In the autumn of 1890, I was leaving the Casino at Monte Carlo in company with an eminent Divine, whose name, for obvious reasons, I suppress. We were engaged in an interesting discussion on the subject of Demons, he contending that they were an unnecessary, not to say prejudicial, element in our civilisation, an opinion which, needless to say, I strongly opposed. Having at length been so fortunate as to convince him of his error, I proceeded to furnish him with various instances in which Demons have proved beneficial to mankind, and at length he exclaimed. “My dear fellow, why do you not write a book about . . .” Here he coughed. The idea took so strong a hold upon me, that from that time I have taken more careful note of the habits and appearance of such specimens as come in my way, and my studies have resulted in the production of this little work, which will, I trust, prove not uninteresting to the youthful seeker after knowledge.