HELIX PISANA. 569 
Diagnosis.—/Teliv pisana differs essentially from /elicella virgata, the 
species with which it is most liable to be confounded, by its larger size, more 
depressed shape, almost closed umbilicus, and the generally numerous slender 
spiral bandlets on the upper surface, while //. wirgatu has usually only 
one broad band in that position, and the umbilicus is always quite open 
and distinct. The presence of a close series of well defined incised spiral 
lines presents a striking character, as these are not possessed by //. virgata. 
It is, however, more closely allied to /7. ortensis, but differs in wanting 
the beautifully reflected outer lip of that species, and in possessing numerous 
distinctly incised lines encircling the whorls, which in //. hortens/s are ouly 
oecasionally and feebly perceptible, while in //. pisana the umbilicus is 
invariably partially open, but always entirely closed in adults of /Z. hortensis; 
there is, also, a peculiar squareness or shonldering of the whorls in piscne, 
which with its more depressed spire impart a characteristic aspect to the shell. 
INTERNALLY, it differs from //. virgata in many important points : the 
right tentacular retractor in //. piswna passes between the branches of the 
genitalia, while in //. virgata it is quite free; the vaginal mucus glands 
are simple in the present species and multifid in //. ergata, which has 
also a short flagellum, an organ quite absent in //. pisana. 
hough closely linked with //. hortens’s by the complex structure of the 
gypsobelum or love-dart, it differs in being totally destitute of a Hagellum 
to the penis sheath, the great development of which organ is so striking a 
feature in that species. It also possesses a long and stout diverticulum 
to the spermatheca-duct which is closely bound to the oviduct by a richly 
vascular membrane, as in the //elicigona, with which group the vaginal 
glands are also in accord. 
Description.—The ANIMAL has an elongate and more or less transparent BODY, 
the viscera being perceptible through the skin; it is obtuse and thick in front, 
tapering to a flat and pointed yellowish TAIL; the DORSUM usually appears of a 
pale translucent grey by direct light, but occasionally is of a darker grey, or even 
a delicate fawn; the SOLE is yellowish, gradually passing into the grey or other tint 
of the dorsal surface; the rngosities are well marked, but not protuberant; the paired 
DORSAL GROOVES enclose a row of indistinctly separated and flattened tubercles ; 
the GENITAL FURROW is not well defined, but is present on both sides of the body, 
and does not constitute a dividing line separating different characters of granula- 
tion as in certain other species ; the tubercles on the muzzle beneath the upper and 
lower pair of tentacles have their summits thickly sprinkled with minute dark or 
black specks, especially at the bases of the upper pair, where they present the 
appearance of a triangular black spot; the OMMATOPHORES are long, slender, 
and sensibly tapering, finely but distinetly granular, and abruptly swollen at the 
apex, of a pale translucent grey, through which the dark RETRACTORS are (is- 
tinectly visible, and also for a distance on the dorsum; LOWER TENTACLES about 
two mill. long, slightly swollen and translucent at the apex, each showing the dark 
retractor, which appears to join that of the larger tentacles six or seven mill, 
from their base; the MANTLE is dark blackish grey, indistinetly speckled with 
pale grey, contrasting with the pale translucent body when the animal is within 
the shell, the part against the penultimate whorl appearing quite black ; the 
RESPIRATORY ORIFICE is irregularly surrounded with dull white; the SLIME is 
thin and colourless, but not viscid, and becomes iridescent when dry. 
The PEDAL GLAND, according to M. André, is much reduced in development, 
and in some parts formed by the excretory canal only ; the roof has, however, the 
characteristic longitudinal folds, and the pedal artery is united to the gland, but it 
is curious to be so feebly developed in a species which lives so largely on thistles, 
Eryngium, and other rough plants, though, on the other hand, it is an animal of 
very sedentary habits, and frequently rests a long time in the same place. 
The EPIPHRAGM is thin, transparent, and vitreous, bestrewn more or less freely 
with minute, opaque-whitish caleareous particles ; opposite the respiratory orifice 
there is often a dull white area, joined up to the outer lip, and irregularly outlined ; 
31,10/11 X 
