Hooper, 1937 Berkeley, Alameda Co., Calif. Mar. 7, Yesterday afternoon, in company with D.H. Johnson and F.G. Palmer in Johnson's car, drove out through Walnut Creek and Pittsburg to the region between Antioch and Mt. Diablo. The purpose of the trip was to find small pocket mice (Perognathus inornatus), remains of which have been found in Barn owl pellets taken from a locality about 3 mi. S Antioch. We searched for likely looking ground (sandy, un-grazed land) but could find none. We finally set out traps at the locality 2 1/2 mi. S Antioch, 250 ft., Contra Costa Co. I put out 20 mouse traps on the crest of a grass-covered hill. Mammal sign was not abundant. Gopher diggings were found. Large, adult (evidently) Ground squirrels were seen running about on the south-facing slope. Traps were set at an average distance of 3 paces apart near old ground squirrel holes (which were evidently being used by some other kind of animal), & near holes which looked suspiciously like kangaroo rat diggings, and around the border of a concavity (probably an old gravel pit or fossil digging - since large limestone outcrops occurred there). In these traps I found this morning