Notes on shell morphology and classification of the Siliquariidae (Gastropoda) : the protoconch and slit of Siliquaria squamata Blainville. American Museum novitates ; no. 2263

Abstract

"Siliquaria, described for the first time, is 0.25 mm. wide, helically coiled, and has a sinuous aperture, whereas that of the other two siliquariid genera is 1 mm. wide and planispiral, with a circular aperture. Protoconch form can no longer be used as the chief diagnostic familial characteristic as proposed by Morton (1951). The siliquariid slit is analogous in form, but not in function, to the selenizone of slit-bearing archaeogastropods. Since the siliquariid slit is much longer than that of archaeogastropods, the morphology of slit healing differs. To prevent lateral filling of the slit by growth increments running longitudinally along the slit toward the slit-healing lamina, such increments are either not deposited or else run underneath, rather than in the same surface, as in their predecessors"--P. 11-12.