92 THE SHELL-FISH OF THE COAST. 
ture, and its direct truncature; but the base of the 
inner side of the aperture shows more or less of a 
fold, which is wanting in the whelk. These active 
creatures of the tide-water pools, whose long and 
slender foot constitutes so marked a feature of 
their anatomy, offer an interesting study to the 
lounger on the sands, and even if their habitat is a 
little moist.a pair of rubbers will readily bring you 
to them without discomfort. Observe them gliding 
along the surface of the mud, furrowing the soft 
bottom with their extended foot. A few, possi- 
bly, are floating, with the foot directed upwards. 
The dog-whelk is decidedly predaceous in its habits, 
boring rapidly through the shells of other mol- 
lusks in quest of animal food, and creating gen- 
eral havoc in its neighborhood. Indeed, it feeds 
not only upon live flesh but upon dead flesh as 
well, acting the part of a scavenger. Hence the 
use to which this little creature has been put to 
clean out the foul animal matter from aquaria. 
Its own shell appears frequently pierced with a 
hole, and rumor points towards cannibalism on the 
part of the animal. One of the foreign dog-whelks 
(Nassa reticulata) is known to prove exceedingly de- 
structive to the oyster-fares of the French coast, 
and so numerous is it that a single tide has yielded 
upwards of 14,000 specimens on a shore area of 
about 100 acres. This species has been known to 
bore through the shell of a three-year oyster within 
eight hours, and to destroy an oyster of a single 
month in a half-hour. 
A large proportion of the dog-whelk shells of our 
