42 THE HAUNTS OF LIFE 



Sponges, sea-anemones, acorn-shells are fixed 



animals, and they depend for food on what 



they can sweep in from the water, or on what 



they can catch as it passes by. But we must 



take some examples of more vigorous ways of 



feeding on the part of animals which roam 



about from place to place. The periwinkles, 



such as Littorina littorea, which is one of the 



poor man's "oysters," creep about browsing 



on delicate seaweeds, and it may be noticed 



that those sea-snails which have an unbroken 



outline to the mouth of their shell are vegetarian, 



while those with a deeply in-cut notch at the 



mouth of the shell (a groove for the protrusion 



of a breathing tube) are carnivorous. The 



vegetarian Gasteropods are palatable ; the 



carnivorous ones hardly ever. So if we are 



wrecked on a desert island we must begin our 



seashore meals with those sea-snails that have 



no notch at the mouth of their shell. 



Very different from the periwinkles are the 

 whelks and "buckies" which roam about in 

 search of animal food. We often find on the 

 sandy beach one of the valves of a bivalve 

 shell, e.g. Venus gallina, with a hole neatly 

 bored through it, as neatly as if it had been 

 made by a gimlet. In many cases this hole 



