﻿541: 
  Mf. 
  R. 
  W. 
  Hooley 
  on 
  the 
  

  

  apparently 
  from 
  the 
  central 
  area 
  o£ 
  the 
  shaft, 
  where 
  the 
  

   bone 
  is 
  smallest 
  in 
  Pterodactyls. 
  The 
  complete 
  bone 
  wouhl 
  

   therefore 
  be 
  of 
  enormons 
  bulk, 
  and^ 
  with 
  the 
  other 
  bones 
  of 
  

   the 
  skeleton 
  in 
  proportion, 
  we 
  shonld 
  have 
  a 
  reptile 
  too 
  

   heavy 
  for 
  flif;ht. 
  Moreover, 
  it 
  reveals 
  no 
  constriction 
  as 
  seen 
  

   in 
  the 
  Pterodactyl 
  humerns. 
  Whether 
  we 
  take 
  the 
  proximal 
  

   or 
  distal 
  ends, 
  the 
  forty-nine 
  specimens 
  naturally 
  form 
  three 
  

   groups. 
  In 
  one 
  group 
  the 
  entire 
  bone 
  is 
  known 
  for 
  certain 
  

   by 
  the 
  perfect 
  example 
  J. 
  a. 
  6, 
  30, 
  and. 
  by 
  comparison 
  with 
  

   Ornithodesmus 
  latidens 
  another 
  is 
  nearly 
  as 
  sure, 
  and 
  there 
  

   is 
  reason 
  to 
  believe 
  that 
  the 
  third, 
  group 
  is 
  comprised, 
  of 
  

   those 
  proximal 
  ends 
  which 
  are 
  different 
  from 
  the 
  other 
  two 
  

   groups, 
  although 
  there 
  can 
  be 
  no 
  positive 
  determination 
  

   until 
  a 
  perfect 
  humerus 
  with 
  the 
  same 
  characters 
  is 
  dis- 
  

   covered. 
  We 
  give 
  on 
  pp. 
  542-54*3 
  the 
  characters 
  of 
  the 
  three 
  

   groups 
  and 
  their 
  examples, 
  and 
  follow 
  by 
  a 
  criticism 
  of 
  some 
  

   of 
  the 
  specimens 
  incluJed 
  in 
  the 
  groups 
  : 
  — 
  

  

  Proximal 
  ends. 
  

  

  Group 
  A, 
  

  

  Seeley 
  * 
  gives 
  J. 
  a. 
  6, 
  .25 
  as 
  an 
  exami)le 
  of 
  the 
  same 
  kind 
  

   of 
  proximal 
  end 
  as 
  seen 
  in 
  the 
  perfect 
  humerus, 
  J. 
  a. 
  6, 
  30, 
  

   "having 
  the 
  pneumatic 
  foramen 
  radially 
  situated 
  on 
  the 
  

   anterior 
  aspect 
  near 
  the 
  articular 
  surface/' 
  The 
  pneumatic 
  

   foramen 
  is, 
  however, 
  found 
  on 
  the 
  postaxial 
  side 
  posterior 
  

   surface 
  as 
  a 
  small 
  circular 
  hole 
  in 
  an 
  oval-shaped 
  depression. 
  

   On 
  its 
  distal 
  margin 
  it 
  is 
  worn 
  away, 
  but 
  the 
  foramen 
  can 
  be 
  

   well 
  determined. 
  In 
  J. 
  a. 
  6, 
  30 
  the 
  deltoid 
  crest 
  is 
  produced 
  

   obliquely 
  to 
  the 
  long 
  axis 
  of 
  the 
  condyle, 
  while 
  in 
  J. 
  «. 
  6, 
  25 
  

   it 
  is 
  nearly 
  a 
  right 
  angle 
  with 
  little 
  or 
  no 
  curve 
  until 
  its 
  

   termination 
  contiguous 
  to 
  the 
  preaxial 
  border 
  of 
  the 
  shaft. 
  

   In 
  J. 
  a. 
  6, 
  25 
  the 
  outer 
  surface 
  of 
  the 
  deltoid 
  crest 
  is 
  fiat. 
  

   As 
  the 
  crescent-shaped 
  condyle 
  in 
  this 
  specimen 
  has 
  a 
  

   greater 
  curve 
  than 
  that 
  of 
  the 
  other 
  examples 
  in 
  this 
  or 
  the 
  

   remaining 
  groups, 
  a 
  greater 
  convexity 
  is 
  found 
  on 
  the 
  dorsal 
  

   and 
  a 
  greater 
  concavity 
  on 
  the 
  ventral 
  margin. 
  J. 
  a. 
  6, 
  26 
  

   approaches 
  closely 
  in 
  character 
  to 
  J. 
  a. 
  6, 
  25 
  ; 
  but, 
  although 
  

   the 
  crest 
  is 
  carried 
  as 
  far 
  down 
  the 
  shaft 
  as 
  in 
  that 
  specimen, 
  

   it 
  is 
  produced 
  more 
  obliquely 
  to 
  the 
  long 
  axis 
  of 
  the 
  condyle, 
  

   recalling 
  J. 
  a. 
  6, 
  30 
  (Group 
  C) 
  in 
  that 
  respect 
  only. 
  

  

  * 
  ' 
  Oruithosauria,' 
  1870,. 
  p. 
  o9. 
  

  

  