BY E. M. JOHNSTON, P.L.S. 



91 



Sub-Family Pomatiopsinje. 



(Shell and operculum as in Eissoinse. Foot with lateral 

 sinus. Amphibious.) 



Genus Pomatiopsis. Tryon. (311-312.) 



Shell elongated, frequently decollated, perforate, smooth ; 

 whorls very convex ; aperture round ; peristome con- 

 tinuous, slightly expanded or reflected. Air breathing 

 animal, preferring damp location in the vicinity of 

 streams or lagoons. Dist. — United States, Central 

 America, Australia, Tasmania, Flinders' Island. 



(xxxvii.) Family Assiminitd^e. 

 Genus Assiminea. Leach. (313.) 

 Shell small, oval, conical, with moderate spire ; aperture 

 rounded, oval, with sharp lip entire ; columella lip 

 somewhat thickened. Dist. — Europe, Asia, America, 

 Tasmania. 







(xxxviii.) Family Valvatidje. 

 Genus Valvata. Mueller. (313 a .) 

 Shell depressed, conical (in the typical group), umbilicated ; 

 covered by a thin greenish epidermis; operculum 

 orbicular, corneous, multispiral. Animal with a pro- 

 duced muzzle ; tentacles long and slender, eyes at their 

 bases ; foot bilobed in front ; branchial plume long, 

 pectinated, partly exerted on the right side when the 

 animal is walking ; lingual teeth broad, uncini 3 

 lanceolate ; all toothed and denticulated. Dist. — 

 Freshwater, mundane. 



(xxxix.) Family Tbitncatellidje. 

 Genus Tbuncatella. Eisso. (314-317.) 

 Shell small, sub-cylindrical or turbinate, with elevated spire ; 

 apex obtuse or truncated ; whorls striated transversely ; 

 aperture oval, entire ; peristome continuous; operculum 

 corneous, sub-spiral. Animal with short diverging 

 tentacles ; eyes centrally behind ; head bilobed ; foot 

 short, rounded at each end. Dist. — On stones and 

 seaweed between tide marks. 



(xl.) Family JSTebitid^. 

 Genus Neeita. Linn. (318.) 

 Shell thick, smooth or spirally grooved ; epidermis horny ; 

 outer lip thickened and sometimes denticulated within ; 

 columella broad and flat, with its inner edge straight 

 and toothed; operculum shelly. Dist. — Nearly all 

 warm seas, living on rocks and stones at low water. 



