R. Zweifel 1953 Journal Santa Cruz Co., Arizona July 21 canyon and caught three adult tarahumaras and some larvae. We returned to Rena Blanca to camp. Following Dr. Blair's directions, we found and caught a single Microhyla in the pool where he had taken several last night. July 22 Drove to Tucson, July 23 Drove from Tucson to the Sluthouse (Yopa) Mountains, Yuma Co., Arizona, to look for Hyba arenicola rumored to be there. The most easterly Washingtonia palma occurs here, so Palm Canyon seemed to be the logical place to look for water and frogs. The palms are reached by a steep, rocky trail, a distance of about one mile from the end of the road. They are located in a narrow, south-facing side canyon, little more than a cleft in the main canyon wall. The canyon containing the palms is about 20-25' wide at the bottom and has nearly vertical walls reaching up 50 to 100'. There seems to be no surface water in this canyon. The canyon is sufficiently dry and narrow that it probably receives very little direct sunlight, with consequent low rate