GENUS VALVATA, Muller. 



PLATE 1. FIG. 1. 



Testa discoidea vel conoidea, umbilicata; anfractibus 

 cylindraceis, cavitatem spiralem non deformantibus: aper- 

 tura rotundata, marginibus connexis, acutis: operculurn 

 orbiculare. 



SYNONYMS AND REFERENCES. 



HELIX. TURBO. CYCLOSTOMA. NERITA. 

 FERUSSAC. Syst. Conch, p. 75. 

 LAMARCK. An. sans vert., vol. viii. p. 398. 

 SOWERBY. Genera of Shells. 



DESCRIPTION. 



ANIMAL spiral; foot of medium size, divided 

 in front, and directed outwards on each: head 

 long, proboscidiform and slender; mouth inferior 

 and terminal, provided with a pair of lateral 

 jaws and a large lingual mass: tentacles long 

 and slender, with the eyes at their posterior 

 base : branchiae plumose, usually exserted; a 

 long retractile filament resembling a tentacle 



H 1 



