J.E.Simpson 1938 23. 2650ft., La Mision, 2 mi.w. Magdalena, Sonora March 16, 1938, continued. Made camp in an earth pit from which the Mexicans take the earth to make adobe bricks. Dr. Benson camped in this pit two years ago. The afternoon was warm and clear with a light wind. The terrain is of low, rochy hills covered with brush which is made up of ochotillo (in bloom), barrel cactus (unfruit), saquero, mesquite, creosote, and many cholla nopal -- mainly, with others that I do not know. In evening Dr. Benson set out 50 live traps, Margarito 75 mouse traps, and I 75 mouse traps baited: oats and March 17, 1938 Results of 75 mouse traps: 1 Perognathous intermedius: rocky arroyo at base of saquaro. 1. P. pencillatus: in brush of wash. 1. P. baileyi: top of rocky hill in low cholla. 2. Dipodomys merriami merriami baileyt: brush of wash. 7. Peromyscus eremicus: in each of the above. The traps of Dr. Benson and Margarito were empty; so Margarito took traps to set for gophers while Dr.Benson gave me instruction in the finer points of putting up specimens. Margarito caught 4 Thomomys bottae in half-day with twenty traps (10 sets). Set 70 mouse-traps on rocky hill sides and hill tops in saquaro "forest".