The most insupportable of all these diseases is the one which, after its Greek appellation, is known to us as "lichen."[1] In consequence, however, of its generally making its first appearance at the chin, the Latin's, by way of joke, originally—so prone are mankind to make a jest of the misfortunes of others —gave it the name of "mentagra;"[2] an appellation which has since become established in general use. In many cases, however, this disease spreads over the interior of the mouth, and takes possession of the whole face, with the sole exception of the eyes; after which, it passes downwards to the neck, breast, and hands, covering them with foul furfuraceous eruptions.