82 UNIVALVES. 



bous ; aperture ovate, effuse at the base, ending 

 either in a notch, or a short canal abruptly 

 curved and turning to the left, that is, from the 

 outer lip ; columellar lip flattened, 



OBSERVATIONS ON THE SHELL AND ITS 

 INHABITANT. 



The characters which principally distinguish 

 this genus do not always occur in each species. 

 The most invariable mark of distinction is the 

 direction of the canal to the left ; and should this 

 fail, as is the case in a few instances, the thick 

 gibbous form or the flattened columellar lip will 

 still point out the proper situation of the shell to 

 be amongst the Buccina. 



One division of this genus is known by the 

 common name of Tuns ; and the scientific one of 

 Dolium. These shells are thin, brittle, turbi- 

 nate, of an inflated or globular form, transversely 

 ribbed, having a large aperture with a notch at 

 the base. The type is the Buccinum Dolium.* 



Many of the Buccina belong to a family called 

 Helmets, f and are distinguished by their inflated 

 turbinate form, and by their short beak abruptly 

 reflected ; their columellar lip is thickened and 

 spread over the body whorl, forming a flat ex- 

 pansion ; their outer lip is also revolute, and 

 often dentated ; their spire is retuse and marked 



* Plate III. fig. 1. f Plate III. fig. 3. 



J Revolute, rolled back. 

 Dentated, toothed, from Latin, dens, a tooth. 



