28 ENTOMOLOGICAL SOCIETY while such a feature is abnormal under the circumstances, it is no more so than many of the other features of Platypsyllus. In the discussion of this subject, Mr. Schwarz held that, if not the ultimate larva of Platypsyllus, it is certainly Coleopter ous, and cannot be referred to the Mallophaga, In the Coleop-tera, the Staphylinid genus Amblyopinus is known to be par asitic on terrestrial rodents, two species having been found in the fur of mice and rats, one in South America and the other in Tasmania. We might reasonably expect to find this genus in North America under similar circumstances, but a glance at Prof. Riley's larva shows that it cannot possibly belong to the Amblyopinus nor to any other genus of Staphylinidae. Dr. Marx read the following paper : A CONTRIBUTION TO THE KNOWLEDGE OF NORTH AMERICAN SPIDERS. BY DR. GEO. MARX. In a large collection of natural history objects from all parts of this country the student will find some specimens, which,, by their peculiar and strange morphological features, he cannot place in any of the established families. They lie, conse quently, buried in the collection, and are thus lost to science. I possess in my collection of North American Arachnida a number of such new forms, which I have hitherto been unable to place in any established family. The principal cause of this difficulty is that the American Arachnologist has still to fol low the classification of the European Arachnida, and that no attempt has so far been made to work out, independently, a sys tematic arrangement, based upon the spider fauna of America. Mr. B. Simon has lately published a list of families of extra-European Aranese in a systematic order,* and he has promised f * Simon, in his " Remarques stir la Classification des Araignees " (Etudes Arachnologiqu.es, 22e memoire, Annales Soc. Bnt., France, 1890, p. 79), presents a "succinct tableau " of the families of Aranece, including those which he had to establish for extra-European Spiders. He withdraws two of his former suborders, the GnaphosfC and Ocu later (L,es Arachnides de France, Vol. I, p. 14), leaving only the Theraphosce and the Aranece verce. These latter denominations Simon prefers in place of Tetrapneumdnes and Dipnemuones, as these names indicate some characters which are subjected to some exceptions, e. g., Hypochi-lidce, which he places amongst the Aranefe vera. The author divides the hitherto described spiders into thirty-nine families, of which eighteen are established upon exotic genera.