﻿204: 
  THE 
  EXTINCT 
  BATRACHIA, 
  REPTILIA 
  

  

  on 
  the 
  outer 
  aspect 
  of 
  the 
  second 
  maxillary. 
  These 
  are 
  not 
  strongly 
  marked, 
  and 
  are 
  separated 
  by 
  concave 
  facets. 
  . 
  

   The 
  basal 
  part 
  of 
  the 
  crown 
  is 
  marked 
  by 
  numerous 
  fine 
  sharp 
  stria?, 
  which 
  are 
  most 
  distinct 
  on 
  the 
  inner 
  face. 
  

  

  The 
  external 
  face 
  of 
  the 
  maxillary 
  bone 
  presents 
  three 
  series 
  of 
  foramina. 
  These 
  rise 
  superiorly 
  on 
  the 
  premaxil- 
  

   lary, 
  and 
  increase 
  in 
  number 
  and 
  become 
  irregular 
  on 
  its 
  extremity. 
  

  

  The 
  ramus 
  of 
  the 
  mandible 
  is 
  massive, 
  and 
  differs 
  from 
  that 
  of 
  Mosasaurus 
  giganteus 
  in 
  continuing 
  its 
  proportions 
  

   to 
  its 
  extremity. 
  Its 
  depth 
  at 
  the 
  latter 
  point 
  is 
  as 
  great 
  as 
  the 
  sixth 
  tooth 
  from 
  the 
  front. 
  It 
  is 
  prolonged 
  beyond 
  

   the 
  first 
  tooth 
  in 
  correspondence 
  with 
  the 
  prolongation 
  of 
  the 
  premaxillary. 
  This 
  extremity 
  is 
  compressed 
  and 
  obtuse; 
  

   its 
  inner 
  face 
  is 
  very 
  rugose, 
  as 
  though 
  there 
  had 
  been 
  a 
  closer 
  union 
  at 
  the 
  symphysis 
  than 
  usual, 
  though 
  it 
  would 
  not 
  

   appear 
  to 
  have 
  been 
  other 
  than 
  ligamentous. 
  The 
  groove 
  for 
  Meckel's 
  cartilage 
  is 
  very 
  large 
  and 
  has 
  been 
  exposed 
  be- 
  

   low 
  the 
  last 
  two 
  teeth, 
  as 
  the 
  splenial 
  terminates 
  at 
  the 
  third. 
  Two 
  series 
  of 
  foramina 
  on 
  the 
  external 
  face 
  of 
  the 
  

   ramus. 
  There 
  are 
  alveola? 
  and 
  bases 
  for 
  thirteen 
  teeth 
  on 
  the 
  dentary 
  bone. 
  This, 
  it 
  will 
  be 
  observed, 
  is 
  one 
  more 
  

   than 
  in 
  M. 
  gracilis, 
  and 
  one 
  less 
  than 
  in 
  other 
  species 
  of 
  Mosasaurus. 
  The 
  posterior 
  extremity 
  of 
  the 
  dentary 
  shows 
  

   its 
  marks 
  of 
  reception 
  into 
  the 
  notch 
  of 
  the 
  coronoid; 
  it 
  is 
  more 
  compressed 
  and 
  less 
  club-shaped 
  than 
  the 
  correspond- 
  

   ing 
  part 
  of 
  M. 
  mitchillii, 
  and 
  would 
  indicate 
  less 
  lateral 
  flexibility 
  than 
  in 
  some 
  other 
  types. 
  

  

  The 
  right 
  pterygoid 
  is 
  of 
  less 
  elongate 
  form 
  than 
  in 
  some 
  other 
  species. 
  It 
  presents 
  the 
  sutural 
  face 
  for 
  union 
  

   with 
  the 
  palatine 
  on 
  the 
  outer 
  anterior 
  extremity, 
  and 
  narrows 
  to 
  an 
  apex 
  a 
  little 
  in 
  advance. 
  The 
  dentigerous 
  face 
  is 
  

   widest 
  at 
  the 
  anterior 
  third 
  the 
  length, 
  where 
  the 
  outer 
  margin 
  is 
  expanded. 
  This 
  then 
  contracts 
  and 
  is 
  compressed 
  

