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The taxonomic status of the green water snake, Nerodia cyclopion, is re-evaluated. The two recognized subspecies are compared by using a variety of standard morphological characters, and significant differences are noted. Discriminant analysis of head-scale measurements provides highly significant separation of the two taxa. Examination of specimens from the zone of parapatry reveals no evidence of recent gene flow between the taxa. Based on these morphological data, plus the biochemical and ecological data of other workers, I suggest that the subspecies be recognized as full species, Nerodia eyelopion and Nerodia floridana.