178 THE RING OF NATURE 



boat if we wish to extend our studies a little 

 further, for the big whelks live beyond low-water 

 mark, where they are usually attracted to pots 

 containing fish or other meat bait, and then hauled 

 up as lobsters are. 



The live whelk placed in a pail of sea water 

 soon extends his horns, his foot, and his siphon, 

 and comes out for a crawl. We see that he carries 

 on the end of his foot a slab of horn called the 

 operculum, which just closes the door when he 

 withdraws into his shell. If we get him to crawl 

 on glass and then look at him underneath, we can 

 see that overlapping the foot is the edge of the 

 mantle not unlike the edge of a man's coat 

 surrounding his waistcoat. If we made a dis- 

 section we should find that the gills are contained 

 in a pocket of the mantle, not unlike the inner 

 breast pocket wherein we keep the most valuable 

 of our papers. In a ticket pocket in the same 

 garment the whelk keeps a smaller set of gills, 

 the function of which is to taste or test the water 

 for purity or other desirable quality. In other 

 words, the whelk's nose is in its ticket pocket. 

 We will not go further to-day into its more intimate 

 anatomy. 



If we do not find many whelks in the rock pools 

 we find plenty of shells. Many are neatly drilled 

 with round holes, showing how some mighty sea 

 monster made a way into the citadel and ate the 

 occupant. That same monster we may find in the 

 shape of a fellow gasteropod, or, at any rate, we 



