Formerly classed with the Nerita, but separated from it because the
Nerita is a marine shell, and those of this genus are fluviatile.
They are generally thin, smooth, or very finely striated; the right side
of the aperture is not crenulated or dentated, and the animal dissolves
the interior of the spire.
Shell thin, ovate, not umbilicated; aperture semilunar; inner lip
reflected on the columella, and sometimes crenated; outer lip without
teeth internally; operculum with a lateral tooth.
Neritina perversa.
N. pulligera.
N. dubia.
N. zebra.
N. zigzag.
N. gagates.
N. lugubris.
N. corona.
N. brevispina.
N. crepidularia.
N. auriculata.
N. Domingensis.
N. fasciata.
N. lineolata.
N. semi-conica.
N. strigilata.
N. meleagris.
N. Virginea.
N. fluviatilis.
N. viridis.
N. Bætica.
_N. fluviatilis._ The fresh-water Neritina.
Shell very small, oval; back convex, smooth, white, with black or brown
spots; spire inclined, lateral lip slightly denticulated; right edge
sharp, operculum very oblique.
_N. zebra._ The zebra or striped Neritina. Pl. 21, fig. 2.
Same as N. fluviatilis, but striped instead of spotted.
_N. corona._ The crown Neritina. Pl. 21, fig. 4.
Species provided with long spines, and with the columellar edge
denticulated.
_N. auriculata._ The eared Neritina.
Species with the columellar edge denticulated; the two extremities of
the right edge extending beyond the aperture, and forming with the
callosity, which is reflected over the columella, a kind or ear,
produced by the tentacular lobe of the animal.
_N. perversa._ The perverse Neritina.
Species shaped like a Calyptræa, with the superior summit vertical,
spiral; the last whorl forming all the base of the shell.