A dozen new or little known forms of Carnivora, collected in the Miocene and Pliocene beds of western Nebraska during the past 55 years by the senior author, and which are in the Cook Museum of Natural History, are discussed and described. These include the oldest known record of the Procyonid genus Bassariscus; 2 new canids, Nothocyon regulus, n. sp., and Tomarctus propter, n. sp.; and a new mustelid, Dinogale siouxensis, n. gen. and n. sp. New occurrences are cited, interpretations of geology are included, and additional data on known forms are discussed. The occurrence of Borophagus in the "Upper Snake Creek beds" of Matthew extends the age of these beds at least into Hemphillian times.