 
  ridge. 
  The 
  

   pneumatic 
  foramen 
  is 
  near 
  the 
  articulation 
  in 
  the 
  centre 
  of 
  

   the 
  ventral 
  surface. 
  The 
  articulation 
  is 
  much 
  worn. 
  This 
  

   specimen 
  is 
  interesting, 
  because 
  from 
  it 
  Seeley 
  obtained 
  the 
  

   suggestion 
  of 
  an 
  olecranon*. 
  There 
  is 
  a 
  well-defined 
  line 
  

   around 
  the 
  upper 
  dorsal 
  half, 
  which 
  might 
  be 
  accidental. 
  

   The 
  surfaces 
  in 
  all 
  the 
  other 
  examples 
  appear 
  to 
  be 
  articu- 
  

   latory, 
  and 
  the 
  roughened 
  edges 
  the 
  effect 
  of 
  wear, 
  and 
  not 
  

   caused 
  by 
  the 
  tearing 
  away 
  of 
  an 
  epiphysis. 
  The 
  main 
  

   articulatory 
  surface 
  is 
  an 
  oblique 
  oval-shaped 
  basin, 
  looking 
  

   upwards, 
  in 
  the 
  centre 
  of 
  which 
  in 
  specimens 
  nos. 
  4, 
  5, 
  and 
  

   6 
  is 
  a 
  circular 
  opening 
  into 
  the 
  ^liaft, 
  as 
  is 
  seen 
  in 
  the 
  

   humerus 
  of 
  Ornithodesmus 
  latidens 
  and 
  in 
  J. 
  a. 
  6, 
  nos. 
  20, 
  

   21, 
  and 
  32. 
  Moreover, 
  the 
  general 
  form 
  of 
  the 
  bone 
  is 
  not 
  

   very 
  different 
  from 
  the 
  distal 
  extremities 
  of 
  the 
  hunieii, 
  

   exhibiting 
  the 
  circular 
  opening 
  into 
  the 
  shaft-^for 
  example, 
  

   J. 
  a. 
  6, 
  20. 
  In 
  those 
  examples 
  wheie 
  the 
  supposed 
  olecranon 
  

   has 
  comcavvay 
  the 
  dorsal 
  half 
  of 
  the 
  articulatory 
  surface 
  iscon- 
  

   cave. 
  It 
  looks 
  upwards 
  and 
  is 
  divided 
  from 
  the 
  ventral 
  half 
  

   by 
  a 
  convex 
  ridge. 
  The 
  ventral 
  surface 
  looks 
  downwards 
  and 
  

   is 
  feebly 
  convex 
  dorso-ventrally 
  and 
  concave 
  pre-postaxially. 
  

   In 
  no. 
  1 
  the 
  ai'ticulation 
  has 
  two 
  feebly 
  concave 
  surfaces, 
  

   with 
  a 
  raised 
  ridge 
  for 
  the 
  trochlea 
  of 
  the 
  distal 
  end 
  of 
  the 
  

   humerus. 
  In 
  no, 
  2 
  the 
  dorsal 
  half 
  of 
  the 
  artieulation 
  is 
  

   destroyed. 
  The 
  postaxial 
  coucave 
  surface 
  is 
  more 
  oblicpie 
  

   and 
  carried 
  further 
  on 
  to 
  the 
  shaft 
  of 
  the 
  bone, 
  thus 
  looking 
  

   more 
  outward 
  than 
  in 
  the 
  other 
  specimens. 
  This 
  example 
  

  

  * 
  II. 
  G. 
  Soelcy, 
  ' 
  Oruitho.^aurKi/ 
  1870, 
  pp. 
  45 
  & 
  46. 
  

  

  