O. Memmler 1942 Peromyscus April 4, mud creek, 800 ft., 3 1/2 mi. S.W. Sawjuan, Monterey Co., Caly. traps were sprung, perhaps due to heavy rainfall during the night. Traps were set in Artemesia about 4 ft. tall on a hill side. April 5, 87 traps set in dense ground cover under Live Oaks caught 18 Peromyscus californicus and 2 P. maniculatus. 27 traps high up on a hillside where Artemesia became dominant in close chaparral, caught 3 P. Californicus and 1 P. maniculatus. A total of 19 traps were sprung. Of the P. maniculatus 5 were ? and 1 was ? with no embryos. Of the Peromyscus californicus, 10 were ? and 11 were ?. Of the ?s ,3 were without embryos. One was nursing of these two. The following are the number and sizes of the embryos in the 8 pregnant ?s. 3, 4 mm., 2, 26 mm., 3, 24 mm., 4, 12 mm., 2, 27 mm., 2, 15 mm., 3, 11 mm., 2, 10 mm. April 17, Muddy Creek, 1000 to 1400 ft., 1 mi S. Chular Canyon, Monterey Co., Calif. One ? P. maniculatus caught in stand of Artemesia and Salvia mellifera at 1,000 ft. on flat ground with sandy soil. 2 ? P. ? perhaps trui or boylii caught on steep slope about 1100 ft. One ? P. californicus and 1 ? caught littera.