a 
398 MONOGRAPH OF BRITISH LAND AND FRESHWATER MOLLUSCA. 
. 
GENUS HELICIGONA Feérussac. 
ISTORY.—This genus, better known as Campylwa, was instituted 
by Baron Férussac in 1819, and embraces the groups Ch/lotrema and 
Ariunta of Leach, propounded in 1831; Chilostoma, [sognomostoma, and 
Latomus of Fitzinger in 1833; Cingulifera, Corneola, and Lenticule of 
Held published in 1837; Campylwa of Beck established in the same year; 
Sterna of Albers in 1850; Hlonw of Adams in 1855, and is included by 
Dr. C. A. Westerlund in his section Paurotenia, characterized by the 
possession of not more than. four bands, and the frequent presence of a 
paler peripheral zone. 
Pilsbry also includes Frauticocampylea and Tacheocampylea, and in fossil 
forms Tropidomphalus, Metacumpylaa, Mesodontopsis, and Galactochilus. 
The Helicigona are really an offshoot or branch from the stemma of the 
true Helicex, still retaining or reverting to several primitive features in 
shell and animal, as the more usual presence of the somewhat highly 
placed pale peripheral zone, while the simple vermiform mucus glands 
recall their distant EKuadeniate ancestry. 
Generic Characteristics.—The anIMat is said to externally resemble 
the true Helices, but it may be noted that in the British representatives of 
the genus the lateral or genital grooves are quite absent on the left side 
of the body and only faintly indicated or deficient on the right side. 
The SHELL is described as turbinately or depressly globose, varying to 
a lenticular shape, usually umbilicated, and of moderate or large size, with 
«i smooth, costulate, granulate, or hairy surface, usually of a brown or an 
unicoloruus horny colour, or may be mottled and streaked, or possess 
a single supraperipheral band, although sometimes more bands may be 
present. APERTURE obliquely lunate or oval; Lip expanded, but reflected 
below, and dilated at its junction with the columella. 
"he true characters of the genus were first indicated by Schmidt to be 
the two-bladed part, the stout diverticulum of the SPERMATHECA DUCT, 
closely bound to the urERUS by a wide vascular membrane, and the simple 
and vermiform paired Mucus GLANDS; and the shell, though frequently 
bandless, is never truly five-banded as in Helia. 
‘he character of the part alone, though so characteristic, is not decisive, 
for other genera possess darts, approaching the two-bladed parr of this 
group, but the highly-developed diverticulum is a constant feature. 
‘he REPRODUCTIVE ORGANS show an elongate OVOTESTIS, a short PENIS 
continued into an EPIPHALLUS, upon which the RETRACTOR is inserted, and 
ending in a long FLAGELLUM spirally twisted at the proximal end, which 
impar ts a characteristic form to the spermatophore by means of which the 
seminal element is transferred during pairing ; the DART SAc is simple and 
somewhat elongate, placed rather high on the vagina, and contains a curved 
dart with a slightly expanded base “and a flattened lanceolate head ; the 
SPERMATHECA is small and globose on a long and slender stem, and bears 
a stout diverticulum, w hich is usually longer than the spermatheca duct, 
and bound closely to the uterus by a broad and richly vascular membrane, 
this being a constant generic character. 
The genus ranges from ;Southern Europe as far north as Sweden and 
England, but it is more especially an Alpine and South European group, 
being less abundant or almost absent in Central Europe, although certain 
members attain the extreme north of Europe. 
