V. Menninger 1942 Reithrodontomys April 1, Berglund Ranch, 1450 ft., 5 mi. N Corralitos, Santa Cruz Co., Calif. One ♀ with no embryo was caught in one of 113 traps set along the edge of dry Chaparral which was quite open near the margins and here consisted largely of Baccharis. Nuts were used as bait. April 7, Muddy Creek, 1000 ft., 1 mi S Chualar Canyon, Monterey Co., Calif. Two ♂ Reithrodontomys were caught in a flat area between two hills beneath a north facing slope. The dominant plants were Salvia mellifera and Artemesia with short grass ground covers. Soil is sandy and in a few drifts. April 8, 4 ♂ and 3 ♀'s were caught in same habitat as above. None with embryos. April 9, 13 ♂ and 6 ♀'s were caught in the same habitat as on April 7. None had embryos. Many of them are caught by the tail and are alive when found. The Museum special traps seem to be a little large for these mice. There are numerous small runs in the grass and the Black Dage and Artemesia where Reithros. are abundant. We believe these are made by the Reithros as almost every trap set in them caught a Reithro. April 10, Johnson Ranch, 800 ft., Chualar Canyon, Monterey Co., Calif. 29 Reithrodontomys were caught in 28 out of