Limnæa (Amphipeplea) glutinosa.—Very local. Somewhat like Ph. fontinalis, but larger and more thin. In young specimens the mantle covers the shell, and in adults the animal is not wholly contained in the shell.
Limnæa (sub-genus Radix) involuta.—Only found in one Irish tarn. Whorls envelop the spire. Very thin, pale amber.
Limnæa (Radix) peregra.—The most common and variable of all our freshwater shells. Spire pointed. Somewhat amphibious. Found practically over the whole of the Eastern Hemisphere.
Limnæa (Radix) auricularia.—Mouth very large, with outer lip widely reflected. Very common and fine in the Thames. Spire very short, apex sharp.
Limnæa (sub-genus Limnophysa) stagnalis.—The largest of the genus. Common, except in Wales. Shell greyish, spire long and tapering to a point; 12210 teeth on its lingual ribbon. See the illustration on [p. 57], which also shows above two specimens of Paludina contecta, one being covered (as freshwater shells often are) by a vegetable growth, which obscures the marking.
Limnæa (Limnophysa) palustris.—Shell tapering, somewhat solid, brown, much smaller than stagnalis. Common in slow or stagnant water. Some varieties much darker than the type.
Limnæa (Limnophysa) truncatula.—Like the last in shape, but much smaller, and with a deeper suture. Common, and fond of being out of the water. A parasite of this mollusc causes “fluke” in sheep which have taken it in by drinking or by eating grass by the side of ponds and ditches.
Paludina contecta (two) and Limnæa stagnalis on water-weeds.