1: height of shell 11.5mm.
2: width of shell 16mm.
3: everted (turned outwards) white lip; indicator of fully mature adult.
4: shell pitted by acidic water exposing white, inner shell layer; indicator of older specimens.
5: sealed end of columella; no umbilicus on adults but see image 1Ch 1 Cepaea hortensis. 13.5mm high X 17mm wide. Pennine foothills, V.C. Derbyshire, England. August 2018. .
6: parietal lip is a glaze on body whorl of older shells.
7: open pneumostome on withdrawn snail to allow breathing and expulsion of faeces.
8: faeces expelled from pneuomostome of withdrawn animal; white as had eaten white cardboard.

marinvert.senckenberg.science/image-browse/

Key identification features

Cepaea hortensis
Features in common with C. nemoralis (Linnaeus, 1758)
1. No umbilicus on adults 3Ch 3 Cepaea hortensis. 11.5mm high X 16mm wide. Pennine foothills, V.C. Derbyshire, England. August 2018. , but present on some juveniles 4Ch 4 Cepaea hortensis. Juvenile. 11.5mm high, 14mm wide. Pennine foothills, V.C. Derbyshire, England. August 2018. .
2. On adults, outer lip of aperture rounded in its upper part, turning sharply into a straight basal part. Juveniles differ. 2Ch 2 Cepaea hortensis. Pennine foothills, V.C. Derbyshire, England. August 2018. .
Feature frequent on Cepaea hortensis, but sometimes on C. nemoralis
3. On adults, outer lip of aperture has a white thickening and rib just within the rim 6Ch 6 Cepaea hortensis. Pennine foothills, V.C. Derbyshire, England. September 2018. & 5Ch 5 Cepaea hortensis. 13.3mm high X 17,5mm wide. Pennine foothills, V.C. Derbyshire, England. September 2018. . Externally, brown pigment bands do not extend onto the rim of the lip; it is usually pale yellow. Lips on juveniles of both Cepaea spp. lack thickening, rib and colour distinction 2Ch 2 Cepaea hortensis. Pennine foothills, V.C. Derbyshire, England. August 2018. . Care is needed not to mistake the pale mantle for a pale lip when sometimes reflected over and concealing the outer lip.
4. The red jaw has 2 to 4 strong ribs is set into the top of the mouth 27Ch 27 Cepaea hortensis. Radula and jaw. Pennine foothills, V.C. Derbyshire, England. August 2018. (Number has overlap with C. nemoralis which has 4 to 7 ribs.)
Reliable diagnostic features that differentiate C. hortensis from C. nemoralis
5. The love dart has four vanes that are thin at base and thicker and bifurcated distally, giving a cross section like a Maltese cross 33Ch 33 Cepaea hortensis, love dart. Pennine foothills, V.C. Derbyshire, England. September 2018. . But, the dart is very brittle and often missing. For examination, a stereoscopic dissecting microscope at c.X20 is needed.
6. A pair of 4-branched (occasionally 5-branched) mucus glands are connected close to the opening of the dart sac 34Ch 34 Cepaea hortensis. Dissection with mantle and body wall removed; organs as uncovered, undisturbed. Pennine foothills, V.C. Derbyshire, England. September 2018. & 35Ch 35 Cepaea hortensis. Dissection with reproductive organs isolated and spread out. Pennine foothills, V.C. Derbyshire, England. September 2018. .

Similar species

Cepaea nemoralis
1. As 1 above for C. hortensis.
2. As 2 above for C. hortensis.
3. On adults, outer lip of aperture usually has a brown thickening and rib just within the rim 45Ch 45 Cepaea hortensis album. COMPARISON images of C. nemoralis with typical brown lip. Pennine foothills, V.C. Derbyshire, England. August 2018. . But white lipped specimens occur 46Ch 46 Cepaea hortensis album. COMPARISON images of C. nemoralis with atypical white lip. Top line: Pennine foothills, V.C. Derbyshire, Aug. 2018. Lower line: Lowland Cheshire, England, March, 2001. . Lips on juveniles of both Cepaea spp. lack thickening, rib and colour distinction. Care is needed not to mistake the pale mantle for a pale lip when sometimes reflected over and concealing the outer lip.
4. The red jaw has 4 to 7 strong ribs (Hudson in Topley, 2006). Number has overlap with C. nemoralis which has 4 to 7 ribs.
5. The love dart has four vanes thickest at base and tapering steadily distally giving a cross section of a simple cross 47Ch 47 Cepaea hortensis album. COMPARISON image of C. nemoralis love dart. Pennine foothills, V.C. Derbyshire, England. August 2018. . But, the dart is very brittle and often missing. For examination, a stereoscopic dissecting microscope at c.X20 is needed.
6. A pair of 2-branched or 3-branched mucus glands are connected close to the opening of the dart sac 48Ch 48 Cepaea hortensis album. COMPARISON dissection of C. nemoralis reproductive organs. Pennine foothills, V.C. Derbyshire, England. August 2018. . (In a Croatian study, two specimens with C. nemoralis type love darts had 4-branched glands (Štamol & Slapnik, 2015)).
7. maximum diameter 24mm, so Cepaea with diameter greater than 20mm (max. for C. hortensis) are most probably C. nemoralis 46Ch 46 Cepaea hortensis album. COMPARISON images of C. nemoralis with atypical white lip. Top line: Pennine foothills, V.C. Derbyshire, Aug. 2018. Lower line: Lowland Cheshire, England, March, 2001. . In mixed populations, C. nemoralis is usually obviously larger than C. hortensis.
Comment:
Relying for identification of a single specimen solely upon the feature suggested by the vernacular names "White-lipped snail" (C. hortensis) and "Brown-lipped snail" (C. nemoralis) can lead to misidentification. In areas where a species has not been previously recorded, several specimens should be examined and the mucus gland and love dart dissected before submitting the record to a recording scheme. The Pennine specimens illustrated in this account come from a garden where for 35 years C. hortensis was common, but C. nemoralis not seen until the hot dry summer of 2018 when 9 adults were found; 8 with brown lips and one with a white lip (love darts and mucus glands examined).
Special care is needed in continental Europe where further similar species occur. On the basis of lip colour, C. hortensis was regarded for over 150 years as living in Croatia. Recent fieldwork at its previously recorded sites failed to discover it, but found 6 white-lipped and 2 brown-lipped specimens with darts and mucus glands as described for C. nemoralis, casting doubt on the occurrence of C. hortensis in Croatia and possibly other Balkan areas (Štamol & Slapnik, 2015).