This is a world wide family which have very different shell shapes.The classification is based on the differences in the genitalia. There are two Subfamilies: Valloniinae:shell small 2-3 mm wide,whitish and disc-shaped.The umbilicus is wide and open,the mouth is round.The snails live in open terrain. Acanthinulinae:shell small 2-4 mm wide,brownish,convex-conical shaped.The umbilicus is narrow.The snails live in damp,sheltered places.
Valloniinae Vallonia costata(Müller,1774)Ribbed Grass Snail The shell is disc-shaped,2,2-2,7 mm wide,with 3,25 whorls.The umbilicus is very wide and the mouth round with a thick lip.The color is greyish white with grooves and ribs. The snails live in dry,open limestone areas,old walls,dunes. In Eurasia and North-America.
Vallonia excentrica(Sterki) This species is very similar to V.pulchella and some authors see it as a subspecies to it or a variety.It lives in open habitats,especially in grassland.
Vallonia pulchella(Müller,1774)Smooth Grass Snail
Shell disc-shaped,2-2,5 mm wide,with 3,25 whorls.It has a thick lip and is
pale,glossy and transparent.
The snails live in more damp places than V.costata,in marshes,dunes and
meadows.
In Eurasia and North-America.
Achantinula aculeata(Müller,1774)Prickly Snail Shell cone-shaped,2 x 2mm,brown,with 4 whorls.The axial ribs have spines. The Prickly Snail lives in woods,under shrubs in Europe.
Achatinula lamellata(Jeffreys) In old woodlands in England north from Stafford and Ireland.
Spermodea lamellata(Jeffreys,1830) Shell convex-cone shaped,2 x 2mm,with 5,5-6 whorls.The umbilicus is open but narrow.The color is pale goldenbrown,glossy with sharp radial ribs. In North-West Europe in decidious woods.Not in Belgium or The Netherlands.
Zoogenetes harpa(Say,1824) Shell cone-shaped,3-4 mm high x 2,4-3 mm wide,pale-brown with 3,5-4 whorls. It has fine radial ribs. In pine forests in The Alps(rare),Eurasia,North-America and Scandinavia.