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.