Metabolism in Relation to Temperature In

1. A zone of thermoneutrality exists for adult female Myotis thysanodes in early September in an ambient temperature range of 32"5-34"5°C with minimum metabolism of 1"74 cm3/g per hr. 2. A transition from a homeothermic to a non-homeothermic metabolism to ambient temperature relation is evident by late September in adult female M. thysanodes. 3. In early September, some adult female M. yumanensis exhibit a homeo-thermic metabolism to ambient temperature relation while others exhibit a non-homeothermic relation. 4. In early September, adult M. ludfugus occultus of both sexes exhibit a non-homeothermic relation. 5. At ambient temperatures above 32.5°C, metabolism in M. thysanodes increases at a significantly more rapid rate than in M. lucifugus occultus. 6. A critical thermal maximum ambient temperature of 44"5°C has been found for each of these three species.