| Umbonium | |
|---|---|
 | |
| Two views of a shell of Umbonium giganteum | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Subclass: | Vetigastropoda |
| Order: | Trochida |
| Superfamily: | Trochoidea |
| Family: | Trochidae |
| Genus: | Umbonium Link, 1807 [1] |
| Type species | |
| Trochus vestiarius | |
| Synonyms [2] | |
| |
Umbonium, sometimes known as the "button top shells", is a genus of sea snails, marine gastropod molluscs in the family Trochidae, the top snails. [2]
The shells of the species in this genus are low-spired and shaped like a button. The orbicular shell is depressed and imperforated. It is polished, porcellaneous and has a very thin pearly layer inside. The whorls are flattened above, bright, smooth or spirally grooved. The small, transverse aperture is wider than high. The thin outer lip is acute. The inner lip is rounded, ending in a simple point. The umbilicus of the shell is often completely covered with a thick and smooth callus. [3]
The animal has a distinct lateral fringe of the foot, with three filaments on each side. The front of the right side near the base of the tentacles is produced into a fleshy lobe. The right tentacle is free, with the eye-peduncle compressed, and bears a rudimentary eye. The left eye-peduncle is cylindrical, with a distinct eye, and furnished with an expansion or frontal lobe, which is folded on itself and fringed at its free margin. The operculum is horny, orbicular, and multispiral. [4]
Species in the genus Umbonium include:
Bulla is a genus of medium to large hermaphrodite sea snails, shelled marine opisthobranch gastropod molluscs. These herbivorous snails are in the suborder Cephalaspidea, headshield slugs, and the order Opisthobranchia.
Buccinum is a genus of medium-sized sea snails, marine gastropod molluscs in the family Buccinidae, the true whelks.
Trochus is a genus of medium-to large-sized, top-shaped sea snails with an operculum, of the family Trochidae, the top snails.
Siphonaria is a genus of air-breathing sea snails or false limpets, marine pulmonate gastropod molluscs in the family Siphonariidae, the false limpets.
Omphalotropis is a genus of minute salt marsh snails with an operculum, terrestrial gastropod mollusks in the subfamily Omphalotropidinae of the family Assimineidae.
Emarginula is a genus of small keyhole limpets, marine gastropod molluscs in the family Fissurellidae.
Acmaea is a genus of sea snails, specifically true limpets, marine gastropod mollusks in the family Acmaeidae, one of the families of true limpets.
Clanculus is a genus of sea snail, marine gastropod molluscs of the family Trochidae, the top shells.
Natica is a genus of small to medium-sized predatory sea snails, marine gastropods in the subfamily Naticinae of the family Naticidae, the moon snails. The genus was erected by Giovanni Antonio Scopoli in 1777.
Nerita is a genus of medium-sized to small sea snails with a gill and an operculum, marine gastropod molluscs in the subfamily Neritinae of the family Neritidae, the nerites.
Patella is a genus of sea snails with gills, typical true limpets, marine gastropod mollusks in the family Patellidae, the true limpets.
Astralium, common name star snails, is a genus of sea snails, marine gastropod mollusks in the family Turbinidae, the turban snails and star snails.
Cerithidea is a genus of medium-sized sea snails or mud snails, marine gastropod mollusks in the family Potamididae, the horn snails.
Ethalia is a genus of sea snails, marine gastropod mollusks in the subfamily Umboniinae of the family Trochidae, the top snails.
Pseudostomatella is a genus of small sea snails, marine gastropod mollusks in the subfamily Stomatellinae of the family Trochidae, the top snails.
Stomatella is a genus of small to medium-sized sea snails, marine gastropod mollusks in the family Trochidae, the top snails and their allies.
Clypeomorus is a genus of sea snails, marine gastropod mollusks in the subfamily Cerithiinae of the family Cerithiidae.
Planaxis is a genus of small sea snails, marine gastropod mollusks in the family Planaxidae.
Ethaliella is a genus of sea snails, marine gastropod mollusks in the family Trochidae, the top snails.
Ethalia guamensis, common name the Guam button top shell, is a species of sea snail, a marine gastropod mollusk in the family Trochidae, the top snails.
