Papa Leon Tree, 150+ ft., Depto. Lima, Peru July 4 (end.) found the skeleton of a fox. This area will probably not prove to be workable for a study of Phyllotis + Dillancia, since it has been very rare that we have found Phyllotis in Dillancia. I put the gecko (MAL 127) in alcohol. In the process, its tail came off very easily and jumped & squirmed a lot. Dr. Pearson did measurements of temperature differences. In the open: 19.6°, in shell 21.6°; in shallow sandy gravel 22.4°, and under a rock 21.0°. I think that temperature probably is not the selective force that causes a gecko to seek shelter in an artiller shell, especially in this season where the temperature range is well within 10°F, and probably well within the operating temperature of a gecko. The reason why we have found 2 geckos in those shells is probably that the shells make a nice convenient and imperviable shelter for these animals. 3:30 We've driven back to the area 5.5 mi NE of San Bartolo and drove past there a kilometer or so, Dr & Mrs. Pearson & Ray set snap traps & small Sherman's in the array. I hiked up a ridge. The soil is full of dark lichen and near the top cactus is growing. We plan to stay overnight here tonight and look for geckos, spiders, etc. Up near the top is lots of insect sign & some fox tracks.