GASTEROPODA PECTINIBRANCHIATA. 265 



j Lin. 



So called from the conical shape of the shell; the spire, either perfectly flat, 

 or but slightly salient, forms the base of the cone, the apex being at the 

 opposite extremity; the aperture is narrow, rectilinear, or nearly so, extend- 

 ing from one end to the other without enlargement or fold, either on its 

 edge or on the columella. The thinness of the animal is proportioned to 

 the narrowness of the aperture through which it issues; its tentacula and 

 proboscis are highly protractile; the eyes are placed on the outer side of the 

 former, and near the point; the operculum, situated obliquely on the hind 

 part of the foot, is too narro vv and short to close the whole of the aperture. 

 The shells of this genus, being usually ornamented with the most beauti- 

 ful colours, are very common in cabinets. The seas of Europe produce 

 very few. 



, Lin. 



The spire projecting but little, and the aperture narrow and extending from 

 one extremity to the other; but the shell, which is protuberant in the mid- 

 dle, and almost equally narrowed at both ends, forms an oval, and the 

 aperture in the adult animal is transversely wrinkled on each side. The 

 mantle is sufficiently ample to fold over and envelope the shell, which at a 

 certain age it covers with a layer of another colour. The animal has 

 moderate tentacula, with the eyes at their external base, and a thin foot 

 without an operculum. 



The colours of these shells, also, are extremely beautiful; they are ex- 

 tremely common in cabinets, though with very few exceptions they all in- 

 habit the seas of tropical countries. 



OVULA, Brug. 



The shell is oval, and the aperture narrow and long, as in Cyprxa, but with- 

 out plicae on the side next to the columella; the spire is concealed, and the 

 two ends of the aperture equally emarginated, or equally prolonged in a 

 canal. The animal has a broad foot, an extended mantle which partly folds 

 over the shell, a moderate and obtuse snout, and two long tentacula, on 

 which, at about the third of their length, are the eyes. 



TEREBEHUM, Lam. 



An oblong shell, with a narrow aperture, without plicae or wrinkles, and in- 

 creasing regularly in width to the end opposite the spire, which is more or 

 less salient, according to the species. The animal is not known. The 



VOLUTA, Lin. 



Varies as to the form of the shell and that of the aperture, but is recognized 

 by the emargination without a canal which terminates it, and by the salient 

 and oblique plicae of the columella. From this genus Brugieres first separa- 

 ted the 



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