﻿Vol. 
  53.] 
  OF 
  THE 
  SKULL 
  OP 
  A. 
  PLIOSATTR. 
  183 
  

  

  roughened 
  and 
  pitted 
  by 
  many 
  foramina. 
  Internally 
  it 
  is 
  bounded 
  

   by 
  the 
  premaxilla 
  and 
  the 
  nostril, 
  of 
  which 
  it 
  forms 
  the 
  outer 
  

   margin. 
  Posteriorly 
  it 
  appears 
  to 
  meet 
  the 
  nasal 
  (?), 
  supra-orbital, 
  

   and 
  lachrymal. 
  

  

  The 
  arrangement 
  of 
  the 
  bones 
  in 
  the 
  upper 
  surface 
  of 
  the 
  skull 
  is 
  

   difficult 
  to 
  determine 
  with 
  certainty, 
  owing 
  to 
  the 
  crushing 
  that 
  has 
  

   taken 
  place. 
  

  

  The 
  fused 
  parietals 
  (fig. 
  2, 
  p. 
  181, 
  par.) 
  form 
  a 
  high 
  massive 
  

   crest 
  between 
  the 
  temporal 
  fossae 
  ; 
  posteriorly 
  they 
  widen 
  out 
  to 
  a 
  

   considerable 
  degree, 
  and 
  no 
  doubt 
  their 
  outer 
  angles 
  joined 
  the 
  upper 
  

   rami 
  of 
  the 
  squamosals, 
  which 
  in 
  the 
  present 
  specimen 
  have 
  been 
  

   dislocated 
  in 
  such 
  a 
  way 
  as 
  to 
  overlap 
  the 
  hinder 
  portion 
  of 
  the 
  skull. 
  

   The 
  inferior 
  borders 
  of 
  the 
  parietals 
  slope 
  outward 
  so 
  as 
  to 
  form 
  a 
  

   roof 
  to 
  the 
  brain-case 
  ; 
  anteriorly 
  they 
  unite 
  with 
  the 
  expanded 
  upper 
  

   end 
  of 
  the 
  epipterygoid. 
  The 
  boundary 
  between 
  the 
  parietals 
  and 
  

   frontals 
  is 
  not 
  clearly 
  denned, 
  and 
  probably 
  the 
  bones 
  were, 
  in 
  fact, 
  

   anchylosed. 
  There 
  are, 
  however, 
  traces 
  of 
  the 
  suture 
  between 
  them 
  

   on 
  the 
  sides 
  of 
  the 
  large 
  pineal 
  foramen 
  / 
  about 
  5 
  cm. 
  in 
  length), 
  

   the 
  walls 
  of 
  this 
  opening 
  being 
  formed 
  by 
  both 
  these 
  elements. 
  

  

  About 
  2 
  cm. 
  external 
  to 
  the 
  pineal 
  foramen 
  there 
  is 
  a 
  suture 
  

   dividing 
  from 
  the 
  frontals 
  and 
  (?) 
  parietals 
  a 
  bone 
  which 
  is 
  clearly 
  

   the 
  post-frontal. 
  Anterior 
  to 
  this, 
  and 
  lying 
  immediately 
  external 
  

   to 
  the 
  frontal, 
  there 
  is 
  a 
  long, 
  narrow 
  bone, 
  apparently 
  the 
  prefrontal. 
  

   In 
  front 
  of 
  this 
  again 
  there 
  is 
  another 
  element 
  which 
  seems 
  to 
  be 
  

   continuous 
  with 
  a 
  narrow 
  strip 
  which 
  thrusts 
  itself 
  between 
  the 
  

   external 
  nares 
  and 
  the 
  facial 
  process 
  of 
  the 
  premaxilla 
  : 
  this 
  I 
  

   regard 
  as 
  the 
  nasal. 
  External 
  to 
  the 
  nasal 
  and 
  prefrontal 
  there 
  is 
  

   a 
  broad, 
  thin 
  plate 
  of 
  bone, 
  the 
  limits 
  of 
  which 
  are 
  not 
  clear. 
  This 
  

   bone 
  overhangs 
  the 
  orbit, 
  or 
  at 
  least 
  the 
  anterior 
  part 
  of 
  it, 
  and 
  is 
  

   a 
  supra-orbital. 
  

  

  The 
  external 
  nares 
  (PL 
  XII, 
  e.na.) 
  are 
  oval 
  apertures, 
  

   about 
  5 
  cm. 
  in 
  length. 
  They 
  are 
  separated 
  from 
  one 
  another 
  by 
  

   an 
  interval 
  of 
  about 
  9*5 
  cm., 
  1 
  occupied 
  by 
  the 
  facial 
  processes 
  of 
  

   the 
  premaxilla 
  and 
  probably 
  also 
  by 
  the 
  nasals. 
  They 
  lie 
  57 
  cm. 
  

   behind 
  the 
  tip 
  of 
  the 
  snout, 
  and, 
  as 
  in 
  Peloneustes, 
  some 
  distance 
  

   behind 
  the 
  internal 
  nares. 
  

  

  The 
  antero-inferior 
  portion 
  of 
  the 
  orbital 
  margin 
  is 
  formed 
  by 
  a 
  

   massive 
  bone 
  which 
  joins 
  the 
  supra-orbital 
  above, 
  the 
  maxilla 
  and 
  

   probably 
  also 
  the 
  jugal 
  below 
  : 
  this 
  element 
  is 
  no 
  doubt 
  a 
  

   lachrymal 
  (I). 
  It 
  is 
  produced 
  inward, 
  into 
  a 
  broad 
  ridge 
  which 
  

   forms 
  an 
  anterior 
  wall 
  to 
  the 
  orbit, 
  and, 
  curving 
  upward 
  and 
  back- 
  

   ward, 
  becomes 
  continuous 
  with 
  a 
  rounded 
  crest 
  on 
  the 
  inferior 
  sur- 
  

   face 
  of 
  the 
  cranial 
  bones 
  forming 
  the 
  inner 
  limit 
  of 
  the 
  orbit. 
  

  

  The 
  form 
  of 
  the 
  post-orbital 
  and 
  jugal 
  (ju.\ 
  as 
  well 
  as 
  

   their 
  relations 
  to 
  one 
  another 
  and 
  to 
  the 
  'squamosal,' 
  are 
  as 
  in 
  

   Feloneustes. 
  

  

  The 
  'squamosal' 
  (sq.) 
  consists 
  of 
  an 
  anterior 
  ramus 
  relatively 
  

   more 
  slender 
  than 
  in 
  the 
  smaller 
  form, 
  and 
  an 
  upper 
  ramus 
  which 
  no 
  

  

  1 
  Probably 
  somewhat 
  exaggerated 
  by 
  crushing. 
  

  

  