Comments: Allozyme data indicate that Euryzonus and F. OLIVACEUS are sister species (Cashner et al. 1992). Exhibits a high degree of genetic variation both within and among populations. The genus Fundulus was removed from Atheriniformes:Cyprinodontidae and placed in Cyprinodontiformes:Fundulidae by Parenti (1981); pending confirmation based on other character suites, this change was not accepted in the 1991 AFS checklist (Robins et al. 1991). See Wiley (1986) for a study of the evolutionary relationships of Fundulus topminnows based on morphological characters. See Cashner et al. (1992) for an allozyme-based phylogenetic analysis of the genus Fundulus.