Three problems in gastropod biology serve as the focus for this research on metamorphosis and morphological diversity. First, development and functional significance of modifications to shell apertures of many marine gastropod species when in the planktic veliger larval stage (the sinusigeral larval form) will be studied. Second, developmental causes of an unusual mechanical deformation occurring in larval shells of some primitive marine gastropod species are to be investigated. A third topic relates to characterizing and evaluating the diversity of sequential events and timing involved in development of trochoidean gastropods, with the specific goal of translating data into characters and character states useful for phylogenetic analysis; such descriptors should be useful in tandem with more traditional morphological characters. %%% This work will inform persistent and unresolved problems of molluscan evolutionary morphology. The first two problems reside in the realm of functional and evolutionary interpretation of features of the larval shell and its relationship to the adult shell, for which solutions require developmental information gathered in a comparative systematic way. Both questions are relevant to phenomena observable in shells of living and fossil gastropods. Addressing the third problem would cultivate a consistent language of characters and character states that translate the rich vocabulary of developmental biology into a language for systematics and phylogenetic analysis.
