18 DIPTERA OF NORTH AMERICA. [PART II. 



Green, shining. Antennae reddish-yellow, with a black supe- 

 rior edge and with the tip of the third joint black ; first joint nar- 

 row and elongated. Face white, yellowish above, much broader 

 in the 9 than in the J*. Cilia of the inferior orbit pale. Fore 

 coxae, tip of the middle and hind coxae and feet yellow ; tarsi black 

 from the tip of the first joint ; the first joint of the fore tarsi some- 

 times altogether dusky ; the root of the second joint of the hind 

 tarsi, on the contrary, is pale. On the upper side of the middle 

 tibiae a bristle is conspicuous by its greater length ; there are two 

 bristles before the tip of the hind tibiae. Tegulae with black cilia, 

 Wings tinged with brownish ; fourth longitudinal vein not broken ; 

 hind transverse vein straight and steep. Four last joints of the 

 middle tarsi compressed in the , beset on the upper side with 

 incumbent black hairs ; the fifth joint much narrower than the pre- 

 ceding ones. Costa with a stout swelling near the tip of the first 

 longitudinal vein. Lamellae of the hypopygium of moderate size, 

 white, bordered with black at the tip, jagged and fringed with 

 black bristles. 



Hob. North Red River. (Kennicott.) 



Gen. II. DOLICHOPCS. 



The principal characters of the genus DoUchopus, as it follows 

 already from what has been said about it in the genus Hygro- 

 celeuthus, are : the presence of hairs on the upper side of the first 

 antennal joint, the shape of the third joint, which is hardly ever 

 very much elongated, the dorsal position of the arista, the en- 

 tirely disengaged hypopygium, the lamelliform shape of its rather 

 large outer appendages and the presence of spine-like bristles on 

 the first joint of the hind tarsi. 



The genus DoUchopus, established by Latreille already in 1796, 

 is the oldest of the family. It comprised at that time all the 

 Dolichopodidse, so that all the other genera have been gradually 

 formed by the separation of some groups and by further subdivision 

 of the latter. In the sense in which this genus was adopted by 

 Wiedemann and Meigen, it still included the present genera Gym- 

 nopternus, Paraclius, Pelastoneurus and Tachytrechus, besides 

 some isolated species belonging to other genera, which had been 

 erroneously located in it. (Such was the case, for instance, with 

 D. adustus Wied., which belongs to Lyroneurus.} The defini- 



