454 



MOLLUSCi 



HUB-KINGDOM VI 



Nerita, Linn. (Fig. 854). Thick, ovoid, or semi-globose, imperf orate. Surface 

 smooth or with spiral ribs. Inner lip callous, flattened, with a straight, often den- 

 ticulate border. Operculum sub-spiral. Trias (?) to Recent. 



Oncochilus, Petho (Fig. 855). Smooth ; inner lip arched, callous, bearing two or 

 three teeth on the margin or smooth ; outer lip sharp. Trias and Jura. 



Lissochilus, Petho (Fig. 856) ; Neritodomus, Morr. and Lye. ; Neritoma, Morris, 

 Jura. Otostoma, d'Arch. ; Dejanira, Stol. Cretaceous. 



Velates, Montf. (Fig. 857). Depressed conical, only the curved apex of the spire 



FIG. 854. 



A, Neriia Laffoni, Merian. Citharella Limestone ; Epfen- 

 hofen, near Schaffhausen, Switzerland. B, N. granulosa, 

 Desh. Eocene (Sables Moyens) ; Auvers, near Paris. 

 (', Operculum of a recent Nerita. 



Oncochilus chromaticus, Zittel. Upper 

 Tithonian ; Stramberg, Moravia. 



visible. Last whorl very large. Inner lip convex or straight, with denticulate margin. 

 Abundant in the European Eocene; sometimes attaining a size of 10 or 12 cm. 



Neritina, Lam. (Fig. 858). Small, semi-globose, lustrous, smooth or spiny, mostly 

 brilliantly coloured. Inner lip flattened, with sharp or finely toothed margin ; outer 



FIG. 856. 



Lissochilus sigaretinus, Buv. 

 Coral-Rag; Hoheneggelsen, 

 Hannover. 



Neritina G-rateloupana, Fer. 

 Miocene ; Haufelburg, near Giinz- 

 burg. 



Fio. 859. 



Pileolus plicatus, Sowb. Bathon- 

 in ; Langrune, Calvados. 3/j. 



FIG. 857. 



Velates Schmidelianus, Chem. Eocene (Lower 

 Meeressand) ; Cuise-la-Mothe. 



lip sharp. Inhabits brickish or fresh water. Abundant in Tertiary and Recent. The 

 supposed Mesozoic forms belong principally to Nerita. 



Pileolus, Sowb. (Fig. 859). Small, cup-shaped to depressed conical, ovoid or round. 

 Apex slightly curved backwards ; only the last whorl visible. Aperture semi-circular ; 

 inner lip broad, callous. Jura to Eocene. 



