The present List of the North American Sphingidæ or Hawk Moths embraces the principal features of my former Lists, in particular the division into groups, retained by Butler and lately by Fernald. I have originally in our Synonymical Catalogue (1865) proposed the genera Macroglossa, Chœrocampa, Smerinthus and Sphinx as typical of the four principal groups recognized by me. A fifth group, represented by the Old World genus Acherontia, seems to me to fall in between the Smerinthinæ and Sphinginæ. It seems to me unimportant whether we consider these groups as Tribes, with the ending ini to the terms, or as Subfamilies, with the ending inœ. I am myself of the opinion that these divisions are only of tribal value, and should prefer to so designate them. But, under this view, the Family Sphingidæ, as here considered, would remain only of Subfamily value, somewhat as intended by Dr. Harris, whose “tribes” have a wider significance, whereas I intend by “tribes” assemblages of genera subordinate in rank to Subfamilies, and as intended by LeConte in Coleoptera. These matters must be left, however, to final revisions of our classification. At this moment I am interested, in view of Prof. Fernald's recent valuable paper, in defending my sequence of the genera and groups as laid down in my former papers.