TESimpson, 1938. Tepachi, Sonora. May 23, 1938, continued. water. In pool (less than 3 ft. sq.) collected 20 minnows which I catalogued (416). Drove on 8.2 miles to Divisadero, 3.1 miles to La Noria, and 5.7 miles more to make camp in arroyo near dark-lava hills: 2550 ft., lava bed, 19 mi. SE Moctezuma, Sonora. May 23, 1938, continued. Set out 44 mouse-traps and 17 rat-traps on sides (in thick brush) and top (light brush) of dark-lava hill and 50 live-traps in arroyo: wash and its banks. May 24, 1938. Caught on side of lava hill in thick brush 4 Perognathus goldmani (♂ 418, ♂ jv 419, ♀ 420, ♀ 421; cheek-pouch contents saved), 4 Peromyscus eremicus (♂ 422, ♀ 423, ♀ 424, ♀ 425 (molting)), and 1 Neotoma albigula (♂ jv. 426; black pelage); on hill-top in light brush 1 Perognathus barleyi (♂ 417; cheek-pouch contents saved) and 2 Peromyscus eremicus (not saved): in live-traps in the arroyo 5 Perognathus penicillatus and 1 Perognathus barleyi (♀ 430 which gave birth to two young (427, 428) in the live-trap and one later in a packing box (429). Set 17 rat-traps on side of rocky hill and 50 live-traps on top; set 44 mouse-traps on rocky hill (not lava but light brown rock) near the lava hill with a heavy mesquite arroyo between the hills. Shot two Gambel's Quail for table; crops empty.