T HE skin, lungs, and buccal cavity may all serve as respiratory surfaces in adult terrestrial amphibians. The relative role of these respiratory surfaces has been shown to be an important consideration in the ecology, geographic distribution, and phylogenetic relationships of caudate amphibians (Whitford and Hutchison, 1963, 1965, 1966, 1967 lung air on which gas exchange with the lung capillaries is dependent and because environmental conditions, particularly temperature, affect the respiratory exchanges and relative role of the respiratory surfaces. Our studies were designed to evaluate the effect of temperature on the role of the skin, pulmonary, and buccopharyngeal surfaces in the respiratory exchanges of a number of anurans representing several families from a variety of habitats; to obtain quantitative measurements of ventilation of the pulmonary surfaces to aid in the interpretation of gas exchange patterns; and to evaluate body size and metabolic rate relationships in anurans. These data are used to evaluate the adaptive significance of differences in respiratory patterns observed with regard to geographic distribution, ecology, and phylogenetic relationships of the forms studied. MATERIAL AND METHODSAll animals were acclimated in constant temperature-photoperiod environmental chambers to the test temperatures and a 16-hr photoperiod for a minimum of 1 week prior to the experiments. Pulmonary (lung and buccopharyngeal) and cutaneous gas exchange were measured separately and simultaneously in constant volume respirometers by a direct manometric method.

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