﻿42 
  ME. 
  R. 
  EYDEKEER 
  ON 
  THE 
  REMAINS 
  AND 
  AFFINITIES 
  

  

  Syngonosaurus, 
  although 
  he 
  suggests 
  affinity 
  to 
  another 
  Cambridge 
  

   form 
  described 
  in 
  the 
  same 
  paper 
  under 
  the 
  name 
  of 
  Eucercosmrus. 
  

   The 
  caudals 
  of 
  the 
  latter 
  are, 
  however, 
  stated 
  to 
  show 
  some 
  resem- 
  

   blance 
  to 
  those 
  of 
  Hylceosaurus, 
  but 
  the 
  dorsals 
  are 
  compared 
  with 
  

   those 
  of 
  the 
  Iguanodonts. 
  In 
  the 
  absence 
  of 
  figures 
  it 
  seems 
  diffi- 
  

   cult 
  to 
  see 
  how 
  the 
  dorsals 
  described 
  as 
  Eacercosaurus 
  differ 
  from 
  

   those 
  of 
  Syngonosaurus. 
  

  

  In 
  recently 
  looking 
  through 
  a 
  number 
  of 
  undetermined 
  specimens 
  

   from 
  the 
  Cambridge 
  Greensand 
  in 
  the 
  British 
  Museum, 
  I 
  noticed 
  

   four 
  imperfect 
  dorsal 
  vertebras 
  (Xo. 
  R. 
  460) 
  of 
  a 
  comparatively 
  

   small 
  Dinosaur, 
  all 
  of 
  which 
  were 
  obtained 
  at 
  the 
  same 
  time 
  and 
  

   are 
  probably 
  associated. 
  One 
  of 
  these 
  vertebras 
  has 
  been 
  fractured 
  

   transversely, 
  and 
  on 
  polishing 
  the 
  broken 
  surfaces 
  of 
  the 
  centrum 
  

   there 
  appeared 
  to 
  be 
  a 
  median 
  cavity 
  suggesting 
  Theropodous 
  

   affinities 
  ; 
  on 
  cutting 
  longitudinally 
  a 
  second 
  centrum 
  it 
  appeared, 
  

   however, 
  that 
  the 
  supposed 
  cavity 
  was 
  merely 
  due 
  to 
  decay, 
  and 
  that 
  

   the 
  centrum 
  consisted 
  internally 
  of 
  the 
  coarse 
  cancellous 
  structure 
  

   found 
  in 
  the 
  Ornithopoda 
  (in 
  which 
  group 
  I 
  include 
  the 
  Stegosauria 
  

   of 
  Professor 
  Marsh). 
  

  

  The 
  two 
  best-preserved 
  specimens 
  respectively 
  correspond 
  so 
  

   closely 
  with 
  Prof. 
  Seeley's 
  description 
  of 
  the 
  anterior 
  and 
  later 
  

   dorsals 
  of 
  Syngonosaurus, 
  that 
  I 
  should 
  have 
  had 
  no 
  hesitation 
  in 
  

   referring 
  them 
  to 
  that 
  form, 
  were 
  it 
  not 
  for 
  the 
  difficulty 
  I 
  find 
  in 
  

   distinguishing 
  the 
  dorsals 
  of 
  the 
  latter 
  from 
  those 
  described 
  as 
  

   Eucercosaurus. 
  I 
  will, 
  however, 
  provisionally 
  regard 
  them 
  as 
  refer- 
  

   able 
  to 
  the 
  former 
  genus, 
  and 
  I 
  bring 
  them 
  to 
  the 
  notice 
  of 
  the 
  

   Society 
  because 
  they 
  appear 
  to 
  me 
  to 
  afford 
  fairly 
  sufficient 
  evidence 
  

   as 
  to 
  the 
  approximate 
  serial 
  position 
  of 
  that 
  genus. 
  The 
  anterior 
  

   dorsal 
  has 
  the 
  triangular 
  terminal 
  faces 
  and 
  strongly 
  marked 
  haemal 
  

   ridge 
  characteristic 
  of 
  the 
  type 
  specimens 
  : 
  the 
  length 
  of 
  the 
  cen- 
  

   trum 
  being 
  1-45 
  inch, 
  and 
  its 
  width 
  superiorly 
  1-3 
  inch. 
  The 
  arch 
  

   is 
  too 
  much 
  damaged 
  for 
  description. 
  

  

  In 
  the 
  later 
  and 
  probably 
  middle 
  dorsal 
  (fig. 
  1) 
  the 
  greater 
  part 
  

   of 
  the 
  arch 
  is 
  preserved, 
  but 
  the 
  centrum 
  is 
  somewhat 
  damaged 
  

   anteriorly, 
  and 
  has 
  been 
  restored 
  in 
  the 
  figure 
  from 
  another 
  speci- 
  

   men. 
  The 
  length 
  of 
  the 
  centrum 
  is 
  approximately 
  1*6 
  inch, 
  and 
  the 
  

   height 
  to 
  the 
  summit 
  of 
  the 
  neural 
  platform 
  2-5 
  inches. 
  The 
  lateral 
  

   surfaces 
  of 
  the 
  centrum 
  are 
  flattened 
  and 
  somewhat 
  depressed, 
  the 
  

   terminal 
  faces 
  have 
  an 
  approximation 
  to 
  a 
  triangular 
  contour, 
  the 
  

   neural 
  arch 
  is 
  tall, 
  and 
  the 
  haemal 
  ridge 
  absent. 
  The 
  most 
  im- 
  

   portant 
  features 
  of 
  the 
  vertebra 
  are, 
  however, 
  to 
  be 
  found 
  in 
  the 
  

   neural 
  arch. 
  The 
  base 
  of 
  the 
  broken 
  transverse 
  process 
  is 
  clearly 
  

   shown, 
  but 
  neither 
  in 
  front 
  of 
  this, 
  nor 
  below 
  it 
  on 
  the 
  anterior 
  

   border 
  of 
  the 
  arch, 
  is 
  there 
  any 
  trace 
  of 
  a 
  rib-facet, 
  thus 
  clearly 
  

   showing 
  that 
  the 
  head 
  of 
  the 
  rib 
  articulated 
  with 
  a 
  " 
  step 
  " 
  on 
  the 
  

   transverse 
  process, 
  as 
  in 
  Crocodiles. 
  This 
  negative 
  feature 
  being 
  

   also 
  shown 
  in 
  the 
  anterior 
  dorsal, 
  and 
  in 
  all 
  of 
  the 
  type 
  specimens, 
  

   is 
  evidently 
  constant 
  throughout 
  the 
  dorsal 
  series. 
  Another 
  marked 
  

   feature 
  is 
  the 
  absence 
  of 
  a 
  deep 
  fossa 
  immediately 
  in 
  advance 
  of 
  

   the 
  postzygapophysis. 
  

  

  