254 MOLLUSCA. 



OLIVA, Drupncir. 



So named from the oblong anil elliptical shape of the shell, the aperture of 

 which is narrow, long, and emarginated opposite to the spire, which is short ; 

 the plica- of the columella are numerous, and resemble stria?; the whorls are 

 sulciform. These shells are quite as beautiful as the Cyprsese. 



The animal has a large foot, the anterior part of which (before the head) is 

 separated by an incision on each side ; its tentacula are slender, and the eyes 

 are on their side about the middle of their length. The proboscis and siphon 

 are tolerably long; but it has no operculum. 



The remainder of the genus Voluta was afterwards divided into five, by 

 Lamarck. They are VOLVARIA, VOLUTA, MARHINELLA, MITRA, and CAN- 



CKLLARIA. 



BucciNUiM, Linneetia. 



This genus comprises all the shells furnished with an emargination or a short 

 canal inflected to the left, and in which the columella is destitute of plica?. 



Brugueir has divided them into the four genera of Buccinum, Purpurn, 

 Cassis, and Terebra, part of which have been again subdivided by Lamarck 

 and de iMontfort. The 



BUCCINUM, Brugueir, 



Includes the emarginated shells without any canal, whose general form as 

 well as that of the aperture is oval. The animals, all such as are known, are 

 deprived of the veil on the head, but are furnished with a proboscis, two sepa- 

 rated tentacula, on the external side of which are the eyes, and a horny 

 operculum. Their siphon extends out of the shell. 



NASSA, Lamarck. 



The side of the columella is covered by a more or less broad and thick plate, 

 and the emargination is deep, but without a canal. The animal resembles that 

 of a true Buccinum, and there are gradual transitions among the shells, from 

 one subgenus to the other. 



EB'JRNA, Lamarck. 



A smooth shell without a plicated margin, and a widely and deeply umbili- 

 cated columella. The general form of their shell is closely allied to that of the 

 Olivse. Their animal is unknown. 



ANCILLARIA, Lamarck. 



The same smooth shell, and at the lower part of the columella a marked lip ; 

 there is no umbilicus, neither is the spire sulcated. The animal of several 

 species resembles that of the Olivse, the foot being still more developed. 



DOLIUM, Lamarck. 



Those in which projecting ribs, that follow the direction of the whorls, 

 render the margin undulated ; the inferior whorl is ample and ventrieose. 



