Published online by Cambridge University Press: 20 May 2016
A new species of planorbid gastropod, Vorticifex taylori, is described from the Late Miocene (Clarendonian) Truckee Formation at its type area in Churchill County, Nevada. Comparison with younger and older species assigned to Vorticifex indicates a high degree of morphologic variation within the genus as contrasted with relatively conservative intraspecific variation, which may reflect ecologic similarities at discrete times during the development of the Great Basin subprovince of the Basin and Range physiographic province.