At the Harvey County study area, bodily temperatures were recorded in many of the racers that were caught in traps. These records are much less significant than the records obtained from racers caught by hand and promptly checked for bodily temperatures. The temperatures of the trapped snakes may, to a large extent, reflect the temperatures of air and soil at the time. However, despite their confinement, the trapped racers probably were able to exercise some control over their temperatures by shifting from shade to sunshine, or from the top of the trap to its bottom, where they would be in contact with the substrate. In most of the racers removed from traps, as in those caught by hand, bodily temperatures were somewhat above air temperatures, but the difference was less in the former group of snakes. Figure 8 shows the bodily temperatures of these snakes removed from traps. Occasionally racers died in the traps from overheating. On July 2, 1960, each of two racers in traps had temperatures of 39.4°. One of these was especially vicious and frantic in its attempts to escape, but otherwise seemed unharmed. The second racer was dead, seemingly having succumbed just before it was found. Probably prolonged exposure to temperature in excess of 39° would always result in death of the snake. Racers and other snakes that had become overheated in the traps and were nearing exhaustion had a characteristic limp feel when they were handled. In June, 1960, heat tolerance of a halfgrown racer was compared with that of several other snakes including a copperhead, garter snakes, and ringneck snakes. Each snake in turn was enclosed in a plastic tube plugged with cotton at one end, the snake having a quick-reading thermometer taped in place for a rectal reading. The tube was then placed in sunshine. Over periods of minutes the enclosed snake passed through a characteristic cycle. Soon it would begin to register discomfort as its temperature rose rapidly. Its struggles would become increasingly violent, then would cease abruptly. The snake would suddenly collapse, its body mostly limp, but knotted in slow contortions, its mouth gaping widely. Within a few seconds all movements would cease, but in each instance the seemingly dead snake was soon revived by holding it in cold running water. The copperhead, garter snakes, and ring-necked snakes all collapsed at temperatures near 41°. At this same temperature the racer showed signs of acute discomfort, but did not collapse even after many minutes of exposure. Probably more protracted exposure at this level would have been fatal to the racer as well as to the other kinds tested. Home Range and Movements