_Specimens examined_ (13).--NE 1/4 sec. 22, R. 1 E, T. 23 N, 6; 2 mi. N, 5 mi. W Ludlow, 1; 2 mi. S, 11 mi. W Reva, 1; 14 mi. S, 4 mi. W Reva, 4; 15 mi. S, 4 mi. W Reva, 1. Ord's kangaroo rat is found in sparsely vegetated flatlands throughout Harding County, although it appears to be uncommon except in localized areas of relatively sandy soils. Five of seven specimens taken from June 18 through 24, 1961, were young of the year, as were three of six individuals trapped on May 31, 1968. One adult female (81.1 grams) obtained on May 31 was lactating and had four placental scars, whereas another that weighed 67.2 grams evidenced no recent reproductive activity. An adult male (67.9 grams) taken on May 31 had testes that measured 9; those of a subadult male (46.5 grams) taken on the same date measured only 6. The two May-taken adult females mentioned above still were completely in winter pelage, but the adult male trapped at the same time was molting. An adult male (57.2 grams) obtained on June 22 had completed molt save for a small patch between the ears and immediately behind the head. ~Castor canadensis missouriensis~ Bailey, 1919 Beaver _Specimens examined_ (2).--Sec. 22, R. 1 E, T. 20 N, 1; 32 mi. SE Buffalo, 1. According to local residents, the beaver is common along many of the water courses in the county. One of our two specimens came from a tributary of the Little Missouri River north of Camp Crook and the other was taken from a tributary of the Moreau River in the southeastern part of the county. Robert Kriege of Buffalo reported to us that beaver are not restricted to wooded areas, but frequently inhabit streams and more or less permanent impoundments bordered by grassland. In such places they are said to construct bank dens and eat principally sage and forbs. Visher (1914:89) reported this species along the Little Missouri River, Boxelder Creek, the forks of Grand River, Bull Creek, and "Devil's Gulch" in the North Cave Hills, and figured (pl. 6) a dam on Rabbit Creek. We have observed evidence of beaver activity along the Little Missouri River southwest of Ladner and along aspen-wooded stream banks in the Short Pine Hills, where in the spring of 1963 abundant sign was found. ~Reithrodontomys megalotis dychei~ J. A. Allen, 1895 Western Harvest Mouse _Specimens examined_ (27).--NE 1/4 sec. 22, R. 1 E, T. 23 N, 1; 4 mi. S, 7 mi. W Ladner, 3; 2 mi. N, 5 mi. W Ludlow, 7; 1/2 mi. W Reva, 14; 10 mi. S, 5 mi. W Reva, 1; 14 mi. S, 4 mi. W Reva, 1.