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 vege- 
tarian, while those with a deeply in-cut notch 
at the mouth of the shell (a groove for the pro- 
trusion 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 
