Alcorn 1939. Perognathus parvus Aug. 10. Kingston Canyon, 7000 ft., Lander Co., Nevada. In a stream about three feet wide a small rock stuck out of the water about four inches. On this rock I set one mouse trap and looking for the trap in the early morning I found it had washed down stream 4 or 8 feet and in it (no.329) was the Perognathus. Apparently, in crossing the stream the rock was used to lessen the distance the animal would have to jump without getting wet. Dense vegetation lined both sides of the stream at this point. Mostly willows and birch trees.