The Whitehorse fauna occurs high in the red beds section of the Mid-continent region near the Paleozoic-Mesozoic boundary. Underlain and overlain by a great thickness of nearly unfossiliferous rocks this fauna occupies a key position for the correlation of a part of the red beds. Although composed dominantly of pelecypods and gastropods the fauna also contains bryozoans, serpulids, and brachiopods. The fossils occur as molds in very long, narrow sandstone and dolomite lenses interpreted here as marine offshore bars. There are 32 species recognized, of which 7 are described as new. They are distributed among 29 genera, of which 6 are presented as new. Pertinent stratigraphic and faunal evidence bearing on the age of the Whitehorse fauna is marshaled, resulting in the conclusion that it is late Permian in age, probably correlative with the Capitan fauna of the standard Permian section in western Texas. The possibility is recognized that the Whitehorse fauna may be slightly younger or older than the Capitan.