=Iowa.= _Howard County_: Chester, 1[12]. _Palo Alto County_: Emmetsburg, 1[65]. _Kassuth County_; Algona, 1[65]. _Clayton County_: National, 1. _Storey County_: Nevada, 1[65]. _Wapello County_: Ottumwa, 1[65]. _Henry County_: Mount Pleasant, 1[66].
=Nebraska.= _Holt County_: Page, 1[35]. _Madison County_: Norfolk 1[35]. _Cuming County_: Beemer, 1. _Hamilton County_: Chapman, 1[35]. _Clay County_: Inland to 1 mi. east thereof, 7[35].
=South Dakota.= _Brown County_: shore of Sand Lake, S. 15 T. 126N, R. 62W, 1. _Day County_: Waubay Migratory Waterfowl Refuge, 1. _McCook County_: Salem, 1[102].
_Type._--_Mustela frenata_ Lichtenstein, Darstellung neuer oder wenig bekannter Säugethiere, pl. 42 and corresponding text unpaged. 1832.
_Range._--From southern Canada southward over all of the United States, México, Central America, Venezuela, and the republics of western South America to southern Perú and extreme northern Bolivia. All the life-zones from Alpine Arctic to Tropical are inhabited. In the extremely desert region of southeastern California and western Arizona the species is scarce or possibly absent although recovery of a skull (see under account of _M. f. neomexicana_) from near the center of this region at Potholes on the Colorado River, and a reported occurrence in the mountains of Baja California, México, indicate that a few individuals of the species live in favorable habitat even in this desert region.
_Characters for ready recognition._--Differs from _Mustela erminea_, in regions where the two species occur together, by tail more than 44 per cent of length of head and body and by postglenoidal length of skull less than 46 per cent of condylobasal length in males and less than 48 per cent in females (see under characters of the species); from _Mustela rixosa_ by presence of black pencil on tail, caudal vertebrae more than a fourth (2/5-3/4) of length of head and body, basilar length of skull more than 34 mm.; from _Mustela africana_ by absence of thenar pad on forefoot, underparts without longitudinal, median, abdominal stripe of same color as upper parts, upper lips narrowly (rather than broadly) edged with color of underparts, longest facial vibrissae extending to or behind posterior margin of ear; presence of p2; more inflated (see pls. 23 and 30) tympanic bullae.