JESimpson, 1938. 2300±ft, 1mi. S. Moctezuma, Sonora. May 27, 1938, continued. in the mousetraps on mesa-top caught two Perognathus penicillatus (♀445; ♂446 as skeleton only), 3 Perognathus baileyi (one juvenile; ♂447, ♀448), and 7 Peromyscus eremicus (saved: ♂449, ♂450); in gopher traps only one Thomomys umbrinus (♀451 as skull only). Put up specimens, broke camp and drove to Moctezuma for water then 12.7 miles to Tecori, 4.1 miles to Nieve Colonia, 0.7 miles to Cumpas, 10.9 miles to Los Hoyos, 3.2 miles to La Noria where we took the better but wrong road which lead to Nacozari and thereby lost only 2.8 miles, from La Noria 8.6 miles to Alvaro Obregon, 4.0 miles more to make camp in: 3400±ft., Arroyo Santa Rosa, 28 mi. N. Cumpas, Sonora. May 27, 1938, continued. Here at dusk set 41 mousetraps on rocky, almost- bare hill above the wash which is cliff-sided on the east and west — the latter side with occasional steep hillside rather than cliff. Black walnut trees (1-2½ ft. dia), mesquite, and brush grow at edges of arroyo but only a few “dead”, black-bushes, ocotillo, and cholla on hillside above (where traps sat). Saw a cottontail as we drove up side of wash to camp-site (very near former campsite of Dr. Benson and Señor Delgadillo when here 2 yrs. ago). Gambel’s Quail, Mourning and white-winged doves, and Phainopepla seen; heard Cardinals.