74 



POPULAR CONCHOLOGY. 



Distinguished from Columbella by the canal at the upper 

 part of the aperture. 



Pollia. Gray. — Shell shaped like a Buccinum, but 

 the lower half narrowed, and the middle more or less 

 ventricose, spire and aperture of equal lengths ; inner lip 

 at the base with two or three obtuse and transverse plaits ; 

 outer lip crenated internally, and with a siphon at the 

 upper part. 



These shells are scarcely to be distinguished from 

 Buccinum. 



Pisanta. Bivona. — Shell with numerous in- 

 distinct varices, or smooth and spirally striated ; 

 notched, or with a short canal ; inner lip having 

 in the upper angle a transverse tooth ; outer lip 

 crenulated ; operculum ovate and acute. Animal 

 externally not to be distinguished from Pur- 

 pura. — Many species, also fossil. 



Found on the shores of Africa, India, and 

 America. 



Nassa. Lam. — Shell globular or oval, according to the 

 spire, which is sometimes short, sometimes 

 rather long ; mouth oblong, notched ; inner lip 

 thickened, and spread out, occasionally very 

 large ; right lip often wrinkled ; operculum 

 horny. Animal, with a lunate, not very broad 

 head, bearing two long, acute, tentacula, fili- 

 form beyond the eyes, which are placed in the 

 hind portions, extending for about a third of their length ; 

 proboscis long, retractile, with corneous jaws, and a tongue 

 armed with a triple row of teeth, of which the axile one 

 is broad, sublimate, with numerous serrations, the laterals 

 large and hamate ; the mantle lax, produced into a long 

 recurved siphon, which extends for a considerable distance 



