Erichson 1934 10 mi. east of Quartzsite 29 washes running from south to north; lava mountains west, and north of camp, low rock strewn ridges to east and south; vegetation creosote, palo verde, ironwood, giant cactus and some cholla. Set 80 medium traps from camp start- west across flat between washes and up on to side of lava hill. Feb. 27. From 40 traps on rocky flat took one Perognathus intermedius; in 40 trap on lava hill had another Perognathus, two Neotoma lepida and two Peromyscus. Hunted Canyon Wrens on lava hill for an hour and a half, secured one, others heard. Set 80 traps, forty on rocky flat along edge of wash, 40 on lava hill. Feb. 28. In traps on flat had one Dipodomys merriami, in trap on hill 2 Peromyscus crinitus and one Peromyscus eremicus. Hunted Canyon Wrens for an hour without securing any; high wind blowing made conditions unfavorable. Moved camp to La Paz slough 9 1/2 mi. north of Ehrenburg, Yuma Co., Ariz. While enroute to slough found gophers in saltgrass mesquite association 4.3 mi. north of Ehrenburg; made 4 settings. Made camp 50 yds from slough in mesquite association, willows and cottonwoods near. Slough at point explored narrow 10-30 ft. across shallow with tule present, but much trampled by cattle; slough reported to extend 2 mi. to north where it connects with Colorado River and 3 mi. to south remaining narrow through- out its length. No very suitable places for Sigmodon found on west side of slough, but 12 rat traps set in