28 DIPTERA OF NORTH AMERICA. 



The N. A. species which I know belong to the genera: 1. Co- 

 nops Linn., 2. Zodion Latr., 3. ^SIy ova. Latr., 4. Stachynia Macq. 



Fam. xxiy. pipuxculidae. 



Charact. — Three basal cells much prolonged, the hindmost closed near the 

 border of the wing ; third longitudinal vein simple, the fourth 

 sometimes almost entirely wanting, sometimes furcate when perfect ; 

 no intercalary vein. Head almost entirely occupied by the eyes, 

 front and face exceedingly narrow ; antenna? with a basal bristle. 

 Hypopygium unsymmetrical. Tibiae without spurs ; empodium 

 wanting. 



This family only comprises the three genera: Xeurophocerus 

 Zett., Pipunculus Latr. and Chalarus Walk. 



The X. A. species known to me belong all to the genus 

 Pipunculus Latr. 



Fam. XXV. SCEXOPINIDAE. 



Charact. — Three basal cells very large ; the third closed rather far from 

 the border of the wing ; third longitudinal vein furcate ; no inter- 

 calary vein ; third joint of the antennae without style or bristle. 

 No empodium. 



This family possesses so many peculiarities that it is very difficult 

 to find a fit place for it among the other families, though it ex- 

 hibits much affinity with some of them. I would especially point 

 out the Bombylidce as deserving a closer comparison in order to 

 investigate their true relationship. At present it seems best to 

 follow those authors who have considered the genus Scenopinus 

 as the type of a separate family. 



Some species of Scenopinus occur in N. A. 



Fam. XXVI. PLATYPEZIDAE. 



Charact. — Three basal cells rather large, the hindmost always ending 

 acutely, at more or less distance from the border of the wing ; third 

 Longitudinal vein simple; no intercalary vein. Antenna 1 with an 

 apical bristle. Hypopygium symmetrically turned under the abdo- 

 men. Middle tibiae with spurs ; empodium wanting. 



The genera which belong to this family are : Peatypeza Mrig., 

 Cali.dmvia Meig. t Opetia Meig., aud Platycnema Zett. 



