Peromyscus maniculatus Palmer 1934 5 mi. E Ontario, 1050 ft., San Bernardino Co., Calif. Dec.22 Caught 4 in 30 gov.-size mousetraps set on a sand dune in an old peach orchard. Only plants present were dry Russian Thistle (Salsola) 7 mi. E Ontario, 1050 ft., San Bernardino Co., Calif. Dec.22 Caught 11 in 50 gov.-size mousetraps set on a large sand dune fairly thickly overgrown with Rhus trilobata, Rumex, Artemisia and Salsola. 1½ mi. N.E. Ontario, 1100 ft., San Bernardino Co., Calif. Dec.23 Caught 3 in 30 mousetraps set in a wash of sandy to rocky soil with the part that was not watercut, covered with green grass, Erodium and scattered low bushes of Artemisia, Senecio douglasii, Eriogonum fasciculatum and Lotus glabra. These were caught by 10 P.M. when traps were examined by flashlight after setting traps about 6 P.M. Dec.24 Caught 1 in 30 traps between 10 P.M. and 6:30 A.M. 2 mi. E.N.E. Ontario, 1100 ft., San Bernardino Co., Calif. Dec.26 Caught 6 in 55 gov.-size mousetraps set down a sandy wash in which was a sparse growth of low shrubs; Eriogonum, Artemisia, Senecio and Lotus glabra.