HELIX ASPERSA. 253 
The ground colouring is said to be greatly affected by the nature of the 
food, lettuce apparently darkening the shells; Mr. J. Hawkins, of York, 
has also recorded that specimens fed on burdock (Arctium minus) are 
much paler in colour than those living upon cow parsley (Heracleum 
sphondylium), while individuals fed upon ivy (Hedera helia) become of a 
bright red colour. 
The var. evalbida is the nearest approach to albinism in this species ; 
but as in the mollusca generally, albinism is usually only partial; thus 
though the shell may be albine, the animal inhabitant is generally normally 
pigmented ; but examples the reverse of this have been found at North- 
ampton by Mr. L. E. Adams and by Mr. Lewis Abbott in St. Margaret’s 
road, St. Leonards-on-Sea, in which although the animals were albine, with 
pale pink eye specks, the shells were quite normal in size and coloration. 
‘otal albinism shared alike by the animal and its shell is quite rare, 
but Mr. W. Gyngell in July 1909 discovered a colony on the sandhills of 
Seaton Carew, in which the var. eralbida constituted seventy-five per cent. 
of the whole colony, though only ten per cent. of these were true albinos, 
in which the animal inhabitant and the shell were equally affected. 
As has been frequently pointed out, this species is exceedingly suscep- 
tible to and responsive to its varying environments; the shells of any 
definite area being characterized by a different facies from those inhabiting 
a neighbouring district which may be of a different character, and, further, 
the geological features of the country impress their mark on the shells of 
this species, and this may be indicated not only in the varying colour and 
markings of the shell, but in its texture and consistency. 
Though usually this species, like others, secretes the thickest and 
heaviest shells when living on limestone soils, and produces thin and 
delicate ones when there is a deficiency of that substance, as in the 
Channel Isles and especially in Guernsey, where owing to the scarcity of 
ealcic material the shells are remarkably thin, such effects may also be 
due solely to the impaired or abnormal selective action of the tissues of 
the individual, as thin and delicate shells may be found in places where 
ample caleic material is available ; whereas, on the contrary, on the mill- 
stone grit about Caton, near Iancaster, Mr. J. Davy Dean has found some 
unusually thick and heavy shells, one weighing more than 129 grains. 
This remarkable instance may be paralleled by Unio murguritifer, “which 
uniformly produces a ponderous shell, although living in water almost 
deficient of calcic carbonate. 
Proximity to the sea usually, though not invariably, has the effect of 
dwarfing the shell, and always bleaches it, until it becomes as white and 
chalky as in the progress of decay. 
VARIATIONS IN SHAPE OF SHELL. 
Var. conoidea Picard, Moll. Somme, 1840, p. 181. 
Helix aspersa var. conica Gassies, Moll. Agenais, 1849, p. 82. 
Heltx aspersa var. acuminata Baudon, Journ. de Conch., 1884, p. 238. 
SHELL thin and fragile, with a very produced conical spire, and small aperture. 
The sub-var. acuminata is described as oblong, very conical and rather narrow. 
ENGLAND AND WALES. 
Channel Isles—A wall on damp ground near Arnold’s Pond in North Guernsey ! 
Rev. Dr. MeMurtrie. Messrs. Tomlin and Marquand record this variety from 
Moulin Huet, Guernsey ; Braye Bay and Mauney, Alderney. 
Cornwall W. —Newquay ! J. H. James. 
Devon N.—Ilfracombe, G. Sherriff Tye. Hele Bay, J. E. Cooper. 
