GASTEROPODA. LIMNADZ. El 
Physa Hypnorum, Drap. Hist. des Moll. 55. pl. 3. figs. 12, 
13. 
Bulla rivalis, Flem. Edinb. Encycl. vii. 85. 
Animal ceerulescente-atrum. Oculi aterrimi. Tentacula ad 
apicem albida. Pes elongatus, acuminatus. 
Habitat in paludibus, et in aquis lenté fluentibus. 
Shell ovately-oblong, diaphanous, horny, polished, and shi- 
ning ; the whorls most delicately striolated transversely. Height 
eleven-sixteenths of an inch: breadth of aperture five-six- 
teenths. 
Animal bluish-black. Eyes very black. Extremities of the 
tentacula whitish. Foot elongate and acuminate. 
It is found in a marsh, near the Ware-head, on the Exe, near 
Exeter; near Lackham, in Wilts; in Battersea fields; in Loch 
Dedinstone, near Edinburgh ; and in the river, near Oxford. 
Genus 50. PLANoRBIS. 
Planorbis, Miller, Draparnaud, Férussac, Cuvier. 
Testa sinistrorsum involuto-spiralis, uni-camerata. Peri- 
trema posticé fortiter inchoatum. Tentacula setacea. 
Synopsis Specierum. 
A. Anfractus pauci. 
* Spira immersa, infundibuliformis. Umbilicus clausus, 
planus. 
1. corneus. Testa cornea, crassiuscula ; anfractibus transversim 
antiquato-striatis. 
** Spira ad apicem immersa. Umbilicus concavus. 
2. albus. Testa griseo-cornea, tenui; anfractibus longitudina- 
liter elevato-lineatis. 
3. carinatus. Testa cornea, pellucida ; anfractibus transversim 
striatis, ad dorsi medium carinatis. 
. marginatus. Testa cornea, fusca, subpellucida, ad sinistram 
planiore ; anfractibus transversim striolatis, ad sinistram 
dorsi carinatis. 
— 
