Hendelsohn 1950 Journal Sept. 15 1 mi W & 3 mi S P into Mt., Riverside Co., Calif. seems, however, that this type of trap is only practicable when it can be left set up for a fairly long period -- two weeks or more, with bi-weekly visits, perhaps. Also, I wonder if small (10 ft.) forces with two traps might not serve better; they could be placed at points of maximum activity (as indicated by trackers). At 6:40 A.M. the temp. of the sand on the top of the dune (in sun) was 26.4°C. At 7:06 the temp. of the sand on the E. end of the dune (near the wash) was also 26.4°C. (about 40 ft. lower than pt. of 1st temp.) Between the two times mentioned above, we had walked from the center of the dune to the E. end, hunting, and had seen only one Crepidophorus. The Uma did not begin to appear until about 8:00 A.M., when the temp. of the sunlit sand was about 40°C. or above. I collected one small Uma, one small Callisaurus, and a large Dophornus agassizii. Left the dune at about 10:30 and returned to camp. Dr. Miller had obtained a number of specimens, and spent the remainder of the day shinning.