A preliminary study of Ostracoda from core samples in the Rodessa Formation (lower Trinity Group), and from the Pearsall, Sligo, and upper Hosston Formations (Coahuila Series), Lower Cretaceous, of the subsurface of northern Louisiana, has yielded 52 species. Only a small fraction of the known ostracode assemblage is dealt with here.

On the basis of present limited knowledge, the Rodessa Formation contains common Eocytheropteron, Hechticythere, Rehacythereis?, and Cornicythereis suggesting an open shelf environment. The Sligo Formation contains common Schuleridea, probably representing an open shelf environment, as well as Fabanella and Hutsonia, representing brackish lagoonal or estuarine environments. The upper part of the Hosston Formation contains common Paraschuleridea (open shelf) and Fabanella (brackish water) and a variety of other forms that suggest a range of conditions from lagoonal and estuarine to open shelf habitats.

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