GASTEROPODA. 237 



Lamellaeia, Montagu. 



Etymology f lamella^ a thin plate. 



Synonyms, Marsenia, Leach. Coriocella, Bl. 



Type, L. perspicua. PI. YIII., Fig. 6. 



Shell ear- shaped ; thin, pellucid, fragile ; spire very small ; 

 aperture large, patulous ; inner lip receding. No operculum. 



Animal much larger than the shell, which is entirely con- 

 cealed by the reflected margins of the mantle ; mantle non- 

 retractile, notched in front; eyes at the outer bases of the 

 tentacles. Lingual uncini 3, similar ; or one very large. 



Distribution, 10 species. Norway, Britain, Mediterranean, 

 New Zealand, Philippines. 



Fossil, 2 species. Pliocene — . Britain (Crag). 



Namca, Eecluz. 



Synonyms, Yanicoro, Quoy. Merria, Gray. Leucotis, Sw. 



Type, N. cancellata. PI. YIIL, Fig. 8. 



Shell thin, white, with a velvety epidermis ; ribbed irregularly 

 and spirally striated ; axis perforated ; operculum very small, 

 thin. 



Animal eyes at the outer base of the tentacles; foot with 

 wing-like lobes. 



Distribution, 26 species. West Indies, Nicobar, Yanikoro, 

 Pacific. 



Fossil. 4 species, Gault — . (D'Orbigny.) Britain, France. 



YELTrriNA, Fleming. 



Etymology, velutinus, velvety (from veil us, a fleece). 

 Type, Y. laevigata. PL YIIL, Fig. Y. 



Fig. 96. Velutina laevigata (Warington). 



Shell thin, with a velvety epidermis ; spire small ; suture 

 deep; aperture very large, rounded; peristome continuous, 

 thin. No operculum. 



Animal with a large oblong foot; margin of tne mantle 

 developed all round, and more or less reflected over the sheU ; 

 gills 2 ; head broad ; tentacles subulate, blunt, far apart ; eyes 

 on prominences at their outer bases. Carnivorous. Lingual 

 dentition (Fig. 96). It resembles that of trivia (Fig. 15, B). 



