286 
MOLLUSCA. 
Genus Helix. 
H. aspersa , Mull. 
Although distributed over the four quarters of the island, this Helix is 
less generally met with than several other common species. In a well- 
cultivated and moderately-wooded district near Belfast, stretching along 
the base of the mountains where chalk chiefly prevails, presenting different 
soils, especially clay and alluvium, and rising to an elevation of 500 feet 
above the sea, it is never found. Mr. Edward Waller, who has success- 
fully investigated the Mollusca about Annahoe, County Tyrone, states 
that the H. aspersa is unknown there. It seems partial to the vicinity of 
the sea; so much so, that about Ballantrae, in Ayrshire, Scotland, I 
have remarked numbers of them on rocks subjected to the spray of the 
waves, which had bleached the portion of the shell thus exposed as white 
as it usually becomes in the progress of decay, although the animal in- 
habitants were all in the highest vigour. In the crannies of the ruined 
castles, which, like Dunluce, are based upon the summits of some of the 
highest cliffs washed by the sea in the North of Ireland, the H. aspersa is 
abundant. 
In one instance which may be mentioned, differences of rocks, soil, or 
shelter will not explain the absence of this species from particular local- 
ities. During a forenoon’s walk on the marine sand-hills of Portrush and 
Macgilligan (County of Londonderry), which are only a few miles apart, 
and present in every respect precisely the same appearance, I found the 
H. aspersa abundant at the former, but at the latter wanting, and here 
the sand-hills are much more extensive than at Portrush. At the nearest 
sand-hills, again, on the coast to the east of the latter, and only a few 
miles distant, I did not during a short visit find the H. aspersa ; and here 
Helix virgata, which is not found at the other two localities, appeared, 
and took the place of H. ericetorum, which is common to them ; here too, 
and at Portrush, Bulimus acutus was present, though not so at Mac- 
gilligan. On the 8th of June I once observed the H. aspersa in coitu, and 
with the spicula adhering (see Montagu in Test. Brit.) ; — these are half 
an inch in length, holloAv, and widen considerably to the base. 
In the Magazine of Natural History, vol. v. p. 490, Mr. Denson states 
that in severe winters the H. aspersa is, in the old Botanic Garden at Bury 
St. Edmunds, eaten in quantity by the Norway rat ; a fact of which I 
some years ago had circumstantial evidence, in the broken shells lying 
about the entrance to this animal’s abode among heaps of stones in the 
Horticultural Society’s Garden, at Chiswick, London.* 
* Helix Pomatia, Linn. The following observations of Professor W. H. 
Harvey, communicated in a letter to me in January, 1834, include all that 
need be said of this shell. “ Dr. Turton, in his Conchological Dictionary, states 
that this species is mentioned by Dr. Rutty in his Natural History of the County 
of Dublin, as not uncommon in his time. On referring to Dr. Rutty’s work, I 
cannot find any such assertion. At p. 379, vol. i., he certainly admits it in the 
following terms : ‘ Cochlea duplex primo terrestris, the terrestrial snail, and par- 
ticularly the house snail, which is thus distinguished by Lister; Cochlea cinerea 
maxima edulis, cujus os operculo crasso gypseo per hyemem clauditur and then 
goes on to tell of its uses as food, the manner of cooking it, &c., but not one word 
about its habitat.” 
The H. Pomatia has of late years been introduced from England to different 
localities in Ireland, as Dalkey Island, off the Dublin coast, Youghal, &c. In the 
autumn of 1834 I turned out a few individuals of this species and of Ci/clostoma 
elegans on the chalk in the neighbourhood of Belfast, but they have not increased ; 
