According to the systematic arrangement of Lamarck, this genus now
consists of shells with peculiar characteristic distinctions.
By Linnæus, marine, land, and fresh-water shells were united in this
genus, and so confounded that the naturalist would often look in vain
for the distinguishing characters which would enable him to class and
determine the genus of the object under examination.
Notwithstanding the divisions of Lamarck, its species are numerous; the
shells are terrestrial, and found in all parts of the globe; some are
rare and beautiful.
The term Helix was given to this genus from the spiral form of the
shell.
Shell extremely variable in form, generally globular, sometimes
ventricose, conoid, never turriculated; summit constantly obtuse and
rounded; aperture generally of a medium size, but sometimes very large
or very small, always modified by the turn of the spire; oval,
semilunar, more wide than long, edges disunited, entering but very
little into the formation of the interior; the right lip or margin
thickened or reflected.
Helix vesicalis.
H. algira.
H. pomatia.
H. aspersa.
H. vermiculata.
H. alonensis.
H. lineolata.
H. picta.
H. mutata.
H. gigantea.
H. polyzonalis.
H. monozonalis.
H. pulla.
H. versicolor.
H. Naticoides.
H. Madagascariensis.
H. galactites.
H. hæmastoma.
H. melanotragus.
H. extensa.
H. lucana.
H. globulus.
H. melanostoma.
H. cælatura.
H. microstoma.
H. maculosa.
H. Richardi.
H. Bonplandii.
H. planulata.
H. labrella.
H. ungulina.
H. pellis-serpentis.
H. Senegalensis.
H. unidentata.
H. cepa.
H. heteroclites.
H. discolor.
H. lactea.
H. zonaria.
H. serpentina.
H. Niciensis.
H. variabilis.
H. fruticum.
H. neglecta.
H. cespitum.
H. ericetorum.
H. intersecta.
H. Carthusianella.
H. Carthusiana.
H. diaphana.
H. concolor.
H. velutina.
H. Javanica.
H. Peruviana.
H. simplex.
H. cidaris.
H. citrina.
H. guttata.
H. verticillus.
H. olivetorum.
H. planospira.
H. Barbadensis.
H. sinuata.
H. hippocastanum.
H. bidentalis.
H. argilacea.
H. vittata.
H. alanda.
H. arbustorum.
H. candidissima.
H. nemoralis.
H. hortensis.
H. sylvatica.
H. pisana.
H. splendida.
H. crenulata.
H. planorbula.
H. macularia.
H. maritima.
H. strigata.
H. muralis.
H. rugosa.
H. cornea.
H. linguifera.
H. incarnata.
H. cinctella.
H. cellaria.
H. nitida.
H. obvoluta.
H. Cookiana.
H. pileus.
H. papilla.
H. punctifera.
H. plicatula.
H. planorbella.
H. scabra.
H. cariosa.
H. plebeium.
H. personata.
H. hispida.
H. rotundata.
H. apicina.
H. striata.
H. conspurcata.
H. conica.
H. conoidea.
H. pulchella.
_H. algira._ The yellow Snail. Pl. 18, fig. 8.
Species shaped like a Planorbis, rough or hairy, more or less largely
umbilicated, margin sharp.
_H. Naticoides._ The Natica-shaped Snail. Pl. 18, fig. 7.
Species ventricose.
_H. obvoluta._ The small white-lipped Snail. Pl. 18, fig. 9.
Species more or less depressed, umbilicated, Planorbis-shaped, the edges
of the aperture thickened, callous, and even toothed.
_H. conoides._ The cone-shaped Snail. Pl. 18, fig. 4.
Species conoidal; the turns of the spire rounded.
_H. pomatia._ The edible Snail.
Species sub-globular, not umbilicated; the margin of the aperture
thickened; aperture covered with a calcareous lid resembling an
operculum.
_H. nitida._ The pellucid Snail.
Species depressed, more or less largely umbilicated; the edges sharp,
but always thin and shining.
_H. nemoralis._ The grove Snail.
Species imperforated, semi-globular, thin, and sub-pellucid; not
umbilicated, with a light inflexion at the place of the junction of the
columella with the margin of the aperture; colour various, inner margin
white or reddish brown; volutions five, with several dark brown bands.
_H. Carthusiana._ The Carthusian Snail.
Species sub-depressed, sub-umbilicated, with a sharp edge, thickened
within by a roll.
_H. arbustorum._ The orchard Snail.
Sub-globular, sub-pellucid, sub-umbilicated, five volutions, finely
striated longitudinally; mottled with greenish yellow, streaked with
deep chestnut, a broad brown band commonly at the edge of the outer lip,
and running round through the volutions to the apex.