2) Tue BLOWFLIES OF NortH AMERICA 
are 83 species belonging in 27 genera recognized from this re- 
gion. Of these, 15 species and 6 genera are described as new. 
The work has been prepared for the use of entomologists, pub- 
lic health officials, physicians, veterinarians, biologists, and stu- 
dents. The keys are designed to assist in the rapid determination 
of the species and, together with the detailed descriptions and 
the illustrations of the more significant morphological ‘eae 
are diagnostic of all the known species from this area. 
Acknowledgements. I find myself indebted to so many in- 
dividuals for so great a variety of assistance, much of it indirect, 
that a complete acknowledgement of leanaie received can 
scarcely be given. An attempt has been made to give a biblio- 
graphy of sources of much of the published information in- 
cluded on biologies and habits, but it has not beén possible to 
show them all. This information has been abstracted from papers 
of biologists all over the world, but especially from papers ori- 
oinating in the Division of Insects Affecting Man and Animals, 
Bureau of Entomology and Plant Quarantine, and I am ars 
ful to the authors of these papers for their assistance. 
This study is based principally upon collections in the United 
States National Museum and upon material personally reared 
and collected. All of the abundant forms were studied and 
reared in the field during the progress of the study and many of 
the species were reared from egg to adult upon numerous oc- 
easions. Other institutions furnishing considerable material are 
American Museum of Natural History, British Museum (Natural 
History), Colorado State College, Commonwealth Council for 
Scientific and Industrial Research, Canberra, F. C. T., Australia, 
Cornell University, Emory University, Field Museum of Natural 
History, Illinois Natural History Survey, Iowa State College, 
Iowa Wesleyan College, Massachusetts Agricultural College, 
Ohio State Museum, Ohio State University, Oregon State Agri- 
cultural College, University of Alberta (Canada), University of 
Idaho, University of Kansas, University of Washington, Utah 
State College, and the Division of Insects Affecting Man and 
Animals, Bureau of Entomology and Plant Quarantine. Valu- 
able material from the collections of T. H. G. Aitken, W. W. 
Baker, A. J. Basinger, E. C. Cushing, Alexander Cuthbertson, 
_R. H. Daggy, D. G. Denning, E. O. Engel, P. W. Fattig, E. F. 
Knipling, Wm. L. Jellison, M. C. Lane, David F. Miller, J. F. 
Neff, R. L. Post, M. P. Riedel, C. W. Sabrosky, F. M. Snyder, 
J. Wilcox, and James Zetek was also examined. Notwithstanding 
the large amount of material studied, doubtless a good many 
species remain to be discovered and the biologies and immature 
