80 DIPTERA OF NORTH AMERICA. [PART II. 



DESCRIPTION OF THE SPECIES. 



I. COLORING OF THE BODY NON-METALLIC. 



1. G. flavus LOEW. and 9 . Flavus, abdominis segmentis interme- 

 diis plerumque virescentibus. 



Yellow ; the middle segments of the abdomen usually greenish. Long, 

 corp. 0.100.11. Long. al. 0.120.13. 



SYN. Gymnopternus flavus LOEW, Neue Beitr. VIII, 28, 1. 



Pale yellowish. Face whitish. Antennae dark yellow, the third 

 joint with a very pointed brownish or blackish tip and with 

 rather distinct hairs, which are visibly shorter in the female. 

 Arista black with an almost imperceptible pubescence. Front 

 and occiput of a greenish color, but thickly dusted with yellow so 

 as to appear dull and altogether light greenish-gray. . Cilia of the 

 inferior orbit white-yellowish. Thorax entirely yellow, not unfre- 

 quently with a slight trace of a greenish lustre, its bristles black, 

 the small hairs pale, scutellum provided with two black bristles, 

 otherwise glabrous. Abdomen with yellow hair, the stout hairs 

 on the incisures somewhat darker, but not black ; the middle and 

 sometimes also the posterior segments of the abdomen show a 

 greenish lustre; hypopygium yellow, lamella small, yellowish- 

 white, without a dark margin, thinly ciliated with short yellowish 

 hairs. Feet white-yellowish, their scanty bristles black ; the 

 smaller hairs yellowish. Cilia of the tegulre yellow. Wings 

 towards the anterior margin yellowish, otherwise more yellow- 

 grayish. 



Hob. Pennsylvania. (Osten-Sacken.) 



II. COLORING OF THE BODY METALLIC. 



A. Third joint of the antennae with an elongated point. 



2. G. sillmlatlis LOEW. . Viridis, thorace subopaco, antennarum 

 articulo tertio acutissitno, hirto, seta subapicali instructo. 



Green; thorax rather dull, tb.6 third joint of the antennae very pointed, 



