30 
when situated near the middle of the length of the segment, and mar- 
ginal when located near its posterior margin. 
The veins and cells of the wings are called by the same terms as in 
the other families of Diptera, except that the first posterior cell is com- 
monly called the apical, and the portion of the fourth vein beyond the 
bend is sometimes termed the apical crossvein. 
TABLE OF GENERA. 
The only attempt at publishing a synoptic table, comprising all of the 
genera reported as occurring in North America, is that by Mr. ©. H. T. 
Townsend, in the Proceedings of the Entomological Society of Wash- 
ington! and in the Transactions of the American Entomological Soci- 
ety.’ That in the former publication is a reprint of the table given by 
Dr. Schiner,*? and that in the latter a reprint of the one by F. M. van 
der Wulp,! both modified so as to comprise only the North American 
genera. As the author did not have access to specimens of many of 
these genera, and as the characters he uses are in many cases not of 
specific, much less of generic, value, the result is not altogether satis- 
factory, and I have therefore constrneted an entirely new table, 
which, however, includes only those genera from America north of 
Mexico of which I have examined representatives. <A list of the remain- 
ing genera reported from this region is giveu at the end of the table. 
In some eases doubt will arise as to which section a given genus 
should be referred, but in such cases, at least so far as they occur to 
the writer, the genus is placed in both sections: 
1) Abdomen provided with trueimacnochcetze 22. 2-— ee =e - eee eee eee 8. 
Abdomen destitute of macrochietie, apical cell ending at or near the extreme 
WME Neooos aeeaso5 Sond poe ees Geos Heo scsocus sasedmecman socss4 Saas 5ceape 2. 
2. Upper side of abdomen very couvex, abdomen subhemispherical, sides of face 
IDURD ppaoccowops pecuioce adadocd bosoao dean sop Ese dodo se Se nee Sane Sacee oaeaccos 3 
Upper side of abdomen flat, or the abdomen elongated and cylindrical....-.. 4. 
3. Antenne not reaching lower third of face-_------<=---- -.2-<- (p. 42) Cistogaster. 
Antenne reaching lowest fifth of face, or even lower----.--- (p. 48) Gymnosoma. 
4, Hind tibie outwardly not ciliate w a scales.aas-hiecees SE a eee 5. 
Hind tibize ciliate with nearly erect scales, sides of face bare.-(p.47) Trichopoda. 
By OES) Ce TENE) WENN 2S 48 © Goce eo esos sees ead. ces aagsor Sus Sous cocoeo aseSay seesce 6. 
Sides of face bristly, third and fourth veins almost equally converging toward 
their tips, which meet or almost meet each other-.---. -- (p. 49) Gymnophania. 
6. Proboscis at most slightly longer than the head, geniculate near the base only, 
antenne at most reaching slightly below middle of face, apical cell closed, the 
petiole at least twice as long as the small crossvein.-.....--..--------- ---- 7 
Proboscis bristle like, almost as long as the body, geniculate near the base and 
alsomear themiddlemesees sess en eee ere eee eae (p. 49) Lusiphona. 
1Vol. II, pp. 92 to 99; April 2, 1891. 
2Vol. XIX, pp. 184 to 141; June, 1892. 
3Fauna Austriaca, Diptera, Vol. 1, pp. UNX to LXXT; 1862. 
4 Biologia Centrali-Americana, Diptera, Vol. II, pp. 5 to7, and 41 to 44; 1888 and 1890. 
