Journal Hafner, M.S. 1977 En Route: Jalpa, Zac. to San Luis Potosí, S.L.P., México. 25 July 0600 awoke - very humid. It had rained most of the night and the ground was extremely muddy. We broke camp and drove 5 on Hwy 51 through the densely vegetated countryside until we arrived at the town of Moyahua. We then turned around and drove to a known locality of Thomomys a few miles north of Moyahua (Goldman & Nelson). We searched the area for several miles in each direction from the known locality and could find no traces of gopher diggings. The ground was a sopping mire of mud - which would seem completely inhospitable for Thomomys. After searching a while longer we decided to head for the next known locality for Thomomys near the City of San Luis Potosí. It is our impression that Thomomys may no longer live in this valley north and south of Jalpa. 0900 We drove east on Hwy 70 from Jalpa, through Aguascalientes (where we bought supplies) and on to the town of Arriaga (Villa de Arriaga). This town, or 1 km. S of this town, is the type locality of another Thomomys race (Dalquest). We searched high and low in the countryside just S of town, and could find no evidence of gophers.