10 ZONITID^E. 



Animal elongate, completely retractile within the shell, having 

 a caudal mucus- pore, more or less developed, but consisting 

 usually of a simple linear slit ; mantle lobes small, not reflected 

 on the shell ; genital orifice distant from the right tentacle ; jaw 

 with a well-marked median rostrum ; lateral teeth bicuspidate, 

 marginals sharp, narrowly unicuspidate. 



Europe, Western Asia, America. 



Subgenus /UNITES (typical). 



Shell depressed orbicular, widely umbilicated, striated above, 

 smooth below, rather solid, whorls numerous (fi or 7), lip sharp, 

 with a slight parietal callus. 



Labial palpi small ; caudal gland reduced to a simple slit. 



Southern Europe, Asia Minor. 



The synonyms are jEgopis, Fitzinger, 1833, Tragomma, Held, 

 1837, Helicodes, Dumas, 1847, Verticillus, Moquin-Tandon, 1855, 

 Archseozonites, Sandberger (fossil). 



Subgenus HYALINIA, Ferussac, em. 1819. 



Shell thin, vitreous, fragile, shining, unicolored, corneous; 

 last whorl not descending at the aperture ; peristome thin, sharp. 



Mucus-pore shallow, hardly distinct, extremity of the tail 

 slightly sinused, skin bluish. 



Northern Hemisphere, species numerous. 



Section VITREA, Fitzinger, 1853. 



Shell small, fragile, shining-, hyaline, smooth, convexly de- 

 pressed, perforate or imperforate, aperture liumtc. 



Crystallus, Lowe, 1854, is a synonym. 



Section POLITA, Held, 1837. 



Shell depressed or subdiscoidal, unibilicate, smooth, shining, , 

 pellucid, corneous, the base more or less milky opaque, aperture 

 obliquely lunate. 



This is the typical group. Its synonyms are Oxychilus, Fitz., 

 1833; Lucilla^'Lowe, 1854; Euhyalina, Albers, 1857; Aploxtoma, 

 Moq.-Tand., 1855. 



Section ZONITOTDES, Lehmann, 1864. 



The animal differs from the typical Hyalinia in possessing- n 

 dart, like the Helicida 1 ; the shell is \\ Polila. 



