76 CLASS GASTEROPODA. 
murices of Linneus. The animal resembles that of a true 
buccinum. (Buccinum persicum, List., &c.) 
The genus LicoRNE, Mont/., MONOCEROS, Lam., consists 
of shells similar to the purpure, but in which the external 
edge of the emargination is furnished with a salient spire. 
(Buccinum monodon, Gm., &c.) 
Others, also resembling purpure, in which the columella, 
or at least the margin, is provided, in the adult, with teeth, 
which narrow the aperture, form the SistrA, Monff., or the 
RICINULA, Lam. (Murex ricinus, L., &c.) 
CoNCHOLEPAS, Lam. 
The general characters of the purpure; but the aperture is 
so enormous, and the spire so small, that the shell has almost 
the appearance of a capulus, or one of the valves of an arca. 
A small salient tooth is visible on each side of the emargina- 
tion. ‘The animal resembles that of a true buccinum, with 
the exception of its foot, which is enormous in width and 
thickness, and that it is attached to the shell by a muscle, 
shaped like a horse-shoe, as in the capuli. It has a thin, 
narrow, and horny operculum. 
But a single species is known, the Buccinum concholepas, 
Brug., Argeny. pl. ii. f. F. D.; and Sowerb. Gen. of Shells, 
No. VI. From the coast of Peru. 
Cassis, Brug. 
The shell oval; aperture oblong or narrow ; the columella 
covered with a plate, as in Nassa, and that plate transversely 
folded, as well as the external margin; the emargination ter- 
minating in a short canal that is reflected and pushed back, as 
it were, to the left; varices are frequently observed upon it. 
The animal resembles that of a true buccinum, but its horny 
operculum is denticulated, in order to pass between the folds 
of the external margin. 
