﻿Varanosanrus 
  acutirostri?, 
  DroiU. 
  307 
  

  

  and 
  the 
  occasional 
  presence 
  of 
  a 
  supratemporal. 
  Varano- 
  

   sanrus 
  is 
  thus 
  probably 
  the 
  most 
  primitive 
  known 
  memb;*r 
  of 
  

   the 
  mamraal-like 
  reptiles, 
  and 
  is 
  of 
  very 
  great 
  interest 
  from 
  

   the 
  standpoint 
  of 
  the 
  origin 
  of 
  Uiat 
  group. 
  

  

  In 
  the 
  paper 
  referred 
  to 
  above 
  I 
  have 
  listed 
  the 
  important 
  

   characters 
  which 
  are 
  common 
  to 
  all 
  South-African 
  Therapsids 
  

   as 
  follows 
  : 
  — 
  

  

  1. 
  There 
  is 
  one 
  lateral 
  temporal 
  fossa 
  bounded 
  primitively 
  

  

  by 
  the 
  postorbital 
  and 
  squamosal 
  alone, 
  the 
  parietal 
  

   and 
  jngal 
  entering 
  later 
  into 
  its 
  borders. 
  

  

  2. 
  The 
  occiput 
  is 
  plate-like. 
  

  

  3. 
  The 
  interparietal 
  and 
  tabulares 
  are 
  on 
  the 
  back 
  of 
  the 
  

  

  skiill 
  overlapping 
  the 
  supraoccipital. 
  

  

  4. 
  The 
  brain-cavity 
  is 
  very 
  high. 
  

  

  5. 
  The 
  ear 
  is 
  very 
  low 
  on 
  the 
  side 
  of 
  the 
  brain-cavity. 
  

  

  0. 
  There 
  is 
  only 
  one 
  temporal 
  element, 
  the 
  squamosal. 
  

  

  7. 
  There 
  are 
  two 
  coracoidal 
  elements, 
  the 
  anterior 
  not 
  

  

  contributing 
  to 
  the 
  glenoid 
  cavity, 
  

  

  8. 
  The 
  flat 
  angular 
  [notched 
  behind]. 
  

  

  9. 
  The 
  contact 
  of 
  the 
  outer 
  end 
  of 
  the 
  stapes 
  with 
  the 
  

  

  quadrate. 
  

  

  Varanosanrus 
  possesses 
  all 
  these 
  characters 
  except 
  6, 
  from 
  

   which 
  it 
  differs 
  by 
  the 
  presence 
  of 
  a 
  minute 
  supratem{)oral, 
  

   ■which 
  is 
  obviously 
  vanishing. 
  

  

  No. 
  5 
  is 
  not 
  very 
  definitely 
  known 
  in 
  Varanosaurus, 
  but, 
  

   judging 
  from 
  the 
  position 
  of 
  the 
  fenestra 
  ovale, 
  it 
  is 
  possessed. 
  

  

  Although 
  the 
  angular 
  is 
  not 
  actually 
  present, 
  the 
  appear- 
  

   ances 
  of 
  the 
  other 
  bones 
  show 
  conclnsively 
  that 
  Varano- 
  

   saurus 
  had 
  a 
  typically 
  Therapsid 
  lower 
  jaw. 
  

  

  Varanosanrus 
  thus 
  possesses 
  all 
  the 
  fundamental 
  Therapsid 
  

   characters. 
  It 
  has 
  also 
  the 
  following 
  primitive 
  features 
  : 
  — 
  

  

  1. 
  The 
  retention 
  of 
  a 
  vestigial 
  supratemporal. 
  

  

  2. 
  The 
  retention 
  of 
  the 
  primitive 
  union 
  of 
  the 
  squamosal 
  

  

  and 
  pterygoid 
  behind 
  the 
  quadrate. 
  

   8. 
  The 
  Cotylosaurian-like 
  basisphenoid. 
  

  

  4. 
  The 
  deep 
  posterior 
  ramus 
  of 
  the 
  pterygoid. 
  

  

  5. 
  The 
  extension 
  of 
  the 
  lachrymal 
  forward 
  to 
  the 
  sei)to- 
  

  

  maxilla. 
  

  

  6. 
  The 
  heavy 
  neural 
  arches 
  and 
  horizontal 
  zygapophysial 
  

  

  articulating 
  faces. 
  

  

  7 
  . 
  The 
  interceutra 
  throughout 
  the 
  column. 
  

  

  8. 
  The 
  holocephalous 
  ribs. 
  

  

  9. 
  The 
  expanded 
  ribs 
  in 
  the 
  pectoral 
  region. 
  

  

  10. 
  The 
  primitive 
  form 
  of 
  the 
  glenoid 
  cavity. 
  

  

  11. 
  The 
  primitive 
  humerus. 
  

  

  12. 
  The 
  primitive 
  type 
  of 
  femtir. 
  

  

  