﻿OSTEOLOGY 
  OF 
  TESTl'DO 
  PR.\KEXTANS 
  — 
  GILMORE 
  

  

  299 
  

  

  T.\BLE 
  1. 
  — 
  Comparative 
  vieaaurements 
  of 
  carapaces 
  of 
  Testudo 
  praeextans 
  

  

  • 
  Shortened 
  by 
  crushing. 
  

  

  Tlic 
  larger 
  size 
  of 
  the 
  National 
  Museum 
  specimens 
  as 
  compaied 
  

   with 
  the 
  type 
  may 
  be 
  accounted 
  for 
  partly 
  by 
  difference 
  in 
  age 
  and 
  

   l)artly 
  by 
  sex. 
  The 
  hollowcd-out 
  plastra 
  of 
  the 
  National 
  Museum 
  

   s])c'cinu'ns 
  clearly 
  indicate 
  them 
  to 
  be 
  males, 
  whereas 
  the 
  flattened 
  

   })lastron 
  of 
  the 
  typo 
  of 
  T. 
  praeextans 
  shows 
  it 
  to 
  be 
  a 
  female. 
  Among 
  

   living 
  land 
  tortoises 
  it 
  is 
  a 
  well-established 
  fact 
  that 
  the 
  males 
  of 
  a 
  

   species 
  attain 
  a 
  larger 
  size 
  than 
  the 
  females. 
  Furthermore, 
  that 
  the 
  

   larger 
  specimens 
  (U.S.N. 
  M. 
  Nos. 
  15874 
  and 
  16732) 
  are 
  aged 
  individ- 
  

   uals 
  is 
  shown 
  by 
  the 
  strong 
  incurving 
  of 
  the 
  pygal 
  region 
  (pi. 
  40, 
  fig. 
  

   1 
  ; 
  pi. 
  41, 
  fig. 
  2), 
  for 
  it 
  has 
  been 
  observed 
  by 
  Lord 
  Rothschild,^ 
  in 
  his 
  

   study 
  of 
  the 
  Galdpagos 
  tortoises, 
  that 
  "very 
  old 
  individuals 
  of 
  both 
  

   sexes 
  show 
  an 
  inclination 
  often 
  very 
  strong, 
  for 
  the 
  supracaudal 
  to 
  

   curve 
  round 
  towards 
  and 
  even 
  under 
  the 
  posterior 
  end 
  of 
  the 
  

   plastron." 
  

  

  Viewed 
  from 
  above, 
  all 
  the 
  specimens 
  (pis. 
  38, 
  39), 
  including 
  the 
  

   type, 
  are 
  very 
  similar 
  in 
  having 
  their 
  anterior 
  borders 
  broadly 
  rounded 
  

   from 
  side 
  to 
  side; 
  the 
  breadth 
  of 
  the 
  shell 
  decreases 
  more 
  rapidly 
  to- 
  

   ward 
  the 
  front 
  than 
  toward 
  the 
  back, 
  and 
  so 
  the 
  posterior 
  half 
  has 
  a 
  

   squarer 
  outline 
  than 
  the 
  anterior 
  half. 
  This 
  is 
  brought 
  about 
  chiefly 
  

   by 
  the 
  enlargement 
  of 
  the 
  ])eripherals. 
  The 
  posterior 
  border 
  may 
  i)e 
  

   described 
  as 
  angularly 
  lounded, 
  though 
  this 
  contour 
  dilFers 
  c<ui- 
  

   siderably 
  with 
  the 
  age 
  of 
  (Ik; 
  individual. 
  The 
  oldest 
  s])ecimens 
  

   (Nos. 
  15874 
  and 
  10732) 
  are 
  more 
  squarely 
  tniiicate 
  across 
  the 
  pygal 
  

   region 
  tlian 
  the 
  otlieis, 
  owing 
  to 
  the 
  do^viiward 
  and 
  f(tI•^\aI•d 
  deflection 
  

   (»f 
  this 
  ini(l])ortion 
  of 
  the 
  shell. 
  

  

  The 
  anterior 
  peripherals 
  in 
  all 
  specimens 
  agree 
  in 
  being 
  produced 
  al- 
  

   most 
  horizontally 
  forward; 
  the 
  hiteral 
  ones 
  continue 
  the 
  geiu'ral 
  con- 
  

   vexity 
  of 
  the 
  shell 
  downward, 
  whereas 
  those 
  more 
  posteriorly 
  Mare 
  

   outward 
  and 
  somewhat 
  njjward 
  above 
  the 
  o[)enings 
  for 
  the 
  posterior 
  

   extremities. 
  

  

  The 
  nuchal, 
  as 
  shown 
  by 
  the 
  measurements 
  in 
  table 
  2, 
  is 
  fairly 
  con- 
  

   stant 
  in 
  its 
  extent 
  and 
  proportions. 
  The 
  same 
  observation 
  may 
  be 
  

   nuide 
  of 
  the 
  pygal, 
  suprapygal, 
  and 
  second 
  su])rapygal. 
  

  

  1 
  liothschlld. 
  I-. 
  W., 
  Nov. 
  Zof.l.. 
  vol. 
  22. 
  i>. 
  42N, 
  1015. 
  

  

  