Generally inhabits fresh water, though some have been found where it is
quite saline.
Shell conoid, covered with epidermis, spiral whorls rounded; rather
longer than broad, edges united, always sharp; the commencement of the
left edge immediately attached to the last whorl of the spire; operculum
horny, complete, or marginal, not spiral, with concentral elements.
Paludina vivipara.
P. achatina.
P. Bengalensis.
P. unicolor.
P. impura.
P. muriatica.
P. viridis.
_P. vivipara._ The viviparous Paludina. Pl. 21, fig. 1.
Thin, ovate, ventricose, wrinkled longitudinally; body with three brown
bands: covered with a greenish epidermis; aperture almost round.