REVISION OF THE TACHIXID.E OF AMERICA 
NORTH OF MEXICO. 
NATURE AND SCOPE OF THE WORK. 
The present paper is the result of several years' study, and is based 
upon the large series of specimens contained in the National Museum 
collection, mainly received from this office, supplemented by those in 
my own and those received for study and identification from various 
correspondents, among whom may be mentioned: Mr. C. W. Johnson, 
Dr. Garry deX. Hough, Mrs. A. T. Slosson, Dr. W. A. Xason. Mr. 
Charles Robertson, Mr. Theodore Pergande, Mr. F. H. Chittenden, 
Prof. H. E. Weed. Mr. R. W. Doane, and L'Abbe Begin. The series 
in the National Museum collection is especially valuable, containing as 
it does a large number of bred specimens, which, more than anything 
else, enables us to correctly judge of the extent to which the various 
specimens of the same species will vary among themselves. This col- 
lection also contains a duplicate set of a series of specimens sent to 
Brauer and Bergenstamm, of Vienna, Austria, in exchange for a 
named series of European forms, and the latter have been very val- 
uable for comparison with our own genera and species. These authors 
returned names, principally generic, of the series sent to them, and 
in the following pages I have indicated these identifications as "mi 
litt." Mr. C. II. T. Townsend kindly sent to the Museum cotypes 
of many of his new species, and Mr. Charles Kobertson generously 
donated specimens from the same series as those from which Mr. 
Townsend described several of his new forms. 
The region covered by this paper includes all of this country north 
of Mexico, but does not take in any of the West Indies. When the 
faunas of these two regions have been carefully compared with our 
own, many additional species will no doubt be found to inhabit two or 
even all of these regions. 
HABITS OF THE FAMILY. 
Among the fifty odd families into which the Diptera of this country 
have been divided, the Tachinidse is by far the most beneficial, judged 
from the standpoint of an agriculturist. The only other family that at 
all competes with it for this honor is the Syrphidae; but in this family 
