UNIVALVES. 



PLATE XLI. 



Genus. OLIVA. 



Character. Shell spiral, of an oval form ; the spire short ; the body and cheek 

 rounded and protuberant ; beak none ; the mouth open at the base ; the columella 

 slightly fluted, with a strong and broad ridge or girdle encircling the bottom of the 

 shell ; cheek indented at the top, and having a girdle or ridge inserted between each 

 fold of the spire. 



Species. 

 No. 1. Olivafusca. Shell brown, richly striped ; the mouth white and spread- 

 ing out. A native of the West Indies, and sometimes varying to a paler 

 colour, or even white. 

 No. 2. Oliva porphyracea. Shell dark purple and white, having three belts or 

 circles enveloping the body; the spire also variegated with dark purple 

 spots ; the mouth red. From a shell in the Museum of Mr. Latham. 

 No. 3. Oliva leveriana. Shell of a pale purple and gray, richly studded and 

 adorned with a close net pattern, inclosing the whole body ; the columella 

 covered with small branched flutings of a white colour, the general colour 

 of the pattern a reddish pink, formed into angular marks. From a shell 

 formerly in the Museum of the late Sir Ashton Lever, in honour of whose 

 zeal for the promotion of natural history and the sciences, I have taken this 

 opportunity of naming it. 

 No. 4. Oliva zigzag. Shell pale yellow, thickly interspersed with brownish lines 

 in an irregular and waving pattern, from whence its name ; the mouth and 

 girdle at the base of a strong orange colour. A native of Ceylon. 

 No. 5. Oliva subviridis. Shell of an olive green, interspersed with curious marks 

 of dark brown, placed in the form of belts ; the mouth gray, the girdle at 

 the base of a rich brown colour. From a shell in the collection of Mr. 

 Jennings of Chelsea, and supposed to be a native of the southern hemisphere. 



REMARKS. 



The genus Oliva has a distant resemblance to the Voluta and Comis, with which it has been 

 much confused and mixed in the different species, both by Linnaeus and other subsequent 

 Writers. Nevertheless, its distinctions are sufficiently striking and obvious to mark its 

 peculiar and undeviating character. The cheek is divided from the spire by a narrow chan- 

 nel, which is filled up in part, by a girdle running round the base, it has also a thickened 

 collar or appendage, which is generally of a different colour and character to the rest of the 

 shell; to these may be added its narrow mouth, bending outwardly in a circular and protu- 

 berant form. The species of this genus or family are remarkable for the pleasing and lively 

 lustre of their colours, and their agreeable contrasts, while the polish is at the same time 

 almost equal to that of the Cowries. It is very probable that the fish places the girdle upon 

 the folds of the spire after its growth is fully completed, and at the same time finishes the 

 inside of its mouth by coating it with a beautiful enamel. In the young shell these circum- 

 stances are never perceptible, as in the S trombus and others, and they serve to mark the 

 maturity or immaturity of their age. 



