2 PROCEEDINGS OF THE NATIONAL MUSEUM, VOL. 62. 
location of the material in brackets. In the listing of specimens ab- 
breviations are used for the names of institutions which have furnished 
material: M.C. Z.= Museum of Comparative Zoology, Cambridge, 
Massachusetts; A. N.S. P. = Academy of Natural Sciences of Phila- 
delphia; Canad. coll. = National Canadian collection at Ottawa; 
Harrisb. coll. = Department of Agriculture, Harrisburg, Pennsylvania; 
Amer. Mus. = American Museum of Natural History, New York City; 
B.S. N. H. = Boston Society of Natural History. 
The writer greatly appreciates the generous loan of material during 
the study of the Therevidae and wishes to thank the following ento- 
mologists for their assistance: Mr. W. L. McAtee, United States 
Biological Survey; Mr. E. P. Van Duzee, California Academy of 
Sciences; Mr. M.C. Van Duzee, Buffalo, New York; Mr. Nathan Banks, 
Museum of Comparative Zoology in Cambridge, Massachusetts; Dr. 
O. A. Johannsen and Prof. M. D. Leonard, Cornell University; Mr. H. 
Kahl, Carnegie Museum; Mr. R. S. Sherman, Vancouver, British 
Columbia; Dr. C. P. Alexander, Illinois Laboratory of Natural History; 
Mr. I. T. Cresson, jr., Philadelphia Academy of Natural Sciences; Mr. 
H. H. Knight, University of Minnesota; Prof. R. A. Cooley, University 
of Montana; Mr. C. H. Curran, Orillia, Ontario, Canada; Prof. J. S. 
Hine, Ohio State University; Dr. S. J. Hunter, Kansas University; 
Dr. J. McDunnough, in charge Canadian collection of insects at 
Ottawa; Dr. F. E. Lutz, American Museum of Natural History, New . 
York City; Mr. A. B. Champlain, department of agriculture, Harris- 
burg, Pennsylvania; Dr. J. M. Aldrich, United States National 
Museum; and Mr. M.C. Lane, United States Bureau of Entomology. 
The writer is especially indebted to Mr. C. W. Johnson for the loan 
of material from his personal collection and from the collection of the 
Boston Society of Natural History and also for notes on various 
species. To Prof. R. W. Doane, of the department of entomology at 
Stanford University, thanks are due for many helpful suggestions 
during the course of the work and for aid in the final preparation of 
the paper for publication. Maj. E. E. Austin has kindly examined 
the types of Walker’s species in the British Museum, and the writer 
is indebted to him for notes on these specimens and for comparison 
of specimens of Thereva vialis with the closely allied Thereva annulata 
Fabricius of Europe. 
HISTORY OF CLASSIFICATION OF FAMILY. 
In the year 1796 Latreille established the genus Thereva.' The 
flies of this genus were, previous to this, placed in the old genus 
Bibi of Fabricius and Musca Linnaeus. In 1838 Zetterstedt founded 
the genus Psilocephala and about two years later Macquart and 
Wiedemann described a number of species in the family. In 1874 
1 Précis des Caractéres génériques des Insectes, etc. 
