| 21. | Mid-frequency sounds radiate from its vocal sac.
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| 22. | "It proved only that the cavity resonance in the vocal sac wasn't the source of the sound,"
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| 23. | Inner vocal sacs are present at the throat and webbings are well developed at the hind feet.
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| 24. | Male " Micrixalus herrei " have a single vocal sac and a nuptial pad on the first finger.
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| 25. | Males have two internal vocal sacs.
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| 26. | Note the sharply contrasted ventral surface, the vocal sac on the male's throat, and the female's larger size.
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| 27. | "Oreobates crepitans " is unusual among " Oreobates " in that its subgular vocal sac is only slightly developed.
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| 28. | Vocal sacs, flexible membranes of skin possessed by most male frogs, are generally used to amplify mating or advertisement calls.
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| 29. | Adult males have large vocal sacs on either side of the head which are used to produce a mating call.
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| 30. | Frogs in the genera " Heleioporus " and " Neobatrachus " lack vocal sacs but can still produce a loud call.
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