Big Black Mountain lies in southeastern Kentucky and adjacent Virginia, occupying parts of Harlan County, Kentucky, and Wise County, Virginia. Highway 160, between Lynch, Kentucky, and Appalachia, Virginia, crosses the mountain; the highest point in Kentucky (elevation 4150 feet) is some half mile west of the highway. About a mile northwest of this peak is a second height, indicated on the United States Geological Survey Estillville Sheet to have an elevation of 4150 feet or more. On this second peak the Civil Aeronautics Authority maintains the Glenbrook Visual-Aural Range Station. According to an engineer who surveyed this area for the station, the elevation of this peak is 4140 feet. With this station as a center, a circle with a four mile radius would include practically every point at which collections discussed in this paper were made. The only collections made outside this area and included were from the Poor Fork of the Cumberland River between the towns of Cumberland and Harlan, Kentucky, and two areas on Pine Mountain, one near Cumberland, and the other near Rosspoint, some four miles from the town of Harlan. This study was initiated on July 19, 1939, and is the result of four collecting trips to the area. The period July 19-August 18, 1939, was spent in the area, the time equally divided between the community of Rosspoint and the summit of Big Black Mountain, near Lynch. On May 3-4, 1940, I accompanied a party from Morehead State College, Morehead, Kentucky, to the area. On July 3, 1946, I accompanied a party of three to the summit of the mountain, to remain until July 7. On June 4, 1948, my family and I made camp near the Glenbrook Visual-Aural Range Station and remained there until September 1, 1948. During these four trips, over 350 mammal skins were prepared, most of them collected in Kentucky. The majority of the skins are in my personal collection; some are in the Cornell University collections, while a few are deposited in the United States National Museum. Big Black Mountain is the highest point of the Cumberland Mountain Section, the physiography of which has been treated by Fenneman (1938). The exposed rocks of the area under consideration belong to the Pennsylvanian series. Bedrock is exposed in but few places other than stream beds; the region is generally covered by a deep soil mantle. The geology of the area has been treated by the United States Geological Survey (1894). The mammalian fauna of the mountainous areas of eastern Kentucky and adjacent states is of considerable interest. It is here that certain northern species reach the southern limits of their range; here some southern species reach the northern limits of their range; here is a region of intergradation of various northern and southern geographic races; and here a few geographic races are confined. This paper presents information on thirty-two species and subspecies of mammals known to occur on Big Black Mountain in southeastern Kentucky and adjacent Virginia. They may be divided into five distributional categories: 100 Vol. 32, No. I