BUCCINUM. WHELK. 83 



their spire is retuse and marked at intervals by 

 curved ridges which are the permanent margins 

 of the former apertures, and are interesting, as 

 marking clearly the various stages of the shell's 

 increase. The Helmets are very common, and 

 many are remarkable on account of their size and 

 solidity. One species (the Buccinum Cornutum) 

 is more than a foot in length. These shells are 

 handsome and are often used as ornaments in 

 rooms. They are found mostly in topical seas, dis- 

 tant from the shores, in sandy bottoms where 

 the animal buries itself in search of prey. They 

 form the modern genus Cassis. 



The most beautiful shells of this genus are 

 called Harps ; * they have an elegant shape, rich 

 tints, and usually a glossy surface ; their form 

 is oval, spire short, aperture large, notched at 

 the base, the inner lip is spread over a portion of 

 the body whorl, the outer lip is thickened and 

 rolled outwards. The animal produces this 

 thickened revolute lip at different periods of its 

 growth, thus forming a number of elevated 

 ridges on the shell. Such marks of increase are 

 observable in many other marine shells, and in 

 a few land species; but in none are they more 

 numerous than in the Harps. The effect 

 of these ribs is very rich and pleasing. The 

 Harps are found in the seas of hot climates, 

 particularly near the Isle of France. The genus 

 they now form is called Harpa. 



* Plate III. fig. 2. 

 G 2 



