﻿20 
  J. 
  W. 
  HTJXKE 
  ON 
  THE 
  ANATOMY 
  OF 
  HYPSILOPHODON 
  rOXII. 
  

  

  In 
  the 
  body 
  of 
  the 
  maxilla 
  above 
  the 
  third 
  to 
  sixth 
  tooth 
  is 
  a 
  large 
  

   subtriangular 
  gap 
  ; 
  it 
  is 
  the 
  aperture 
  between 
  the 
  orbit 
  and 
  external 
  

   nostril 
  seen 
  in 
  Mr. 
  Fox 
  s 
  skull. 
  Below 
  this, 
  and 
  extending 
  nearly 
  

   the 
  whole 
  length 
  of 
  the 
  bone, 
  the 
  outer 
  surface 
  of 
  the 
  maxilla 
  is 
  

   pierced 
  by 
  a 
  chain 
  of 
  conspicuous 
  foramina, 
  such 
  as 
  are 
  seen 
  in 
  the 
  

   maxillae 
  of 
  Megalosaurus 
  and 
  Teratosaurus. 
  

  

  The 
  divergence 
  of 
  the 
  maxillae 
  posteriorly 
  partially 
  exposes 
  the 
  

   palatal 
  apparatus, 
  the 
  hinder 
  part 
  of 
  which 
  lies 
  in 
  the 
  right 
  orbit. 
  

   The 
  pterygoids 
  (Pt, 
  Pt'), 
  not 
  mesially 
  joined, 
  but 
  separated 
  by 
  a 
  fissure, 
  

   have 
  a 
  remarkably 
  stout 
  body, 
  the 
  posterior 
  border 
  of 
  which 
  bears 
  a 
  

   very 
  large 
  basisphenoidal 
  process, 
  anteriorly 
  limited 
  by 
  a 
  prominent 
  

   ridge 
  produced 
  downwards, 
  and 
  terminating 
  angularly 
  at 
  the 
  mesial 
  

   border. 
  The 
  left 
  pterygoid 
  (Pt') 
  retains 
  the 
  root 
  of 
  a 
  strong 
  quadratic 
  

   process 
  directed 
  outwards 
  and 
  backwards, 
  in 
  front 
  of 
  which 
  the 
  hollow 
  

   outer 
  border 
  runs 
  out 
  in 
  an 
  ectopterygoid. 
  In 
  front 
  of 
  the 
  ptery- 
  

   goids 
  the 
  palatals 
  (PI, 
  PV) 
  are 
  partially 
  visible, 
  their 
  inner 
  borders 
  

   also 
  separated 
  by 
  a 
  fissure. 
  The 
  left 
  palatal, 
  which 
  is 
  best 
  seen, 
  is 
  a 
  

   flat 
  rod 
  -35 
  inch 
  wide, 
  with 
  (so 
  far 
  as 
  it 
  is 
  exposed) 
  parallel 
  margins. 
  

   Its 
  buccal 
  surface 
  is 
  longitudinally 
  grooved. 
  

  

  It 
  is 
  almost 
  superfluous 
  to 
  remark 
  that 
  the 
  skull 
  of 
  Hypsilophodori, 
  

   as 
  was. 
  indeed, 
  shown 
  by 
  Mr. 
  Fox's 
  specimen, 
  is 
  constructed 
  after 
  

   the 
  lacertilian 
  and 
  not 
  after 
  the 
  crocodilian 
  pattern. 
  In 
  this 
  respect, 
  

   so 
  far 
  as 
  the 
  material 
  allows 
  of 
  the 
  comparison 
  being 
  made, 
  it 
  agrees 
  

   with 
  the 
  large 
  skull 
  from 
  Brooke 
  which 
  I 
  brought 
  under 
  the 
  notice 
  

   of 
  the 
  Society 
  two 
  years 
  ago, 
  and 
  provisionally 
  referred 
  to 
  Iguanodon 
  

   Mantelli. 
  

  

  Spinal 
  Column 
  (fig. 
  2.) 
  — 
  Crossing 
  the 
  block 
  from 
  right 
  to 
  left, 
  at 
  a 
  

   little 
  distance 
  from 
  the 
  skull, 
  is 
  a 
  continuous 
  chain 
  of 
  eight 
  consecutive 
  

   vertebrae. 
  The 
  ventral 
  surface 
  of 
  the 
  centra 
  is 
  uppermost. 
  The 
  

   first 
  three 
  from 
  the 
  right 
  are 
  too 
  much 
  mutilated 
  for 
  description 
  ; 
  

   the 
  fourth 
  is 
  much 
  abraded, 
  the 
  fiftb 
  less 
  so 
  ; 
  but 
  the 
  sixth, 
  seventh, 
  

   and 
  eighth 
  are 
  sufficiently 
  preserved 
  to 
  exhibit 
  all 
  their 
  essential 
  

   characters. 
  These 
  three 
  last 
  centra 
  are 
  inseparably 
  anchylosed, 
  

   every 
  trace 
  of 
  their 
  primitive 
  separateness 
  (which 
  is 
  still 
  evident 
  

   between 
  each 
  of 
  the 
  central 
  (Is, 
  2s) 
  to 
  their 
  right) 
  has 
  quite 
  disap- 
  

   peared. 
  The 
  seventh 
  and 
  eighth 
  centra 
  are 
  further 
  distinguished 
  by 
  

   the 
  confluence 
  of 
  the 
  expanded 
  distal 
  ends 
  of 
  their 
  transverse 
  pro- 
  

   cesses. 
  These 
  two 
  marks 
  — 
  confluence 
  of 
  the 
  vertebral 
  centres 
  of 
  

   the 
  outer 
  ends 
  of 
  the 
  transverse 
  processes 
  — 
  make 
  it 
  certain 
  that 
  

   the 
  seventh 
  and 
  eighth 
  vertebrae 
  are 
  part 
  of 
  the 
  sacrum. 
  The 
  

   sixth 
  vertebra 
  (L) 
  has 
  distinct 
  transverse 
  processes 
  which 
  stand 
  out 
  

   from 
  the 
  neural 
  arch 
  in 
  the 
  form 
  of 
  flattened, 
  tapering 
  blades, 
  

   •4 
  inch 
  long. 
  Confluent 
  with 
  that 
  border 
  of 
  the 
  transverse 
  processes 
  

   furthest 
  from 
  the 
  sacrum, 
  at 
  their 
  union 
  with 
  the 
  neural 
  arch, 
  is 
  a 
  

   pair 
  of 
  articular 
  processes, 
  the 
  articulating 
  surfaces 
  of 
  which 
  have 
  an 
  

   upward 
  and 
  inward 
  aspect 
  ; 
  this 
  aspect 
  and 
  their 
  position 
  prove 
  

   them 
  to 
  be 
  j>rcezygapophyses 
  (Prz.). 
  A 
  vertebra 
  whose 
  centrum 
  has 
  

   coalesced 
  with 
  that 
  of 
  a 
  next 
  sacral, 
  which 
  yet 
  has 
  its 
  own 
  separate 
  

   transverse 
  processes, 
  and 
  also 
  whose 
  articular 
  processes 
  furthest 
  

   from 
  the 
  sacrum 
  bear 
  the 
  characters 
  of 
  ^#?zygapophyses, 
  must 
  

  

  