Section MACROCHLAMYS, Benson, 1832. 



Shell depressed globose, pellucid or corneous, smooth and 

 shining. 



Mantle with two long tongue-shaped shell lobes ; left cervical 

 lobe divided into two diverging portions ; mucous pore with 

 conical appendage. India, etc. 



Tanychlamys, Benson, 1834, and Orobia, Albers, 1860, are 

 synonyms. 



Section MACROCERAS, Semper, 1870. 



Conical appendage of the mucous pore very long. Philippines. 



Section BENSONIA, Pfeiffer, 1855. 



Shell thin, perforate, obliquely sculptured above, crossed by 

 impressed revolving lines. India. 



Section SOPHINA, Benson, 1859. 



Shell with a callous columella, angulated at the basal margin, 

 and with a more or less acute umbilical carina. 



Foot long, obliquely truncate, with a large tail gland and 

 distinct horn-shaped appendage; mantle lobes as large as in 

 Helicarion. Burmah. 



Section EURYPUS, Semper, 1870. 



Shell with obscurely keeled periphery, umbilicus very narrow.- 

 Foot with the back broad, not carinated. Fiji Islands. 



Aulacopus, Pfeffer, is a synonym. 



Section DURGELLA (Blanford), Stoliczka, 1871. 



Shell thin or membranaceous, globose or globosely conoid, 

 polished, narrowly perforate, columellar margin not much 

 thickened. 



Dorsal lobes moderate, shell lobes very ample, triangular 

 when extended ; mucous pore well developed, with large over- 

 hanging lobe. India, Burmah. 



Section MICROCYSTIS, Beck, 1837. 



Shell small, snbperfo rated, usually slightly keeled, glabrous ; 

 aperture large, subvertical. 



Mantle margin with shell lobe on right side only ; left cervical 

 lobe bipartite. Polynesia. 



Helicopsis, Beck, 1837, find ? Platycloster, Hasselt, are syno- 

 nyms. 



