82 GASTEROPODA. HELICIDZ. 
Umbilicus nullus. Tentacula supériora mediocria: inferiora 
breviuscula. 
Shell ovately-oblong, its apex somewhat obtuse. Aperture 
acuminately-ovate. Peritreme thickened; only commenced 
behind. Umbilicus none. Superior tentacula moderately 
long ; inferior ones rather short. 
ZUA LUBRICA. 
Z. testa pellucida, cornea, glaberrima, nitidissima. 
Helix lubrica, Mill. Verm. Hist. 303; Mont. Test. Brit. 390; 
M. & R. Trans. Linn. Soc. viii. 213; Turt. Conch. Dict. 
64. 
Turbo glaber, Da Costa, 87? 
Bulimus lubricus, Brug. Encycl. Méth. Vers. 23; Drap. Hist. 
des Moll. 75. pl. 4. fig. 24. 
Lymneea lubrica, lem. Edinb. Encycl. vii. 78. 
Helix subcylindrica, Dill. Desc. Cat. 952. 
Animal czerulescente-nigricans, subtus cinereum. Tentacula 
nigricantia. 
Habitat sub lapidibus et muscis, in campis, et nemoribus. 
Shell pellucid, horny, very smooth, and very shining. Height 
rather more than one quarter of an inch. 
Animal bluish, inclining to sooty-blackish, underneath cine- 
reous. Tentacula inclining to sooty-black. 
Zua lubrica is generally diffused throughout Britain. — It is 
found under stones, in moss, amongst the roots of grass; and 
sometimes in the trunks of trees after rain. 
STIRPS VII. 
The genera of this stirps have been referred to the genus 
Turbo, by the Linnzean school. We have but two of the genera 
in Britain, one named Clausilia, by Drapernaud, who first dis- 
covered the existence of its internal spiral operculum, which is 
wanting in the new genus Balzea. 
All the members of this stirps that have hitherto been dis- 
covered are reversed. 
