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C. J. Cornish - The Naturalist on the Thames
elegant shells of much the same appearance, but of a different race.
The minute elegance of many of these shells is very striking. Tiny physas and succineas,
no larger than shot, live among big paludinas 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 such
common objects as land shells, these have no popular names. The river limpets are called ancylus
fluviatilis. Some 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. Two centuries ago Lister made several
experiments in the hope that he might 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 river. 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.
[1] I have a series of neretina shells from the Philippines, much larger in size and brown in
colour, in which many of the same kinds of ornament occur.
[2] A fresh-water mussel shell from North America in my possession is coloured green, and so marked
and crimped as to resemble exactly a patch of water-weed, such as grows on stones and piles.
THE ANTIQUITY OF RIVER PLANTS
In the still gossamer weather of late October, when the webs lie sheeted on the flat green meadows and
spools of the air-spiders' silk float over the waters, the birds and fish and insects and flowers of the best
of England's rivers show themselves for the last time in that golden autumn sun, and make their bow to
the audience before retiring for the year. All the living things become for a few brief hours happy and
careless, drinking to the full the last drops of the mere joy of life before the advent of winter and rough
weather. The bank flowers still show blossom among the seed-heads, and though the thick round rushes
have turned to russet, the forget-me-not is still in flower; and though the water-lilies have all gone to the
bottom again, and the swallows no longer skim over the surface, the river seems as rich in life as ever;
and the birds and fish, unfrightened by the boat traffic, are tamer and more visible.
The things in the waters and growing out of the waters are very, very old. The mountains have been burnt
with fire; lava grown solid has turned to earth again and grows vines; chalk was once sea-shells; but the
clouds and the rivers have altered not their substance. Also, so far as this planet goes, many of the water
plants are world-encircling, growing just as they do here in the rivers of Siberia, in China, in Canada, and
almost up to the Arctic Circle. The creatures which lived on these prehistoric plants live on them now,
and in exactly the same parts of the stream. The same shells lie next the banks in the shallows as lie next
the bank of the prehistoric river of two million years ago whose bed is cut through at Hordwell Cliffs on
the Solent. The same shells lie next them in the deeper water, and the sedges and rushes are as
"prehistoric" as any plant can well be. In the clay at Hordwell, which was once the mud of the river, lie
sedges, pressed and dried as if in the leaves of a book, almost exactly similar in colour, which is kept,
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