MOLLUSC A 



121 



but living in the sea between tide-marks and feeding on 

 seaweeds. These " winkles " are largely used for food ; 

 nineteen hundred tons are said to be annually consumed in 

 London alone ! 



Genus Buccinum undatum is the common Whelk, 



Buccinum. a large snail, having an operculum, and breathing 



Whelks, below the water by a gill, but differing from 



periwinkles, or fresh-water winkles, in being carnivorous ; 



Fig. 74. — The Common Whelk (Buccinum undatum). (Nat. size.) 



also the mantle round the respiratory aperture is drawn out 

 into a long, trough-shaped siphon, 

 causing a distinct notch in the 

 margin of the shell on the left side. 

 The whelk feeds on decaying animal 

 matter, but also on living "shell- 

 fish," such as oysters or periwinkles, 

 sucking out their soft bodies through 

 a hole bored right through their Fig. 75. 

 shells by its strong-toothed rasp, 

 which is carried inside a protrusible 

 snout. This rasp may be an inch long, and bears 220 to 

 250 sharply-pointed teeth (Fig. 75). 



The eggs of the whelk are well-known seaside objects, 

 for they are very often thrown up on the beach by the waves. 



■Two Rows of Teeth 

 from the "Rasp" of a 

 Whelk. 



