A juvenile or young animal, a male, captured in May, 1936, at Lafayette, Contra Costa County, California, was kept there until August 13, 1936, when transferred to Calneva at the north end of Lake Tahoe, California. The weasel was kept at Calneva until its death on December 23, 1937. In both the winter of 1936-'37 and in that of 1937-'38, the winter coat was brown as in animals from its place of origin (Contra Costa County) and unlike weasels of the Tahoe region nearly all of which turn white in winter. Two females, each approximately two months old, captured on May 1, 1936, at James Landing, 4 miles northwest of San Pablo, Contra Costa County, California, were kept in Berkeley, California, until August 13, 1936, when they were transferred to the mouth of Blackwood Creek, on the west side of Lake Tahoe, California. On October 25, 1936, both weasels escaped. On December 25, 1936, the headless body of one of these was found approximately 300 yards south of the mouth of Blackwood Creek. The animal had been dead at most a few days when found and was in the brown winter coat. At the place of its origin all weasels are brown in winter but at the mouth of Blackwood Creek only 2 of 60 weasels caught there in the winter coat were brown; the other 58 were white. The headless weasel was identified, as one of the two formerly in captivity, by means of certain short toes, the ends of which had been clipped off when the animal was a captive. No trace of the second female was found. A female of unknown age, in white winter pelage, captured 4 miles southeast of Tahoe City, California, and kept there until April 3, 1937, on which date it was brought to Berkeley, California, molted to brown in the spring. The first signs of the brown coat were noted on April 14. On May 24 or 25 she gave birth to 4 young which lived less than ten days. In the following winter this animal acquired a white coat. As previously noted, weasels native to the Berkeley area, where this female was kept, have brown coats in winter. The weasels were in every instance kept in cages out-of-doors. The sides of the cages were open to the elements. A nest box in each cage provided shelter. All were of the species _Mustela frenata_. The significant results, it seemed to me, were that the winter coat was the kind found in the area where the weasel originated instead of the kind found in weasels native to the areas in which the specimens were held in captivity.