155 



semi-imbricata. 

 echinulata. 

 clavus. 

 fasciolaris. 

 vexillum. 

 P. bizonalis. 

 P. trochlea. P. nucleus. 



P. Persica. The Persian Purpura. PI. 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 mucro- 

 nate ; 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 character- 

 istic difference the description of the shell of the Purpura 

 will answer for this genus. 



Monoceros cingulatum. Monoceros striatum. 



M. imbricatum. M. glabratum. 



M. crassilabrum. 

 M. cingulatum. The belted Monoceras. 

 Cylindrical, columella not smooth, but irregularly plaited 

 or wrinkled, and the tooth does not extend within the interior 

 of the whorls as in the other species, but appears affixed 

 only to the edge of the lip ; volutions flattened in their upper 

 .edges ; transverse spiral brown bands. 



6. Concholepas. One species. 

 Formerly considered a Patella, but distinct from it on ac- 

 count of having an operculum. It is particularly distin- 

 guished by having two teeth at the base of the right side. 



