ine 
MONOGRAPH OF BRITISH. LAND AND FRESHWATER MOLLUSCA. 209 
GENUS HELIX Linneé. 
(Cochlea, Da Costa; Helicogena, Férussac ; Pomatia, Leach; T.ucena, Hartmann ; 
Ceenatoria, Held; Helicodonta, von Ihering). 
ISTORY.—"The genus /eliv (€AXxE, a coil) 
is here associated with the immortal 
Swedish systematist, Carl von Linné, 
who first established the present group, 
and in the year 1758 applied the binomial 
method of nomenclature to all branches 
of the animal and vegetable kingdoms, 
although the system had been partially 
in use prior to that date by himself and 
the more advanced specialists of the age. 
The group, as defined by Linné, 
embraced a large number of species, 
which differed widely in organization 
and in their shells. These wide limits 
have been gradually curtailed, and the 
group 1s now understood to include only 
species closely allied to Helix pomatia. 
This, the typical genus, embraces the 
Ce”: oe most highly organized and adaptable 
species of the family //elicidw, as is 
evidenced by their dominance and ability 
to prosper and increase under many diverse conditions to the disadvantage 
and detriment of the less-advanced species with which they may be 
brought into competition. 
Ee 
Generic Characteristics.—The ANIMAL is large, with a tough and 
granulate skin, showing the paired DORSAL GROOVES, the GENITAL FURROWS, 
etc., and bearing the REPRODUCTIVE, ANAL, and RESPIRATORY ORIFICES on 
the right side of the body; the MANTLE is furnished with distinct pro- 
longations ; the LABIAL PROCESSES are large; the roor fleshy, without 
distinet SUPRA-PEDAL GROOVES, and the soLe undivided. 
he SHELL varies in shape, but is usually more or less globose, and 
capable of containing the retracted animal, narrowly umbilicate or imper- 
forate, with about five striate, malleate, or granulate wHoRLS, and a 
discontinuous but reflected peRtsrome. ‘The species of the genus are 
typically Pentatzniate, or five-banded, although a special modification of 
this formula may usually be more particularly characteristic of each species 
and due to the absence, coalition, or splitting of the component bands. 
INTERNALLY, the REPRODUCTIVE ORGANS display a compact OVOTESTIS, 
imbedded in the DIGESTIVE GLAND or LIVER; a short PENIS, continued as 
an EPIPHALLUS, to which a RETRACTOR is affixed, and usually terminating 
in a long and slender FLAGELLUM; there is a well-developed Dart-sac 
or stylophore, containing a four-bladed parr and a pair of multifid digitate 
MUCUS GLANDS, disposed on each side of the FREE OvipUCT above the dart 
sac and lying free in the body cavity ; the SPERMATHECA is globose, borne 
on a long stem, and often furnished with a branch or diverticulum. 
The saw is well developed and odontognathous in type, crescentic in shape, 
distinctly arcuate, with prominent ribs denticulating both margins. 
20/9/09 N 
