This is the first of a series of papers dealing with the Menoponidae of North America, in which it is hoped that each genus can be discussed and illustrated. The author wishes to acknowedge the kindness of Dr. G. F. Ferris in lending the Stanford Collection, containing V. L. Kellogg's type material, which is being used in these studies; and of Dr. C. F. Mr. Musebeck, for the loan of material from the United States National Museum.