Corix� vary much in size, the largest and one of the commonest species being the Corixa geoffroyi, which is about half an inch long.

Corixæ, which thrive in ponds and sluggish waters, should always be introduced.

In the louse, the embryo, late in its life, resembles the embryos of other insects, even Corixa, a member of a not remotely allied family.