﻿AND 
  AVES 
  OF 
  NORTU 
  AMERICA. 
  223 
  

  

  Lines. 
  

  

  Length 
  of 
  sixth 
  cervical, 
  neural 
  arch, 
  13.6 
  

   "Width 
  at 
  narrowest 
  point 
  of 
  " 
  " 
  8 
  

  

  Expanse 
  of 
  zygosphens, 
  4 
  

  

  " 
  " 
  zygapophyses 
  (anterior), 
  13.2 
  

  

  " 
  " 
  diapophyses, 
  19 
  

  

  "Width 
  cup, 
  8.5 
  

  

  Depth 
  centrum 
  and 
  hoth 
  hypapophyses, 
  14.8 
  

   Length 
  free 
  hypapophysis, 
  5 
  

  

  " 
  centrum 
  (inch 
  ball) 
  of 
  twenty-third 
  V., 
  16.8 
  

  

  " 
  neural 
  arch, 
  1G.G 
  

   " 
  between 
  anter. 
  zygapoph. 
  and 
  diapoph. 
  7 
  

  

  Depth 
  diapophysis, 
  5.3 
  

  

  " 
  neural 
  arch 
  and 
  centrum, 
  14 
  

   Width 
  centrum 
  (least), 
  7.5 
  

  

  " 
  ball, 
  9.3 
  

  

  Depth 
  " 
  7.8 
  

  

  Length 
  of 
  an 
  anterior 
  caudal 
  (no 
  diapoph.}, 
  7.2 
  

  

  Width 
  cup, 
  8 
  

   Depth, 
  7 
  

  

  Total 
  depth 
  centrum 
  and 
  spines, 
  54.8 
  

  

  Neural 
  spine 
  and 
  arch, 
  16 
  

   Antero-posterior 
  width 
  base 
  spine, 
  7.2 
  

  

  Length 
  of 
  13th 
  caudal 
  from 
  the 
  last, 
  . 
  5.8 
  

  

  Width 
  cup, 
  7 
  

  

  Depth 
  " 
  5.8 
  

  

  Length 
  distal 
  caudal, 
  3.4 
  

  

  "Width 
  cup, 
  . 
  2.3 
  

  

  Depth 
  " 
  3. 
  

  

  The 
  form 
  of 
  the 
  cranium 
  is 
  that 
  of 
  an 
  elongate 
  flat 
  wedge. 
  The 
  lateral 
  outlines 
  are 
  slightly 
  contracted 
  just 
  be- 
  

   hind 
  the 
  anterior 
  opening 
  of 
  the 
  nostrils. 
  A 
  deep 
  emargination 
  occurs 
  at 
  the 
  orbits, 
  while 
  the 
  temporal 
  fossaj 
  inter- 
  

   rupt 
  the 
  outline 
  more 
  deeply 
  still. 
  The 
  projection 
  of 
  the 
  opisthotic 
  and 
  squamosal 
  is 
  about 
  as 
  extensive 
  as 
  that 
  of 
  the 
  

   post-frontal. 
  Throughout, 
  the 
  surface 
  from 
  muzzle 
  to 
  occiput 
  is 
  quite 
  plane, 
  though 
  the 
  latter 
  region 
  has 
  been 
  evi- 
  

   dently 
  slightly 
  crushed, 
  and 
  the 
  posterior 
  median 
  frontal 
  region 
  is 
  slightly 
  concave. 
  Transversely, 
  there 
  is 
  a 
  strong 
  

   concavity, 
  with 
  vertical 
  inner 
  margin 
  on 
  each 
  side 
  the 
  median 
  parietal 
  region. 
  The 
  post-frontals 
  are 
  slightly 
  decurved, 
  

   the 
  pre-frontals 
  still 
  less 
  so. 
  The 
  nasal 
  region 
  woidd 
  be 
  plane 
  transversely 
  but 
  for 
  two 
  shallow 
  longitudinal 
  grooves, 
  

   separated 
  by 
  a 
  low 
  raised 
  line 
  which 
  extends 
  from 
  the 
  middle 
  of 
  the 
  front 
  along 
  the 
  nasal 
  septum. 
  

  

  A 
  section 
  of 
  the 
  muzzle 
  in 
  front 
  of 
  the 
  nostrils 
  would 
  be 
  a 
  semi-circle; 
  posterior 
  to 
  this 
  point 
  the 
  sides 
  of 
  the 
  

   maxillaries 
  are 
  more 
  vertical. 
  The 
  edges 
  of 
  the 
  projecting 
  orbital 
  bones 
  are 
  thin, 
  as 
  well 
  as 
  the 
  orbital 
  rim 
  of 
  the 
  

   frontal. 
  The 
  inner 
  margin 
  of 
  the 
  maxillaries 
  is 
  very 
  thin 
  and 
  rolled 
  over 
  the 
  outer 
  margin 
  and 
  extremity 
  of 
  the 
  thin 
  

   pre-frontal. 
  The 
  bones 
  are 
  all 
  relatively 
  more 
  fragile 
  than 
  in 
  Mosasaurus. 
  The 
  posterior 
  process 
  of 
  the 
  post-frontal, 
  

   which 
  is 
  received 
  into 
  a 
  groove 
  on 
  the 
  inner 
  face 
  of 
  the 
  squamosal, 
  is 
  sub-trigonal. 
  

  

  The 
  parietal 
  crests 
  are 
  the 
  lateral 
  angles 
  above 
  mentioned. 
  They 
  are 
  nearly 
  parallel 
  behind, 
  and 
  diverge 
  gently 
  

   in 
  front; 
  they 
  then 
  diverge 
  still 
  more, 
  and 
  extend 
  along 
  the 
  suture 
  between 
  the 
  parietal 
  and 
  frontal 
  bones, 
  and 
  then 
  

   disappear. 
  There 
  are 
  no 
  other 
  ridges 
  on 
  the 
  cranium, 
  except 
  the 
  median 
  occipital, 
  which 
  is 
  low. 
  

  

  The 
  premaxillary 
  and 
  anterior 
  maxillary 
  teeth 
  are 
  more 
  rounded 
  than 
  the 
  posterior 
  maxillaries. 
  The 
  former 
  have 
  

   an 
  angle 
  separating 
  inner 
  and 
  outer 
  planes, 
  in 
  front 
  only, 
  the 
  latter, 
  commencing 
  at 
  the 
  sixth 
  maxillary, 
  on 
  both 
  an- 
  

   terior 
  and 
  posterior 
  lines. 
  In 
  the 
  tooth 
  named, 
  the 
  inner 
  face 
  is 
  the 
  more 
  convex 
  and 
  extensive; 
  there 
  are 
  no 
  facets 
  

  

  