Lacuna (gastropod)
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| Lacuna | |
|---|---|
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| Lacuna crassior shell | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Subclass: | Caenogastropoda |
| Order: | Littorinimorpha |
| Family: | Littorinidae |
| Genus: | Lacuna Turton, 1827 |
| Synonyms[1] | |
| |
Lacuna is a genus of sea snails, marine gastropod mollusks in the family Littorinidae, the winkles or periwinkles.[1]
The spiral animal body is elongated. The mouth has a proboscis with two thick lips and a spiral, filiform tongue. There are two slender, contractile tentacles with the eyes on small pedicels near their base. The foot is oval and somewhat broader behind.
The thin shell has an ovate-conical or subglobose shape and is covered with a delicate horny periostracum. It has a short spire with convex whorls that are rapidly expanding. The last whorl is ventricose, i.e. inflated in the middle. The apex is rather obtuse. The oval or roundish aperture is covered with a horny, spirally marked operculum. The peristome is incomplete behind. The columella is flattened and forms with the peristome an elongated groove continued from the umbilicus. This groove is bounded internally by the decurved margin of the pillar.[2]
