600 THE WENTLETRAP AND THE PHEASANT-SHELLS. 



Now, however, its glory has departed, for a tolerably good specimen 

 may be procured for a few shillings, and a Wentletrap which would a 

 few years ago have been sold for fifty pounds can now be purchased 

 for fifteen shillings. 



Putting aside, however, the question of rarity or cost, this shell is a 

 verv interesting one, both for its beauty and for the mode of its con- 

 struction. It is purely white and partly transparent, the elevated 

 ridf'es being of a more snowy white than the body of the shell, on ac- 

 count of their superior thickness, which does not permit the light to 

 pass through them, as in the case of the thinner body. The whorls of 

 this shell are separate from each other and apparently bound together 

 only by the projecting ridges, so that the general appearance is as if a 

 long conical tube had been loosely coiled and each whorl kept in its 

 place l)y a succession of shelly elevations. This beautiful shell is found 

 in the Indian and Chinese seas. 



The Common or False Wentletrap, is a species tolerably plentiful 

 upon our coasts. 



In this shell the whorls are united together and furnished with a 

 number of circular elevations, which, however, are not nearly so bold 

 as those of the preceding species, but thick in proportion to their height, 

 set obliquely on the shell, and smooth. 



We now arrive at another family, termed the Litorinidse, or Shore 

 Molluscs, because the greater number of them frequent the coasts and 

 feed upon the various algse. The shell is always spiral and never 

 pearly, by which latter characteristic it may be distinguished from 

 certain shells belonging to another family, but somewhat similar in 

 external appearance. The aperture is rounded. The animal has 

 its eye set at the outer base of the tentacles, and the foot is remarkable 

 for a longitudinal groove along the sole, so that in the act of walking 

 each side advances in its turn. The tongue is rather long, and is armed 

 with 'a formidable series of sharp teeth that serve admirably for the 

 purpose of scraping away the vegetable matter on which the animal 

 feeds. The operculum is horny and rather spiral. The common 

 Periwinkle (Litorina litorea) is the most familiar example of this 

 family, and is too well known to need any detailed description. The 

 Periwinkle is found upon our rocks in great profusion, occupying the 

 zone between high and low water and always being found near the edge 

 of the tide. 



In former days the Pheasant-shells were articles of great price 

 and rarity, some specimens almost rivalling the precious wentletrap 

 in the enormous sums asked and obtained for them. Now, however, 

 that their habitations have been discovered and more frequent voy- 

 ages are made, they have become comparatively plentiful, although, 

 irom the fragility of their structure, a perfect specimen is not at 



