﻿VOICE. 
  

  

  61 
  

  

  YIII. 
  Voice. 
  

  

  All 
  our 
  male 
  Batrachians 
  are 
  endowed 
  with 
  a 
  voice, 
  

   wliicli 
  they 
  produce 
  at 
  least 
  during 
  the 
  pairing 
  season. 
  

   Females 
  are 
  mute, 
  or 
  respond 
  to 
  the 
  male 
  by 
  a 
  mere 
  

   grunt. 
  The 
  larynx 
  is 
  provided 
  with 
  vocal 
  cords, 
  

   which 
  are 
  set 
  vibrating 
  as 
  the 
  air 
  is 
  rapidly 
  shifted 
  

   from 
  the 
  lungs 
  into 
  the 
  buccal 
  cavity. 
  In 
  many 
  

   species 
  the 
  sound 
  is 
  intensified 
  by 
  resonance 
  in 
  

   special 
  vocal 
  sacs 
  situated 
  in 
  the 
  gular 
  region, 
  or 
  at 
  

   the 
  sides 
  of 
  the 
  head 
  behind 
  the 
  commissures 
  of 
  the 
  

   jaws. 
  The 
  vocal 
  sacs 
  are 
  called 
  internal 
  when 
  

  

  Fig. 
  23. 
  

  

  -r 
  

  

  > 
  

  

  A. 
  Bana 
  esculenta, 
  (^, 
  witli 
  inflated 
  external 
  vocal 
  sacs 
  (lower 
  view). 
  

  

  B. 
  Rana 
  temporaria, 
  ^, 
  witli 
  inflated 
  internal 
  vocal 
  sacs 
  (lower 
  view), 
  

  

  covered 
  by 
  the 
  unmodified 
  gular 
  integument, 
  how- 
  

   ever 
  much 
  this 
  may 
  be 
  distended 
  ; 
  external 
  when 
  their 
  

   membrane, 
  a 
  diverticulum 
  of 
  the 
  mylohyoid 
  muscle, 
  

   projects 
  through 
  slits 
  at 
  the 
  sides 
  of 
  the 
  throat, 
  as 
  

   in 
  Bana 
  esculenta, 
  or 
  when 
  the 
  skin 
  is 
  thinned 
  and 
  

   converted 
  into 
  a 
  bladder-like 
  pouch, 
  as 
  in 
  Hyla 
  

   arhorea. 
  In 
  some 
  forms 
  there 
  are 
  two 
  distinct 
  

   sacs, 
  in 
  others 
  but 
  one. 
  The 
  air 
  penetrates 
  by 
  one 
  or 
  

   two 
  openings 
  in 
  the 
  floor 
  of 
  the 
  mouth, 
  small, 
  rounded, 
  

   and 
  situated 
  near 
  the 
  commissures 
  of 
  the 
  jaws, 
  as 
  

  

  