26 MOLLUSCA OF SOMERSET. 
General Pitt-Rivers, when excavating at Bokerly Dyke in 
1888, found a large number of shells, including 183 of oysters 
and 109 of H. aspersa. Apparently the latter mollusc was 
an article of food in Romano-British times in the West of 
England, and the practice of eating it has lingered on to the 
present time. Mr. St. George Gray records that many shells 
were found in Wick Barrow, Stogursey, dating from the Karly 
3ronze Age, about 1800 B.c. 
‘Ten varieties and two monstrosities of this species are 
enumerated in the Conchological Society’s List of British 
non-marine Mollusca: all of them have been found in Somer- 
set. Concerning colour variation, Miss F. M. Hele, a well- 
known Bristol conchologist, informed Mr. J. W. Taylor that 
the form prevalent near Bristol is “dark-coloured ;” at Weston- 
super-Mare it 1s brown with black markings; near Bath very 
pale and much mottled ; at Cheddar the shells are very solid 
and large; but at Clevedon no special peculiarity has been 
noticed (Journ. Conch. IV, 93). I have seen very fine speci- 
mens in the Wincanton district ; many years ago | obtained 
a very large and dark-coloured one from a hedge at Bratton 
St. Maur, it was quite as large and nearly as solid as an adult 
H. pomatia. Mr. St. George Gray found a very large one in 
Wick Barrow. There are specimens in the British Museum, 
labelled var. major, from Blagdon and Weston-super-Mare. 
Very small and thin forms are not infrequently met with ; 
these must not be confused with immature shells; they usually 
occur near the sea, but I have taken examples at Bratton St. 
Maur. 
A most interesting fact in connection with this species is its 
ability to bore into limestone. Whilst examining the Carbon- 
iferous Limestone cliffs on the south side of Brean Down in 
June, 1910, I found cavities in the face of the rock (Plate II1) 
which were obviously retreats of H. aspersa. After an exami- 
nation of a number of them I concluded that these molluscs 
were responsible for their formation. In many the aperture 
was circular and large enough to admit the shell easily. In 
the majority the cavity was about two inches deep and con- 
tained a single individual, but in some the tunnel was five or 
six inches long and was occupied by two or three. My atten- 
tion was first directed to them by observing a large heap of 
excrement at the base of a vertical rock in which the hole was 
about eighteen inches above the ground. The homing instinct 
of these snails is well known, and in all probability each animal 
has its own particular hybernaculum. ‘The discovery of these 
burrows on Brean Down is of some interest in that they are 
