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  THE 
  EXTINCT 
  BATRACHIA, 
  REPTILIA 
  

  

  Articular 
  faces 
  posterior 
  cervical 
  round 
  or 
  slightly 
  depressed; 
  hypapophysis 
  very 
  large; 
  

   surface 
  everywhere 
  sculptured 
  striate; 
  centrum 
  long 
  ; 
  small. 
  l. 
  congrops. 
  

  

  Articular 
  faces 
  of 
  all 
  dorsals 
  compressed, 
  deeper 
  than 
  wide 
  ; 
  median 
  line 
  below, 
  broadly 
  

   prominent, 
  l. 
  l;evis. 
  

  

  LIODOX 
  PRORIGER, 
  Cope. 
  

  

  Maerosaurus 
  proriger, 
  Cope, 
  Proceed. 
  Ac. 
  Nat. 
  ScL, 
  Phil., 
  1869, 
  p. 
  123. 
  Hujiis 
  operis 
  Tab. 
  XII, 
  figs. 
  22-24. 
  

   Leidy, 
  Cretac. 
  Rept. 
  II, 
  15-16 
  (caudal 
  vertebra). 
  

  

  The 
  history 
  of 
  this 
  large 
  Mosasauroid 
  is 
  based 
  on 
  material 
  in 
  the 
  Museum 
  Comparative 
  Zoology, 
  Cambridge, 
  Mass., 
  

   brought 
  by 
  Prof. 
  Louis 
  Agassiz 
  from 
  the 
  cretaceous 
  beds 
  in 
  the 
  neighborhood 
  of 
  Fort 
  Hayes, 
  Kansas, 
  and 
  near 
  the 
  

   line 
  of 
  the 
  Southern 
  Pacific 
  Railroad. 
  It 
  consists 
  of 
  the 
  greater 
  part 
  of 
  the 
  muzzle 
  from 
  the 
  orbits, 
  with 
  the 
  right 
  den- 
  

   tary 
  and 
  left 
  pterygoid 
  bones 
  nearly 
  complete; 
  one 
  cervical 
  vertebra 
  (with 
  hypapophysis), 
  one 
  dorsal, 
  .one 
  caudal 
  with 
  

   diapophysis, 
  and 
  ten 
  caudals 
  without 
  diapophysis. 
  

  

  The 
  characters 
  presented 
  by 
  the 
  vertebral 
  column 
  indicate 
  an 
  excessively 
  elongate 
  reptile; 
  the 
  transverse 
  diameter 
  

   of 
  one 
  of 
  the 
  distal 
  caudal 
  vertebrae 
  is 
  less 
  than 
  one-fifth 
  that 
  of 
  a 
  proximal 
  with 
  short 
  diapophysis; 
  while 
  four 
  consecu- 
  

   tive 
  ones 
  of 
  the 
  former 
  show 
  but 
  little 
  variation 
  in 
  dimensions. 
  This 
  diminution 
  amounts 
  to 
  f 
  of 
  a 
  transverse 
  diameter 
  

   of 
  the 
  larger 
  form. 
  With 
  this 
  ratio 
  as 
  a 
  basis, 
  fifty-three 
  § 
  vertebras 
  would 
  form 
  a 
  complete 
  series 
  from 
  caudals 
  one- 
  

   half 
  the 
  diameter 
  of 
  the 
  last 
  of 
  the 
  four, 
  to 
  the 
  proximal 
  caudal 
  above 
  mentioned. 
  There 
  have 
  been, 
  no 
  doubt, 
  several 
  

   caudals 
  in 
  advance 
  of 
  the 
  latter, 
  as 
  the 
  diapophyses 
  are 
  small. 
  From 
  the 
  slow 
  rate 
  of 
  diminution 
  of 
  the 
  columns 
  of 
  

   other 
  species 
  examined, 
  it 
  may 
  be 
  supposed 
  that 
  sixty 
  caudal 
  vertebrae 
  is 
  bf.ow 
  rather 
  than 
  above 
  the 
  true 
  number. 
  

