Mus musculus July 1 Columbia R. 300 ft. at mouth of Deschutes R. Wasco Co. Dec 187 Mus musculus was caught at this locality. It was caught in a mouse trap baited with bacon fat set on a small islet about 20 ft. from shore in the Deschutes R. On the islet was a heavy growth of Carex sp? Between the islet and the bank the water was shallow and there were numerous boulders so that the mouse could have found its way to the islet with only very little swimming.