Rissoina pusilla
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| Rissoina pusilla | |
|---|---|
 | |
| Fossil shell of Rissoina pusilla, as illustrated in Brocchi (1814). | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Subclass: | Caenogastropoda |
| Order: | Littorinimorpha |
| Family: | Rissoinidae |
| Genus: | Rissoina |
| Species: | †R. pusilla |
| Binomial name | |
| †Rissoina pusilla (Brocchi, 1814) | |
| Synonyms[1] | |
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Rissoina pusilla (Brocchi, 1814) is an extinct species of small marine gastropod mollusc in the family Rissoinidae.[1] The species is known only from fossil material from Italy.[2]
The shell is minute, oblong, and blunt, with longitudinal folds. The whorls are weakly convex and closely spaced. The aperture is ovate, narrowing to a slightly pointed upper end. The shell length is approximately three lines (about 6–7 mm).[2]
A fossil variety, Rissoina pusilla var. promyosoroides, has been described, characterized by a shorter, more pupoid shell and smaller initial whorls.[3]