SNAILS I N ARCHAEOLOGICAL EXCAVATIONS T H E E A R L OF C R A N B R O O K
Helix aspersa, the Common Snail, is the second largest snail found in the British Isles being only exceeded in size by H. pomatia, the Roman or edible snail. The two are much alike in shape but pomatia is considerably the larger, about 45 mm. in height and width as opposed to 35 mm. in aspersa. Both are edible and commonly eaten as food, and both are equally tasty when cooked in the conventional butter and garlic. It seems probable that both were introduced into this country if not by the Romans at least in the Iron Age, the often quoted Pleistocene records not having been substantiated. Like other edible creatures, the Great Afncan Snail being another example, H. aspersa has been introduced into many countries and flourishes in Orkney, New Zealand, the West Indies, St. Helena, Pitcairn Island, etc., etc. It is a gregarious creature roosting in colonies during the day in appropriate refuges, under stones, behind Vegetation growing against the wall of a house or at the base of trees, hedgerows, and the like. In limestone districts they are found roosting in vertical holes which seem to have been occupied and enlarged by successive generations of snails the mucus secreted by the foot being slightly acid. From these roosts they go out at night to feed, returning to the same place of refuge for the following day. If such a group is found and each individual marked with paint or nail varnish they will be found to be absent soon after dark and to have returned by the following morning, the remains of an absentee being sometimes recognised by paint on fragments of shell near a thrushes anvil. Fairly early in the winter, usually in October, they go into hibernation in similar colonies in similar retreats, sometimes burying themselves in the ground. They then close the mouth of the shell with a diaphragm made of dried mucus, called an epiphragm, which protects the animal from the cold and from desiccation by evaporation while it is torpid. As the cold weather increases it retreats further into its shell, a second and sometimes a third epiphragm being secreted as further protection. T h e epiphragm will also prevent the mouth of the shell being filled with mud if heavy rain carries silt into the hibernaculum. In the spring, usually sometime in April, they come out of hibernation. Mating then takes place after a fairly prolonged courtship, the animals caressing each other with their "horns" until both are sufficiently stimulated erotically to copulate. They then separate and each one, for they are hermaphrodite and each simultaneously acts as both male and female, digs a pit in the ground in which to lay its eggs. T h e snail then Covers the eggs with earth, and thus protected both from desiccation and predators, they are left to hatch on their own. Land snails are slow-moving
507 creatures only moving about at night-time when there is high relative humidity, and were they created male and female like most animals couldfindit difiicult to acquire a mate, as only 50% of the other snails met with would be of the opposite sex. Much of this difficulty is resolved by being hermaphrodite: when two such snails come across each other during their nocturnal wanderings, inevitably boy meets girl while the colonial habits of H. aspersa obviously provide opportunities for recurrent matings. In fact during the summer further matings and egg laying do take place, so the snails may have to dig holes for the eggs more than once in a season. It will be seen therefore that both in their ordinary day-to-day life and in their reproductive behaviour these snails are in the habit of hiding away under cover, sometimes in holes in the ground and also of excavating holes in the ground themselves. In colour the shell is fawn, buff or yellowish with typically five spiral dark bands. Any one of these bands may be absent altogether or joined to one or both of the adjoining ones, giving a large number of possible combinations to describe which a system of notation has been devised. The bands on a typical five banded shell are numbered 1 2 3 4 5, the top one being 1 and the lowest 5. If one band, say the third, is missing the formula is written 1 2 0 4 5, if all are missing 0 0 0 0 0. If two are fused together, say the second and third, the commonest form of H. aspersa, they are bracketed 1 (2 3) 4 5. The bands are sometimes obliterated altogether by a series of blotches so that the shell appears to have transverse instead of spiral bands. Though a completely uniform population has never been found in the wild these different variations do seem to be inherited, one band formula tending to be more common in one area, another in another. Today such differing populations are separated in space and when in 1960 Mrs. A. Harrison kindly gave me some shells of H. aspersa found while excavating some late Saxon to Mediaeval "ovens" at Snape Hall, it seemed worthwhile recording the band patterns to see if there were differences between them and present day H. aspersa, i.e., between populations separated in time. With many H. aspersa were found a few specimens of Cepaea nemoralis, the Grove Snail. This animal is smaller than H. aspersa, height 15-20 mm., width 18-25 mm., and though also edible is so much smaller that many would be needed to make even an hors d'oeuvre, much less a meal. Like H. aspersa it is typicallyfivebanded and with similar variations. It is a common and ubiquitous snail, usually found in colonies. In 1969 Mrs. Harrison sent to me fourteen more collections made during the excavation of similar "ovens" at Snape Hall and in 1971 a further collection made at a Roman bath house at Farnham. In 1971 the Misses Copinger Hill sent me a small collection made four feet below ground level when road widening at Hacheston revealed a Roman site. SNAILS IN ARCHAEOLOGICAL EXCAVATIONS
508
Suffolk Natural History,
Vol. 15, Part 6
