﻿•58 
  ME. 
  E. 
  LYDEKKEE 
  ON 
  THE 
  EEMAINS 
  AND 
  AEEINITIES 
  

  

  whether 
  it 
  should 
  remain 
  in 
  the 
  same 
  family 
  cannot 
  be 
  determined 
  

   until 
  the 
  characters 
  of 
  the 
  skull 
  are 
  fully 
  known. 
  

  

  Before 
  leaving 
  this 
  subject 
  it 
  is 
  well 
  to 
  call 
  attention 
  to 
  the 
  cir- 
  

   cumstance 
  of 
  the 
  absence 
  of 
  dermal 
  scutes 
  in 
  this 
  group 
  of 
  Croco- 
  

   diles 
  being 
  accompanied 
  by 
  the 
  development 
  of 
  sclerotic 
  plates, 
  

   although 
  I 
  am 
  unable 
  at 
  present 
  to 
  assign 
  any 
  reason 
  for 
  this 
  

   correlation. 
  

  

  EXPLANATION 
  OF 
  PLATE 
  II. 
  

  

  Peloneustes 
  pkilarckus 
  (Seeley), 
  from 
  the 
  Oxford 
  Clay 
  near 
  Bedford. 
  

  

  Fig. 
  1. 
  Palatal 
  aspect 
  of 
  greater 
  part 
  of 
  mandible. 
  ^ 
  nat. 
  size. 
  

  

  2. 
  Posterior 
  aspect 
  of 
  centrum 
  of 
  caudal 
  vertebra, 
  c. 
  Chevron- 
  facet. 
  Nat. 
  

  

  size. 
  

  

  3. 
  Terminal 
  aspect 
  of 
  imperfect 
  pectoral 
  or 
  lumbar 
  vertebra. 
  Nat. 
  size. 
  

  

  Discussion. 
  

  

  Prof. 
  Seeley 
  remarked 
  that 
  the 
  difficulties 
  presented 
  by 
  such 
  

   materials 
  as 
  were 
  before 
  the 
  Society 
  would 
  justify 
  great 
  caution 
  in 
  

   accepting 
  the 
  interpretation 
  offered, 
  and 
  he 
  was 
  not 
  prepared 
  to 
  

   offer 
  serious 
  criticisms 
  without 
  having 
  the 
  materials 
  before 
  him 
  on 
  

   which 
  they 
  might 
  be 
  based. 
  It 
  was 
  probable 
  that 
  Syngonosaurus, 
  

   formerly 
  referred 
  to 
  the 
  Dinosauria, 
  belonged 
  to 
  the 
  group 
  which 
  

   he 
  preferred 
  to 
  name 
  Ornithischia. 
  He 
  was 
  glad 
  to 
  find 
  that 
  the 
  

   Author 
  was 
  disposed 
  to 
  separate 
  the 
  Iguanodon 
  Prestwichii 
  from 
  the 
  

   genus 
  to 
  which 
  it 
  had 
  been 
  referred. 
  If 
  the 
  femur 
  of 
  which 
  a 
  cast 
  

   was 
  exhibited 
  was 
  referable 
  to 
  the 
  same 
  species, 
  it 
  fully 
  justified 
  

   that 
  conclusion 
  ; 
  but 
  nothing 
  was 
  known 
  of 
  the 
  femur 
  of 
  Campto- 
  

   saurus 
  from 
  specimens 
  in 
  this 
  country, 
  and 
  he 
  would 
  only 
  mention 
  

   the 
  opinion 
  given 
  generally 
  by 
  Prof. 
  Marsh 
  that 
  no 
  American 
  genus 
  

   of 
  Reptiles 
  could 
  be 
  with 
  certainty 
  identified 
  as 
  occurring 
  in 
  

   Britain. 
  He 
  thought 
  the 
  characters 
  which 
  had 
  been 
  pointed 
  out 
  

   made 
  it 
  convenient 
  to 
  refer 
  the 
  type 
  of 
  Iguanodon 
  Prestwichii 
  to 
  

   the 
  genus 
  Cumnoria. 
  

  

  The 
  Plesiosaurians 
  were 
  first 
  divided 
  by 
  Cope 
  into 
  two 
  families 
  

   on 
  characters 
  drawn 
  from 
  the 
  shoulder-girdle. 
  Prof. 
  Seeley 
  had 
  

   found 
  further 
  modifications 
  in 
  the 
  Eeptiles 
  of 
  this 
  country 
  to 
  which 
  

   generic 
  names 
  had 
  been 
  given, 
  because 
  the 
  vertebral 
  column, 
  the 
  

   limbs, 
  and, 
  in 
  some 
  cases, 
  the 
  skull 
  furnished 
  confirmation 
  of 
  their 
  

   generic 
  differences. 
  He 
  might 
  remark 
  that, 
  after 
  studying 
  the 
  

   types 
  of 
  Yon 
  Meyer's 
  genus 
  Thaumatosaurus, 
  he 
  was 
  convinced 
  that 
  

   both 
  in 
  the 
  teeth 
  and 
  in 
  the 
  vertebral 
  characters 
  it 
  is 
  identical 
  with 
  

   Pliosaurus. 
  But 
  Pliosaurus 
  varied 
  so 
  much 
  in 
  its 
  different 
  repre- 
  

   sentatives 
  that 
  he 
  was 
  not 
  prepared 
  to 
  say 
  that 
  every 
  Pliosaurian 
  

   reptile 
  belonged 
  to 
  the 
  genus 
  Pliosaurus. 
  Whether 
  the 
  genus 
  Pelo- 
  

   neustes 
  was 
  distinct 
  from 
  types 
  already 
  described 
  might 
  require 
  

   consideration, 
  but 
  he 
  believed 
  that 
  farther 
  research 
  would 
  sustain 
  

   the 
  genera 
  of 
  Plesiosaurians 
  which 
  he 
  had 
  already 
  established. 
  

  

  The 
  Autbioe, 
  in 
  reply, 
  observed 
  that, 
  immediately 
  before 
  departing 
  

   for 
  America, 
  Prof. 
  Marsh 
  informed 
  him 
  that 
  he 
  regarded 
  certain 
  

  

  