46 DIPTERA OF NORTH AMERICA. 



first longitudinal vein is exceedingly abbreviated ; of the auxiliary 

 vein there is only a rudiment ; the discal cell is usually, but not in 

 all genera, united with the foremost of the two small basal cells. 

 Claws and pulvilli very small. 



Numerous species of DROSOPHILA are found in N". A., some of 

 which are perfectly identical with European species, and one STE- 

 GANA, the difference of which from the European Stegana hypoleuca 

 is at least liable to doubt. 



FAM. LVI. OSCINIDAE. 



Charact. Front without bristles, the crown having only a few short ones ; 

 border of the mouth without vibrissse, which, however, are repre- 

 sented sometimes by a small hair on each side. Middle tibiae with 

 small spurs ; all the tibiae without erect bristle on the exterior side 

 before the tip. Costa of the wings without bristles. The auxiliary 

 vein is completely wanting; the anterior of the two small basal 

 cells is united with the discal cell, the posterior one is totally 

 wanting. 



The N. A. species of this family known to me are distributed 

 among the genera CHLOROPS, CRASSISETA, SIPHONELLA, MEROMYZA, 

 and OSOINIS. The species described by Wiedemann under the 

 name of Homalura plumbella likewise belongs to the genus Sipho- 

 nella. Macquart has established a genus, ECTECEPHALA, on a 

 N. A. species, and he says it is nearly related to Platycephala and 

 Eurina; if that is really the case, it must also be recorded here. 



FAM. LVII. AGROMYZIDAE. 



Charact. Front with strong bristles ; border of the mouth with a vibrissa 

 on each side. Middle tibiae with a terminal spur ; all the tibiae on 

 the exterior side without erect bristle before the tip. Wings with- 

 out bristles on the costa; first longitudinal vein very short, and the 

 auxiliary vein connected with it at the tip ; basal cells existing, but 

 small ; posterior transverse vein generally far distant from the bor- 

 der of the wing. 



The N. A. species which I have seen belong to the genera AGRO- 



MYZA, LOBIOPTERA, and MlLICHIA. 



