Mayhew 1958 Sept. 20 Colorado Desert, Calif. the soil surface temp. in the shade at the point of capture was 42.6°C. An immature Crotaphytus wislizeni was captured while it was resting in a burrow (in the shade) with its head exposed. No other animals were seen, so we drove to an area 5 miles north of Jalllwild in the San Jacinto Mts. We reached the area at 1515. The air temp. was 24°C., surface temp. (in shade) was 24.8°C., surface temp. (in sun) was 40.6°C. Some Sceloporus graciosa and one Sceloporus occidentalis were caught at this location. We returned to Riverside from this site, reaching Riverside at 1740 after traveling a total of 822 miles during the 3 days. Oct. 10 Barton Flats area, San Bernardino Co., Calif. This morning Frank Aubrey, & I left UCR at 0915. We reached the 3000 foot level in Mill Creek Canyon at 1000 (about 10 miles N.E. of Redlands). Here we worked the rocky stream bed. We captured Uta stansburiana and Sceloporus occidentalis, and saw several more. At this time the air temp. was 30°C., the soil surface temp. (in sun) was 50°C. Most of the animals were seen sitting on the tops of