Moore. 43 1/2 N. San Bernardino 1600 ft. San Bernardino Co., Calif. May 22, 1951. Last evening went north from San Bernardino through the Shannon Hills to a lone hill rising out of the valley floor just at the base of the main slope of the San Bernardino Range. The south facing slope, where 100 mice traps were set at the 1600 ft level was covered sparsely with chaparral, and an occasional blooming Yucca dotted the hillside. The soil was of a clay like structure and fairly hard. Part of the hillside had been burned over some years ago and was covered with white sage. About twenty traps were set through this area but yielded only Peromyscus m. sonoriensis, Reithrodontomyss, and Peromyscus boylii rowleyi. No Perognathus were found within the burned over area although they were taken at the edge on both sides. Seven Perognathus fallax fallax were taken, mostly on the hard ground. One Dipodomys m. garneri was taken on open, hard ground, while one other individual was taken down in the soft, fine sand of the wash bottom. The sand in the wash bottom was of 'dune' like texture, or was blown up in piles, which were covered sparsely with coarse sword-like glass that grew in clumps: Here one Perognathus longemontis was taken. The trapline covered approximately one mile in distance, through chaparral and wash-litter and yielded a total of 87 mammals in the following proportion: 11 Peromyscus m. sonoriensis, 8 Peromyscus boylii rowleyi, 4 Peromyscus californicus, 1 Reithrodontomyss, 7 Perognathus fallax fallax,