HELIX ASPERSA. 241 
The JAW measures two to three millimetres from side to side, strongly areuate 
from front to back, somewhat creseentic in shape, with attenuate and rounded 
ends, thick, hard and dark-brown in colour; with six 
to twelve prominent vertical ribs or folds strongly 
denticulating both margins and showing perceptible 
longitudinal striation or lines of increase, with a . 
few less prominent intermediate ribs, which may 
sometimes reach to and ecrenulate the lower or gz 
cutting margin. Fic. 316.—Jaw of /elix aspersa, 
x 8, from Christchurch, Hants. 
The ODONTOPHORE or radula is of the usual oblong shape, and constituted by 
regularly curved transverse rows and straight longitudinal series of teeth, each 
transverse row composed of a symmetrical median tooth, with an elongate basal 
attachment; the mesocone being stout and conical, with a small lateral ectocone 
at each side; the laterals are decidedly asymmetrical, the inner angle of the basal 
attachment and the inner cutting point or endocone gradually becoming deficient, 
but the outer cutting point or ectocone is gradually more largely developed, and 
eventually as the marginals are approached, becomes very symmetrically bifid; the 
mesocone also gradually becomes bifid, so that the denticles near the margins present 
four strongly developed sub-equal denticulations with a narrow basal attachment. 
The number of teeth on the membrane varies considerably in different individuals, 
possibly due in part to the age of the animal. 
Fic. 317.— Representative teeth of half a transverse row of teeth of //e//x asfersa Miill., collected 
by Dr. Scharff near Dublin (highly magnified). 
The numerals appended to the figures of the teeth indicate their position in the transverse row. 
The formula of the Dublin specimen was 
>13+10 20 20 O 3 = ) ez 
PUSELO P20 2p 20 4 2OrUS= \ 145 — 12,615. 
Reproduction and Development.—Though no fully detailed account 
of the conjugation of this species has been published, yet Mr. R. Standen 
and others have observed that the act is, as usnal, preceded by many 
amatory caresses and blandishments, persistent fondling with their palpi, 
and the use of the love-dart, the tentacles meanwhile beine bent down- 
wards as though the animals were looking at each other: this peculiar 
attitude being only observable at these periods, may be owing to the 
diversion of the blood to other organs.!| Though the dart is used appar- 
ently as an excitant of sexnal desire, yet it is not an essential organ for 
that purpose, as pairings have been noted in young animals even before 
the formation of a dart has taken place. 
The pairing takes place soon after their awakening from hibernation, 
which is seldom before April in this country, but in other countries this 
period will be modified in accordance with the climate and the rigours of 
the seasons ; but the function is exercised throughout the summer months, 
as the sexual instinct is very strong and persistent, and in captivity can 
be excited almost at any time by a good meal and a thorough spraying 
with water. 
According to Pascal, the actual congress sometimes oceupies a period of 
ten to fifteen hours, the shape of the intromittent organ which, according 
to Mr. Butterell, has a movable apex, may be one of the reasons of this 
prolonged connection. 
1 Monog. i., p. 372, f. 688, 
10/2/10 P 
