Vitrea contracta

Vitrea contracta, the milky crystal snail, is a species of small, air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Pristilomatidae.^[1]

Vitrea contracta
Shell of Vitrea contracta (specimen at MNHN. Paris)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Order:	Stylommatophora
Superfamily:	Gastrodontoidea
Family:	Pristilomatidae
Genus:	Vitrea
Species:	V. contracta
Binomial name
Vitrea contracta (Westerlund, 1871)
Synonyms
Crystallus contractus (Westerlund, 1871) Crystallus contractus subcontractus A. J. Wagner, 1907 (junior synonym) - Hyalinia abchasica Retowski, 1914 (junior synonym) Hyalinia blanci P. Hesse, 1882 (junior synonym) Hyalinia zakynthia P. Hesse, 1882 (junior synonym) Vitrea (Crystallus) contracta (Westerlund, 1871) Vitrea (Crystallus) zapateri Westerlund, 1898 (junior synonym) Vitrea botteri O. Boettger, 1905 · junior homonym (invalid, non Helix botterii L....) Vitrea lepta Westerlund, 1902 · (junior synonym) Zonites crystallina var. contracta Westerlund, 1871 (original name)

Description

Vitrea contracta figure 4

For terms see gastropod shell.

The 2.2-2.6 mm. shell is colourless translucent and shiny. It is almost smooth with 4-5 whorls, the last whorl width seen from above 1.4-1.6 x of penultimate whorl. The umbilicus is moderately wide, becoming wider at the last whorl.

Distribution in Europe of Vitrea contracta

The coiled, rather small, dextral shell is strongly oblate-conical, almost disc-shaped. When mature, the shell is 1.8 to 3.0 (usually about 2 mm) wide (diameter) and 1.0 to 1.4 mm high. Viewed from its side, the seam is only slightly raised. The shell consists of 4 to 5 whorls, which increase slowly and regularly. The body whorl is relatively narrow. Seen from above, each whorl increases by about 1.4 to 1.6 times the size of the previous whorl. The top of the whorls has a flat curve, so that the seams are also very flat. The outline of the shell is well rounded, its bottom is relatively flat. The aperture has a flattened-elliptical shape in its entire circumference and is obliquely crescent-shaped because of the deep cut of the previous whorl. The outer lip is straight and tapering and not thickened . The umbilicus is deep and broad, becoming wider at the body whorl. All convolutions are visible in the navel.

The epidermis of the shell is colorless and translucent to slightly milky. The surface is very glossy. There are very fine, irregular growth lines and a suggestion of spiral lines.^{[2][circular reference]}

Distribution

This species occurs in countries and islands of central and northwestern Europa including:

• Czech Republic
• Ukraine^[3]
• Great Britain
• Ireland
• Iceland
• and sometimes introduced in other areas such as Palestine, California, Washingston (state) and Toronto, Ontario.

These snails live hidden in the litter, in loose soil, at the foot of rocks or among rubble, in meadows with rubble, forests with stones and rubble, but also in cool gorges and swampy alder grooves, even in holes and crevices. In protected biotopes they also remain active in winter. The species occurs in moist to dry habitats on calcareous soils.