The midlittoral trochid, Monodonta turbinata (Born) has a higher rate of oxygen consumption in air than in water at temperatures between 15 and 25d̀C. The temperature coefficient of its oxygen consumption is higher for the temperature interval 15 to 25d̀C than it is for the interval 5 to 15d̀C. The aerial oxygen consumption is increased by forced emersion or immersion for 24 hours. Immersion has the greater effect. It would appear that the trochid shows respiratory adaptation to zonation and environmental temperature.