~Lynx canadensis canadensis~ Kerr, 1792.--We have no reports of this species in Harding County save that Visher (1914:90) noted that local residents claimed specimens had "been taken recently in the Cave Hills." Hoffmann and Pattie (1968:53) reported that the lynx occurs presently in eastern Montana and we suspect that individuals may occasionally range into Harding County. ZOOGEOGRAPHIC COMMENTS Of the 53 mammals listed in the foregoing accounts, all but one (_Mus musculus_) are native North American species. These fall into five rather well-defined faunal groupings as outlined by Hoffmann and Jones (1970:364-365). A majority (27) can be characterized as "widespread species." Most of these have broad distributions over much of North America; a few do not, but are widely enough distributed that it is impossible to assign them with certainty to a more circumscribed assemblage. Mammals from northwestern South Dakota that can be characterized as widespread are: _Myotis leibii_, _Myotis lucifugus_, _Eptesicus fuscus_, _Lasionycteris noctivagans_, _Lasiurus cinereus_, _Castor canadensis_, _Peromyscus maniculatus_, _Ondatra zibethicus_, _Erethizon dorsatum_, _Canis latrans_, _Canis lupus_, _Vulpes vulpes_, _Ursus americanus_, _Ursus arctos_, _Procyon lotor_, _Mustela frenata_, _Mustela vison_, _Taxidea taxus_, _Mephitis mephitis_, _Lutra canadensis_, _Felis concolor_, _Lynx rufus_, _Cervus elaphus_, _Odocoileus hemionus_, _Odocoileus virginianus_, _Antilocapra americana_, and _Bison bison_. The above list is composed mainly of volant or relatively large and mobile mammals, several of which occur also in Eurasia or range well into the Neotropics. A few widespread species deserve special comment. Two, the pronghorn and bison, are typical inhabitants of the interior grasslands of North America and might be considered steppe species save for the fact that each has an extensive distribution beyond that region. Four other species, _Erethizon dorsatum_, thought of primarily as a mammal of coniferous forests, and _Ursus arctos_, _Taxidea taxus_, and _Odocoileus hemionus_, all more or less western taxa, are not so broadly distributed as are other members of this grouping. Of the five bats, three are year-round residents, but _Lasiurus cinereus_ and evidently _Lasionycteris noctivagans_ are migrants. The remaining 25 kinds of mammals are representative of four regional faunal groupings as follows: boreomontane species (10), steppe species (nine), species with Sonoran affinities (four), and species of the eastern deciduous forest (two).