Since the revision of this genus by the late Dr. Hulst, in 1884, contributions to our knowledge have not been extensive, while the material gathered in recent years has been very great. The popularity of the genus among students of Lepidoptera had made the necessity for a revision very keenly felt, so that when Prof. French generously undertook the work, a year or so ago, a feeling of gratitude was aroused by enthusiasts, who have known the thoroughness with which his work would be attended.