Charles Ottley Groom Napier, Lakes and Rivers, Natural History Rambles, Londres, Society for Promoting Christian Knowledge, 1879, p. 221.

February is not much more productive than january but still our brooks afford the water-fleats, Cyclops and daphnia pulex, and the Hydra vulgaris, a radiated animal, with atttaches itself to minutes plants, the empty shells of molluscs and the empty cases of caddis-worms. The latter attach to themselves numerous shells, sticks, and other substances, which cause them to assume a most extraordinary appearance. In the summer they are found creeping, as in the cut, on aquatic plants.