EE VISION OF THE NORTH AMERICAN EMPID.E— A FAMILY OF TWO-WINGED INSECTS. By D. W. COQUILLETT, Honorary Custodian of the Collection of Diptera. The present paper, which is entirely preliminary in its character, is based upon a study of the rich material contained in the collection of the United States National ^Museum, supplemented by my own collec-tion and the specimens received from several correspondents, notably from Dr. W. A. Nason, of Algonquin, Illinois; Annie Tinimbull Slosson, of New York City; Mr. Charles Robertson, of Carlinville, Illinois, and Prof. Howard Evarts Weed, of Agricultnral College, Mississippi. I desire in this place to thank all of those who by the gift or loan of specimens or in other ways have aided in the preparation of this paper, and especially the authorities of the United States National Museum, for the privilege of studying the fine series of specimens in the collection of that institution. Types of the new species, not jireviously possessed by the Museum, have been deposited with it. With all this material before me, however, there are still several spe-cies of which I have seen no representative, and in the tables which accompany this paper I have in several instances been compelled to make use of only those characters mentioned in the existing descrip-tions. These tables, despite these imperfections, have been very use-ful to me in identifying the species, and they are given in the hope that other students nmy find them equally helpful. Only those genera iu which new species are herewith described are tabulated in the present paper, which deals only with the North American forms. In Osten Sacken's Catalogue of the Described Diptera of North America, twenty-four genera of Empidie are credited to our fauna. The following observations on some of them may not be out of place here: Tachydromia. — The species catalogued under this genus belong to PlatypaJpus. Tachypeza. — The species placed under this genus belong to Tachydro-viia. Macquart restricted the latter name to the present grouj) and applied the name PJatypalpus to the preceding group three years before Meigen proposed the name Tacliypeza for the jiresent group; conse-quently Macquart's name, being the earlier, must be retained. This Proceedings of tlio Uuited States National Museum, Vol. XVIII — Xo. 1073. 387
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