Vertigo pusilla
Encyclopedia
Vertigo pusilla is a species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of minute air-breathing land snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...

, a terrestrial
Terrestrial animal
Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...

 pulmonate gastropod mollusk or micromollusk
Micromollusk
A micromollusk is a descriptive term for a shelled mollusk which is extremely small, even at full adult size. The word is usually, but not exclusively, applied to marine mollusks, although in addition, numerous species of land snails and freshwater mollusks also reach adult size at very small...

 in the family Vertiginidae
Vertiginidae
Vertiginidae is a family of minute, air-breathing land snails, terrestrial pulmonate gastropod molluscs or micromollusks in the superfamily Pupilloidea.- Distribution :...

.

Vertigo pusilla is the type species of the genus Vertigo.

Shell description

Shell
Gastropod shell
The gastropod shell is a shell which is part of the body of a gastropod or snail, one kind of mollusc. The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage...

 subfusiform, with, somewhat of a quadrangular outline, thin and semitransparent, very glossy, horn-color, with a faint tinge of yellow, very slightly and remotely striate in the line of growth; periphery rounded, with a tendency to angularity; epidermis thin; whorls
Whorl (mollusc)
A whorl is a single, complete 360° revolution or turn in the spiral growth of a mollusc shell. A spiral configuration of the shell is found in of numerous gastropods, but it is also found in shelled cephalopods including Nautilus, Spirula and the large extinct subclass of cephalopods known as the...

 4 ½ or 5, very convex and cylindrical, gradually increasing in size, the penultimate whorl as broad as the last, which occupies about two-fifths of the shell. Spire
Spire (mollusc)
A spire is a descriptive term for part of the coiled shell of mollusks. The word is a convenient aid in describing shells, but it does not refer to a very precise part of shell anatomy: the spire consists of all of the whorls except for the body whorl...

 is shortish, but rather tapering, and blunt at the point. Suture is very deep.

Aperture
Aperture (mollusc)
The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where part of the body of the animal emerges for locomotion, feeding, etc....

 is semioval, contracted or sinuous in the middle of the outer edge; teeth six or seven, viz. two on the pillar [parietal wall], two on the pillar lip (the inner one of which is always larger, and the outside one tubercular and placed in the angle where the outer lip joins), and two or three within the outer lip (the third, when it is present, placed near the pillar lip and being a mere tubercle:) outer lip rather thick and slightly reflected, strengthened by a strong rib both outside and inside, which is situate near the opening of the mouth and is yellowish-white; outer edge rather abruptly inflected; inner lip slightly thickened in full grown specimens; umbilicus small and narrow, contracted by a rather sharp and gibbous crest or ridge at the base of the shell.

Distribution

This snail occurs in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

an countries and islands including:
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