[February 1885. BULLETIN BROOKLYN ENTOM. SOC. VOL. VII. 129 
On the classification of North American Diptera. 
(First paper.) 
By Dr. S. W. WIL Liston. 
It is proposed here, in order to render the study of the neglected 
order of diptera less difficult, to present tabular synopses of the families 
and genera, with remarks upon their structure and external characters. 
The work involved is necessarily very great, and the families can— 
not at present be given in their natural sequence.. The next paper will 
shortly be ready, containing a classification of the Xylophagidae and 
Stratiomyidae, and some time during the year will follow one giving a 
tabular classification of the families, with plates showing the more im- 
portant structural characters. The present paper is extracted froma 
monograph of the North American Syrphidae, now ready for the 
press. Itis the result of a careful study of nearly two hundred and 
seventy five species, occurring within our limits. The following figure 
will explain sufficiently the terms here used; a discussion of the termino- 
logy of the order will accompany the paper on the family classification. 
ee lone. Auxilv Cost.v. 
TOCOSUAC, 
Posten ' ; 
Ant.cyoss-vi 6.U.v. '5.lone.v. 
Pst. basal. crost-v. 
CHARACTERS OF THE FAMILY SYRPHIDAE. 
A false longitudinal vein between the third and fourth longitudinal ves ; 
fourth longitudinal vein united al its extremity with the third; one sub- 
marginal cell, three posterior cells; basal cells large; face without subanten- 
nal grooves, two pulvilli. 
Head hemispherical, often elongated or produced in the lower part, 
as broad or a little broader than the thorax. Face moderately broad, bare, 
or clothed with short pile or dust, excavated in profile under the antennze 
and projecting below, or with a distinct protuberance near the middle 
part: never with longitudinal furrows or lateral ridges, usually convex 
transversely, sometimes with a median ridge. Oral opening large; pro- 
_ boscis rarely much elongated, usually but little projecting, and, when 
