﻿ON 
  THE 
  REMAINS 
  AND 
  AFFINITIES 
  OF 
  MESOZOIC 
  REPTILES. 
  41 
  

  

  2. 
  On 
  ^Remains 
  and 
  Affinities 
  of 
  five 
  Genera 
  of 
  Mesozoic 
  R,ep- 
  

  

  tiles. 
  By 
  R. 
  Lydekker, 
  Esq., 
  B.A., 
  E.G.S. 
  (Head 
  November 
  21, 
  

  

  188S.) 
  

  

  [Plate 
  II.] 
  

  

  Introductory. 
  

  

  The 
  following 
  communication 
  treats 
  of 
  certain 
  remains 
  referred 
  to 
  

   four 
  species 
  of 
  English 
  Mesozoic 
  Reptiles, 
  some 
  of 
  which 
  were 
  first 
  

   described 
  or 
  named 
  by 
  Professor 
  H. 
  G. 
  Seeley, 
  and 
  also 
  includes 
  

   a 
  discussion 
  as 
  to 
  the 
  affinities 
  of 
  a 
  fifth 
  form. 
  The 
  substance 
  of 
  

   that 
  portion 
  of 
  the 
  paper 
  relating 
  to 
  Peloneustes 
  pTiilarchus 
  was 
  pre- 
  

   viously 
  brought 
  under 
  the 
  notice 
  of 
  the 
  Society 
  at 
  the 
  Meeting 
  held 
  

   on 
  May 
  23rd 
  as 
  a 
  separate 
  communication, 
  entitled 
  " 
  On 
  the 
  Skeleton 
  

   of 
  a 
  Sauropterygian 
  from 
  the 
  Oxford 
  Clay 
  near 
  Bedford 
  " 
  *, 
  but, 
  on 
  

   account 
  of 
  a 
  change 
  of 
  view 
  on 
  the 
  part 
  of 
  the 
  Author, 
  it 
  was 
  con- 
  

   sidered 
  advisable 
  that 
  it 
  should 
  be 
  again 
  presented 
  in 
  a 
  revised 
  

   form. 
  

  

  I. 
  Vertebra 
  of 
  an 
  Ornithopobous 
  Dinosaur 
  from 
  the 
  

   Cambridge 
  Greensand. 
  

  

  On 
  page 
  621 
  of 
  a 
  memoir 
  on 
  the 
  remains 
  of 
  Dinosaurs 
  from 
  the 
  

   Cambridge 
  Greensand, 
  published 
  in 
  the 
  35th 
  volume 
  of 
  the 
  Society's 
  

   ' 
  Journal,' 
  Professor 
  Seeley 
  applied 
  the 
  name 
  Si/ngonosaurus 
  macro- 
  

   cercus 
  to 
  a 
  series 
  of 
  nineteen 
  vertebras 
  from 
  the 
  cervical, 
  dorsal, 
  

   sacral, 
  and 
  caudal 
  regions, 
  which 
  were 
  said 
  to 
  be 
  associated, 
  and 
  

   indicate 
  a 
  medium-sized 
  species. 
  At 
  the 
  conclusion 
  of 
  the 
  descrip- 
  

   tion 
  of 
  these 
  vertebras 
  mention 
  is 
  also 
  made 
  of 
  certain 
  dermal 
  

   scutes, 
  which 
  it 
  was 
  suggested 
  might 
  also 
  be 
  associated. 
  I 
  have 
  no 
  

   intention 
  of 
  entering 
  into 
  the 
  question 
  whether 
  the 
  alleged 
  associa- 
  

   tion 
  of 
  all 
  these 
  remains 
  is 
  absolutely 
  certain, 
  and 
  I 
  shall 
  accord- 
  

   ingly 
  confine 
  my 
  remarks 
  to 
  the 
  one 
  cervical 
  and 
  eight 
  dorsal 
  

   vertebras, 
  which, 
  as 
  being 
  the 
  first 
  described 
  (although 
  not 
  figured), 
  

   may, 
  I 
  presume, 
  be 
  regarded 
  as 
  the 
  types. 
  

  

  All 
  the 
  dorsals 
  are 
  amphiccelous, 
  and 
  characterized 
  by 
  their 
  

   compressed 
  centra 
  to 
  which 
  the 
  arches 
  are 
  firmly 
  united, 
  the 
  

   absence 
  of 
  rib-facets 
  on 
  the 
  arches, 
  and 
  the 
  height 
  of 
  the 
  neural 
  

   canal. 
  In 
  the 
  four 
  anterior 
  dorsals 
  the 
  centrum 
  is 
  comparatively 
  

   short, 
  with 
  triangular 
  terminal 
  faces 
  and 
  a 
  sharp 
  hasmal 
  ridge 
  ; 
  

   while 
  in 
  the 
  four 
  later 
  ones 
  the 
  centrum 
  is 
  longer, 
  the 
  haemal 
  ridge 
  

   disappears 
  more 
  or 
  less 
  completely, 
  being 
  represented 
  by 
  a 
  tubercle 
  

   at 
  either 
  end 
  f 
  , 
  and 
  the 
  terminal 
  faces 
  are 
  less 
  triangular. 
  In 
  the 
  

   anterior 
  dorsals 
  the 
  length 
  of 
  the 
  centrum 
  varies 
  from 
  1*5 
  to 
  1*7 
  

   inch 
  ; 
  while 
  in 
  the 
  first 
  of 
  the 
  four 
  later 
  ones 
  this 
  length 
  is 
  1*75, 
  

   and 
  the 
  height 
  from 
  the 
  base 
  of 
  the 
  centrum 
  to 
  the 
  summit 
  of 
  the 
  

   neural 
  platform 
  2" 
  5 
  inches. 
  

  

  Prof. 
  Seeley 
  makes 
  no 
  attempt 
  to 
  determine 
  the 
  serial 
  position 
  of 
  

  

  * 
  Proc. 
  Geol. 
  Soc. 
  1888, 
  p. 
  89. 
  

  

  t 
  I 
  take 
  the 
  character 
  from 
  page 
  621 
  of 
  Prof. 
  Seeley's 
  memoir 
  ; 
  there 
  is 
  

   some 
  discrepancy 
  with 
  this 
  on 
  p. 
  623. 
  

  

  