﻿396 
  PROF. 
  H. 
  G. 
  SEELF.T 
  OX 
  THE 
  PELVIS 
  OF 
  OEXIIHOPSI3. 
  

  

  distinction 
  of 
  this 
  type 
  from 
  the 
  American 
  genus 
  Morosaurus*, 
  and 
  

   to 
  show 
  that 
  Brontosaurus 
  cannot 
  be 
  identified 
  with 
  it, 
  although 
  

   there 
  is 
  some 
  resemblance 
  to 
  that 
  genus 
  in 
  the 
  ilium 
  and 
  pubis. 
  

  

  Discrssiox. 
  

  

  Mr. 
  Ltdeeker 
  observed 
  that 
  the 
  identification 
  by 
  Prof. 
  Seeley 
  of 
  

   the 
  proper 
  ventral 
  and 
  dorsal 
  surfaces 
  of 
  the 
  pelvis 
  of 
  Ornithopsis 
  

   was 
  of 
  considerable 
  importance, 
  since 
  it 
  removed 
  all 
  objections 
  which 
  

   had 
  been 
  raised 
  as 
  to 
  the 
  close 
  affinity 
  between 
  that 
  form 
  and 
  the 
  

   American 
  Brontosaurus. 
  &c., 
  which 
  he 
  had 
  always 
  believed 
  to 
  be 
  

   closely 
  related. 
  

  

  He 
  was 
  unable, 
  however, 
  to 
  assent 
  to 
  the 
  amalgamation 
  of 
  Cetio- 
  

   saurus 
  and 
  Ornithopsis 
  which 
  the 
  Author 
  appeared 
  to 
  suggest, 
  the 
  

   difference 
  in 
  the 
  pelvis 
  of 
  the 
  two 
  forms 
  indicating 
  a 
  character 
  of 
  

   at 
  least 
  generic 
  value. 
  

  

  The 
  speaker 
  had 
  already 
  pointed 
  out 
  the 
  resemblance 
  of 
  the 
  pelvis 
  

   of 
  Cetiosaurus 
  oxoniensis 
  to 
  that 
  of 
  Morosaurus, 
  and 
  he 
  was 
  glad 
  to 
  

   observe 
  that 
  Prof. 
  Seeley 
  agreed 
  with 
  him 
  in 
  this 
  respect. 
  

  

  "With 
  regard 
  to 
  nomenclature, 
  after 
  alluding 
  to 
  his 
  previous 
  state- 
  

   ment 
  that 
  he 
  believed 
  the 
  name 
  Cetiosaurus 
  ought 
  to 
  yield 
  to 
  the 
  

   earlier 
  Cardiodon, 
  Mr. 
  Lydekker 
  observed 
  that 
  he 
  had 
  two 
  days 
  ago 
  

   received 
  a 
  letter 
  from 
  Dr. 
  Baur, 
  pointing 
  out 
  to 
  him 
  that 
  the 
  tooth 
  

   from 
  the 
  Wealden 
  originally 
  figured 
  by 
  Dr. 
  Wright 
  had 
  been 
  named, 
  

   in 
  1852, 
  JEToplosaurus 
  t 
  armatus. 
  The 
  speaker 
  had 
  suggested 
  that 
  

   this 
  tooth 
  really 
  belonged 
  to 
  Ornithopsis, 
  and 
  Prof. 
  Seeley 
  had 
  re- 
  

   garded 
  this 
  suggestion 
  as 
  a 
  certainty. 
  Under 
  this 
  circumstance 
  

   there 
  was 
  no 
  question 
  but 
  that, 
  if 
  the 
  two 
  are 
  really 
  identical, 
  the 
  

   name 
  Ornithopsis 
  must 
  yield 
  place 
  to 
  the 
  much 
  earlier 
  Hoplosaurus, 
  

   even 
  if 
  the 
  latter 
  had 
  not 
  to 
  give 
  way 
  to 
  the 
  still 
  earlier 
  Pelorosaurus. 
  

   It 
  was 
  curious, 
  after 
  the 
  complex 
  synonymy, 
  to 
  find 
  that 
  both 
  the 
  

   Wealden 
  Hoplosaurus 
  ('? 
  OmitTiopsis) 
  and 
  the 
  Lower 
  Jurassic 
  Car- 
  

   diodon 
  (? 
  Cetiosaurus) 
  were 
  both 
  based 
  on 
  the 
  evidence 
  of 
  teeth, 
  and 
  

   were 
  therefore 
  strictly 
  comparable. 
  

  

  Air. 
  Leeds 
  considered 
  that 
  Prof. 
  Seeley 
  had 
  given 
  the 
  correct 
  in- 
  

   terpretation 
  about 
  these 
  bones. 
  

  

  Prof. 
  Seeley 
  said 
  his 
  thanks 
  were 
  due 
  to 
  lL"r. 
  Alfred 
  X. 
  Leeds 
  

   for 
  the 
  opportunity 
  of 
  clearing 
  up 
  the 
  structure 
  of 
  the 
  Saurischian 
  

   pelvis. 
  He 
  was 
  not 
  aware 
  that 
  the 
  structures 
  now 
  described 
  had 
  

   been 
  previously 
  recognized 
  by 
  any 
  other 
  observer. 
  He 
  had 
  en- 
  

   deavoured 
  in 
  his 
  paper 
  to 
  make 
  it 
  clear 
  that 
  while 
  on 
  the 
  one 
  hand 
  

  

  * 
  Since 
  writing 
  the 
  note 
  on 
  Jristosuchus 
  pusillus 
  (Quart. 
  Journ. 
  Geol. 
  Soc. 
  

   vol. 
  xliii. 
  May 
  1357) 
  I 
  have 
  been 
  led 
  to 
  notice 
  that 
  the 
  position 
  of 
  the 
  pelvic 
  

   bones 
  in 
  relation 
  to 
  the 
  sacrum 
  gives 
  grounds 
  for 
  suspecting 
  that 
  the 
  bone 
  there 
  

   regarded 
  as 
  pubis 
  is 
  likely 
  to 
  be 
  an 
  ischium, 
  notwithstanding 
  its 
  resemblance 
  in 
  

   form 
  to 
  the 
  pubis 
  in 
  some 
  American 
  genera. 
  Professor 
  Marsh's 
  figure 
  of 
  Cera- 
  

   tosanrus 
  shows 
  that 
  the 
  ischium 
  may 
  have 
  an 
  anterior 
  syruphysial 
  expansion, 
  like 
  

   the 
  posterior 
  expansion 
  of 
  the 
  pubis 
  in 
  that 
  genus 
  and 
  other 
  types. 
  Whether 
  

   Jristosuchus 
  may 
  have 
  had 
  cervical 
  vertebrae 
  like 
  that 
  which 
  I 
  provisionally 
  

   referred 
  to 
  Tkecospowdylus 
  (Quart. 
  Journ. 
  Geol. 
  Soc, 
  Feb. 
  1888) 
  may 
  deserve 
  

   consideration. 
  

  

  t 
  Originally 
  Oplosaurus. 
  

  

  