o6 Lamarck's Genera of Shells. 



3. Ricinula*. 



Shell oval, generally tubercular or spinous externally. Aperture 

 oblong, with a semi-canal at the lower part, curved towards the 

 back, and terminated by an oblique notch. Unequal plaits on the 

 columella and on the inner side of the right lip, usually con- 

 tracting the aperture. 



The Ricinulse are generally small shells ; the spire often low, 

 and covered with tubercles or spinous points like the fruit of the 

 ricinus. The aperture is generally tinged with purple or violet. 



Type. Ricinula horidai. (Murex neritoideus. Gmel.) 



Shell ovate, subglobular, covered with thick, short, acute, black 

 tubercles ; interstices white ; spire very short ; aperture ringent, 

 violet coloured. Indian Ocean. PI. v. Fig. 189. 9 Species. 



4 Purpura f. 



Shell oval, smooth, tubercular, or angular. Aperture dilated, 

 terminating below in an oblique, subcanaliculated notch. Colu- 

 mella flattened, pointed at the base. 



This is the last genus whose shells present any appearance of a 

 canal at the base of the aperture ; they are distinguished by the 

 dilated aperture, and the flattened and generally naked columella, 

 terminating in a point at the base, whose notch turns a little up- 

 wards posteriorly. 



Type. Purpura persica§. (Buccinum persicum. Linn.) 



Shell ovate, transversely sulcated, rather rough, blackish brown; 

 furrows obsoletely rugged, spotted with white ; spire short; aper- 

 ture dilated ; columella brownish yellow, longitudinally excavated 

 in the middle ; interior margin of the lip sulcated, blackish, inter- 

 nally white, painted with brownish yellow lines. Indian Ocean. 

 PI. v. Fig. 190. 50 Species. 



* Dim. from Ricinus, from the seed of one species of which, R. communis, 

 the Castor Oil is procured. 



t Rugged. 



X Purple, applied, xaT i^m, to this genus, for the reason already given. 

 The term was also used, to denote this peculiar shell fish, by Pliny, Lib. 9, § 36. 



<i Persian, 



