﻿OSTEOLOGY 
  OF 
  TESTUDO 
  PRAEEXTANS— 
  GILMORE 
  301 
  

  

  both 
  T. 
  laticunea 
  and 
  T. 
  -praeextans. 
  In 
  my 
  judgment 
  the 
  dirt'orence 
  

   found 
  in 
  the 
  neural 
  bones 
  of 
  the 
  specimens 
  under 
  consich-ration 
  repre- 
  

   sents 
  individual 
  variations 
  well 
  within 
  the 
  species. 
  

  

  Specimen 
  U.S.N.M. 
  No. 
  15878 
  (pi. 
  38, 
  fig. 
  2) 
  has 
  an 
  extra 
  neural, 
  

   or 
  nine 
  in 
  all. 
  It 
  is 
  quite 
  evident 
  from 
  an 
  examination 
  of 
  the 
  speci- 
  

   men 
  that 
  the 
  extra 
  element 
  has 
  ileveloped 
  between 
  number 
  7 
  and 
  the 
  

   last, 
  which 
  is 
  without 
  corresponding 
  costals. 
  Lambe 
  * 
  has 
  described 
  

   a 
  greater 
  deviation 
  of 
  carapace 
  structure 
  in 
  a 
  specimen 
  of 
  Stylemys 
  

   nebrascensis, 
  which 
  has 
  not 
  only 
  an 
  extra 
  neural 
  but 
  also 
  a 
  ninth 
  pair 
  

   of 
  costal 
  bones 
  and 
  an 
  additional 
  vertebral 
  scute. 
  Tliis 
  same 
  authority 
  

   points 
  out 
  that 
  the 
  type 
  of 
  Stylemys 
  culhertsoni 
  likewise 
  has 
  an 
  addi- 
  

   tional 
  neural. 
  

  

  The 
  variation 
  in 
  shape 
  of 
  the 
  neurals 
  has 
  brought 
  about 
  a 
  corre- 
  

   sponding 
  variation 
  in 
  the 
  proportions 
  of 
  these 
  bones, 
  as 
  shown 
  in 
  table 
  

   4. 
  In 
  Tf.stvdo 
  praeertans 
  the 
  first 
  neural 
  is 
  consistently 
  the 
  longest 
  of 
  

   any 
  of 
  the 
  series. 
  

  

  The 
  costal 
  plates 
  in 
  all 
  these 
  specimens 
  are 
  highly 
  modified, 
  and 
  as 
  

   usual 
  in 
  Testudo 
  the 
  second, 
  fourth, 
  and 
  sixth 
  are 
  widened 
  distally 
  and 
  

   narrowed 
  proximally, 
  while 
  the 
  third 
  and 
  fifth 
  are 
  narrowed 
  distally 
  

   and 
  widened 
  at 
  the 
  proximal 
  ends. 
  

  

  The 
  sulci 
  in 
  most 
  of 
  the 
  specimens 
  are 
  narrow 
  and 
  shallowly 
  im- 
  

   pressed, 
  and 
  where 
  they 
  reach 
  the 
  free 
  edges 
  of 
  the 
  peripherals 
  there 
  is 
  

   usually 
  a 
  small 
  obtuse 
  projection 
  or 
  mucro. 
  

  

  In 
  the 
  type 
  of 
  Testudo 
  praeextans 
  the 
  sulcus 
  forming 
  the 
  posterior 
  

   boundary 
  of 
  the 
  third 
  vertebral 
  curves 
  strongly 
  forward 
  at 
  the 
  center 
  

   where 
  it 
  crosses 
  the 
  fifth 
  neural, 
  as 
  in 
  U.S.N.M. 
  Nos. 
  15878, 
  16728, 
  and 
  

   1G7.32. 
  In 
  specimen 
  No. 
  15874, 
  however, 
  the 
  sulcus 
  crosses 
  the 
  sixth 
  

   neural 
  as 
  in 
  the 
  type 
  of 
  T. 
  laticunae 
  Cope. 
  

  

  The 
  proportions 
  of 
  the 
  vertebrals 
  are 
  variable, 
  as 
  shown 
  in 
  tal)le 
  5. 
  

   In 
  the 
  type 
  of 
  7'. 
  laticunea 
  and 
  No. 
  15878 
  the 
  fifth 
  vertebral 
  is 
  the 
  

   longest 
  of 
  the 
  series, 
  whereas 
  in 
  No. 
  15874 
  the 
  first 
  is 
  the 
  longest. 
  

   In 
  the 
  type 
  of 
  T. 
  laticvnea 
  and 
  No. 
  15874 
  the 
  first 
  vertebral 
  is 
  longer 
  

   than 
  wide, 
  but 
  in 
  the 
  type 
  of 
  T. 
  praeexiuns 
  and 
  No. 
  15878 
  this 
  same 
  

   vertebral 
  is 
  wider 
  than 
  long. 
  No. 
  15874 
  is 
  the 
  only 
  specimen 
  having 
  

   the 
  third 
  vertebral 
  longer 
  than 
  wide. 
  

  

  The 
  most 
  distinctive 
  feature 
  of 
  the 
  plastron 
  is 
  the 
  extended 
  epiphis- 
  

   tnd 
  lip 
  that 
  always 
  projects 
  well 
  Ix'vond 
  the 
  line 
  of 
  the 
  front 
  margin 
  of 
  

   the 
  carapace. 
  It 
  was 
  the 
  "marked 
  prominence 
  and 
  size 
  of 
  the 
  

   epiplastral 
  lip" 
  that 
  Lanibe' 
  stressed 
  as 
  the 
  most 
  important 
  character 
  

   for 
  distinguishing 
  Testvdo 
  praeextans, 
  a 
  character 
  to 
  which 
  the 
  specific 
  

   name 
  refers. 
  In 
  the 
  light 
  of 
  these 
  additional 
  spc'cimens 
  it 
  is 
  clearly 
  

   shown 
  that 
  the 
  extent 
  and 
  shape; 
  of 
  this 
  lip 
  constitute 
  one 
  of 
  the 
  more 
  

   stable 
  characters 
  of 
  this 
  species. 
  

  

  < 
  I-ambp. 
  L. 
  M., 
  Ottawa 
  Nat., 
  vol. 
  27, 
  p. 
  W, 
  1013. 
  

  

  • 
  LanilH!, 
  L. 
  M., 
  Ottawa 
  Nat., 
  vol. 
  27, 
  pp. 
  57-fil, 
  pl«<, 
  1. 
  o. 
  UM.1. 
  

  

  