﻿FROM 
  IHE 
  KETTPER 
  SANDSTONE 
  OF 
  WARWICK. 
  421 
  

  

  4. 
  Mastodonsattrus 
  pachygnathtts, 
  Owen 
  — 
  postero-external 
  angle 
  

  

  of 
  skull 
  (right 
  side). 
  Warwick, 
  1864. 
  PL 
  XXVII. 
  fig. 
  2. 
  

  

  This 
  fragment 
  is 
  bounded 
  on 
  all 
  sides 
  by 
  lines 
  of 
  fracture. 
  The 
  

   upper 
  surface 
  is 
  much 
  obscured 
  by 
  matrix 
  ; 
  the 
  part 
  visible 
  displays 
  

   a 
  boldly 
  sculptured 
  pattern. 
  The 
  lower 
  surface 
  is 
  smooth. 
  Upon 
  

   it 
  portions 
  of 
  an 
  extremely 
  jagged 
  suture, 
  which 
  divides 
  the 
  bone 
  

   into 
  two 
  nearly 
  equal 
  parts, 
  may 
  be 
  traced. 
  These 
  are 
  probably 
  the 
  

   quadrato-jugal 
  and 
  jugal 
  ossifications 
  ; 
  part 
  of 
  a 
  third 
  bone 
  (supra- 
  

   temporal 
  ?) 
  may 
  be 
  indistinctly 
  seen 
  in 
  the 
  angle 
  between 
  the 
  other 
  

   two. 
  At 
  the 
  postero-external 
  corner 
  a 
  hook-like 
  fragment 
  projects 
  

   inwards 
  and 
  downwards. 
  This 
  is 
  evidently 
  part 
  of 
  the 
  articular 
  

   process 
  described 
  in 
  the 
  account 
  of 
  the 
  preceding 
  fossil. 
  

  

  The 
  greatest 
  thickness 
  (towards 
  the 
  posterior 
  end) 
  is 
  T 
  5 
  ^ 
  inch. 
  

  

  5. 
  Mastodonsattrtts 
  — 
  portion 
  of 
  occipital 
  border. 
  Warwick, 
  1864. 
  

  

  PL 
  XXVI. 
  figs. 
  2 
  A, 
  2 
  B, 
  2 
  C. 
  

   The 
  next 
  fossil 
  to 
  be 
  described 
  comprises 
  the 
  epiotic 
  and 
  portions 
  

   of 
  adjacent 
  bones 
  of 
  the 
  left 
  side 
  of 
  the 
  skull. 
  Some 
  of 
  the 
  margins 
  

   are 
  rounded, 
  as 
  if 
  by 
  attrition 
  ; 
  but 
  the 
  fossil, 
  though 
  very 
  imperfect, 
  

   is 
  for 
  the 
  rest 
  in 
  good 
  condition. 
  I 
  believe 
  it 
  to 
  belong 
  to 
  Masto- 
  

   donsaurus, 
  though 
  no 
  other 
  examples 
  of 
  the 
  genus 
  present 
  the 
  same 
  

   view 
  of 
  the 
  same 
  parts, 
  so 
  as 
  to 
  permit 
  an 
  accurate 
  comparison. 
  The 
  

   large 
  notch, 
  or 
  auditory 
  fossa, 
  upon 
  the 
  posterior 
  border 
  is 
  eminently 
  

   characteristic 
  of 
  the 
  Labyrinthodont 
  skull. 
  Its 
  horizontal 
  outline 
  

   is, 
  in 
  the 
  present 
  case, 
  nearly 
  semicircular. 
  In 
  none 
  of 
  the 
  German 
  

   specimens 
  of 
  Mastoclonsaurus 
  is 
  the 
  fossa 
  exhibited 
  without 
  consider- 
  

   able 
  distortion 
  ; 
  but 
  the 
  Warwick 
  fossil 
  affords 
  an 
  excellent 
  view 
  of 
  

   its 
  boundaries 
  and 
  form. 
  Nevertheless 
  the 
  difficulties 
  of 
  interpre- 
  

   tation, 
  arising 
  chiefly 
  from 
  our 
  ignorance 
  of 
  the 
  soft 
  parts, 
  are 
  con- 
  

   siderable. 
  The 
  inner 
  wall 
  of 
  the 
  fossa 
  is 
  formed 
  by 
  the 
  epiotic 
  (Ep). 
  

   Its 
  original 
  surface 
  has 
  been 
  broken 
  away 
  from 
  the 
  upper 
  half. 
  The 
  

   lower 
  half 
  recedes 
  inwards 
  and 
  forwards 
  ; 
  it 
  is 
  irregular 
  in 
  form, 
  and 
  

   appears 
  to 
  have 
  served 
  for 
  muscular 
  attachment. 
  A 
  broken 
  vertical 
  

   section 
  of 
  the 
  epiotic, 
  internal 
  to 
  the 
  fossa, 
  is 
  upwards 
  of 
  half 
  an 
  

   inch 
  thick. 
  The 
  bone 
  slightly 
  diminishes 
  in 
  thickness 
  forwards. 
  

   Upon 
  the 
  internal 
  wall 
  of 
  the 
  fossa 
  it 
  passes 
  down 
  to 
  a 
  depth 
  of 
  

   nearly 
  an 
  inch 
  from 
  the 
  superior 
  surface. 
  Beneath 
  the 
  epiotic 
  plate, 
  

   an 
  ascending 
  process 
  of 
  the 
  exoccipital 
  bounds, 
  if 
  I 
  mistake 
  not, 
  the 
  

   inner 
  side 
  of 
  the 
  fossa. 
  This 
  ascending 
  process 
  runs 
  out 
  to 
  a 
  nearly 
  

   vertical 
  edge 
  behind 
  ; 
  it 
  increases 
  in 
  thickness 
  forwards, 
  giving 
  

   strong 
  support 
  to 
  the 
  superior 
  wall 
  of 
  the 
  cranium. 
  Below, 
  it 
  is 
  ter- 
  

   minated 
  by 
  fracture 
  ; 
  it 
  may 
  have 
  been 
  continued 
  downwards 
  as 
  a 
  

   ridge 
  leading 
  to 
  the 
  condyle. 
  The 
  large 
  skull 
  of 
  Mastoclonsaurus 
  

   from 
  Gaildorf 
  gives 
  evidence 
  as 
  to 
  the 
  existence 
  of 
  such 
  a 
  ridge. 
  

   On 
  the 
  inner 
  side 
  of 
  this 
  exoccipital 
  buttress, 
  and 
  in 
  the 
  angle 
  be- 
  

   tween 
  it 
  and 
  the 
  epiotic, 
  is 
  a 
  deep 
  pit, 
  the 
  analogue, 
  possibly, 
  of 
  the 
  

   posterior 
  temporal 
  fossa 
  in 
  the 
  Crocodilian 
  skull*. 
  Behind 
  this 
  pit 
  

   the 
  occipital 
  buttress 
  is 
  smooth 
  and 
  gently 
  convex. 
  

  

  * 
  A 
  similar 
  pit 
  exists 
  in 
  Capitosaurus. 
  See 
  Quenstedt, 
  Mastodonsaurier 
  &c, 
  

   tab. 
  ii. 
  fig. 
  3. 
  

  

  