Shell oval or sub-globular, thick, armed with points or tubercles, with
a depressed spire; aperture narrow, elongated, notched, sometimes
canaliculated anteriorly, and digitated externally; the left edge more
or less callous, sometimes denticulated; operculum horny, oval,
transverse, with elements slightly imbricated.
Ricinula horrida.
R. clathrata.
R. arachnoidea.
R. miticula.
R. digitata.
R. pisolina.
R. aspera.
R. morus.
R. mutica.
_R. horrida._ The horrid Ricinula. Pl. 26, fig. 2.
Species without a canal; exterior covered with strong, obtuse black
tubercles, with the interstices white, striated transversely; interior
rich purple colour; outer lip with five triangular grooved radii,
between which at their base the margin is crenulated.
_R. digitata._ The digitated Ricinula.
Species canaliculated; two long palmated digits at the side of the
aperture.