JEFFREYSIID^E-SKENEID.*;. 323 



Genus JEFFKEYSIA, Alder. 1849. 



Characters those of the family. Distr. Europe, Japan. 



J. DIAPHANA, Alder. 



Jeffreysia lives on algse, from which it can suspend itself by a 

 mucous thread. The eyes are visible through the shell. 

 Rissoella, Gray, 1847 (not described), is a synonym. 



Subgenus TATEA, Tenison Woods. 1879. 



Shell elongate pyramidal. Operculum calcareous, with a vertical, 

 >eubmarginal claw. Animal with truncate foot and long tentacles. 

 T. HUONENSIS, Woods. Tasmania. 



Subgenus DARDANIA, Hutton. 1882. 



Shell ovate, subconical, smooth, imperforate, olivaceous ; aperture 

 oval, entire, rounded in front ; peritreme not continuous, outer lip 

 thin. Operculum like Jeffreysia. D. OLIVACEA, Hutton. 



New Zealand. 



F \KIL\- 8KENEIDA1. 



Head large, proboscidiform, foot truncate in front, operculigerous 

 lobe without appendages, tentacles long, cylindrical, eyes nearly 

 ; -jsessile, at their external base (PI. -34, fig. 100). Jaws tuberculate. 

 Radula like Hydrobia (PL 54, fig. 99). 



Shell depressed, nearly discoidal, few-whorled, widely umbili- 

 cated, aperture rounded, peristome continuous. Operculum corne- 

 ous, multispiral. 



Genus 8KENEA, Fleming. 1828. 



Characters those of the family. Northern Seas. Low water, 

 under stones and on algse. S. PLANORBIS, Fabr. 

 Delphinoidea, Brown, is a synonym. 



FAMILY CHOEISTID^E. 



Shell heliciform, thin, perforate, covered by an epidermis; aper- 

 ture oval, peristome continuous, sharp. Operculum corneous, 

 spiral. 



Head short, large, two short anterior tentacles are connected by 

 a frontal veil, the posterior tentacles are simple, thick, conical ; no 

 eyes ; proboscis retractile ; foot large, oval, with two anterior ten- 



