266 RlSSOID.'E. 



In L. minuta the rostrum is rather long, the tentacles very 

 slightly tapering, blunt at the end, foot rounded behind. 



Hydrobia, Hartmann. 



/S</7i.— Paludinella, Loven. Peringia, Paladilhe. 



Distr. — World-wide, brackish water. H. ulvse, Pennant 

 (Ixxii, 54). 



Shell ovate or elongated, smooth, subperfo rate ; spire conic; 

 whorls flat; apex acute; aperture ovate; inner lip not thickened. 

 Operculum corneous. 



Rostrum rather long, tentacles somewhat tapering, but blunt 

 at the extremity. Foot somewhat pointed behind. 



Emmericia, Brusina. 



Distr. — Living, 2 sp. Adriatic Region. U. patula, Brum. 



Shell small, conoidal, rimate, smooth, shining, spire elevated ; 

 aperture patulous ; peristome subcontinuous, inner lip adnate, 

 the outer lip sinuate, wide, reflected. Operculum corneous, ovate, 

 paucispiral, nucleus excentric. 



TOURNOUERiA, Brusina. Peristome inferiorly evased, simple. 

 1 recent, sevei'al tertiary species. Europe. 



STALiOLA, Brusina, 1870. Peristome with a strong exterior 

 margiiial rib. Tertiary ; Europe. 1 recent sp. 



NYSTiA, Tournouer, 1869, (Forbesia, Nyst.) Aperture oblique, 

 exteriorly swollen, spire truncate. Tertiary; Europe. E.- 

 microstoma, Desh. 



BiTHYNELLA, Moquin-Taudou. 



Syn. — Leacliia,Risso. Subulina,Troschel. Paludinella, Frau- 

 enfeld. Microna, Ziegler. Thermhydrobia, Paulucci. Frauen- 

 feldia, Clessin. 



Distr. — Fresh water, Europe, America, including California. 

 B. ^)^r^(i^s, Moquin-Tandon (Ixxii, 55, 56). 



Shell elongated-ovate, usually somewhat pupiform, imperforate, 

 or simply rimate ; apex obtuse ; aperture oval or rounded '; peri- 

 treme continuous, outer lip sliglitly thickened. Operculum 

 corneous, nucleus moderately large, not very close to the basal 

 margin. 



Tentacles tapering, blunt at the tip ; foot rather narrow, 

 rounded behind ; verge bifid. 



STiMPSONiA, Clessin. Proposed for the North American species, 

 which differ from the European tj^pe in dentition. 



viTRELLA, Clessin. (Bythiospeum, Bourg., 1882.) Shell small, 

 thin, without sculpture ; peritreme continuous, sharp. Operculum 

 paucispiral. Animal blind. Inhabits caves and streams in 

 Europe. 15 sp. B. pellucida, Clessin (Ixxii, 5*7). 



MOiTESSiERiA, Bourg. Shell inoperculate (?), diaphanous, crys- 

 talline, very fragile, microscopic, cylindrical, elongated; form of 



