Deep wells in central and southern Florida have yielded 68 species of marine and brackish-water Ostracoda of Early Cretaceous and earliest Late Cretaceous ages. About 40% of the ostracods are referable to described species. The rock sequence is more than 2,250 m thick.

A partly oolitic limestone facies of the Washitan Stage (early Cenomanian-late Albian) contains 17 species, of which 15 are restricted to the unit. Brackish-water, and perhaps freshwater, as well as marine Ostracoda are represented.

Pre-Washitan Cretaceous rocks of peninsular Florida are principally massive, interbedded carbonate rocks and evaporites and thin shales. Ostracods occur chiefly in the shales. Of 23 species in the Fredericksburgian Stage (middle Albian), nine are restricted to the unit; marine and a few brackish-water species are represented.

Trinitian Stage (early Albian-late Aptian) ostracods are represented by 21 species, of which seven are restricted to that unit; several are brackish-water forms.

Coahuilan Series (early Aptian-Neocomian) rocks contain 35 species, of which 25 are confined to that unit; several are brackish-water types.

The environment represented by the ostracod populations is mainly that of an open-marine shelf bordered by partly brackish-water lagoons. Trinitian Stage rocks contain representatives of a few species which indicate outer-shelf or slope environments.

The population as a whole has strongest affinities for Cretaceous species of the Gulf coastal or Atlantic coastal United States. Several of the Coahuilan and Trinitian species show relationships to European and to South American forms. Few such relations are shown by Fredericksburgian and Washitan species.

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