36 BRITISH MOLLUSKS. 



ovate, of three to four transparent amber whorls, the last of 

 which is capaciously inflated. 



3. Zonites. Animal carrying an umbilicated subdiscoidal shell, 



occasionally partially enveloped by a reflected lobe of the 

 mantle, lower tentacles short, foot truncated behind. Shell 

 of three to five colourless shining whorls. 



4. Helix. Animal carrying an orbicularly coiled shell, not en- 



veloped in any part by the mantle, foot lanceolate behind. 

 Shell sometimes solid, brightly coloured, sometimes thin, 

 horny, of four to six whorls. 



5. Bulimus. Animal carrying a turriculate shell, upper pair of 



tentacles rather long, foot lanceolate behind. Shell of eight 

 to nine elongately convoluted whorls. 

 G. Zua. Animal carrying an oblong glossy shell, upper pair of 

 tentacles long, with the bulbous extremities rather length- 

 ened. Shell of four to five transparent vitrified whorls obso- 

 letely truncated at the end. 



7. Azeca. Animal carrying a cylindrical chrysalis-shaped shell, 



upper tentacles slender. Shell attenuately contracted towards 

 the base, of seven smooth whorls, of which the aperture is ear- 

 shaped and toothed. 



8. Achatina. Animal carrying a narrow hyaline-white shell, 



upper tentacles slender, eyeless. Shell of six smooth, acicu- 

 larly convoluted, imperforate whorls. 



9. Clausilia. Animal carrying a slenderly acuminated, sinis- 



trally convoluted shell, in which it encloses itself by a clausi- 

 lmm, tentacles short. Shell of nine to twelve attenuately 

 elongated whorls, mostly densely wrinkled, contracted and 

 toothed at the aperture. 



10. Balea. Animal carrying a thin, sinistrally convoluted shell, 

 tentacles short, upper pair approximating. Shell of seven 

 conically turreted, transparent, horny whorls. 



11. Pupa. Animal carrying a small horny narrow- whorled shell, 

 upper pair of tentacles short, lower pair very short. Shell of 

 six to nine closely convoluted whorls, more or less toothed in 

 the aperture. 



12. Vertigo. Animal carrying a minute, tumidly whorled shell, 

 upper tentacles rather short, no lower tentacles. Shell of 

 four to six whorls, sometimes convoluted sinistrally, more or 

 less toothed in the aperture. 



