Genus PLANORBIS, 3milcr. 



Plate 1.— Figs. 1,2. 



Testa discoidea, spira valde depressa: anfractibus omni- 

 bus utrinque conspicuis: apertura lunata, ab axe reniotis- 

 sima. 



SYNONYMS AND REFERENCES. 



Helix, Linnaeus, Gmelin, Wood, &c. 

 Planorbis. Muller, Bruguiere, &c. 

 Lamarck. An. sans Vert., viii. p. 379. 

 Deshayes. In the same, viii. p. 380. Anno 1838. 

 SowERBY. Genera and Manual. 



CuviER. An. du Mus. Memoires, Anno 1817, Regne ani- 

 mal, pi. 26, fig. 4. 

 Desmoulins. Tr. Soc. Lin. Bordeaux. Anno 1831. 

 Penny Cyclopedia, xiii. p. 495. 



DESCRIPTION. 



Animal elongated, slender, and closely rolled 

 up; head saddle-shaped and slightly emarginate, 

 anteriorly: tentacles long and setaceous; mouth 

 provided with a spoon-shaped tongue, opposed 

 to a concave tooth anterior to it; respiratory 

 orifice upon the left side. 



K 1 



