﻿INTRODUCTION. 
  

  

  329 
  

  

  especial 
  attention 
  to 
  "Cistudo" 
  which, 
  while 
  superficially 
  a 
  land 
  tortoise, 
  is 
  classed 
  by 
  him 
  

   as 
  an 
  Emydian 
  by 
  means 
  of 
  its 
  intestinal 
  measurements. 
  The 
  length 
  of 
  the 
  whole 
  intestine 
  

   in 
  comparison 
  with 
  the 
  length 
  of 
  the 
  shell 
  of 
  the 
  animal 
  is 
  proportionately 
  greater 
  in 
  herbivor- 
  

   ous 
  than 
  in 
  carnivorous 
  turtles. 
  The 
  heart 
  is 
  three-chambered 
  and 
  its 
  rate 
  of 
  contraction 
  slow. 
  

   The 
  voice 
  in 
  most 
  turtles 
  is 
  only 
  sUghtly 
  developed, 
  a 
  faint 
  piping 
  note 
  being 
  emitted, 
  chiefly 
  

   during 
  the 
  mating 
  seasons. 
  The 
  sea 
  turtles 
  are 
  more 
  efficiently 
  equipped, 
  especially 
  the 
  Leather- 
  

   back 
  Turtle, 
  one 
  of 
  whose 
  Latin 
  names 
  is 
  Sphargis 
  (coming 
  from 
  the 
  Greek, 
  crcf)apayeeo, 
  to 
  

   make 
  a 
  noise) 
  since 
  it 
  is 
  said 
  to 
  give 
  vent 
  to 
  loud 
  cries 
  or 
  barks 
  when 
  wounded 
  or 
  being 
  cap- 
  

   tured 
  (Sears, 
  18SG). 
  

  

  The 
  respiration 
  of 
  turtles 
  is 
  interesting 
  in 
  that 
  owing 
  to 
  the 
  bony 
  and 
  unjdelding 
  chest 
  

   wall 
  there 
  can 
  he 
  no 
  expansion 
  and 
  contraction, 
  necessitating 
  the 
  passage 
  of 
  air 
  under 
  pres- 
  

   sure 
  into 
  the 
  lungs. 
  This 
  is 
  accomplished 
  partly 
  b^' 
  means 
  of 
  the 
  highly 
  developed 
  hyoidean 
  

   apparatus 
  (the 
  air 
  being 
  swallowed 
  or 
  pumped 
  into 
  the 
  lungs) 
  and 
  partly 
  by 
  the 
  neck 
  and 
  

   limbs 
  which 
  act 
  as 
  pistons 
  when 
  drawn 
  in 
  or 
  out. 
  The 
  following 
  is 
  a 
  very 
  interesting 
  tal)le 
  

   showing 
  the 
  capacity 
  of 
  the 
  lungs 
  as 
  compared 
  with 
  the 
  weight 
  of 
  the 
  body 
  in 
  various 
  species 
  

   of 
  turtles, 
  after 
  L. 
  Agassiz 
  (1857, 
  vol. 
  1, 
  p. 
  283). 
  

  

  Pulmonary 
  respiration 
  is 
  supplemented 
  by 
  two 
  accessory 
  systems: 
  (I) 
  a 
  pair 
  of 
  thin- 
  

   walled, 
  highlj' 
  vascularized 
  anal 
  sacs 
  which 
  are 
  from 
  time 
  to 
  time 
  emptied 
  and 
  refilled 
  with 
  

   water, 
  and 
  (2) 
  in 
  some 
  aquatic 
  turtles 
  by 
  vascularized 
  areas 
  suggestive 
  of 
  gills, 
  in 
  the 
  pharyngeal 
  

   region. 
  During 
  hibernation 
  (regularly 
  performed 
  in 
  this 
  latitude) 
  pulmonary 
  respiration 
  is 
  

   entirely 
  suspended.^ 
  

  

  ' 
  Aestivation 
  has 
  also 
  been 
  observed 
  in 
  certain 
  species 
  (see 
  G, 
  P. 
  Engelhardt, 
  1916, 
  on 
  "Burrowing 
  Habits 
  of 
  the 
  Box 
  

   Turtle"). 
  

  

  