TACIIYTRECHUS. Ill 



Zlalc. Face very loner and narrow, more broad below, almost 

 golden-yellow, but without an)- lustre. Palpi small, blackish. 

 Antennae, in consequence of the rudimentary condition of the 

 second joint, apparently two-jointed, as in the male of the 

 genus Halter icer us ; the first joint elongated and somewhat 

 swollen, of a bright dark-yellow, bare on the under side, on the 

 upper side covered with black hairs ; the rudimental second joint 

 of the same color ; the third joint also extremely small, rounded 

 or somewhat kidney-shaped, brownish-black and only at the root 

 yellow. The arista very slender, bare, half as long as the thorax 

 and abdomen taken together ; it is black, only at the extreme tip 

 white, and ends in a small, deep-black, rather rounded lamella, which 

 is white at its extreme, somewhat attenuated, basis. Front metallic- 

 green, rather without lustre, covered with brown-gray dust, which 

 is only visible when viewed from the side. Cilia of the posterior 

 orbit black above, yellowish below. Thorax metallic-green, 

 usually with a more bronze or copper-colored or even violet mid- 

 dle line ; it is rather shining, covered, however, with a distinct 

 brownish-yellow dust. Scutellura and abdomen have the same 

 color and dusted covering. Hypopygium pedunculated, black, 

 upon the lower side more black-green, and covered with yellow 

 dust ; the yellow, rather rounded lamelhe with not very long black 

 hairs. Pleural with a covering of thick dark-yellow dust upon 

 bronze-green ground. Fore coxae bright yellow with almost gol- 

 den-yellow dust, without any lustre and with some delicate sparse 

 black little hairs. Middle and hind coxa? blackish, gray on ac- 

 count of a yellowish dust. Feet bright yellow; middle and hind 

 tarsi from the middle of the first joint brownish-black ; fore tarsi 

 almost imperceptibly flattened; in a certain direction they show 

 a bright snow-white lustre, which reaches as far as the root upon 

 the fore tibiae. Hind femora before the tip with a single bristle. 

 Cilia of the tegulae black. Wings tinged with gray. The tip of 

 the fourth longitudinal vein is near the tip of the third. 



Female. It differs remarkably from the male in color. Face 

 very narrow for a female, a little broader below, pale gray-yellow- 

 ish, seldom white-grayish, and then at least upon its inferior part 

 yellowish. Palpi small, blackish. First joint of the antennae 

 much smaller than that of the male, less swollen, and more of a 

 reddish-yellow color; the second joint of the same color and less 

 abortive than in the male ; the third joint a little larger than that 



