] 12 DIPTERA OF NORTH AMERICA. [PART PI. 



of the male, brownish-black, reddish-yellow only on the inferior 

 side of the basis, rounded. The black arista plain, bare, gradually 

 thinner towards the end. Front and cilia of the posterior orbit the 

 same as those of the male. Upper side of the thorax less green, 

 more bronze-colored, the dust more brown, and the middle line, 

 which is of a different color, more distinct. The abdomen is more 

 of a bronze color ; ^he dust upon it, however, is rather whitish. 

 The dust on the pleurae is also more whitish than yellow. The 

 fore coxae are likewise blackened as far as the extreme tip ; femora 

 green-black ; their tip to a considerable extent with a yellowish- 

 brown tinge, which extends further on the lower side than on the 

 upper side ; hind femora before the tip only with one bristle. Fore 

 tibiae usually brownish-yellow, with a very thin whitish pruinose 

 covering ; fore tarsi black, with the exception of their extreme 

 basis. Middle and hind tibiae usually dark brown, with yellowish- 

 brown basis and with black tip. Hind tarsi brownish-black. Cilia 

 of the tegulae black. Wings clouded with blackish-gray. 

 Hob. Trenton Falls, K Y. (Osten-Sacken.) 

 , Observation. — A genus, based upon the present .very remark- 

 able species, would be entitled to the same claims as the genus 

 Hdltericerus, with which it nearly coincides in the structure of 

 the antennae. I consider the establishment of such a genus as un- 

 necessary, as this species agrees in all other respects with the 

 already known species of Tachytrechus, which, however, are as 

 yet not very numerous. 



II. The second joint of the antennae of the usual 



STRUCTURE. 



2. T. vorax Loew. % and 9 • — iEneus, abdomine seneo-viridi, anten- 



nis pedibusque nigris, femorum apice tibiisque prater apicem flavis. 

 % . Apice alarum gutta Candida maculaque adjecta atra ornato. 

 9 . Alis immaculatis. 



Bronze-colored, abdomen bronze-green, antennae and feet black, tip of 

 femora and the tibiae, with the exception of the tip, black. 



% . Tip of the wings with a snow-white drop, and with an adjoining deep- 

 black spot. 



9. Wings spotless. Long. corp. 0.26—0.27. Long. al. 0.23—0.24. 



Syn. Tachytrechus vorax Loew, Neue Beitr. VIII, 41, 2. 



Face narrow, but considerably broader than that of the previous 



