HELIX HORTENSIS. 327 
Description.—The ANIMAL is very variable in colour, but is usually dark 
greenish-grey, with a well defined pair of longitudinal DORSAL GROOVES, enclosing @ 
well defined row of TUBERCLES of a paler tint than the markedly darker subdorsal 
shade bordering them, which pales rapidly towards the foot. There are about six- 
teen oblique rows of tubercles at each side of the body from the dorsal groove to 
the foot fringe ; GENITAL GROOVE distinct, often forming a boundary to the darker 
pigmentation; SOLE greyish yellow; MANTLE sometimes distinctly yellowish or 
translucent grey with yellowish specks, tail and hinder part pale, often Jemon- 
yellow ; OMMATOPHORES long and slender, and nearly four times the length of the 
jower tentacles, slightly bulbous at the end, with black eye specks; the dark 
RETRACTORS showing through the skin. 
SHELL sub-globose, comparatively thin and pellucid, glossy with delicate trans- 
verse striation, usually yellow in colour with or without five dark revolving bands ; 
SPIRE bluntly pointed, somewhat elevated; WHORLS about five, convex in form, 
and inereasing progressively in size; SUTURE rather deep. APERTURE oblique, 
bordered by a white rim and a submarginal white rib encireling the aperture. 
UMBILICUS open in the young, but becoming closed in adult life. 
Diam. 18 mill. ; alt. 15 mill. ; and the average weight is nearly six grains, but 
varying from two grains to ten or even more. 
The EPIPIIRAGM is usually very thin, somewhat transparent and iridescent in 
parts, but with numerous caleareous particles intermingled in its substance, which 
heeome concentrated opposite the respiratory orifice and form an opaque-white spot. 
In very cold weather it is always thickened, apparently by the addition of one 
or more layers of mucus, and then becomes dull, opaque and creased, resembling 
crumpled tracing paper. 
The NERVOUS SYSTEM as concentrated around the gullet does not appreciably 
differ from that of its congeners, but, like them, shows in the immature stage the 
composite ganglionic structure, which becomes obscured with age. 
The OLOCONIA contained in the otocysts are usually oval in shape, and very 
numerous, but difficult to count, though exceeding a hundred in each capsule. 
Fic. 373. Fic. 374 Hic. 3/0. 
Fic. 373.—Pedal and visceral ganglia of Helix hortensis as seen from beneath. 
Fic. 374.—Nerve ring of Helix hortensis as seen from the front, and showing the otocysts and 
the arrangement of the pedal and visceral ganglia. 
Fic. 375.—Varied forms of Otoconia of /lelix hortensis, highly magnified (after Schmidt). 
The REPRODUCTIVE ORGANS resemble generally those of H. nemoralis, ut 
present some striking differences. The OVOTESTIS is large and compact; the 
HERMAPHRODITE DUCY is ditty cream colour, besprinkled with minute deposits of 
lime, stout and closely convolute in its middle course, but slender at each extremity ; 
the ALBUMEN GLAND is large and very variable in colour, sometimes light green 
or dirty ochreous-yellow ; the CLAW or vesicula seminalis minutely spotted; the 
ovipuct is of a yellowish or buff colour; FREE OVIDUCT or vagina ark brown ; 
PENIS short and blackish-brown in colour, darker basally, the retractor muscle 
being attixed to the anterior floor of the mantle cavity, a little to the right of the 
median line; FLAGELLUM long and slender, white with tinge of brown; EPIPHALLUS 
dark brown. SPERMATHECA small and globose, of a reddish colour, with a very 
long and slender dark brown stem, from which a short but tumid diverticulum 
arises towards the summit. 
The MUCUS GLANDS are paired structures, and each divides into two branches, 
which subdivide into two or three other ceca, which may exceptionally again 
fureate ; these mucus glands most frequently show four branches in one group 
and five in the other, and are not so strictly cylindrical and uniform as in //e/ic 
nemoralis, but are irregularly swollen, especially towards the extremities; a medial 
constriction, which is often present, detining the junction of the white and tumid 
free distal portion with the pale violet or pale pink and more regularly cylindrical 
basal portion, 
