﻿532 
  Ml-. 
  R. 
  W. 
  Hooley 
  on 
  the 
  

  

  included 
  the 
  greater 
  portion 
  of 
  tlie 
  binder 
  part 
  of 
  the 
  sluill 
  

   of 
  Ornithostoma 
  (Fteranodon) 
  , 
  from 
  tlie 
  posterior 
  moiety 
  of 
  

   the 
  orbits 
  to 
  the 
  occiput, 
  sbowing 
  tbe 
  base 
  of 
  a 
  true 
  and 
  

   powerful 
  supraoccipital 
  crest. 
  This 
  interesting 
  fossil 
  he 
  

   described 
  and 
  figured 
  * 
  as 
  the 
  orbito-ethmoid-splienoid 
  bone. 
  

   The 
  taldet 
  J. 
  c. 
  9, 
  upon 
  which 
  this 
  specimen 
  is 
  mounted, 
  

   has 
  been 
  labelled 
  " 
  Ethmoid 
  with 
  basisphenoid.''' 
  An 
  ink- 
  

   line 
  has 
  since 
  been 
  drawn 
  through 
  this, 
  and 
  someone 
  has 
  

   written 
  " 
  Parietal 
  with 
  supra-occipital.'' 
  A 
  cast 
  in 
  wax 
  of 
  

   the 
  aspect 
  shown 
  in 
  Seeley's 
  fig. 
  9 
  is 
  also 
  on 
  the 
  tablet 
  

   marked 
  '* 
  cerebral 
  hemispheres 
  and 
  pineal 
  body.'' 
  In 
  

   pi. 
  xi. 
  fig. 
  8 
  * 
  the 
  left 
  side 
  is 
  shown. 
  As 
  the 
  bone 
  is 
  figured, 
  

   the 
  occi[)ut 
  is 
  horizontal, 
  whereas 
  it 
  should 
  be 
  oblique. 
  

   'Ihe 
  hinder 
  border 
  of 
  the" 
  orbit 
  is 
  seen 
  on 
  the 
  left 
  upper 
  half 
  

   of 
  the 
  bone. 
  The 
  base 
  of 
  the 
  supraoccipital 
  crest 
  extends 
  

   from 
  the 
  top 
  right-hand 
  corner 
  of 
  the 
  figure 
  to 
  the 
  emar- 
  

   gination 
  near 
  the 
  lower. 
  Fig. 
  7 
  ^ 
  is 
  a 
  portion 
  of 
  the 
  occiput 
  

   placed 
  upside 
  down. 
  The 
  indentation 
  in 
  the 
  upper 
  border 
  

   of 
  the 
  figure 
  is 
  the 
  dorsal 
  half 
  of 
  the 
  foramen 
  magnum, 
  

   while 
  the 
  two 
  foramina 
  on 
  either 
  side 
  below 
  are 
  the 
  post- 
  

   tempoi-al 
  fossae 
  [cf. 
  PI. 
  XXII. 
  fig. 
  2). 
  The 
  hinder 
  moieties 
  of 
  

   the 
  orbits 
  are 
  preserved, 
  and 
  are 
  exhibited 
  in 
  fig. 
  9, 
  pi. 
  xi. 
  

   In 
  Seeley's 
  explanation 
  of 
  the 
  figure 
  they 
  are 
  called 
  ''the 
  cups 
  

   which 
  covered 
  the 
  anterior 
  termination 
  of 
  the 
  cerebral 
  lobes." 
  

   The 
  cerebral 
  hemispheres 
  are 
  not 
  exposed 
  at 
  all. 
  The 
  

   frontal 
  bone 
  immediately 
  posterior 
  to 
  tlie 
  orbits 
  is 
  greatly 
  

   compressed, 
  beconiinga 
  deep 
  strong 
  keel, 
  which 
  intensifies 
  in 
  

   the 
  parietal 
  region. 
  Here, 
  where 
  it 
  meets 
  the 
  upper 
  border 
  

   of 
  the 
  occi])ital 
  plane, 
  it 
  shows 
  the 
  base 
  of 
  a 
  crest 
  which 
  is 
  

   destroyed, 
  but, 
  from 
  the 
  section 
  of 
  the 
  bone, 
  it 
  was 
  deep 
  and 
  

   rol)ust 
  and 
  produced 
  far 
  beyond 
  the 
  occiput, 
  as 
  in 
  Ornitho- 
  

   stoma 
  {Pteranodon) 
  (PI. 
  XXII. 
  fig. 
  1). 
  It 
  has 
  no 
  connection 
  

   with 
  the 
  occiput, 
  which 
  lies 
  below 
  it. 
  The 
  occipital 
  area 
  

   preserved 
  is 
  small 
  and 
  triangular. 
  There 
  is 
  a 
  strong 
  median 
  

   vertical 
  ridge 
  to 
  the 
  foramen 
  magnum, 
  on 
  either 
  side 
  of 
  

   which 
  the 
  surface 
  is 
  concave. 
  In 
  the 
  centre 
  of 
  these 
  

   surfaces, 
  slightly 
  above 
  the 
  level 
  of 
  the 
  foramen, 
  are 
  the 
  

   post-temporal 
  fossae, 
  which 
  are 
  small 
  and 
  subcircular. 
  The 
  

   skull 
  below 
  the 
  dorscil 
  half 
  of 
  tlie 
  foramen 
  magnum 
  is 
  

   destroyed. 
  

  

  The 
  back 
  of 
  the 
  skull 
  J. 
  c. 
  8, 
  2 
  is 
  the 
  type 
  of 
  Ornitho- 
  

   cheirus, 
  and 
  J*, 
  c. 
  9 
  belongs 
  to 
  OrnitJiostoma 
  {Pteranodon) 
  , 
  

   and 
  the 
  two 
  genera 
  are 
  totally 
  distinct, 
  as 
  the 
  muzzles 
  also 
  

   prove. 
  The 
  genus 
  Ornithoc/ieirus 
  has 
  been 
  given 
  all 
  the 
  

  

  * 
  II. 
  G. 
  Sueley, 
  ' 
  Oruithosauria,' 
  1S70, 
  pp. 
  So, 
  86, 
  pi. 
  xi. 
  figs. 
  7-9. 
  

  

  