Abstract Trilobites collected from six locations of the Madison Group (middle to late Tournaisian) of Montana consist of 17 taxa and 11 new species. New species include Proetides raymondi new species, Brachymetopus swimmingwomanensis new species, Liobolina montanaensis new species, Belgibole complanata new species, Belgibole ? madisonensis new species, Phillibole ? acutis new species , Piltonia sandoi new species, Piltonia douglassi new species, Perexigupyge angusticapitalis new species, and Thigriffides ? andersoni new species . Eoameura kollari new genus new species is also recognized, and neotypes are designated for Phillipsia peroccidens (Hall and Whitfield, 1877) and Perexigupyge loganensis (Hall and Whitfield, 1877). The overall taxonomic makeup of the trilobite faunas from the Madison Group is markedly different from that of contemporary strata of the central and eastern United States in that it appears to have a distinctly European generic composition. The lowest unit of the Madison Group (Lodgepole Formation) appears to exhibit a distinct upsectional change from deep- to shallow-water paleobathymetric characteristics that translate into a paleoecological gradient of trilobite species consistent with those seen in contemporary units of western Europe. UUID: http://zoobank.org/22821775-6c6a-4ac5-8fe6-2a34a26db9ab
David K. Brezinski (Tue,) studied this question.