CRAB-LICE, a troublesome kind of vermine, which stick so fast with their claws to the skin as to render it difficult to dislodge them. They are called pluctule, morpiones, petole, and pessolae: they usually infest the arm-pits and pudenda. Cleanliness is the best preventive. But these vermine may be easily removed with the application of a little mercurial ointment.