Voice 



usually by the males only of a given species. The air enters at 

 the nostrils (the mouth is kept closed) and passes back and forth 

 from mouth to lungs over the vocal cords. The sounds can be 

 produced under water, and often are in the case of our common 

 bullfrogs. 



The Salientia possess internal vocal sacs in the region of the 

 throat or on each side at the shoulder. These, when inflated, may 

 push out and stretch the loose outer skin of the body, and thus 

 show as external vocal pouches. The vocal sacs are filled with 

 air, through openings from the mouth, and act as resonators, in- 

 creasing the volume of sound. Single external vocal pouches at 

 the throat are possessed by Engystoma and Hypopachus, by 

 Bufo jowlen, Bujo punciaius, Bufo lentiginosus, Bufo americanus, 

 Bufo I. woodhousei, and by all members of the Hylidae. (Fig. 7.) 



Fig. 7. The Common Tree Frog — (i) in resting position 

 with lungs inflated and body large, and (2) singing, the air 

 from the lungs forced into the throat vocal pouch. 



Vocal bladders inflated from the middle of the base of the throat 

 are to be found in Bufo cognatus, Bujo compaclilis, and Bujo 

 quercicus.^ (Fig. 8.) Vocal pouches visible at the shoulder are 



^ Living male specimens of Bujo hemiophrys and Bufo debilis have not been examined. 



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