THE SHELLS OF THE RIVER THAMES.
OF the thousands who boat on the Thames during the summer, few know or notice the beauty of the river shells. They are among the most delicate objects of natural ornament and design in this country. Exquisite pattern, graceful shapes, and in some cases lovely tints of colour adorn them. There are many kinds and diverse forms. In addition, Nature for once relaxed in their favour her rigid rules, by which she turns out things of this kind not only alike in shape, but with identical colour and ornament. In the Gould cases of humming-birds, for instance, at South Kensington, each bird is like the other, literally to a feather. The lustre on each ruby throat or amethyst wing shines in the same light with the same prismatic divisions. But go four miles to the west and seek among pebbles above Hammersmith Bridge when the river is low, and there you may find a score of neretina shells not one of which is coloured like the rest or ornamented with exactly the same pattern, yet each is fit to bejewel the coronet of some Titania of the waters. Forty of these shells, gathered from below the bridge, lie before the writer, set on black satin to display the hues. They look at a little distance like a series of mixed Venetian beads, but of more elegant form, for the shells are something between the pattern of a nautilus and that of the green shells from which the green mother-of-pearl is taken. From whichever side they are seen, the curves are the perfection of flowing line. The colouring and ornament of each is a marvel and delight. Some are black, with white spots arranged in lines following the curves, and with the top of the blunt spiral white. These "black-and-white-marble "patterns are followed by a whole series in which purple takes the place of black, and the spots are modified into scales. Then comes a row of rose-coloured shells, some with white lance- heads, or scales, others with alternate bands of white scales and white dots. Some are polished, others dull, some rosy pink, others almost crimson. Some are marked with cream and purple like the juice of black currants with cream in it. In some the scale pattern changes to a chequer, some are white with purple zig-zags. And lastly comes a whole series in pale olive, and olive and cream, in which the general colour is that of a blackcap's egg, and the pattern made by alternate spots of olive and bands of cream. If these little gems of beauty come out of the London river, what may we not expect in the upper waters of the silver Thames ? A search in the right places in its course will show. But these neretinx are everywhere up to the source of the river, for they feed on all kinds of decaying substances. If the pearl is the product of a disease or injury, the beauty of the neretina is a product or transformation from foul things to fair ones.
As the Thames is itself the product and union of all its vassal streams, an "incarnation" of all the rest, like a pre- potent god of old Egypt, so in its bed it holds all the shells collected from all its tributaries. Different tribes of shells live in different waters. Some love the "full-fed river winding slow," some the swift and crystal chalk-stream. Some only flourish just over the spots where the springs come bubbling up from the inner cisterns of earth, and breathe, as it were, the freshness of these untainted waters; others love the rich, fat mud, others the sides of wearings and piles, others the river- jungles where the course is choked with weeds. But come
what may, or flourish where they please, the empty shells are in time rolled down from trout-stream and chalk-stream, fountain and rill, mill-pool and ditch, cress- bed and water-cut, from the springs of the Cotswolds, the Chilterns. the Downs, from the valleys of Berkshire, Buckinghamshire, Surrey, Gloucester, Oxford, and Essex, into the Thames. Once there the river makes shell collections on its own account, sorting them out from everything else except a bed of fine sand and gravel, in which they lie like birds' eggs in bran in a boy's cabinet, ready for who will to pick them up or sift them out of it. These shell collections are made in the time of winter floods, though how they are made or why the shells should all remain together, while sticks, stones, and other rubbish are carried away. it is impossible to say. They are laid on smooth points of land round which the waters flow in shallow ripples. Across the river it is always deep, swift, and dark, though the sandbanks come in places near the surface, and in the shallows grow water-ranunculus, with waving green hair under water, and white stems above it. The clean and shining sand shelves down to the water's edge, and continues below the surface. Here are living shells, or shells with living fish in them. In the bright water lie hundreds of the shells of the fresh-water mussels. the bearers of pearls sometimes, and always lined with that of which pearls are made, the lustrous nacre. The mealy masses of dry sand beyond the river's lip are stuffed with these mussel shells. They lie all ways up, endways, sideways, on their faces, on their backs. The pearl lining shines through the sand, and the mussels gleam like silver spoons under the water. They crack and crunch beneath your feet as you step across to search the mass for the smaller and rarer shells. Many of those in the water contain living mussels, yellow. looking fat molluscs, greatly beloved of otters, who eat them as sauce with the chub or bream they catch, and leave the broken shells of the one by the half-picked bones of the other. There was a popular song which had for chorus the question, "Did you ever see an oyster walk upstairs ? " These mussels walk, and are said to be "tolerably active," by a great authority on their habits. They have one foot, on which they travel in search of feeding ground, and leave a visible track across the mud. There are three or four kinds, two of which some- times hold small pearls, while a third is the pearl-bearer proper. Unio pictorum is the scientific name of one, because the shells were once the cups in which the old Dutch painters kept their colours, and are still used to hold ground gold and silver for illuminating. The pearl-bearing mussel is longer than the other kinds, flatter and darker, and the lining of mother-of-pearl is equal to half the total thickness of the shell.
Though not so striking from their size and pearly lustre, there are many shells on the Thames sandbanks not less in- teresting and in astonishing numbers. Among these are multitudes of tiny fresh-water cockle shells of all sizes, from that of a grain of mustard seed to the size of a walnut, flat, curled shells like small ammonites, fresh-water snail shells of all sizes, river limpets, multitudes of many-coloured neretinx, and other and rounder bivalve shells allied to the cockles. The so-called " snails " are really quite different from each other, some, the paludinas, being large, thick- striped shells, while the limnwas are thin, more delicately made, some with fine, pointed spiral tops, and others in which the top seems to have been absorbed in the lower stories. There are eight varieties of these limmas alone, and six more elegant shells of much the same appearance, but of a different race.
Most of these are of most respectable antiquity. You can pick them up alive in the Thames, and find exactly the same shells among the fossils. The minute elegance of many of these river shells is very striking. Tiny physas and succineas, no larger than shot, live among big paliulinas as large as a garden snail, while all sizes of the larger varieties are found, from microscopic atoms to the perfect adult. Being water shells, and not seen except by rivers, these shells have no popular names. The river limpets are called ancylus
They are no larger than a yew berry, and are shaped like a Phrygian cap; but they " stick " with proper limpet-like tenacity. On the stems of water-lilies, on piles, on weeds and roots in any shallow streams, but always on the under side of the leaves, are the limpets of the Thames. The small ammonite- like shells are called planorbis, and like most of the others
belong also to the upper tertiary fossils. They feed on the decaying leaves of the iris and other water plants, and from the number of divisions on the shell are believed to live for• sometimes twenty years. Of the many varieties, one, the largest, the horn-coloured planorbis, emits a purple dye, which stains the water. Two centuries ago Lister made several experiments in the hope that he 'flight succeed in fixing this dye, as the Tyrians did that of the murex, but in vain. There are eleven varieties of this creature alone. It is easier to find the shells than to discover the living creature in the Thames. For many the deep, full river is not a suitable home; they only come there as the water does, from the tributary streams. Far up in some rill in the chalk, from the bed of which the water bubbles up and keeps the stones and gravel bright, whole beds of little pea-cockles may be found, lying in masses side by side, like seeds sown in the water-garden of a nymph.
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