Mayhew 1961 Journal 37. June 4 Northern Baja California, Mexico for a sandy habitat, there seem to be relatively few animals living here. The dominant perennials are Prosopis juliflora, Larrea divaricata, Ephedra sp. with such plants as Coldenia plicata, etc. forming an understory. The dominants all looked in good shape with lots of leaves. However, animals + tracks were not at all plentiful. We captured 2 Uma notata, 1 Crepidophorus tigris, & 1 Diposaurus dorsalis. We also saw 4 other Uma, 1 Diposaurus, & 1 Crepidophorus. At 0930 we drove north toward Mexicali until we reached La Puerta. There we turned east to cross the Colorado River near Kilometro 57 and Riito. Northern Sonora, Mexico We drove through farmland until we reached San Luis. Then we drove east on Highway 2 into the Gran Desierto. Fourteen miles east of San Luis we tried to leave the highway and drive south to some sand dunes that looked like the Kelso Dunes in the Mojave Desert. However, about a mile from the highway the sand became so soft under the heavy load we were carrying that the vehicle became stuck even in 4-wheel drive. We