GASTROPODA | SCISSURELLIDAE |
Shells minute to small, of many forms and bearing many different sculptures depending of the genera. « Usually with selenizone and slit or single foramen; also without selenizone, and/or without foramen or slit (Coronadoa, Larochea, Larocheopsis, Trogloconcha). Anomphalous or umbilicate. Nacre inconspicuous. Coiled operculum with central nucleus usually present (absent in Larochea, Larocheopsis). » (Geiger, 2003). If there is a selenizone, it is placed on the shoulder. It is almost impossible to assign valuable criteria to the morphological description of this family, and the only characteristic (anatomical) shared by the whole members, the rhipidoglossate (fan-shaped dentition) radula, is also common to other families of Vetigastropoda. |
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Scissurella d’Orbigny, 1824:« Shell trochiform, shoulder rounded or angular. Sculpture usually reticulate, but also with predominating axials or axials only; no spiral keel(s) on base. Slit open, selenizone on shoulder, starting at less than 3/4 whorls of teleoconch I, with moderately elevated keels. Protoconch with variable sculpture: smooth, spirals, fine axials, strong axials; varix absent or present, if present restricted to aperture, or connecting to embryonic cap; aperture sinusoid or simple convex curve. Umbilicus usually open, with or without carina, some with funiculus; rarely anomphalous. Operculate. » – D. Geiger: “Phylogenetic assessment of characters proposed for the generic classification of Recent Scissurellidae”, Molluscan Research vol.23(1), 2003, p.26. |
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Sinezona Finlay, 1926:Shell trochoid. « Protoconch usually with strong axials; spirally sculptured and smooth ones also known. Protoconch varix present with or without contact to embryonic cap. Anomphalous or umbilical wall forming continuous curve with base of shell, without carina or funiculus. Sculpture usually with axials predominating over spirals, no spiral keel(s) on base. Selenizone on shoulder, slit closed anteriorly forming foramen, keels of selenizone and foramen of more than 1/4 up to the full width of the selenizone. […] The only diagnostic character is the presence of a selenizone in conjunction with the slit closing anteriorly to form a foramen. » – D. Geiger: op. cit. p.32. |
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