In a recent summary of the natural history of this species in South Dakota, Henderson _et al._ (1969) listed seven localities in Harding County (all in prairie dog "towns") at which ferrets had been sighted or trapped as follows (dates in parentheses): near Ladner (March, 1963); 17 mi. N Camp Crook (about 1956 or 1957); T. 20 N, R. 3 E (1964); T. 20 N, R. 4 E (winter, 1964); T. 19 N, R. 1 E (late November, 1966); T. 17 N, R. 8 E (summer, 1965); T. 15 N, R. 1 E (winter, 1963). These authors also reported a specimen in the U.S. National Museum (no. 243990) that was taken at Govert on November 1, 1923. Additionally, Wesley Broer, then the local game warden, reported to one of our parties that a ferret was seen on February 27, 1963, at a place 7 mi. N and 16 mi. W Buffalo. Visher (1914) made no mention of this species in his report of the natural history of Harding County. ~Mustela vison letifera~ Hollister, 1913 Mink Tracks of a mink were observed by a member of one of our field parties (T. H. Swearingen) in late March of 1963 at a pond 5 mi. S and 14 mi. E Buffalo, and one was reported to have been trapped in the same area the previous winter. Reports by local residents indicate that mink occur along the Little Missouri River as well as streams on the north side of the North Cave Hills. Visher (1914:91) reported the species to be uncommon but he knew of one trapped in February of 1911 on Bull Creek. ~Taxidea taxus taxus~ (Schreber, 1778) Badger _Specimens examined_ (4).--Sec. 25, R. 3 E, T. 22 N, 1; NE 1/4 sec. 28, R. 4 E, T. 19 N, 1; 4 mi. E Reva, 1; 10 mi. S, 2 mi. W Buffalo, 1. Local residents regarded the badger as relatively common in the grasslands of Harding County, although this species was only rarely observed by members of our field parties. Visher (1914:91) reported it to be "quite common." ~Spilogale putorius interrupta~ (Rafinesque, 1820) Spotted Skunk We took no spotted skunks in northwestern South Dakota and both local residents and government trappers reported this species to be rare in the area. Visher (1914:91) indicated that it was "much more common than the large skunk" in the early part of this century. ~Mephitis mephitis hudsonica~ Richardson, 1829 Striped Skunk Visher (1914:91) found this species to be "uncommon" in Harding County, as we did more than a half century later. Some local residents, however, reported this skunk to be fairly abundant. We took one specimen, an adult female having enlarged mammae that was captured on July 6, 1965, at a place 7 mi. S and 4-1/2 mi. E Harding, just south of the Short Pine Hills. Site records of several other striped skunks were obtained as follows: 14 mi. N Buffalo; 6 mi. N and 2-1/2 mi. W Camp Crook; 5-1/2 mi. WNW Buffalo; 1-1/2 mi. S and 1/2 mi. E Buffalo; 4 mi. S Buffalo; 10 mi. SW Ralph; and 1 mi. S Reva. ~Lutra canadensis interior~ Swenk, 1920 Otter