This shell resembles the Melania, but is easily distinguished by having
a sinus at the base and another at the summit.
Shell turreted, aperture oblong, closed by a horny operculum; right lip
sharp, with a distinct sinus at the base and another at the summit; base
of the columella inclined towards the right.
Pirena terebralis.
P. spinosa.
P. aurita.
P. granulosa.
_P. terebralis._ The wimble Pirena.
Subulate, longitudinally striated, covered with a dark-brown epidermis;
aperture white, outer lip expanded.
FAMILY X.
PERISTOMIDES. Three genera.