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  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  

  

  The 
  prefrontals 
  meet 
  along 
  the 
  median 
  line, 
  a 
  distance 
  of 
  16 
  mm., 
  

   and 
  this 
  is 
  also 
  the 
  length 
  of 
  the 
  suture 
  between 
  the 
  frontals. 
  The 
  

   lateral 
  angles 
  of 
  the 
  skull 
  extend 
  backward 
  to 
  a 
  point 
  slightly 
  posterior 
  

   to 
  the 
  occipital 
  condyle. 
  The 
  orbit 
  has 
  a 
  greatest 
  anteroposterior 
  

   diameter 
  of 
  23 
  mm.; 
  the 
  nasal 
  opening 
  is 
  17 
  mm. 
  wide; 
  the 
  interorbital 
  

   space 
  is 
  22 
  mm. 
  wide. 
  

  

  Viewed 
  from 
  above, 
  the 
  skull 
  of 
  Testudo 
  praeextans 
  has 
  its 
  closest 
  

   resemblances 
  in 
  the 
  cranium 
  of 
  the 
  Miocene 
  T. 
  osborniana, 
  differing 
  

  

  Figure 
  22. 
  — 
  Palatal 
  view 
  of 
  the 
  skull 
  of 
  Testudo 
  praeextans 
  Lambe 
  (U.S.N.M. 
  No. 
  15874): 
  

   bo, 
  basioccipital; 
  bsp, 
  basisphenoid; 
  ect, 
  ectopterygoid; 
  mx, 
  maxillary; 
  occ, 
  occipital 
  

   condyle; 
  pi, 
  palatine; 
  pmx, 
  premaxillary; 
  pt, 
  pterygoid; 
  qu, 
  quadrate; 
  so, 
  supraoccipital; 
  

   sq, 
  squamosal; 
  v, 
  vomer. 
  Natural 
  size. 
  

  

  in 
  its 
  smaller 
  size, 
  the 
  more 
  abruptly 
  truncated 
  snout, 
  the 
  more 
  

   bluntly 
  pointed 
  squamosal 
  region, 
  the 
  longer 
  supraocciptal 
  process, 
  

   and 
  the 
  straighter 
  cutting 
  edge 
  of 
  the 
  maxillary. 
  The 
  orbit 
  also 
  has 
  

   a 
  greater 
  anteroposterior 
  diameter, 
  being 
  one-fourth 
  the 
  over-all 
  

   length 
  of 
  the 
  skull. 
  The 
  anteroposterior 
  extent 
  of 
  the 
  otic 
  region 
  

   measured 
  across 
  the 
  paraoccipital 
  and 
  the 
  prootic 
  is 
  22 
  mm. 
  

  

  The 
  incomplete 
  skull 
  of 
  Testudo 
  thomsoni, 
  the 
  only 
  other 
  Oligocene 
  

   species 
  in 
  which 
  the 
  cranium 
  is 
  now 
  known, 
  differs 
  from 
  the 
  skull 
  

  

  