84 
EDIBLE BRITISH MOLLUSKS. 
soutb-west of Tyrone, and one at Ardfry Point. The 
Creggaun heap consists principally of the shells of the 
oyster, mussel, and common cockle, though the whelk, 
Pecten varius, periwinkle, limpet, Nassa reticulata, He- 
lix nemoralis, Trochus, and Venerupis decussata [Tapes 
decussata ?), are also found in it. There are also layers 
of wood-ashes and stones, apparently used as hearth- 
stones, showing the marks of having been subjected to 
fire, but no weapons. The heap occupies an irregular 
space of two hundred feet long, and sixty feet wide, and 
ranges from six to eight feet deep.^^ There are various 
traditions as to the age of the heaps ; and it is said, 
that ninety years ago a series of high tides cast up the 
heap of shells from adjoining beds.* 
At the present day the Baltic appears to be almost 
the only sea where the oyster will not grow, — a fact at- 
tributable to the very great influx of fresh water from 
the mouths of its many rivers, and the less powerful 
current from the ocean, so that, in the words of Sir 
Charles Lyell, The Ostrea edulis cannot live at present 
in the brackish waters of the Baltic, except near its en- 
trance.^^ Yet, from the examination of the Danish 
Kjokkenmbddings, it appears, that the oyster flou- 
rished in places from which it is now excluded, attaining 
its full size.^^ 
Oysters may be eaten in various ways, either cooked 
or raw. 
“ The pepper-box, the cruet, — wait 
To give a relish to the taste ; 
The mouth is watering for the bait 
Within the pearly cloisters cased. 
* The ‘ Field,’ February 4th, 1865. 
