Ursus Linnaeus, 1758 . Syst. Nat., 10th ed., 1:47.

TYPE SPECIES: Ursus arctos Linnaeus, 1758, by tautonymy (Melville and Smith, 1987).

SYNONYMS: Thalarctos .

COMMENTS: The close relationship of these four species has been generally recognized by morphological and molecular studies (Goldman et al., 1989; Hendey, 1980a; Kurtén and Anderson, 1980; Shields and Kocher, 1990). Allen (1938) proposed a close relationship between thibetanus and americanus . Thenius (1953), Goldman et al. (1989), and Shields and Kocher (1991) gave support to the monophyly of arctos with maritimus .