Journal Hafner, M.S. 1977 En Route: Mexico City, D.F., to Rio Frio, Mexico, Mexico. 4 August (cont.) 2130 we pulled off the road just outside Rio Frio, Mexico after re-fueling and 2230 retired. Rio Frio, Mexico, Mexico. 5 August 0630 awoke. Immediately noted gopher mounds in our vicinity. JCH soon discovered that all the diggings were those of Pappogeomys. The mounds were exceedingly thick in this area (just w. of Rio Frio (centro) on Hwy 190 libre). We drove east on Hwy 190 libre (ie. not the toll road) and noted gopher diggings (Pappogeomys) most of the way in meadows and fields adjacent to the road. We stopped at a point 5 mi. NW (by road) San Martin Texmelucan where we discovered Thomomys diggings. The animals were too sparse in numbers to warrant our trapping so we continued east into San Martin. We turned around just after entering town and decided that perhaps we should try for T.u. volcanos on the north slopes of Volcan Popocatepetl (17,761 ft. elev.). We drove west, (re-tracing our steps), to Rio Frio, stopping occasionally to search for Thomomys signs. We then drove just west of the town of