COLEOPTERA. 473 
A small species, Hydrous caraboides, is commoner than the large 
one; its body is more rounded behind. 
We are now going to consider a series of aquatic and carnivorous 
insects : the Dytisci, Water Beetles, the Cybisters,and the Gyrinide, 
or Whirligig Beetles. These are perfect corsairs, whose rapacity 
even exceeds that of many of the land Coleoptera. Not contented 
with devouring one another, when pressed by hunger, with attack- 
ing especially the larvee of all aquatic insects, such as the Libel- 
lule and Ephemere, they feed also on molluscs, on tadpoles, and 
on small fish. It is easy to rear them in captivity. If confined 
in a small aquarium, their habits would be much more amusing 
than a few golden fish, which one meets with everywhere, and 







Fig. 473. —Dytiscus marginalis, male and female, and front leg of male magnified. 
which are only good enough to amuse European Schaabahams. 
Care must be taken to cover the aquarium at the top with gauze, 
to prevent the perfect insects from escaping. This tribe is not 
very numerous, nor varied in its forms. An oval body, legs 
_eurved and widened into oars, provided with hairs, distinguish 
the insects which compose it. They imbibe air at the surface of 
the water, like porpoises. 
The most carnivorous of this group are the Dytisci and the 
Cybisters. They may be called the sharks of the insect world. 
Nothing which lives in the water is safe against the voracity of the 
Dytiscus. They attack small molluscs, young fish, tadpoles, larvee 
of insects, and suck greedily the bits of raw meat which are thrown 
