Borlaware, ST 1942 Microtus californicus Apr. 2 Berglund Ranch, 1450 ft., 5 mi. N Corralitos, Santa Cruz Co., Calif. Two were caught in about 15 Museum Special traps baited with a mixture of peanut butter and rolled oats. The traps were set in a grassy hollow between two hills. The grass was filled with dry stalks of various Compositae. Traps set on the edge of the open stand of chaparral on the adjoining hillsides did not catch any Microtus. The soil of the grassy hollow is sandy and was wet from recent rains. Microtus runs and holes and feces very numerous. Both of these specimens were female, one with 6 embryos measuring 4mm. and the other with 5 embryos which were not measured by V. Memmler, the preparator, but were saved in alcohol. A third female caught on our second night of trapping here contained no embryos. Apr. 4 Mud Creek, 300 ft., 3 1/2 mi. SW to SW San Juan, Monterey Co., Calif. One was caught in a line of 134 Museum Special traps placed all the way around a hilltop on the edge of an open stand of Artemisia californica containing poison oak, some Baccharis and deer clover (Lotus sp.), and low grass. The specimen was a female, nursing. Apr. 5 One female with no embryos was caught in one of 87 Museum Special traps set along a fence enclosing a dense growth of wet chaparral including poison oak, bracken, Artemisia, Bract Baccharis, blackberry, elderberry, snow-berry, coffeeberry, and monkey flower. Apr. 7 Muddy Creek, 1600 ft., 1 mi. S Chualar Canyon, Monterey Co., Calif. One was caught in a line of 13 traps set on the meadowy top of a hill with scattered shrubs of