﻿art. 
  28 
  SKULL 
  OP 
  ZARHACHIS 
  FLAGELLATOR 
  KELLOGG 
  13 
  

  

  palatine 
  are 
  clearly 
  outlined. 
  It 
  is 
  a 
  relatively 
  narrow 
  bone 
  mortised 
  

   into 
  the 
  maxilla 
  above 
  and 
  bounded 
  externally 
  by 
  the 
  upper 
  margin 
  

   of 
  the 
  external 
  reduplication 
  of 
  the 
  pterygoid. 
  As 
  now 
  understood, 
  

   each 
  pyramidal 
  cavity 
  is 
  inclosed 
  on 
  the 
  rear 
  by 
  the 
  internal 
  plate 
  of 
  

   the 
  pterygoid, 
  on 
  the 
  outside 
  by 
  the 
  external 
  reduplication 
  of 
  the 
  

   pterygoid, 
  on 
  the 
  inside 
  by 
  a 
  thin 
  internal 
  plate 
  of 
  the 
  pterygoid 
  

   posteriorly 
  and 
  by 
  the 
  vomer 
  anteriorly, 
  and 
  above 
  by 
  the 
  palatine 
  

   posteriorly 
  and 
  the 
  maxilla 
  anteriorly. 
  The 
  thin 
  internal 
  plate 
  of 
  the 
  

   pterygoid 
  does 
  not 
  project 
  as 
  far 
  forward 
  as 
  in 
  Platanista, 
  but 
  other- 
  

   wise 
  the 
  relations 
  between 
  the 
  palatines 
  and 
  pterygoids 
  are 
  essen- 
  

   tially 
  the 
  same 
  in 
  both 
  genera. 
  The 
  external 
  reduplication 
  of 
  the 
  

   pterygoid 
  is 
  not 
  developed 
  on 
  skulls 
  of 
  Inia 
  and 
  Lipotes, 
  thus 
  ex- 
  

   posing 
  the 
  entire 
  alisphenoid. 
  On 
  the 
  ZarhacMs 
  skull 
  the 
  extremity 
  

   of 
  the 
  alisphenoid 
  is 
  not 
  overspread 
  by 
  the 
  external 
  reduplication 
  of 
  

   the 
  pter\ 
  T 
  goid 
  and 
  it 
  appears 
  within 
  the 
  temporal 
  fossa 
  in 
  the 
  same 
  

   relative 
  position 
  as 
  in 
  Inia. 
  In 
  Platanista 
  the 
  extremity 
  of 
  tho 
  ali- 
  

   sphenoid 
  is 
  overspread 
  by 
  the 
  external 
  reduplication 
  of 
  the 
  pterygoid. 
  

  

  The 
  keel 
  of 
  the 
  trough 
  of 
  the 
  vomer 
  is 
  exposed 
  between 
  the 
  nasal 
  

   passages 
  and 
  the 
  anterior 
  extremity 
  of 
  the 
  external 
  reduplication 
  of 
  

   the 
  pterygoid. 
  In 
  its 
  shape 
  and 
  relations 
  with 
  the 
  surrounding 
  

   bones, 
  the 
  vomer 
  does 
  not 
  differ 
  from 
  that 
  on 
  the 
  first 
  skull. 
  It 
  ex- 
  

   pands 
  horizontally 
  posterior 
  to 
  the 
  nasal 
  passages, 
  but 
  terminates 
  

   near 
  the 
  anterior 
  margin 
  of 
  the 
  basisphenoid. 
  

  

  The 
  median 
  region 
  of 
  the 
  basicranium 
  is 
  rather 
  broad, 
  bounded 
  on 
  

   each 
  side, 
  as 
  mentioned 
  above, 
  by 
  a 
  continuous 
  wall 
  formed 
  by 
  the 
  

   vaginal 
  plate 
  of 
  the 
  pterygoid 
  and 
  the 
  adjoining 
  falcate 
  process 
  of 
  the 
  

   basioccipital. 
  The 
  surface 
  of 
  the 
  median 
  area 
  between 
  these 
  sloping 
  

   walls 
  is 
  more 
  or 
  less 
  concave. 
  The 
  basioccipital 
  is 
  a 
  much 
  larger 
  

   bone 
  than 
  the 
  basisphenoid; 
  the 
  transverse 
  suture 
  between 
  these 
  

   bones 
  is 
  unusually 
  distinct. 
  The 
  occipital 
  condyles 
  are 
  large 
  and 
  are 
  

   separated 
  mesially 
  by 
  a 
  deep 
  groove. 
  A 
  deep 
  jugular 
  incisure 
  ap- 
  

   pears 
  between 
  the 
  internal 
  margin 
  of 
  the 
  exoccipital 
  and 
  the 
  posterior 
  

   margin 
  of 
  the 
  falcate 
  process 
  of 
  the 
  basioccipital. 
  A 
  small 
  condylar 
  

   foramen 
  is 
  present 
  on 
  each 
  side 
  between 
  the 
  base 
  of 
  the 
  falcate 
  process 
  

   of 
  the 
  basioccipital 
  and 
  the 
  condyle. 
  

  

  The 
  body 
  of 
  the 
  squamosal 
  contributes 
  a 
  part 
  of 
  the 
  lateral 
  wall 
  of 
  

   the 
  brain 
  case 
  and 
  its 
  lateral 
  projection 
  or 
  zygomatic 
  process 
  serves 
  

   as 
  the 
  articular 
  surface 
  for 
  the 
  condyle 
  of 
  the 
  lower 
  jaw. 
  The 
  gle- 
  

   noid 
  articular 
  surface 
  on 
  the 
  zygomatic 
  process 
  curves 
  upward 
  and 
  

   forward 
  and 
  is 
  concave 
  from 
  side 
  to 
  side. 
  Tho 
  external 
  border 
  of 
  

   the 
  zygomatic 
  process 
  is 
  prolonged 
  downward, 
  forming 
  a 
  thin 
  crest; 
  

   the 
  internal 
  border 
  is 
  rounded 
  off. 
  The 
  postglenoid 
  process 
  is 
  short 
  

   and 
  curves 
  forward. 
  A 
  shallow 
  groove 
  for 
  the 
  external 
  auditory 
  

   meatus 
  traverses 
  the 
  squamosal 
  behind 
  the 
  postglenoid 
  process. 
  A 
  

   narrow 
  posteriorly 
  directed 
  process 
  of 
  the 
  squamosal 
  is 
  suturally 
  

  

  