1975 Nov. 26 (cont.) The rock lizard was then sprayed (rock half) with silver = no diff from control liquid. Then sprayed all over (top side only) = no obvious diff. Then sprayed bottom all over = slightly cooler (less than 1/2 degree). Then chose 4 adult females of about same size and placed them out in bright sun on Pycrophyllum. Their equilibrium temperatures were in this order from hottest to coldest: black, normal + belly silver, silver all over + under, range 4 to 5°. The above four were then moved to a cold rock covered with sleeping bag. During cloudy-bright they were consistently black warmest, normal next, silver coolest (silver belly excepted). The difference never exceeded 3°. When moved back to Pycrophyllum they sorted out the same, not diff 4°. Then compared dead #1 with live #2 (yesterday's pair) placed out on Pycro in wind and hot sun. The live one reached 36° then dropped off a little. The dead one read 37°. Good comparison because the live one lay motionless the whole time, so the position of the dead one matched well. The live one did not overheat (but sun/Pycro and windgave up to 22 1/2° and did not keep him smooth after. Natural selection favoring the skin color of lizards for thermoregulatory purposes doesn't seem to have improved more than a degree or two C° over black or silver! Then ran black and silver film canisters in wind and hot sun, small hole on shady side covered with masking tape. The Schnabels then slid through a small hole in the tape. Tight fit. The black can ran about 5° warmer - and same temp. as a lizard!!