31 
(2) Marine SHELLS. 
Nerita.—Shell solid, semi-globular, flattened beneath, not umbilicated: aperture entire, 
semi-circular, the left margin flat, septiform, acute, often toothed; teeth or crenu- 
lations on the inner surface of the right lip. Operculum with a projecting tooth. 
Plate XVI. Fig. 1. N. peloronta. (Idem.—Linn.) 
Natica.—Shell subglobular, umbilicated: aperture entire, semi-circular ; left lip oblique, 
not toothed, callous; the callosity modifying the umbilicus, and sometimes cover- 
ing it; right lip acute, always smooth inside. An operculum. 
Plate XVI. Fig. 2. N. vitellus. (Nerita vitellus.—Linn. ) ; 
JANTHINEA. 
JANTHINA.—Shell ventricose, conoidal, thin, transparent: aperture triangular; columel- 
la straight, passing beyond the base of the right lip, which has a sinus in the mid- 
dle. No operculum. 
Plate XVI. Fig. 3. J. communis. (Helix janthina.—Linn.) 
MACROSTOMIANA.—4 GENERA. 
Shell ear-shaped, the aperture much dilated, the margins disunited, no columella, no operculum. 
Sic¢areTus.—Shell sub-auriform, nearly orbicular; the left lip short and spiral: aperture 
entire, much dilated, rounded-oblong; the margins not united. 
Plate XVI. Fig. 4. S. concavus. 
StomaTELLA.—Shell orbicular or oblong, ear-shaped, imperforate: aperture entire, large, 
sub-longitudinal ; right lip effuse, dilated, open. 
Plate XVI. Fig. 5. S. imbricata. 
Sromatra.—Shell ear-shaped, imperforate, spire prominent: aperture entire, large, ob- 
long; right margin and columella equally raised; a transverse and tuberculated 
rib on the back. 
Plate XVI. Fig. 6, 6 (a). S. phymotis. (H. imperforata.—Chem.) 
Hatioris.—Shell ear-shaped, mostly flattened; the spire very short, sometimes depress- 
ed, nearly lateral: aperture very large, ovate-oblong, and entire in perfect shells ; 
disk pierced with holes disposed in a line parallel to, and near the left margin, 
the last commencing with a notch. 
Plate XVI. Fig. 7. H. asinina. (Idem.—Linn.) 
PLICACEA. —2 GENERA. 
Aperture of the shell not effuse ; columella plaited. 
TorNATELLA.—Shell convolute, ovate-cylindrical, mostly striated transversely; no epi- 
dermis : aperture oblong, entire, the right lip sharp; one or more plaits on the 
columella. 
Plate XVI. Fig. 8. 'T. fasciata. (Voluta tornatilis.—Linn. ) 
