™, 
398 HELIX HORTENSIS. 
In Band Variation, Helix hortensis differs markedly from H. nemoralis 
in the comparative paucity of its mutations, for whereas in //. nemoralis 
all the possible eighty-nine band variations are actually known to exist, 
in //. hortensis no less than twenty-eight possible arrangements have 
never yet been observed or reported, and their discovery awaits the 
energetic observer. 
Although five is the normal number of bands on the shell, yet extra 
bands are occasionally present, due to a development of additional pigment 
cells on the mantle margin of the 
animal, or to a splitting-up of the 
cellules normally present, evidenced 
by the separation of each fascia into 
two or more slender lines or bandlets. 
his inerease in the zonulation may also arise from the concentration ot 
the colouring matter at the outer edges of the zones, thus apparently 
doubling their number. 
The band formule more especially characteristic of Helia hortensis are, 
according to Lang, 10305 and 02340, while in HZ. nemoralis he regards 
00345, 00(; 345), 003(45), and 00045 as the most distinctive banding. 
y <>, 
Fic. 397.—Helix hortensis 
(Folkestone, Mrs. Fitz: gerald), 
showing the concentration of 
pigment at the margins of the 
spival banding of the shell. 
The five-banded variations are sixteen in number, and all are on 
record for this country and abroad. 
12345 (123)45 (12)(345) 1(23)45 
(12345) (123)(45) (125(34)5 1(28,(45) 
(123.4)5 12(345) (12)3(45 12(34)5 
1(2345) (LQ Ns4aS 1(234)5 123(45) 
he most abundant variation is the formula 12345, the guinquevittata 
of Moquin-l'andon, which is considered as the type and 1s usually the 
most plentiful wherever the species is found, but in New England, on the 
contrary, it 1s according to Mr. G. H. Clapp the most uncommon form. 
Somewhat less common are (123)(45) and (12845), which are also known 
from Germany, France, Sweden, and North America. 
The formule 123(45), 1(23)45, (12)3(45), (12)345, (123)45 and 1(23)(45) 
are still more uncommon, but all are reported on (rermany, and many 
of them from other countries in Europe or from North America. 
The formule Ca 1(234)5, and 1(2345) are of much less frequent 
occurrence, while 12(345) (12)(345), (12)(3 34)5, and 12(34)5 are by far 
the rarest of the section, but yet occur in our own and other countries. 
The four-banded section embraces twenty-eight different forms, and 
includes, as in Helix nemoralis, a larger proportion of rare or unknown 
band variations than any other group. 
273 .4.10 12(34)0 20475) 0(2345) 
(1234)0 e223 Ono (12)0(45) 0(234)5 
(123)40 (Ch2 3505 lips 0(23)(45) 
(12)(34)0 a 2)305 1045) 0(23)45 
(1 2)340 (23)05 10(34)5 02(34 5) 
1(234)0 20455 103(45) 02(34 
1(23)40 (12)045 On273 45 023(45) 
The very commonest varieties in the British Isles are 10345 and 12044, 
which are found in Germany, France, Scandinavia, Switzerland, and North 
America, 12045 being also recorded from Finland. 
