« “These animals,” observes Mr. Clark, “creep with great rapidity, and float with the foot uppermost by means of a hydrostatic apparatus, as air-bubbles are seen continually to proceed from the aperture; they are strictly littoral, and inhabit in myriads the green oozes of estuaries.” This common Mollusk is found in all brackish water, and estuary localities between tide marks round the British Isles, where it is a favourite food of water-birds. » – Forbes & Hanley: op. cit. vol. III, London 1853, p.144.