JESimpson, 1938 50. 1775+ ft., 8 mi.s San Luis, 34 mi. nw Caborca, Sonora. April 13, 1938 Caught in area adjacent to and similar to that of last night's trap-line: Perognathus intermedius (♀157; no emb; cheek-pouches empty), 1 Perognathus baileyi (♂/158; cheek-pach contents saved), and 4 Peromyscus eremicus (407-5). Broke camp and drove toward Caborca; camped: 1000+ ft., 10 mi. nw Caborca, Sonora April 13, 1938, continued. Set out 50 mousetraps and 7 rat-traps on rocky and calve traps hill among palo verde, creosote, and torote; 50 live trapson wash-banks (in bloom) April 14, 1938. Caught 4 Perognathus intermedius (♂/161, 162; ♀/163, 164) (in bloom) (cheek-pouch contents saved) and two Neotoma albigula (♀/159, 160) Noemb Both woodrats had bot-fly larvae on throat. (live-traps empty). Broke camp and drove to Caborca where we sought a welder to fix the truck; no adequate apparatus available; so drove out of town and made camp: 925+ ft., 1 mi.e. Caborca, Sonora. April 14, 1938, continued. Set out 50 mousetraps in dense mesquite. April 15, 1938. Caught 6 Perognathus penicillatus (all ♀/5: 165, 166, 167). Señor Delgadillo caught a round-tailed ground-squirrel which I catalogued (168 & no emb). Cheek-pouch contents of mice saved. Shot two lizards from mesquite branches. (169, 170). Dr. Benson drove the truck to Miña Juarez, near Trajitos, where the rear-chassis shackles were brazed to the axle. While