zoology either of the loose folds of skin on each side of the mouth in many male frogs that can be inflated and act as resonators
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How to use vocal sac in a sentence
The vocal sac was brownish gray; the iris was a bright golden color.The Amphibians and Reptiles of Michoacn, Mxico | William E. Duellman
The belly and tips of digits were white; the vocal sac was purplish brown, and the iris was dark grayish gold.The Amphibians and Reptiles of Michoacn, Mxico | William E. Duellman
Although Osteocephalus and Argenteohyla have similar vocal sac structure, they are obviously distinct.
The vocal sac structure of Trachycephalus is like that of Phrynohyas and therefore further distinguishes it from Osteocephalus.
Osteocephalus and Argenteohyla are similarly distinguished from Phrynohyas and Trachycephalus on the basis of vocal sac structure.