1954 80 Palin San Carlos, Sonora, Mexico April 25 The vegetation is typical arid desert. A few columnar cactus, pricklypear and numerous small shrubs and small trees. Few of the plants are in leaf, so the aspect is rather gray at this time. April 26 This morning we moved our camp to a canyon at the head of San Carlos Bay, now that the Sunday puma crowd has gone. The canyon is narrow, steep and rocky. Mesquite and similar trees are present where the canyon bottom is wider near the mouth, but there are few such trees higher up on the rockier part of the canyon. Palm trees are present both in a few clumps in the canyon bottom and one in draws on the canyon walls. There were seven palms growing along the rim of the canyon, particularly along the west side. I assume that some peculiarity in the rock structure must force water high up on this ridge. The only surface water in the canyon is in two potholes in a narrow stretch relatively near the canyon mouth. Above that the canyon widens and terminates as a top canyon. The length of the two potholes is about 10 feet long (at water level) and 2 1/2 feet deep, the other 7 feet by 1 1/2 feet. To judge from water marks on the walls, each would be about twice as deep when filled in the rainy season. In the evening I dig- netted several shrimp from the potholes. The shrimp have been preserved. I found a few Cnemidophorus lutei in the canyon, both on the rocky hillside and in the more heavily shaded part of the canyon bottom. Uta taylors is also present on the canyon. Ursusme ornatus and Sceloporus clarki were seen on a tree * see note on back