Only within the last twenty-five years has it been known to science that North American flying squirrels may infrequently build outside nests of leaves and twigs as is common practice with regard to fox and gray squirrels. Such discerning field naturalists of the last century as John Bachman (1846, p. 221) and Robert Kennicott (1857, p. 70) stated that flying squirrels do not build outside nests. Some years after the turn of the century, however, examples of such nests began to be reported from the northern states and Canada. Stupka (1935, p. 4) found an outside nest of the northern species Glaucomys sabrinus in Maine, and Cowan (1936, p. 60) and Rust (1946, p. 319) added records of outside nests of this species from British Columbia and northern Idaho. Of the southern species Glaucomys volans, Snyder (1921, p. 171) discovered an outside nest in Ontario, Landwer also (1935, p. 67) found one and Burt (1940, p. 48) recorded two in Michigan. The writer observed one in Harmony hollow about four miles from Front Royal, Virginia, on August 25, 1933, against the trunk near the top of a twentyfive-foot red oak. Roughly spherical in shape, this nest was composed ex. ternally of leafy twigs from the nest tree, and upon climbing to it the writer frightened from it three young which were about forty-five days old. The tree stood in an open pasture just barely within gliding distance of a mature mixed hardwood forest. During the most extensive study of the breeding habits of a North American flying squirrel, Sollberger (1943, p. 169) in New York and Pennsylvania found more than thirty-five females with young in tree hollows but only one in an outside nest. He entertained serious doubts that flying squirrels actually build outside nests.