One of a race of highly improper demons who, though probably not wholly extinct, may be said to have seen their best nights. For a complete account of _incubi_ and _succubi_, including _incubae_ and _succubae_, see the _Liber Demonorum_ of Protassus (Paris, 1328), which contains much curious information that would be out of place in a dictionary intended as a text-book for the public schools. Victor Hugo relates that in the Channel Islands Satan himself -- tempted more than elsewhere by the beauty of the women, doubtless -- sometimes plays at _incubus_, greatly to the inconvenience and alarm of the good dames who wish to be loyal to their marriage vows, generally speaking. A certain lady applied to the parish priest to learn how they might, in the dark, distinguish the hardy intruder from their husbands. The holy man said they must feel his brown for horns; but Hugo is ungallant enough to hint a doubt of the efficacy of the test.