1400+ ft., 1 mi. ne Sonora, Sonora. April 10, 1938 In the 123 mousetraps: 50 in dense mesquite caught only two Dipodomys merriami (1♂; 1♀ imm.) in clearing; 50 in rocky hills caught 2 Perognathus intermedius (140♂; 141♀ imm.; cheek-pouch contents of the former saved.) and 3 Peromyscus eremicus (142♂; 143♀; 144♀). (07142 first thought to be P. erinitus, but Dr. Benson decided it [illegible] eremicus). Surprised that no mice were taken in the dense mesquite; the trees provide food and over-head cover, but there is little ground cover due to over-grazing and the extreme density of the mesquite. The lack of ground-cover and periodic flooding probably keep the mice out. A contrasting catch was of 14 Dipodomys merriami (8♂; 6♀) [cheek-pouch contents saved] in the "sand and sage" area which is border by the mesquite. Here in typical kangaroo-rat ground near the mesquite for amply food supply along with heavy ground vegetation at edge of mesquite the rats abound as shown by high trap percentage. Dr. Benson finished repairing truck in late afternoon; so broke camp and drove two miles beyond Sonora and made camp for the night. April 11, 1938. Drove from Sonora to Quitovac to Costa Rica Ranch to Cozonto San Luis to St. Elena and camped at: