O. Mermuler 1943 Leithrodontomys May 24, West Side Arroyo Seco, 500 ft., 4 mi.'S Soledad, Monterey Co., Calif. One lactating ♀ caught in live trap. May 25, Galician Range, 1500 ft., 5½ mi. ENE Soledad, Monterey Co., Calif. One ♂ caught in grass and tall grey plant. May 26, Two ♂'s and one ♀ were caught last night. Two were caught in grass near Bluebush and Artemesia. One was caught along the stream under willows. May 27, 6 were caught in live traps. 2 ♀ + 4 ♂. One female had 3, 4 mm embryo. They were caught in: pathway under Adenostoma, Open run in grass, Calicut run in Grass, Mound under Blue Bush in Grass, run under Artemesia, and a mound in gross. May 29, One ♂ was caught in a snap trap set in a microtus run. May 30, The Halls brought us a mother and 4 young in their nest which they found under hay. Their eyes were still closed. I caught 2 ♂'s in Microtus runs in snap traps. May 31, I caught 5 in live traps set in field on a hillside facing west. There was an abundance of grass and Blue bush. June 1, Metz, 250 ft., Monterey Co., Calif. I caught 1 in a live trap set along the overflow bank of the Salinas river. Willows + Starthistle are abundant here.