Thirty-three ostracod taxa are reported from Upper Silurian (Pridolian) rocks of the Roberts Mountains Formation. This diverse, unique ostracod fauna contains both North American and Eurasian elements and has closest similarities with ostracode faunas of northwestern Canada and eastern Alaska. Three new genera and 18 new species are proposed. The three new genera are: Paranoviportia, with P. reticulata as its type species; Nevadabolbina, with N. confluens as its type species; and Botulobolbina, with B. paulisagena as its type species.--Modified journal abstract.