This monograph is the first compilation of all known data on fossil rodents in North America. The author includes illustrations of all fossil families of rodents, the phylogenies for all familes, a discussion of the problematical taxa of rodents which are not referable to known families, and lists of all described fossil species. His work will serve as an indispensible reference for the paleontologist who wishes to identify specimens, and for the mammologist studying fossil history.