Pitelka 1946 June 25 Southern Lyon County, Nevada. separating these valleys are without junon-juniper, so far as could be observed from the southwest at Wellington. The pass over the gap separating the Pine Nut Range from the northern outliers of the Stillwater Mts. is generally bare, but there are a few scattered junonis. We then returned to Hollbrook in southern douglas County, and proceeded southward along the west side of Antelope Valley, noting that south of the valley, piñon-juniper formed an east-west connection between the main Sierra Nevada mass and the smaller ranges west and south of Walker Lake. From the above preliminary observations, i would conclude tentatively that the lowlands of the Black Rock Desert, Granite Spring Valley, Carson Sink, and Walker Lake form the main barrier separating nevadae from superciliosa; that throughout Virginia Range is probably inhabited by superciliosa; that superciliosa may extend down into the northern part of the Pine Nut Range or possibly even farther south; that superciliosa extends south along the east slopes of the Sierra Nevada.