   vertical 
  at 
  the 
  tenth 
  tooth, 
  where 
  it 
  is 
  broken 
  off. 
  The 
  transverse 
  process 
  is 
  given 
  off 
  a 
  little 
  anterior 
  to 
  the 
  ninth 
  

   tooth. 
  The 
  interior 
  face 
  of 
  the 
  bone 
  is 
  a 
  vertical 
  plane, 
  without 
  projection, 
  except 
  a 
  slight 
  obliquity 
  at 
  the 
  anterior 
  

   extremity, 
  and 
  it 
  is 
  clear 
  there 
  has 
  been 
  some 
  interval 
  between 
  this 
  pterygoid 
  and 
  its 
  fellow. 
  The 
  superior 
  margin 
  is 
  

   obtusely 
  rounded. 
  

  

  The 
  bases 
  of 
  the 
  pterygoid 
  teeth 
  are 
  exposed 
  for 
  two-thirds 
  their 
  length, 
  on 
  the 
  outer 
  side 
  of 
  the 
  bone, 
  thus 
  ap- 
  

   proaching 
  the 
  Platecarpus. 
  The 
  antero-median 
  are 
  large, 
  and 
  the 
  anterior 
  most 
  closely 
  placed. 
  Their 
  crowns 
  are 
  

   strongly 
  recurved, 
  round 
  in 
  section, 
  and 
  with 
  a 
  fine 
  sculpture 
  of 
  straight 
  striae, 
  most 
  marked 
  near 
  the 
  base 
  and 
  on 
  the 
  

   inner 
  side. 
  They 
  are 
  more 
  spaced 
  posteriorly 
  than 
  any 
  other 
  species 
  except 
  M. 
  mitchillii, 
  and 
  are 
  relatively 
  larger 
  than 
  

   in 
  any 
  except 
  the 
  same 
  species. 
  They 
  have 
  not 
  the 
  compressed 
  form 
  with 
  basal 
  shoulder, 
  characteristic 
  of 
  the 
  M. 
  

   dekayi. 
  

  

  Measurement 
  of 
  Muzzle. 
  Indies. 
  

  

  Length 
  of 
  fragment, 
  31. 
  

  

  " 
  from 
  end 
  muzzle 
  to 
  pre-frontal, 
  21.5 
  

  

  " 
  " 
  " 
  " 
  nares, 
  11.75 
  

  

  " 
  " 
  " 
  " 
  " 
  maxillary, 
  5.75 
  

  

  " 
  " 
  " 
  " 
  " 
  first 
  tooth, 
  2.5 
  

  

  Width 
  of 
  muzzle 
  at 
  end, 
  1.5 
  

  

  " 
  "at 
  anter. 
  extremity 
  nares, 
  8 
  

  

  " 
  premaxillary 
  " 
  " 
  " 
  3.3 
  

  

  " 
  maxillary 
  betw. 
  10th 
  and 
  11th 
  teeth, 
  3.2 
  

  

  Depth 
  mandible 
  at 
  extremity, 
  2.5 
  

  

  " 
  " 
  " 
  sixth 
  tooth, 
  3.5 
  

  

  " 
  pterygoid 
  at 
  transverse 
  process, 
  2.5 
  

  

  Width 
  " 
  " 
  " 
  " 
  * 
  1.4 
  

  

  " 
  " 
  in 
  front, 
  2.2 
  

  

  Length 
  " 
  anterior 
  to 
  transverse 
  process, 
  7.2 
  

  

  " 
  crown 
  5th 
  pterygoid 
  tooth, 
  1. 
  

  

  " 
  " 
  2nd 
  maxillary 
  tooth, 
  • 
  1.9 
  

  

  Diameter" 
  " 
  " 
  " 
  at 
  base, 
  1.1 
  

  

  The 
  vomers 
  are 
  as 
  usual, 
  separate 
  and 
  narrow. 
  They 
  are 
  in 
  close 
  contact 
  from 
  the 
  second 
  maxillary 
  to 
  the 
  second 
  

   premaxillary 
  tooth. 
  Throughout 
  this 
  part 
  of 
  their 
  length 
  they 
  arc 
  embraced 
  by 
  posteriorly 
  produced 
  vertical 
  lamina? 
  

  

  