﻿- 
  Or/iiliosaurian 
  Genus 
  Oniitlioclieinis. 
  531 
  

  

  minatiou 
  *. 
  An 
  examination 
  of 
  this 
  specimen 
  shows 
  that 
  

   the 
  bone 
  at 
  the 
  junction 
  of 
  the 
  parietal 
  and 
  occipital 
  regions 
  

   is 
  raised 
  into 
  a 
  ridge, 
  which 
  is 
  continued 
  laterally, 
  forming 
  

   tlie 
  margin 
  of 
  the 
  hinder 
  border 
  of 
  the 
  supratemporal 
  fossa\ 
  

   Tliis 
  edge 
  is 
  much 
  worn, 
  but 
  it 
  is 
  clear 
  that 
  it 
  was 
  jjroduccd 
  

   upwardly 
  and 
  outwardly, 
  and 
  formed 
  no 
  part 
  of 
  a 
  backward 
  ly 
  

   directed 
  crest. 
  Seeley 
  f 
  remarks 
  that 
  the 
  occiput 
  is 
  flat, 
  

   but, 
  if 
  the 
  borders 
  were 
  perfect, 
  there 
  would 
  be 
  a 
  slight 
  con- 
  

   cavity. 
  Above 
  the 
  foramen 
  magnum 
  are 
  the 
  remains 
  of 
  a 
  

   vertical 
  ridge. 
  Its 
  present 
  vertical 
  extent 
  is 
  6 
  mm., 
  its 
  

   j)robable 
  length 
  in 
  life 
  10 
  mm. 
  Its 
  greatest 
  breadth 
  is 
  only 
  

   4 
  mm. 
  It 
  is 
  very 
  insignificant, 
  and 
  no 
  more 
  than 
  the 
  ridge 
  

   along 
  the 
  line 
  of 
  tlie 
  median 
  union 
  of 
  tlie 
  occipitals, 
  as 
  in 
  

   many 
  of 
  the 
  Reptilia. 
  The 
  angles 
  at 
  which 
  the 
  sides 
  con- 
  

   verge 
  prove 
  its 
  posterior 
  termination 
  to 
  have 
  been 
  near, 
  with 
  

   no 
  production 
  backwards 
  as 
  a 
  crest. 
  Seeley 
  + 
  says 
  " 
  it 
  may 
  

   liave 
  given 
  attachment 
  to 
  a 
  bone 
  like 
  that 
  post-superoccipital 
  

   crost 
  desci'ibed 
  by 
  Qucnstcdt 
  in 
  the 
  Plerodactyius 
  suevicus." 
  

   The 
  surface 
  is 
  very 
  small, 
  and 
  laiger 
  by 
  being 
  worn 
  to 
  its 
  

   base, 
  therefore 
  no 
  bone 
  of 
  any 
  extent 
  or 
  strength 
  could 
  have 
  

   been 
  attached 
  here. 
  Moreover, 
  as 
  will 
  shortly 
  be 
  shown, 
  

   the 
  crest 
  of 
  Ornithostoma 
  {Pteranodon) 
  arises 
  superior 
  to, 
  

   overhangs, 
  and 
  has 
  no 
  connection 
  whatever 
  with, 
  the 
  occipital 
  

   area. 
  In 
  Scelcy^s 
  figure 
  this 
  ridge, 
  which 
  is 
  depicted 
  with 
  too 
  

   great 
  a 
  vertical 
  exten>ion, 
  does 
  not 
  approach 
  so 
  close 
  to 
  the 
  

   foramen 
  magnum. 
  The 
  brain-case 
  and 
  occiput 
  are 
  expanded, 
  

   totally 
  unlike 
  the 
  compressed 
  condition 
  in 
  OriiiUiostoma 
  

   {Pteranodon), 
  and, 
  by 
  its 
  form, 
  it 
  suggests 
  relationship 
  wirb 
  

   the 
  toothed 
  and 
  pointed 
  jaws. 
  The 
  sagittal 
  crest 
  of 
  the 
  genus 
  

   OrnithucJieirus 
  is 
  a 
  myth. 
  The 
  supratemporal 
  fossae 
  were 
  ap])a- 
  

   rently 
  narrow 
  and 
  deep, 
  with 
  the 
  parietal 
  region 
  of 
  tbe 
  ^kiill 
  

   constricted, 
  as 
  in 
  Omithodesmus 
  latide/is. 
  No 
  post-temporal 
  

   foss0e 
  are 
  observable. 
  There 
  is 
  nothing 
  in 
  the 
  Cambridge 
  

   material 
  to 
  prove 
  the 
  absence 
  or 
  presence 
  of 
  an 
  antorbital 
  

   vacuity. 
  The 
  facts 
  do 
  not 
  favour 
  an 
  Ornithostoma 
  {Ptera- 
  

   nodon)-\}k& 
  skull^ 
  but 
  one 
  with 
  a 
  general 
  form 
  corresponding 
  

   to 
  the 
  shrewd 
  restoration 
  of 
  Pterodactylus 
  compressirostris 
  by 
  

   Owen 
  § 
  and 
  classified 
  by 
  autiiors 
  under 
  this 
  very 
  genus 
  Oniitho- 
  

   cheirus. 
  The 
  specimen 
  J. 
  c. 
  8, 
  2 
  was 
  St 
  eley^s 
  type 
  for 
  the 
  back 
  

   of 
  the 
  skull 
  of 
  Ornithocheirus, 
  and 
  the 
  only 
  hinder 
  region 
  of 
  

   the 
  skull, 
  other 
  than 
  J. 
  c. 
  8, 
  1, 
  known 
  to 
  him. 
  It 
  is 
  very 
  

   remarkable 
  that 
  all 
  the 
  while 
  the 
  Cambridge 
  material 
  actually 
  

  

  * 
  II. 
  G. 
  Seeley, 
  Ann. 
  .t 
  Mag-. 
  Nat. 
  Hist. 
  (6) 
  vol. 
  vii. 
  p. 
  443 
  (1891). 
  

   t 
  Id. 
  ' 
  Ornithosauria,' 
  1870, 
  p. 
  84. 
  

   t 
  Id. 
  ibid. 
  p. 
  84. 
  

  

  § 
  E. 
  Owen, 
  Cret. 
  Rep. 
  (Mon. 
  Pal. 
  Soc. 
  1851) 
  pi. 
  xxvii. 
  fi?. 
  1. 
  

  

  3G^ 
  

  

  