commonest molluscs, one is a vegetable feeder. It is found living on water
plants, the snails being of all sizes, from that of a mustard seed to a
walnut. The other will feed not only on dead animal substances, but on
living creatures, and is equipped with sharp teeth, which work like a saw.
One of these kept in an aquarium fastened on to and slowly devoured a
small frog confined in the same vessel. The large dytiscus beetle is the
great enemy of small fish. If the salmon is ever restored to the Thames
these creatures will be among the worst enemies of the fry, though in
swift rivers they are not plentiful. Frank Buckland states that in
Hollymount Pond they killed two thousand young salmon. One of these was
put into a bowl with a dytiscus beetle, which, "pouncing upon him like a
hawk upon an unsuspecting lark, drove its scythe-like horny jaws right
into the back of the poor little fish. The little salmon, a plucky fellow,
fought hard for his life, and swam round and round, up and down, hither
and thither, trying to escape from this terrible murderer; but it was no
use, he could not free himself from his grip; and while the poor little
wretch was giving the last few flutterings of his tail, the water-beetle
proceeded coolly to peck out his left eye, and to devour it at once." The
larva not only of the carnivorous dytiscus but also of the
vegetable-feeding water-beetle are ferocious and carnivorous, and deadly
enemies of young fish and ova.

[1] In mentioning some of the Thames _insecta_ I have also noticed some of
the _mollusca_ and _crustacea_. It is a pity these have not some common
names. One cannot write easily of "pulmonate gasteropods."




"THE CHAVENDER OR CHUB"