﻿420 
  L. 
  C. 
  MIALL 
  ON" 
  THE 
  BEMAINS 
  OP 
  IABYBINTHODONTA 
  

  

  The 
  articular 
  process 
  (Art.) 
  is 
  very 
  strong, 
  its 
  broken 
  inner 
  face 
  

   being 
  |- 
  inch 
  by 
  f 
  inch. 
  The 
  lower 
  and 
  posterior 
  surfaces 
  are 
  contri- 
  

   buted 
  by 
  the 
  quadrate 
  ( 
  Q) 
  ; 
  and 
  the 
  suture 
  between 
  this 
  and 
  the 
  qua- 
  

   drato-jugal 
  can 
  be 
  made 
  out 
  without 
  much 
  difficulty. 
  In 
  its 
  lower 
  

   half 
  the 
  process 
  presents 
  roughly 
  the 
  form 
  of 
  a 
  semicylinder 
  placed 
  

   transversely, 
  with 
  the 
  convex 
  surface 
  downwards. 
  The 
  anteroposte- 
  

   rior 
  measurement 
  of 
  the 
  semicylinder 
  is 
  rather 
  less 
  near 
  the 
  middle 
  

   than 
  at 
  either 
  of 
  the 
  two 
  ends 
  ; 
  its 
  lower, 
  or 
  articular, 
  surface 
  is 
  there- 
  

   fore 
  somewhat 
  saddle-shaped. 
  Above 
  the 
  lower 
  convex 
  part 
  of 
  the 
  

   articular 
  process, 
  and 
  on 
  the 
  posterior 
  surface, 
  is 
  a 
  rounded 
  protube- 
  

   rance 
  (pr), 
  about 
  § 
  inch 
  in 
  transverse 
  width, 
  and 
  not 
  quite 
  so 
  wide 
  in 
  

   the 
  vertical 
  direction. 
  This 
  also 
  is 
  furnished 
  by 
  the 
  quadrate. 
  It 
  rises 
  

   nearly 
  f 
  inch 
  from 
  the 
  vertical 
  surface 
  to 
  which 
  it 
  is 
  attached, 
  and 
  

   lies 
  directly 
  above 
  the 
  narrowed 
  part 
  of 
  the 
  saddle-shaped 
  articular 
  

   surface. 
  Above 
  the 
  prominence 
  a 
  thin 
  vertical 
  plate, 
  lying 
  in 
  the 
  

   angle 
  between 
  the 
  articular 
  process 
  and 
  the 
  expanded 
  subcutaneous 
  

   part 
  of 
  the 
  quadrato-jugal, 
  connects 
  the 
  two 
  firmly 
  together. 
  It 
  

   thins 
  off 
  to 
  an 
  edge 
  internally, 
  and 
  is 
  there 
  deeply 
  arcuated, 
  forming 
  

   the 
  external 
  border 
  of 
  an 
  opening 
  in 
  the 
  posterior 
  wall 
  of 
  the 
  tem- 
  

   poral 
  fossa, 
  through 
  which 
  an 
  apertor 
  oris, 
  or 
  some 
  analogous 
  muscle, 
  

   arising 
  from 
  within 
  the 
  temporal 
  fossa, 
  and 
  inserted 
  into 
  the 
  post- 
  

   articular 
  process 
  of 
  the 
  mandible, 
  may 
  have 
  passed. 
  In 
  front 
  of 
  the 
  

   semicylindrical 
  articular 
  surface 
  a 
  thin 
  expansion 
  of 
  the 
  quadrato- 
  

   jugal 
  partly 
  conceals 
  the 
  quadrate, 
  descending 
  upon 
  it 
  lower 
  at 
  the 
  

   sides 
  than 
  in 
  the 
  middle 
  of 
  the 
  articular 
  surface. 
  An 
  articular 
  car- 
  

   tilage 
  probably 
  commenced 
  where 
  the 
  descending 
  edge 
  of 
  the 
  

   quadrato-jugal 
  terminates. 
  

  

  Measurements 
  : 
  — 
  in. 
  

  

  Greatest 
  length 
  of 
  fragment 
  4 
  

  

  Greatest 
  width 
  3 
  

  

  Greatest 
  thickness 
  of 
  plate 
  T 
  7 
  ^ 
  

  

  Articular 
  process, 
  transversely, 
  about 
  1 
  

  

  Articular 
  process, 
  longitudinally, 
  about 
  -| 
  

  

  Fig. 
  1. 
  — 
  Section 
  of 
  the 
  mandibular 
  articulation 
  of 
  Mastodonsaurus. 
  

   (The 
  bones 
  supposed 
  to 
  be 
  cut 
  through 
  are 
  shaded.) 
  

  

  If. 
  

  

  ^r 
  1 
  V 
  

  

  The 
  continuous 
  line 
  represents 
  the 
  contour 
  of 
  the 
  upper 
  jaw, 
  and 
  the 
  broken 
  

   line 
  that 
  of 
  the 
  mandible 
  (M). 
  The 
  zigzag 
  line 
  (c) 
  shows 
  the 
  junction 
  

   of 
  the 
  quadrate 
  (QU) 
  and 
  quadrato-jugal 
  (Q, 
  J). 
  

  

  