P. nucleus.
P. Persica. The Persian Purpura. Pl. [28], fig. 4.
Transversely sulcated and striated between the ridges; colour burnt-umber, ridges yellowish, with dark brown spots; upper ridge and the superior edges of the volutions mucronate; interior sulcated and striated.
P. lapillus. The common Purpura.
Species small, white, sometimes banded with yellow or brown, with a scaly surface.
5. Monoceros. The Unicorn. Five species.
Derived its name from the long, conical-pointed, somewhat recurved tooth in the outer lip, by which alone it can well be distinguished from the Purpura; and with this characteristic difference the description of the shell of the Purpura will answer for this genus.
Monoceros cingulatum.
M. imbricatum.
M. striatum.