2 DIPTERA 
Adolphus Lutz, Sao Paulo, Brazil; William M. Mann, Washington, D. C.; C. L. Metcalf, 
Urbana, Ilinois; W. L. McAtee, Washington, D. C.; Harold Morrison, Ithaca, New 
York; William Nason, deceased; H. S. Parish, Toronto, Canada; C V. Piper, deceased; 
F. Rogers, Kansas City, Missouri; Pablo Schild, La Suiza de Turrialba, Costa Rica; R. C. 
Shannon, Washington, D. C.; F. Sherman, New York, N. Y.; Mrs. Annie T. Slosson, New 
York, N. Y.; A. H. Sturtevant, New York, N. Y.; Roland Thaxter, Cambridge, Massachu- 
setts; E. S. Tucker, deceased; M. C. Van Duzee, San Francisco, California; O. S. Westcott, 
deceased; William M. Wheeler, Boston, Massachusetts; P. W. Whiting, Boston, Massachusetts ; 
A. J. Wiedt, Newark, New Jersey; M. A. Yothers, Yakima, Washington. 
A most important set of specimens was secured in the unworked material belonging to the United 
States National Museum and that of the Bureau of Biological Survey. This represents the Empid 
collecting of the Government entomologists and contains much material from the following : J. M: 
Aldrich, H. S. Barber, G. W. Belfrage, F. C. Bishopp, Robert Brown, Owen Bryant, 
August Busck, A. N. Caudell, T. D. A. Cockerell, D. W. Coquillett, Crevecceur, 
R. P. Currie, R. A. Cushman, E. Daecke, George Dimmock, H. G. Dyar, A. K. 
Fisher, O. Heidemann, L. O. Jackson, C. R. Jones, J. R. Malloch, W. L. McAtee, 
J. D. Mitchell, H. K. Morrison, W. D. Pierce, F. C. Pratt, C. V. Riley, S. A. 
Rohwer, E. A. Schwarz, R. C. Shannon, Mrs. Annie T. Slosson, E. S. G. Titus, 
C. H. T. Townsend, L. M. Turner, W. V. Warner and E. B. Williamson. 
Through the courtesy of C. Howard Curran the unworked Empid material belonging to the 
Canadian National Museum has been procured and this collection has added several species to the 
following pages. 
A splendid reference collection of about five hundred determined species from Europe and other 
foreign places has been gathered together through the interest of the following well known dipterests, 
and has furnished a basis for much of the work. 
Theo. Becker, Liegnitz, Germany; Mario Bezzi, Torino, Italy; E. Brunetti, Calcutta, 
India; E. O. Engel, Dachau, Germany; Richard Frey, Helsingfors, Finland; F. Hermann, 
Berlin, Germany; F. W. Hutton, New Zealand (deceased); K. Kertész, Budapest (deceased); 
William Lundbeck, Copenhagen, Denmark; David Miller, Wellington, New ZA; Lorenz 
Oldenberg, Berlin, Germany; Gabriel Strobl, Admont, Austria. : 
In the preparation of this work there have been studied the types of eighty-five per cent. of the 
North American species, amounting to nearly four hundred species. The remainer, the types of the 
species described by Say, Macquart, Bigot, Walker and Osten-Sacken, are either no longer 
in existence or are not available to the American student. 
The following pages include a discussion of the genera of the Empididz, a list of the known 
species together with their bibliography, descriptions of new forms, and here and there tabular keys to 
species, particularly to those of North America. (Unless otherwise designated the types of the new 
species are in the author's collection. "Where no individual is mentioned by name as collector for the 
new species, the material has been collected by the author. : 
This study was presented at Harvard University in 1914 in fulfillment of the thesis requirement 
for the degree of Doctor of Science. At that time the breaking out of the World War and its centrali- 
zation in Belgium precluded publication in Wytsman's Genera Insectorum, and the report has 
been held in abeyance during the meantime. It is now presented with the inclusions and modifications 
necessitated by the lapse of ten years. 
Contribution no240 from the Entomological Laboratory of the Bussey Institution 
for Applied Biology, Harvard University. 
