Field Trips Sept. 7 - 1931. One mile north of Fort Hall. I left Pocatello at 5:30 P.M., Sept 6, and drove to a location one mile north of the village of Fort Hall, where fine sand blows noticeably across the Yellowstone Hi-way. I commenced placing mouse traps about 2 rods from the highway and continued to place them about the same truck in groups of four at intervals of about 2 rods. 56 traps were set in a line about 300 yards long. I reached the sets at 8 A.M. Sept. 7, 1931. The catch was as follows: 1 Grasshopper Mouse. 1 Lagurus. 6 Pocket Mice. 2 Chip Munks. 1 Reithrodontomys. 17 Peromyscus. It was dusk when I finished the sets and the chipmunks probably entered unmolested traps during the early morning of the 7th.