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  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  

  

  Table 
  2. 
  — 
  Comparative 
  measurements 
  {in 
  jnillimeters) 
  of 
  nuchals, 
  pygals, 
  and 
  

   suprapygals 
  of 
  Testudo 
  praeextans 
  

  

  Table 
  3. 
  — 
  Comparison 
  of 
  shape 
  of 
  neurals 
  of 
  Testudo 
  praeextans 
  

  

  The 
  free 
  border 
  of 
  the 
  pygal 
  in 
  specimen 
  No. 
  15874 
  differs 
  from 
  the 
  

   others 
  in 
  being 
  strongly 
  toothed. 
  The 
  bifurcated 
  first 
  suprapygal 
  

   in 
  the 
  type 
  and 
  in 
  specimen 
  No. 
  15874 
  is 
  in 
  contact 
  with 
  the 
  pygal 
  

   and 
  eleventh 
  peripheral, 
  whereas 
  in 
  the 
  other 
  three 
  specimens 
  it 
  

   articulates 
  only 
  with 
  the 
  eleventh 
  peripheral. 
  

  

  In 
  the 
  shape 
  of 
  the 
  neural 
  bones 
  three 
  features 
  are 
  found 
  common 
  

   to 
  all 
  available 
  specimens: 
  (1) 
  The 
  first 
  neural 
  is 
  the 
  longest 
  of 
  the 
  

   series; 
  (2) 
  the 
  thii'd 
  neural 
  is 
  always 
  quadrangular; 
  (3) 
  the 
  fifth 
  to 
  

   eighth 
  neurals, 
  inclusive, 
  are 
  hexagonal. 
  One 
  individual, 
  No. 
  15878, 
  

   has 
  two 
  octagonal 
  neurals, 
  the 
  second 
  and 
  fourth; 
  one. 
  No. 
  16732, 
  

   has 
  only 
  the 
  second 
  neural 
  octagonal; 
  and 
  No. 
  16728 
  has 
  none 
  octago- 
  

   nal. 
  In 
  most 
  species 
  of 
  Testudo 
  there 
  are 
  two 
  octagonal 
  neurals, 
  the 
  

   second 
  and 
  fourth, 
  but 
  a 
  series 
  of 
  specimens 
  of 
  other 
  species 
  might 
  

   show 
  them 
  to 
  be 
  equally 
  variable 
  as 
  in 
  T. 
  praeextans. 
  The 
  variation 
  

   in 
  the 
  form 
  of 
  the 
  neurals 
  in 
  T. 
  praeextans 
  is 
  shown 
  in 
  table 
  3. 
  

  

  In 
  discussing 
  the 
  neurals 
  of 
  T. 
  laticunea, 
  Hay^ 
  says, 
  "The 
  nem-als 
  

   have 
  not 
  attained 
  so 
  high 
  a 
  degree 
  of 
  differentiation 
  of 
  form 
  as 
  they 
  

   have 
  in 
  most 
  of 
  the 
  species 
  of 
  the 
  genus." 
  If 
  reference 
  is 
  made 
  to 
  the 
  

   absence 
  of 
  octagonal 
  neurals 
  the 
  statement 
  is 
  true 
  of 
  the 
  types 
  of 
  

  

  3 
  Hay, 
  O. 
  P., 
  Carnegie 
  Inst. 
  Washington 
  Publ. 
  75, 
  p. 
  403, 
  1908. 
  

  

  