In order to avoid needless repetition, I wish here to express my sincere thanks to Prof. John B. Smith and Dr. H. G. Dyar for numerous favours, and also to Mr. O. C. Poling for his great liberality in furnishing me with many of the species here described. Mr. Poling has made a number of collecting trips to little known parts of Arizona and Utah, and in addition to many new species has turned up many rare forms discovered years ago by Morrison and Doll. The fauna of Southern Arizona is essentially Mexican, and as there is at present no collection of Mexican Lepidoptera in this country worth mentioning, one in describing apparently new species from that region is certain to make synonyms.