28 DIPTERA OF NORTH AMERICA. 



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

 NOPS Linn., 2. ZODION Latr., 3. MYOPAZafr-., 4. STACHYNIA Macq. 



FAM. XXTV. PIPUNCULIDAE. 



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 ; antennae with a basal bristle. 

 Hypopygium unsymrnetrical. Tibiae without spurs ; empodiuni 

 wanting. 



This family only comprises the three genera: NEUROPHOCERUS 

 Zett., PIPUNCULUS Lair, and CHALARUS Walk. 



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

 PIPUNCULUS Latr. 



FAM. XXV. SCENOPINIDAE. 



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 Bornbylidce 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 X. 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. Antennae 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 : PLATYPEZA Meig., 

 CALLOMYIA Meig., OPETIA Meig., and PLATYCNEMA Zett. 



