No. 13. — The Geophiloidea of the Southeastern States. By Ralph V. Chamberlin. Our knowledge concerning the Chilopoda of the southeastern section of the United States has long been so meager and fragmentary, that it is considerable satisfaction to present a revision of the Geo-philoidea of the region based upon the study of rather extensive material. Most of this material was secured by the author himself through systematic collecting carried out during the summer of 1910, every section of the region being visited excepting southern Florida (which, as belonging rather to another fauna, is not included) and the coastal portions of Georgia and the Carolinas. It has been possible to ascertain somewhat clearly the limits of distribution of a number of important species together with the range and directions of their variations and thereby to bring about simplification through the relegation to synonymy of many names given to forms of non-specific grade. All the species previously recorded from the region were secured, as well as representatives of a number of undescribed ones, among which are the types of two genera for which it seems necessary to erect a new family. Of importance, also, was the rediscovery of Bollman's Scolioplancs gracilis, later made the type of the genus Agathothus, the affinities of which have for twenty years been in doubt, no diagnosis having heretofore been published. Dr. Meinert's types of North American species in the collection of the Museum of Comparative Zoology have been available for study and comparison during the preparation of this paper. The types of the new species are also in the collection of the Museum. The following list is introduced by way of summary; synonyms are printed in italics. GEOPHILIDAE. GEOPHILINAE. Polycricus Humbert and Saussure. P. floridanus Cook = P. marginalis (Meinert). P. marginalia (Meinert).