There being no published list of the American species of Thysanoura, I have thought it advisable to bring my notes together in a connected form. The names adopted are based on a careful study of many specimens from all parts of the country, and the arrangement of families and genera is a combination of that of Tullberg, Lubbock, and Comstock. I have preceded the catalogue by a list of the more important papers containing descriptions of American species, and I have followed the names of all those species known to me by an exclamation point.