Remains of H. aspersa have bcen reported from many kitchen middens and occupation sites dating from neolithic times onwards but, like the remains of rabbits or other burrowing animals mentioned in such reports, these must always be looked upon with some suspicion, certainly those found in excavations made before the days of General Pitt-Rivers. As noted above H. pomatia was almost certainly introduced by the Romans, H. aspersa probably, just as the rabbit seems to have been introduced by the Normans. T h e discovery of remains of either of the two snails on a preRoman site or rabbits on one earlier than the 12th Century would be of the greatest interest. General Pitt-Rivers himself found in 1888 many shells of H. aspersa, associated with those of C. nemoralis, oysters, and a few fragments of mussei shells, when excavating the Bokerly Dyke, Woodyates, a Romano-British entrenchment. Mrs. Harrison is satisfied that all the shells which she sent to me come from natural colonies and are not the remains of human meals. In two of the collections made in 1969 there was a single winkle but these Mrs. Harrison thinks came there by chance: isolated remains of "sea food" in the shape of oyster, mussei, and winkle shells were not infrequently found. T h e shells, both of snails and winkles, were filled with sandy silt when they had not been cleaned by the finder. If these were all natural colonies the question arises as to whether they were occupied and the snails died there at or about the time when the various sites were occupied by human beings, or whether potential refuges were created at the occupation site level by erosion or other mechanical means years or even centuries later. Mrs. Harrison teils me that no signs of such later intrusion were noticed while the excavations were being made and the presence of C. nemoralis in some of the sites tends to confirm this: that animal is not such a determined intruder into underground refuges as is H. aspersa and its presence suggests a relatively easy means of access on or near the surface of the ground. It seems probable therefore that these snails died in Roman and late Saxon to Mediaeval times. T h e presence of C. nemoralis suggests that those found at Hacheston were also of the same date as the deposit in which they were found In 1971, a mechanical trench digger was at work close to the Hall Farm, Great Glemham and revealed the bottom of a glass bottle in the side of the trench. Further investigation revealed a small collection of broken bottles buried between 2 feet 6 inches and 3 feet below the surface and of a type which the Curator of the Ipswich M u s e u m teils me were in use at the end of the 18th and beginning of the 19th Centuries. In the bottoms of six of these bottles and in one broken neck were twenty-nine shells of H. aspersa which are also analysed below. Apart from one or two fragments o f a china bowl there was no other debris mixed with
S N A I L S I N ARCHAEOLOGICAL EXCAVATIONS
509
the broken bottles, no bones or other kitchen refuse. This too seems to have been a natural colony, certainly not more than 200 years old. The bottom of the hole in which the bottles had been thrown was just on the top of the unweathered chalky boulder clay; the snail shells were filled with fine clay washed out of the top soil above. The shells both of H. aspersa and C. nemoralis found at Hacheston were fragile and so bleached that the band pattern was difficult to determine but there was no obvious material difference between the snails found at Great Glemham and those found at Snape and Farnham. In all the periostracum or outer skin had disappeared and with it the ground colour of the shells: in most cases the bands could only be distinguished by Wetting them. All were much less bleached than are many shells of dead H. aspersa found lying above ground in some hedge or garden, which have probably not been dead for more than a year or so. Rainwater and exposure will notoriously bleach dead snail shells, per contra shells have been found in Pleistocene deposits almost as clean and clear as when they were alive. If therefore empty shells are left uncovered for a year or so they may well bleach and deteriorate before they are buried by mud or sand carried into the roost by water or some other means. When that has happened the rate of deterioration must depend upon the physical condition, acidity, amount, and origin of percolating water, etc., of the matrix in which they lie and in these cases some lay in "tender-heavy wheat and bean land" the others in light sand: they are not comparable. Their physical condition therefore gives no help in deciding whether or not the shells are contemporary with the deposit in which they are found. In this case the observations of those working on the site are confirmed by the presence of Cepaea nemoralis and neither that nor H. aspersa are snails which normally live and feed underground. On all the sites under review the most frequent band patterns at all three periods were on H. aspersa 1 (2 3) 4 5 and on C. nemoralis 1 2 3 4 5 and 0 0 3 0 0. These are all amongst the commonest found today. It is perhaps worth drawing the attention of archaeologists to one subterranean species, the Blind Snail Cecilioides acicula, an animal with a small tapering shell some 5 mm. long and 1 mm. or so wide at the base, transparent and colourless when fresh but becoming milkily opaque with time after the animal is dead. Some snails are carnivorous, some vegetarian or feeding on the moulds and fungi which develop as animal or vegetable matter decays and the Blind Snail seems to be one of those associated with animal remains. It only comes to the surface by accident, in mole heaps or when found by a spade on meadows, downs,
510
Suffolk Natural History, Vol. 15, Part 6
graveyards, etc., and it has been suggested that the presence of its white shells in any numbers can be an indication of the presence of skeletons on an archaeological site. More information about this relationship would be of great interest. Summary A number of shells of Helix aspersa and Cepaea nemoralis were found on archaeological sites and all the evidence goes to show that they were contemporary with the deposits in which they were found, Roman, late Saxon to Mediaeval and late 18th early 19th Century. The band patterns on the shells were similar to those which would be expected on similar collections made today. Notation Site
H. aspersa
"> ^
Snape, 1968 17/5 19/5 21/5 22/5 3/6 4/6 Snape, 1969 1 ...... 2
«"
« •+
~
C- ^
2 4 — — — 1 1 — — — 1 — 1 1 1 1 — 1 — — 2 1 — —
— 1 — — — —
10 Z 11 12 Un/n Un/n
Z
— 7 1 — 4 1 1 9 3 — 28 6 4 73 —
— — — 2 5
11 151 20 10
— — — — 2
~
^ ^
o
o
^ S,
~
O
O
C
— — — — — —
2 — — — — 4 1 1 — —
— —
Hall Farm
Ö .g
7 — — — — 1 2 — — —
::
Total Roman
.1 B
— —
7 :::: 8
Farnham Hacheston
« 2
— 1 2 1 — — 1 1 1 — — —
4 5
Total Snape
" S
C. nemoralis
— —
4 2 — 2 — 1 —
2
— — — — —
1 —
3 —
18
— 4 — — — — 2 3 — — — 1 2 7
— — —
1
— 24
4 — —
1
1 — — —
1 — — 3 — —
1 _ 1 _ 1 — — —
5 — 4 — — s _ _ _ _ 4
9
3 —
7 — 1 —
6 1 1 2 2 —
8 —
8 3 1