Valles, San Luis Potosi, Mexico to Mexico, D.F. June 28, 1946 Trill: At the town of Cuesta Colorado, the earth appeared very red. Temperature was 80°F. Just beyond the town a madrone and several cypresses (not Taxodium) were noted. 8 miles south of Jacala, in fine oak country, a Red-tailed Hawk with a clear white breast was noted sitting on a dead stub. 10 miles south of Jacala, a White-eared Hummingbird was noted perched on a telephone wire by the side of the road. 20 miles south of Jacala 2 Juncoes were noted in the pines. 30 miles south of Jacala the pines and oaks drop out, and open grassland, and xerophytic vegetation begins. Maguey, tuna and organ-type Cactus are common. This high desert extends for several miles on either side of the road. Jimafan, altitude 5650 feet, is in this high desert country. Temperature at Jimafan was 85°F. 19 mi south of Jimifan a heavy cloudburst was noted about 3 miles west of the road. Grass at this point is greener and more widespread than heretofore noted, and there are more trees. This stretch of land is probably irrigated. At Atostan Barn swallows were noted flying above the road. We arrived at the city limits of Mexico, D.F. at about 6:00 p.m. and obtained a room at the Guadalupe Courts, just off the main highway near the city limits, on Calzada Troman.