Body temperatures of 153 box turtles that were known definitely to be active, ranged from 15.3 to 35.3 degrees. The mean body temperature for active turtles was 28.8 degrees (± 3.78[sigma]) (Fig. 22). Ninety-two per cent of the temperatures were between 24 and 30 degrees and 50 per cent were between 28 and 32; temperatures of 29 and 30 degrees occurred most frequently (22 and 21 times, respectively). The ten body temperatures below 24 degrees all were recorded before 9 A. M. on overcast days when the air was cool and humid. It is noteworthy that two of these low temperatures (18.8° and 19.0°) were from a copulating pair of turtles; two others (21.8° and 22.0°) were from individuals that were eating. The highest temperature (35.3°) was from a large female that was feeding at mid-morning in a partly shaded area. The mean body temperature for active individuals (Fig. 22) is probably somewhat below the ecological optimum, because a few temperatures were abnormally low. The large number of body temperatures in the range of 29 to 31 degrees indicates an optimum closer to 30 degrees. Optimum body temperatures may vary somewhat with the size, sex, or individual preference of the turtle concerned. Basking Although basking is common in terrestrial turtles, only a few authors have mentioned it. Woodbury and Hardy (1948:177-178) did not use the term in their account of thermal relationships in _Gopherus agassizi_; their discussion indicates, however, that the tortoises move alternately from sunny to shady areas to regulate body temperature. Desert tortoises removed from hibernacula and placed in the sun warmed to approximately 29.5 degrees before they became active, although a few did so at temperatures as low as 15 degrees. According to Cagle (1950:45), Sergeev (1939) studied body temperature and activity in the Asiatic tortoise, _Testudo horsefieldi_, and found that individuals basked for as much as two hours in the morning before beginning the first activity of the day (feeding), but that tortoises did not bask after a period of quiescense from late morning to late afternoon, during which body temperatures were seemingly maintained nearer the optimum than they were during nocturnal rest; body temperatures rose to approximately 30 degrees before the tortoises became active. Since body temperatures of 23 to 24 degrees were maintained at night, the basking range of _Testudo horsefieldi_ may be considered to be approximately 23 to 32 degrees.