

314 assimihiidje. 



they are not, however, on the ends of cylindrical pe- 

 duncles, as in the Helicidte, but on the upper surface of 

 flat, subulate tentacles, near their tips. 



Fam. ASSIMINIIDjE. 



Teeth on lingual membrane, 5 7, cusped, the first and 

 second uncini dentated, the third rounded. Head rostrate, 

 produced and emarginate anteriorly ; eyes on the middle of 

 the tentacles near their tips. Foot flat, moderate. 



Operculum horny, sub-spiral. 



Shell ovately conical, or sub-globose, covered with a 

 homy epidermis. 



The shells of these animals resemble those of Hydrobia 

 and Amnicola among the Littorinida, but the position of 

 the eyes is very different. In their habits they nearly re- 

 semble the Cyclostomatous genus Hydrocena, and the 

 genera Geomelania and Truncatella. 



Genus ASS1MINIA, Leach. 



Tentacles short, obtuse, with the eyes near the ends. 



Operculum of few, rapidly-increasing whorls. 



Shell ovato-conical, with the spire more or less produced, 

 whorls flattened, axis not perforate, or slightly rimate ; 

 aperture ovate, entire, columellar lip thickened, outer lip 

 acute. 



Syn. Syncera, Gray. Assiminea, Auct. 



Ex. A. Gray ana, Leach, pi. 88, fig. 5. Operculum, A. 

 Grayana, fig. 5, a, 5, b. Shell, A. Grayana, fig. 5, c. 



Species of this genus are found in India, China, and 

 Australia; they are amphibious, and generally inhabit 



