Hooper, Microtus californicus 1 1/2 mi. SW Five Brooks, Daveness Ridge, Marin Co., Calif. June 27, 1938 4 traps set in the heavy Baccharis Ophirral for chipmunks netted 1 meadow mouse; no grass about; something had been eating seeds of poison hemlock where this animal taken. 30 traps set in a sedge littered marsh netted 8 Microtus all but 1 of which were young, i.e. more over 1 yr. old. marshes at mouth of Corte Madera Cr., Marin Co., Calif. June 28, 1938 This is the same area trapped previously this year by Arney, North and myself. In the same area- sometimes same identical spots- where we caught numerous meadow mice and Reithrodontomyss saxiventris feathers and 2 toad only 1 song sparrow + 2 house mice in 100 traps. High water floated many of my traps. The animals must migrate back and forth with each high and reep season.