  

  The 
  cervical 
  and 
  dorsal 
  vertebra? 
  have 
  been 
  slightly 
  crushed 
  as 
  they 
  laid 
  on 
  the 
  side, 
  and 
  present 
  a 
  narrower 
  diam- 
  

   eter 
  than 
  is 
  normal; 
  the 
  cup 
  of 
  the 
  cervical 
  has 
  not 
  been 
  distorted, 
  and 
  is 
  deeper 
  than 
  wide, 
  presenting 
  the 
  character 
  

   of 
  Maerosaurus. 
  The 
  rudimental 
  zygosphen 
  consists 
  of 
  a 
  continuation 
  of 
  the 
  roof 
  of 
  the 
  neural 
  canal 
  in 
  front, 
  to 
  adapt 
  # 
  

   itself 
  to 
  the 
  inner 
  face 
  of 
  the 
  down-looking 
  zygapophysis 
  of 
  the 
  preceding 
  vertebra. 
  The 
  latter 
  is 
  thus 
  received 
  into 
  

   a 
  groove 
  on 
  the 
  inner 
  side 
  of 
  the 
  up-looking 
  posterior 
  zygapophysis. 
  The 
  dorsals 
  and 
  caudals 
  exhibit 
  with 
  the 
  cervicals 
  

   that 
  minute, 
  sharply 
  defined 
  rugosity, 
  Avhich 
  characterizes 
  all 
  the 
  projecting 
  margins, 
  especially 
  those 
  of 
  the 
  hypapo- 
  

   physis 
  and 
  diapophyses, 
  in 
  this 
  genus 
  and 
  Clidastes. 
  The 
  whole 
  surface 
  of 
  the 
  cervical 
  is 
  marked 
  with 
  either 
  inoscir- 
  

   lating 
  striae 
  or 
  impressed 
  punctae. 
  The 
  same 
  character 
  marks 
  the 
  cranial 
  bones, 
  though 
  they 
  do 
  not 
  present 
  such 
  ru- 
  

   gosity 
  as 
  the 
  vertebrae. 
  

  

  The 
  proximal 
  caudal 
  presents 
  a 
  subhexagonal 
  section, 
  of 
  which 
  the 
  inferior 
  add 
  supero-lateral 
  sides 
  are 
  longest; 
  

   articular 
  faces 
  about 
  as 
  bi-oad 
  as 
  high. 
  A 
  broad 
  smooth 
  space 
  between 
  the 
  chevron 
  bones. 
  Diapophyses 
  with 
  broad 
  

   ovate 
  transverse 
  section. 
  

  

  A 
  caudal 
  without 
  diapophyses, 
  anterior 
  to 
  the 
  middle 
  of 
  the 
  series, 
  estimated 
  by 
  the 
  size, 
  is 
  but 
  slightly 
  deeper 
  

   than 
  long, 
  and 
  with 
  parallel 
  lateral 
  outlines 
  of 
  the 
  articular 
  faces. 
  The 
  neural 
  arch 
  is 
  very 
  much 
  narrowed 
  antero- 
  

   posteriorly, 
  but 
  has 
  a 
  greater 
  transverse 
  extent 
  at 
  its 
  lower 
  part; 
  above 
  the 
  spine 
  is 
  much 
  compressed, 
  but 
  not 
  widened. 
  

   The 
  zygapophyses 
  remain 
  as 
  rudiments 
  just 
  above 
  the 
  small 
  neural 
  canal, 
  but 
  do 
  not 
  probably 
  touch 
  each 
  other. 
  There 
  

   are 
  two 
  anterior 
  and 
  two 
  posterior 
  narrow 
  ribs 
  on 
  the 
  upper 
  portion 
  of 
  the 
  neural 
  spine. 
  The 
  more 
  distal 
  caudals 
  have 
  

   wider 
  neural 
  spines, 
  and 
  the 
  arch 
  also 
  has 
  a 
  greater 
  antero-posterior 
  extent. 
  The 
  zygapophyses 
  are 
  scarcely 
  traceable 
  

   and 
  the 
  neural 
  spine 
  is 
  strongly 
  striate. 
  The 
  reverse 
  arrangement 
  is 
  observed 
  in 
  Clidastes 
  propython, 
  where 
  the 
  neu- 
  

   ral 
  spine 
  of 
  the 
  proximal 
  caudal 
  has 
  considerable 
  extent, 
  while 
  those 
  of 
  the 
  posterior 
  and 
  distal 
  vertebrae 
  are 
  almost 
  

   cylindric, 
  especially 
  the 
  neurapophyses. 
  

  

  Dimensions. 
  In. 
  

  

  Dorsal, 
  length, 
  3.85 
  

  

  " 
  widtli 
  cup, 
  2.5 
  

  

  " 
  depth 
  " 
  2.77 
  

  

  Proximal 
  caudal, 
  length, 
  2.14 
  

  

  