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| The families of non-marine molluscs of Britain and Ireland (slugs, snails and mussels) |
Morphology. Snails, with a conspicuous, spiral, univalve shell.
The animal with two pairs of tentacles. Eyes at the tips of the posterior tentacles.
The shell mostly with a ‘clausilium’, which functions as an operculum when the animal retracts (a flexible, spoon-shaped plate, attached to the columella, which blocks the entrance when the animal withdraws), or inoperculate (and lacking a clausilium, in Balea); rising-spiral; 9–13 whorled; typically sinistral; higher than wide; 8–17 mm high; 2.2–4 mm wide; height about 3.7–4.3 x the width; high-spired and tapered gradually from the body whorl. The height of the spire about 0.64–0.7 x that of the shell. The shell fusiform, or tear-shaped; shallowly sutured to deeply sutured. The body whorl only slightly convex to moderately convex. The whorls of the spire feebly convex. The whorls neither shouldered nor keeled. The shell usually more or less conspicuously and regularly striated across the whorls (or finely ribbed), or not markedly striated across the whorls (e.g., glossy and somewhat translucent in Cochlodina laminata). The aperture relatively small, pear-shaped; bearing teeth (usually), or bearing calluses (sometimes in Balea). The columella folded. The shell somewhat thick-lipped; thin and translucent, or opaque; grey, yellowish- or reddish-brown, blackish or horn-coloured, but commonly bleached grey; conspicuously colour-patterned, or conspicuously colour-patterned to plain (sometimes streaked with white).
General biology, ecology. Terrestrial. Often in moss or ground litter, or lichen-encrusted walls.
Hermaphrodite; viviparous (Balea), or oviparous.
Classification. Gastropoda; Pulmonata.
Representation in Britain and Ireland. “Door snails, Tree snails”: Balea (2), Clausilia (2), Cochlodina (1), Macrogastra (1).
Illustrations. • Balea perversa, Clausilia spp. and Macrogastra rolphii, with Chondrinidaeidae, Cochlicopidae, Enidae, Ferussaciidae and Pupillidae (Ellis). CLAUSILIIDAE. 10, Macrogastra rolphii (Turton), "Rolph's Door Snail", 11–14 mm. 11, Clausilia bidentata (Ström), "Common Door Snail", or "Two-toothed Door Snail". 12, Clausilia dubia Draparnaud, "Craven Door Snail, 11–14(-16) mm. 13, Balea biplicata (Montagu), "Thames Door Snail", 16–18 mm. 14, Cochlodina laminata (Montagu), "Plaited Door Snail", 15–17 mm. 15, Balea perversa (L.), "Tree Snail", 8–10 mm. CHONDRINIDAE. 8–9, Abida secale (Draparnaud), "Large Chrysalis Snail", 6.0–8.5 mm. PUPILLIDAE. 3–4, Pupilla muscorum (L.), "Moss Chrysalis Snail", 3–4 mm. 5–6, Lauria cylindracea (da Costa), "Common Chrysalis Snail", 3.0–4.4 mm. 7, Leiostyla anglica (Wood), "English Chrysalis Snail", 3.0–3.7 mm. ENIDAE. 16, Ena montana (Draparnaud), "Mountain Bulin", 14–17 mm.; 17–18, Ena obscura (Müller), "Lesser Bulin", 8.5–9.0 mm. COCHLICOPIDAE. 22–23, Cochlicopa lubrica (Müller), "Slippery Moss Snail", 5–7 mm. 26–27, Azeca goodalli (Férussac), "Three-toothed Moss Snail", 5.5–7.0 mm. FERUSSACIIDAE. 28, Cecilioides acicula (Müller), "Blind Snail" or "Agate Snail", 4.5–5.5 mm. From Ellis (1926); all displayed at the same enlargement, to assist comparisons. • Balea biplicata, Balea perversa, Clausilia bidentata, Cochlodina laminata (live animal), Macrogastra rolphi (Reeve). CLAUSILIIDAE. 1, Cochlodina laminata (Montagu), "Plaited Door Snail". 2, Balea biplicata (Montagu), "Thames Door Snail". 3, Macrogastra rolphii (Turton), "Rolph's Door Snail". 4, Clausilia bidentata (Ström), "Common Door Snail", or "Two-toothed Door Snail". 5, Balea perversa (L.), "Tree Snail". From Reeve (1863), with approximate shell lengths added. • Balea, Clausilia, Cochlodina and Macrogastra, with Aciculidae, Cochlicopidae, Ellobiidae, Ferussaciidae (Adams). CLAUSILIIDAE. 1a and 1b, Clausilia bidentata (Strom), "Common Door Snail, Two-toothed Snail". 2a and 2b, Macrogastra rolphii (Turton), "Rolph’s Door Snail". 3a and 3b, Cochlodina laminata (Montagu), "Plaited Door Snail", with detail of an oral lamina. 4a and 4b, Balea biplicata (Montagu), "Thames Door Snail". 5, Balea perversa (Linn.), "Tree Snail". COCHLICOPIDAE. 6, Cochlicopa lubrica (Müller), "Slippery Moss Snail". 7a and 7b, Azeca goodalli (Férussac), "Three-toothed Moss Snail". FERUSSACIIDAE. 8, Cecilioides acicula (Müller), "Blind Snail, Agate Snail". ELLOBIIDAE. 9, Carychium minimum Müller, "Least Herald Snail, Sedge Snail". ACICULIDAE. 11a, Acicula fusca (Montagu), "Point Snail", with (11a) detail of the operculum. TO BE IDENTIFIED. 12, Stenogyra goodallii Miller, name not located in recent lists, and identity not established. From Adams (1890).
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2005 onwards. The families of non-marine molluscs of Britain and Ireland (slugs, snails and mussels). Version: 5th August 2019. delta-intkey.com’.
