ZONTTID^C. 1 1 



Section NAUTILI NUS, Mousson, 1872. 

 Shell nautiloicl, involute. 



Section CONULUS, Fitzingcr, 1833. 



Shell small, pellucid, corneous, globosely turbinated or conic, 

 thin, usually perforate, aperture lunar, oblique. 



Trochiscus, Held, 1837, and Petasia, Beck, 1837, are S3'nonyms. 



Section CONULOPOLITA, Bottger, 1879. 



Not umbilicated, base planate, excavated in the middle ; shell 

 large, subturbinate ; whorls 6^-7, very slowly increasing ; aper- 

 ture depressed, lunar. Caucasus. 



Section DIERAMA, Pfeilfer, 1877. 



Not described ; instituted for a single species, H. DIERAMA, 

 Pfr. Hab. unknown. 



Subgenus PHACUSSA, Button, 1884. 



Shell depressed ; periphery rounded ; whorls 5-6, graduall}' 

 increasing. Mantle included. Jaw with flat ribs. New Zealand. 



Subgenus STENOPUS, Guilding, 1828. 



Shell depressed or conical, perforated, thin, diaphanous, lip 

 sharp. 



Animal with a linear locomotive disk, separated from the 

 lateral parts by a groove on either side as in Vaginula ; caudal 

 gland with a retractile appendage. 



Mexico, Venezuela, West Indies. 



Is Guppya, Morch, 1867, and Habroconus, Crosse and Fischer, 

 1872. 



Subgenus OMPHALINA, Ralinesque, 1819. 



Shell widely umbilicated, depressed orbicular, striated above, 

 smooth and shining below, aperture large. Labial palpi large, 

 caudal pore well-marked. 



Europe, United States, Mexico, Guatemala. 



Section OMPHALINA (restricted). United States. 



Section MORELETIA, Gray, 1855. Mexico, Guatemala. 



Section ZONYALINA, Martens, 1865. Mexico. 



Said to be distinguished from Moreletia by the want of the 

 outer cervical lobe of the mantle. 



