XI. The Hydrophilidæ of Ontario and Quebec.

These water-beetles differ from Dytiscidæ especially in having the antennæ terminated by a distinct club instead of being filiform; and while, as the name implies, they are usually found in ponds or streams, they are much more feeble swimmers than the Dytiscids, and are exponents of a more generalized type. Several genera are truly terrestrial in habit, the beetles occurring about decomposing animal matter or in manure. The larvæ somewhat resemble those of the Dytiscidæ in general appearance, but differ so far as my experience goes in having toothed mandibles instead of the single suctorial ones characteristic of the other family. Pupation takes place on land in an underground cell, or in a cavity scooped out beneath a stone or piece of wood.