Wolfson 1938 June 28 Microtus richardsoni Jumalo Cr., 15 mi. W Bend, 6100 ft., Deschutes Co., Oregon. Workings of this mouse are common in wet meadows where fallen timber is present or other types of cover, such as, spruce trees at stream edge. More commonly runs are found under logs in entirely wet places. Holes found at end of runs may be full of water, and in one instance a mouse was seen to enter such a hole and disappear below the water! The runs are shallow and are completely visible unless they are under cover of logs or trees. The grass, sedge, Ranunculus and Liliaceous plants of the meadow are not tall enough to cover the runs. Cut grass and leaves are found commonly in the runs and fresh workings are easily recognized. Traps set at night have failed to lure this species until by early next morning but traps left