J.R. Aleorn 1940 Thomomys ? Yellowstone River, 5 mi. W Forsyth, 2750 ft, Rosebud Co., Montana. June 8, 1940. In a grassy field near camp many Gopher mounds were seen. Traps were set and a few Gophers were taken. In setting the traps I noted that the lateral varied in length from about 1 1/2 to 2 feet and the both the lateral and main burrow were large for the size of the Gopher. I could stick my arm down many of the burrows. Most of the Pocket Gophers taken were F's and they apparently were lactating or had already weaned their young. The soil is heavy and without rocks. The mounds made by the Gophers are large, some 1 1/2 to 2 feet across.