﻿PROF. 
  H. 
  G. 
  SEELEY 
  ON 
  THE 
  PELVIS 
  OF 
  ORNITHOPSIS. 
  395 
  

  

  is 
  the 
  same 
  kind 
  of 
  oblique 
  V-shaped 
  union 
  as 
  in 
  Ornitliopsis 
  Leedsii, 
  

   it 
  is 
  very 
  small 
  and 
  short, 
  so 
  that 
  the 
  bones 
  did 
  not 
  converge 
  towards 
  

   each 
  other 
  in 
  similar 
  curves. 
  The 
  antero-posterior 
  extension 
  of 
  these 
  

   pelvic 
  bones 
  in 
  the 
  symphysial 
  line 
  appears 
  to 
  me 
  to 
  have 
  been 
  

   relatively 
  greater 
  in 
  ( 
  Ornitliopsis) 
  Leedsii 
  than 
  in 
  Ornitliopsis 
  Hulhei. 
  

  

  These 
  species 
  may 
  be 
  further 
  compared 
  with 
  {Ornitliopsis) 
  

   oxoniensis. 
  In 
  relative 
  proportions 
  of 
  the 
  ischium 
  and 
  pubis 
  the 
  

   bones, 
  as 
  represented 
  in 
  Prof. 
  Phillips's 
  figure, 
  closely 
  correspond 
  

   with 
  the 
  Oxford-clay 
  species 
  ; 
  for, 
  though 
  there 
  is 
  a 
  comparatively 
  

   long 
  articular 
  head 
  to 
  the 
  pubis 
  as 
  well 
  as 
  the 
  ischium 
  (absent 
  from 
  

   the 
  Isle-of-Wight 
  fossil), 
  the 
  forms 
  and 
  proportions 
  of 
  both 
  sets 
  of 
  

   Oolitic 
  bones 
  are 
  otherwise 
  respectively 
  nearly 
  identical, 
  and 
  these 
  

   two 
  species 
  are 
  apparently 
  referable 
  to 
  one 
  genus. 
  It 
  is, 
  moreover, 
  

   interesting 
  that 
  the 
  ilium 
  of 
  (0.) 
  o.voniensis, 
  which 
  has 
  some 
  re- 
  

   semblance 
  to 
  the 
  ilium 
  of 
  Brontosaurus. 
  appears 
  to 
  have 
  been 
  pro- 
  

   longed 
  anteriorly 
  in 
  a 
  wedge-shaped 
  mass, 
  and 
  that 
  the 
  imperfectly 
  

   preserved 
  ilium 
  of 
  (0.) 
  Leedsii 
  appears 
  to 
  show 
  a 
  similar 
  character. 
  

   But 
  the 
  ilium 
  of 
  Ornitliopsis 
  Hulhei 
  is 
  not 
  known, 
  and 
  the 
  nearly 
  

   equal 
  size 
  in 
  that 
  species 
  of 
  pubis 
  and 
  ischium, 
  seem, 
  with 
  the 
  other 
  

   differences 
  pointed 
  out, 
  to 
  justify 
  a 
  suspension 
  of 
  judgment 
  as 
  to 
  its 
  

   generic 
  identity 
  with 
  the 
  closely 
  allied 
  fossils 
  from 
  older 
  strata 
  ; 
  for 
  

   the 
  slender 
  ischia 
  give 
  a 
  good 
  character 
  for 
  generic 
  separation 
  when 
  

   compared 
  with 
  the 
  expanded 
  ischium 
  of 
  Ornitliopsis 
  Hidhei. 
  

  

  At 
  the 
  Bath 
  Meeting 
  of 
  the 
  British 
  Association 
  Professor 
  Marsh 
  

   expressed 
  the 
  belief 
  that 
  Ornitliopsis 
  held 
  a 
  systematic 
  position 
  

   midway 
  between 
  Morosaurus 
  and 
  Diplodocus. 
  I 
  have 
  unfortunately 
  

   no 
  means 
  of 
  forming 
  an 
  independent 
  opinion. 
  But 
  Professor 
  Marsh 
  

   defines 
  the 
  shaft 
  of 
  the 
  ischium 
  in 
  Diplodocus 
  as 
  not 
  twisted, 
  and 
  states 
  

   that 
  it 
  " 
  is 
  directed 
  downward 
  and 
  backward 
  with 
  the 
  ends 
  meeting 
  

   on 
  the 
  median 
  line 
  "*. 
  I 
  fail 
  to 
  recognize 
  in 
  the 
  condition 
  here 
  

   represented 
  any 
  approximation 
  to 
  the 
  description 
  of 
  Diplodocus. 
  

   The 
  description 
  of 
  Morosaurus 
  seems 
  to 
  me 
  closely 
  to 
  approximate 
  

   to 
  the 
  Ornithopsoid 
  reptiles 
  from 
  the 
  Forest 
  Marble 
  and 
  Oxford 
  

   Clay, 
  while 
  there 
  is 
  much 
  to 
  be 
  said 
  in 
  favour 
  of 
  the 
  view 
  of 
  

   Mr. 
  Hulke 
  that 
  Ornitliopsis 
  Hulhei 
  approximates 
  to 
  Atlantosaurus. 
  

   I 
  hesitate 
  to 
  formulate 
  the 
  inference 
  of 
  generic 
  distinction 
  

   between 
  these 
  Wealden 
  and 
  Oolitic 
  reptiles 
  from 
  these 
  resemblances 
  

   to 
  American 
  types 
  until 
  it 
  is 
  shown 
  that 
  the 
  American 
  genera 
  all 
  

   have 
  the 
  pubic 
  bones 
  united 
  by 
  a. 
  long 
  median 
  symphysis 
  as 
  in 
  

   these 
  British 
  types, 
  which 
  probably 
  belong 
  to 
  closely 
  allied 
  genera, 
  

   although 
  they 
  may 
  be 
  more 
  distinct 
  from 
  each 
  other 
  than 
  are 
  

   Morosaurus 
  and 
  Atlantosaurus, 
  The 
  nature 
  of 
  the 
  relation 
  between 
  

   the 
  three 
  British 
  types 
  may 
  be 
  better 
  gathered 
  from 
  the 
  accompany- 
  

   ing 
  figures 
  of 
  the 
  pelvic 
  bones 
  (p. 
  392). 
  

  

  After 
  the 
  bones 
  of 
  (Ornitliopsis) 
  Leedsii 
  had 
  been 
  put 
  together 
  in 
  

  

  their 
  natural 
  anatomical 
  relations, 
  Mr. 
  Alfred 
  N. 
  Leeds 
  made 
  a 
  

  

  model 
  of 
  them 
  in 
  pasteboard 
  ; 
  and 
  I 
  now 
  submit 
  a 
  slightly 
  restored 
  

  

  model 
  of 
  these 
  bones, 
  which 
  I 
  think 
  serves 
  to 
  establish 
  the 
  generic 
  

  

  * 
  American 
  Journal 
  of 
  Science, 
  vol. 
  xxvii., 
  Feb. 
  1884. 
  

  

  