﻿FROM 
  THE 
  KEUPER 
  SANDSTOKE 
  OE 
  WARWICK. 
  427 
  

  

  alveolar 
  canal. 
  They 
  are 
  separated, 
  for 
  a 
  length 
  of 
  about 
  3| 
  in., 
  

   by 
  an 
  elongated 
  oval 
  space 
  upwards 
  of 
  ^ 
  in. 
  wide 
  in 
  its 
  widest 
  part. 
  

   Towards 
  the 
  fore 
  part 
  of 
  the 
  fossil 
  the 
  dentary 
  bone 
  overlies 
  the 
  

   upper 
  and 
  outer 
  surfaces 
  of 
  the 
  external 
  wall 
  of 
  the 
  ramus. 
  It 
  ter- 
  

   minates 
  behind 
  in 
  an 
  elongated 
  pointed 
  slip, 
  which 
  is 
  confined 
  to 
  

   the 
  outer 
  surface 
  ; 
  the 
  apex 
  was 
  originally 
  about 
  | 
  in. 
  distant 
  from 
  

   the 
  ascending 
  condylar 
  process. 
  Upon 
  the 
  upper 
  surface 
  of 
  the 
  

   dentary 
  bone 
  the 
  bases, 
  or 
  cavities, 
  of 
  about 
  seventeen 
  teeth 
  are 
  

   visible. 
  Such 
  as 
  admit 
  of 
  measurement 
  are 
  about 
  | 
  in. 
  from 
  side 
  to 
  

   side, 
  and 
  ^ 
  in. 
  in 
  the 
  antero 
  -posterior 
  direction. 
  They 
  are 
  there- 
  

   fore 
  much 
  compressed 
  in 
  the 
  direction 
  of 
  the 
  axis 
  of 
  the 
  ramus. 
  

   In 
  form 
  and 
  size 
  they 
  seem 
  to 
  resemble 
  the 
  teeth 
  of 
  Capitosawus 
  ; 
  

   but 
  a 
  detailed 
  microscopic 
  examination 
  is 
  necessary 
  to 
  elucidate 
  their 
  

   structure 
  and 
  relationship 
  *. 
  

  

  Diadetognathiis 
  is 
  sufficiently 
  distinguished 
  from 
  Mastodonsaurus 
  

   by 
  the 
  characters 
  of 
  its 
  mandibular 
  articulation 
  as 
  given 
  above. 
  In 
  

   Capitosaurus 
  we 
  may 
  note, 
  among 
  other 
  differences, 
  that 
  the 
  ascend- 
  

   ing 
  condylar 
  process 
  is 
  concave 
  backwards, 
  instead 
  of 
  forwards 
  as 
  

   in 
  Diadetognatlius, 
  while 
  there 
  is 
  a 
  well- 
  developed 
  internal 
  articular 
  

   process. 
  Trematosaurus 
  differs 
  essentially 
  in 
  the 
  postarticular 
  pro- 
  

   cess, 
  Labyrinthodon 
  in 
  the 
  form 
  and 
  size 
  of 
  the 
  teeth. 
  The 
  data 
  

   for 
  a 
  full 
  and 
  accurate 
  comparison 
  with 
  the 
  last-mentioned 
  genus 
  do 
  

   not 
  as 
  yet 
  exist. 
  

  

  Measurements 
  : 
  — 
  in. 
  

  

  Length 
  of 
  fragment 
  of 
  ramus 
  8f 
  

  

  Greatest 
  depth 
  2| 
  

  

  Length 
  of 
  postarticular 
  process 
  1| 
  

  

  Distance 
  of 
  centre 
  of 
  radiation 
  of 
  sculpture 
  from 
  poste- 
  

   rior 
  extremity 
  4^ 
  

  

  Distance 
  of 
  internal 
  mandibular 
  foramen 
  from 
  posterior 
  

  

  extremity 
  5A 
  

  

  Height 
  of 
  ascending 
  condylar 
  process 
  | 
  

  

  "Width 
  of 
  ascending 
  condylar 
  process 
  1-^ 
  

  

  9. 
  Diadetognathus 
  varvicejstsis 
  — 
  fragment 
  of 
  right 
  ramus 
  of 
  man- 
  

   dible. 
  

  

  Both 
  ends 
  are 
  broken 
  off. 
  The 
  external 
  surface 
  shows 
  the 
  radiating 
  

   structure 
  upon 
  the 
  angular 
  bone 
  as 
  in 
  the 
  last 
  specimen 
  ; 
  and 
  the 
  ter- 
  

   mination 
  of 
  the 
  descending 
  groove 
  is 
  seen 
  upon 
  the 
  inferior 
  border. 
  

   Above 
  the 
  angular 
  element, 
  for 
  a 
  distance 
  of 
  nearly 
  1-| 
  in., 
  the 
  

   external 
  dentary 
  process 
  of 
  the 
  articular 
  bone 
  (that 
  destined 
  for 
  the 
  

   support 
  of 
  the 
  dentary 
  piece) 
  still 
  remains 
  in 
  position. 
  The 
  inner 
  

   aspect 
  shows 
  a 
  smooth 
  splenial 
  plate 
  and 
  part 
  of 
  the 
  border 
  of 
  the 
  

   internal 
  mandibular 
  foramen. 
  The 
  suture 
  between 
  the 
  articular 
  and 
  

   angular 
  pieces 
  can 
  be 
  traced 
  upon 
  the 
  internal 
  surface 
  from 
  the 
  poste- 
  

   rior 
  extremity 
  of 
  the 
  internal 
  mandibular 
  foramen 
  backwards 
  to 
  near 
  

   the 
  broken 
  end 
  of 
  the 
  ramus. 
  At 
  first 
  it 
  lies 
  nearly 
  halfway 
  between 
  

   the 
  upper 
  and 
  lower 
  borders; 
  about 
  1 
  in. 
  behind 
  the 
  foramen 
  it 
  takes 
  

   an 
  upward 
  course 
  ; 
  and 
  it 
  descends 
  again 
  somewhat 
  abruptly 
  behind. 
  

   * 
  See 
  Addendum, 
  p. 
  434. 
  

  

  2u2 
  

  

  