Planorbis (Gyrorbis) spirorbis.—Very flat, glossy, brown, whorls 5 to 6. Common in ponds and ditches.
Planorbis (Gyrorbis) vertex.—Very like the last, but flatter and thinner, and with a prominent keel. More local than spirorbis, but sometimes found with it. Whorls 6 to 8.
Planorbis (Gyrorbis) carinatus.—Larger than spirorbis and vertex. Sharply keeled in the centre of the outer margin. Mouth angulated above and below. Local, mainly in the south and east of England.
Planorbis (Gyrorbis) umbilicatus.—Like the last, but the keel is below and not on the centre. Mouth rhomboidal. More common than carinatus.
Planorbis (Coretus) corneus.—Far the largest species. Dark brown, lighter below. Mouth nearly circular. Spire sunk. In boiling water often exudes a crimson fluid. Common.
Planorbis (Bathyomphalus) contortus.—Small, 8-whorled, flat above, very convex below. Fairly common in still water. Very compact in appearance.
The sub-family Physa has two genera, Aplecta and Physa.
Physa (Aplecta) hypnorum is a spindle-shaped, very glossy, semi-transparent, dark reddish brown, shell, with 6 to 7 whorls. Not common. Found in still water.
Physa (Physa) fontinalis.—More common, and found in running as well as in still water. Shorter and more rounded than the last. Shell very thin, greenish horn-colour. Lobes of the mantle expand over the shell. Seen in an aquarium are its perpendicular threads of mucus, up and down which the animals climb.