Quast 1948 Journal 21 April 17 Cerro Prieto 30 ft 20 mi SSE Mexicali, Baja Calif. this afternoon. Dr Benson said they were probably Citellus tereticaudus from my description. Many Nighthawks hide among the mesquite lining the day trail in the sandy areas at the mountain base 100-500 yds west of camp. Cottontail signs are plentiful. shot 4 Dipsosaurus (#60,61,62,63) and one Cenuridophorus (#64) in sand at base of mountainslope between 1 and 3 P.M. All the Dipsosaurus were under or in dead brushwood on the sand within 75 feet of the igneous talus slopes except the small one which was shot on hard sand - blending in so well with the sand that I could not distinguish it from a crevic at 50 feet. I had to dig one wounded Dipsosaurus out of the soil and talus conglomerate. Birds seen in the mesquite at base of slope this afternoon were a flock of probable Gambel Quail, an Olive-sided Flycatcher, a Black-throated Grey Warbler, a small Thrasher, and a small flycatcher (Western ?). set out 110 traps tonight: 50 live traps where volcanic rock borders desert sand