The range of variation exhibited by individuals in clonal populations of a minute apogamic miliolid from the subtidal waters of La Jolla, California, overlaps to a confusing degree that of individuals from mass cultures of one from the intertidal waters of Panama City, Florida. Although they thus appear to belong to the same species, the two groups must be assigned to different subspecies because of differences in cultural requirements and subtle differences in test proportions, the latter observable when large laboratory populations are compared.

The most common of the morphological anomalies exhibited by this polymorphic miliolid are (1) the production of chambers aberrant either in shape or in arrangement and (2) the fusion of the tests of two individuals.

The degree of rotation between successive chambers, including the embryonic or prolocular apparatus, is highly variable. In striking disaccord with the general belief that such basic differences in chamber arrangement reflect and are invariably correlated with an alternation between sexual and asexual generations in the life cycle, a single brood of young, asexually produced by an isolated parent, may develop spiroloculine (=biloculine), quinqueloculine and, more rarely, triloculine tests. From a study of the living animal, then, has come confirmation of the major aspects of predictions about initial polymorphism in miliolids made decades ago by Munier-Chalmas and Schlumberger. Uncoiling may occur at any stage in the individual's ontogeny, suggesting a need for the re-evaluation of th se phylogenetic conclusions that presuppose it to be of phyloephebic or phylogerontic character.

Fusion of tests may occur between individuals of disparate age or size. Post-conjugal chambers are added either as two relatively independent series, producing a test that is obviously doubled, or as a single series that superficially masks fusion. Test fusion appears to be fortuitous, not a part of the species' reproductive behavior.

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